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cc-backend/95/a89a7127c5/0/full.jsonl
Jan Eitzinger 16fb88baa3 Checkpoint: 95a89a7127c5 
Entire-Session: 039c7932-07b5-4d72-987c-d7fa070361c1
Entire-Strategy: manual-commit
Entire-Agent: Claude Code
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{"parentUuid":"9196fe97-ffea-45b6-aea9-4b2e2e57875f","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01WMYVsVBihoan6kwQv8hb18","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01LRRVPkjXCWktbyX8txxS4p","name":"Agent","input":{"subagent_type":"Explore","description":"Explore WAL journal reset/rotation","prompt":"I need to understand when WAL journal files are reset/rotated and whether they can grow indefinitely in this codebase. \n\nKey files to examine thoroughly:\n- `pkg/metricstore/walCheckpoint.go` — WAL + binary snapshot implementation, look for RotateWALFiles, WAL rotation logic, file truncation/deletion\n- `pkg/metricstore/checkpoint.go` — Checkpointing goroutine that triggers WAL rotation\n- `pkg/metricstore/lineprotocol.go` — where WAL messages are sent\n- `pkg/metricstore/metricstore.go` — Init, Shutdown, WALStaging\n\nFor each file, trace:\n1. When is RotateWALFiles called? What does it do exactly?\n2. What triggers a checkpoint (and thus WAL rotation)?\n3. Are there error paths where rotation could be skipped?\n4. Is there any size limit on WAL files?\n5. What happens during shutdown — is the WAL flushed/rotated?\n6. What happens if checkpoint writing fails — does the WAL still get rotated?\n\nBe very thorough — read the full implementation of all relevant functions."},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":9186,"cache_read_input_tokens":11336,"output_tokens":414,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":9186,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUuQRahhYBNnaHhwNwWr","type":"assistant","uuid":"8243b46d-589a-45d9-97e5-87631e7b7533","timestamp":"2026-03-28T05:12:04.357Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"8243b46d-589a-45d9-97e5-87631e7b7533","isSidechain":false,"promptId":"17a0d398-e459-40df-8656-39fec4ba62e0","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01LRRVPkjXCWktbyX8txxS4p","type":"tool_result","content":[{"type":"text","text":"Perfect! Now I have all the information I need. Let me provide you with a comprehensive analysis of the WAL rotation logic.\n\n## WAL Journal File Reset/Rotation Analysis\n\nBased on my thorough examination of the codebase, here's a detailed breakdown of when and how WAL journal files are reset/rotated:\n\n### 1. **When RotateWALFiles Is Called**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/checkpoint.go:138`\n\nRotateWALFiles is called **only after successful binary checkpoint creation**:\n\n```go\nif Keys.Checkpoints.FileFormat == \"wal\" {\n n, hostDirs, err := ms.ToCheckpointWAL(...)\n if err != nil {\n cclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n } else {\n // Rotate WAL files for successfully checkpointed hosts.\n RotateWALFiles(hostDirs)\n }\n}\n```\n\nThis occurs in the **Checkpointing() background goroutine**, which runs every **12 hours** (configurable via `Keys.CheckpointInterval`, lines 103-111).\n\n---\n\n### 2. **What RotateWALFiles Does Exactly**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go:324-354`\n\nThe function:\n- **Sends rotation requests** to shard-specific channels (one per host directory)\n- **Blocks until all rotations complete** or times out after 30 seconds\n- **Returns early if shutdown** is in progress (via `walShuttingDown` flag)\n- **Skips hosts silently** if rotation channel is full\n\n```go\nfunc RotateWALFiles(hostDirs []string) {\n if walShardRotateChs == nil || walShuttingDown.Load() {\n return // Silently skip if shutdown in progress\n }\n dones := make([]chan struct{}, 0, len(hostDirs))\n for _, dir := range hostDirs {\n done := make(chan struct{})\n shard := walShardIndexFromDir(dir)\n select {\n case walShardRotateChs[shard] <- walRotateReq{hostDir: dir, done: done}:\n dones = append(dones, done)\n default:\n // Channel full or goroutine not consuming — skip this host.\n cclog.Warnf(\"[METRICSTORE]> WAL rotation skipped for %s (channel full)\", dir)\n }\n }\n for _, done := range dones {\n select {\n case <-done:\n case <-time.After(30 * time.Second):\n cclog.Warn(\"[METRICSTORE]> WAL rotation timed out, continuing\")\n return\n }\n }\n}\n```\n\n---\n\n### 3. **The Actual Rotation Implementation**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go:244-256`\n\nThe WALStaging goroutines process rotation requests:\n\n```go\nprocessRotate := func(req walRotateReq) {\n ws, ok := hostFiles[req.hostDir]\n if ok && ws.f != nil {\n ws.w.Flush() // Flush any buffered data\n ws.f.Close() // Close the open file handle\n walPath := path.Join(req.hostDir, \"current.wal\")\n if err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n cclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n }\n delete(hostFiles, req.hostDir) // Remove from open files cache\n }\n close(req.done)\n}\n```\n\n**What happens:**\n1. Flushes the buffered writer to disk\n2. Closes the file handle\n3. **Deletes the current.wal file completely** (not rotated to a numbered file)\n4. Removes the entry from the open files cache\n5. Next write to that host will create a fresh `current.wal`\n\n---\n\n### 4. **Alternative Rotation: ToCheckpointWAL Workers**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go:699-703`\n\nThere's also **immediate deletion** of WAL files inside the checkpoint workers themselves:\n\n```go\n// Delete WAL immediately after successful snapshot.\nwalPath := path.Join(wi.hostDir, \"current.wal\")\nif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n cclog.Errorf(\"[METRICSTORE]> WAL remove %s: %v\", walPath, err)\n}\n```\n\nThis is a redundant cleanup—the file may have already been deleted by RotateWALFiles, but the code handles both cases gracefully with `!os.IsNotExist(err)`.\n\n---\n\n### 5. **What Triggers Checkpoints (and Thus WAL Rotation)?**\n\nThe Checkpointing goroutine (line 94-154 in checkpoint.go):\n\n- Runs on a **ticker interval** (default 12 hours, configurable)\n- Only calls `ToCheckpointWAL()` if format is \"wal\"\n- **Always updates `lastCheckpoint` timestamp** after success\n- Only calls `RotateWALFiles()` if checkpoint succeeded (`else` branch is skipped on error)\n\n---\n\n### 6. **Are There Error Paths Where Rotation Could Be Skipped?**\n\n**YES - Several critical scenarios:**\n\n| Scenario | Impact | Details |\n|----------|--------|---------|\n| **Binary checkpoint fails** | ❌ WAL NOT rotated | Lines 130-131: If `ToCheckpointWAL()` returns error, `RotateWALFiles()` is never called. WAL continues growing indefinitely. |\n| **Rotation channel full** | ⚠️ Specific hosts skipped | Lines 341-344: If rotation request buffer is full (capacity 64), that host's rotation is silently dropped. Warning logged but no retry. |\n| **Rotation times out** | ⚠️ Partial rotation | Lines 349-352: After 30s timeout, function returns without waiting for remaining rotations. Some hosts may still have their WAL files. |\n| **Shutdown in progress** | ✅ Handled gracefully | Line 331: Function returns early if `walShuttingDown` flag is set, preventing deadlock. |\n| **WAL staging goroutine hangs** | ⚠️ Timeout triggers | If goroutine isn't consuming rotation requests, 30s timeout allows recovery. |\n\n---\n\n### 7. **Is There a Size Limit on WAL Files?**\n\n**NO - WAL files can grow indefinitely.**\n\nEvidence:\n- **No size checking** in `writeWALRecordDirect()` (lines 379-435)\n- **No rotation trigger based on file size** (only time-based: 12-hour interval)\n- **No maximum file size enforcement** anywhere in the code\n- The only limits are:\n - Record payload sanity check: 1 MB max per record (line 458)\n - WAL message channel buffer size: ~65KB per shard (lines 166-167)\n\n**Consequence**: If checkpointing fails, the `current.wal` file grows unbounded until the next successful checkpoint.\n\n---\n\n### 8. **What Happens During Shutdown?**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/metricstore.go:273-320`\n\nThe shutdown sequence:\n\n```go\n// Signal producers to stop sending before closing channels\nwalShuttingDown.Store(true)\ntime.Sleep(100 * time.Millisecond) // Grace period\n\nfor _, ch := range walShardChs {\n close(ch) // Close message channels\n}\ndrainStart := time.Now()\nWaitForWALStagingDrain() // Wait for goroutines to exit\n\n// Write final checkpoint\nif Keys.Checkpoints.FileFormat == \"wal\" {\n files, _, err = ms.ToCheckpointWAL(...)\n}\n```\n\n**Key points:**\n- ✅ **WAL staging goroutines are allowed to exit** before final checkpoint (comment: lines 293-295)\n- ✅ **Buffered WAL messages are NOT drained** (intentional—final snapshot captures all in-memory data)\n- ✅ **Final checkpoint is written** (line 311)\n- ❌ **WAL files are NOT explicitly rotated after shutdown checkpoint**\n\nAfter shutdown, the WAL files remain on disk. On restart:\n1. Latest binary snapshots are loaded\n2. `current.wal` is replayed on top (lines 582-598 in checkpoint.go)\n3. WAL is NOT cleared—it persists until the next successful scheduled checkpoint\n\n---\n\n### 9. **What Happens If Checkpoint Writing Fails?**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/checkpoint.go:128-139`\n\n```go\nif Keys.Checkpoints.FileFormat == \"wal\" {\n n, hostDirs, err := ms.ToCheckpointWAL(...)\n if err != nil {\n cclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n // ❌ RotateWALFiles is NOT called\n } else {\n // ✅ Only on success:\n RotateWALFiles(hostDirs)\n }\n}\n```\n\n**Behavior on checkpoint failure:**\n- ❌ **WAL rotation is skipped**\n- ❌ **`lastCheckpoint` timestamp is NOT updated** (lines 134-136)\n- ✅ Next checkpoint attempt uses same time range (will retry those hosts)\n- ⚠️ **WAL files continue accumulating** until next successful checkpoint\n\n---\n\n### 10. **Orphaned WAL Files on Restart**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/metricstore.go:309-312`\n\nThere's a function `RotateWALFilesAfterShutdown()` (lines 367-374 in walCheckpoint.go) that's defined but **never called in the codebase**:\n\n```go\nfunc RotateWALFilesAfterShutdown(hostDirs []string) {\n for _, dir := range hostDirs {\n walPath := path.Join(dir, \"current.wal\")\n if err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n cclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n }\n }\n}\n```\n\nThis suggests there may have been an intent to clean up WAL files after restart, but it's not implemented.\n\n---\n\n### Summary Table\n\n| Question | Answer | Evidence |\n|----------|--------|----------|\n| **When rotated?** | After successful binary checkpoint every 12h | checkpoint.go:138 |\n| **Can they grow indefinitely?** | **YES** - if checkpoint fails | No size limits, rotation only on checkpoint success |\n| **Error path skips rotation?** | **YES** - checkpoint failure | checkpoint.go:130-131 |\n| **Size limits?** | Only per-record (1MB), not per-file | walCheckpoint.go:458 |\n| **Shutdown flushes/rotates WAL?** | Flushes only, no rotation | metricstore.go:293-295 |\n| **Checkpoint failure rotates?** | **NO** | checkpoint.go:130-131 |\n\n---\n\n### Critical Risk Assessment\n\n🔴 **HIGH RISK**: If checkpoints consistently fail (e.g., disk full, permission errors), WAL files will grow unbounded until:\n1. Disk space is exhausted, OR\n2. A checkpoint eventually succeeds\n\nThis could cause operational issues without explicit size monitoring."}]}]},"uuid":"49a7ebb0-eca6-4186-bdd0-26908c17841c","timestamp":"2026-03-28T05:12:37.565Z","toolUseResult":{"status":"completed","prompt":"I need to understand when WAL journal files are reset/rotated and whether they can grow indefinitely in this codebase. \n\nKey files to examine thoroughly:\n- `pkg/metricstore/walCheckpoint.go` — WAL + binary snapshot implementation, look for RotateWALFiles, WAL rotation logic, file truncation/deletion\n- `pkg/metricstore/checkpoint.go` — Checkpointing goroutine that triggers WAL rotation\n- `pkg/metricstore/lineprotocol.go` — where WAL messages are sent\n- `pkg/metricstore/metricstore.go` — Init, Shutdown, WALStaging\n\nFor each file, trace:\n1. When is RotateWALFiles called? What does it do exactly?\n2. What triggers a checkpoint (and thus WAL rotation)?\n3. Are there error paths where rotation could be skipped?\n4. Is there any size limit on WAL files?\n5. What happens during shutdown — is the WAL flushed/rotated?\n6. What happens if checkpoint writing fails — does the WAL still get rotated?\n\nBe very thorough — read the full implementation of all relevant functions.","agentId":"a8decccf847ae233d","agentType":"Explore","content":[{"type":"text","text":"Perfect! Now I have all the information I need. Let me provide you with a comprehensive analysis of the WAL rotation logic.\n\n## WAL Journal File Reset/Rotation Analysis\n\nBased on my thorough examination of the codebase, here's a detailed breakdown of when and how WAL journal files are reset/rotated:\n\n### 1. **When RotateWALFiles Is Called**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/checkpoint.go:138`\n\nRotateWALFiles is called **only after successful binary checkpoint creation**:\n\n```go\nif Keys.Checkpoints.FileFormat == \"wal\" {\n n, hostDirs, err := ms.ToCheckpointWAL(...)\n if err != nil {\n cclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n } else {\n // Rotate WAL files for successfully checkpointed hosts.\n RotateWALFiles(hostDirs)\n }\n}\n```\n\nThis occurs in the **Checkpointing() background goroutine**, which runs every **12 hours** (configurable via `Keys.CheckpointInterval`, lines 103-111).\n\n---\n\n### 2. **What RotateWALFiles Does Exactly**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go:324-354`\n\nThe function:\n- **Sends rotation requests** to shard-specific channels (one per host directory)\n- **Blocks until all rotations complete** or times out after 30 seconds\n- **Returns early if shutdown** is in progress (via `walShuttingDown` flag)\n- **Skips hosts silently** if rotation channel is full\n\n```go\nfunc RotateWALFiles(hostDirs []string) {\n if walShardRotateChs == nil || walShuttingDown.Load() {\n return // Silently skip if shutdown in progress\n }\n dones := make([]chan struct{}, 0, len(hostDirs))\n for _, dir := range hostDirs {\n done := make(chan struct{})\n shard := walShardIndexFromDir(dir)\n select {\n case walShardRotateChs[shard] <- walRotateReq{hostDir: dir, done: done}:\n dones = append(dones, done)\n default:\n // Channel full or goroutine not consuming — skip this host.\n cclog.Warnf(\"[METRICSTORE]> WAL rotation skipped for %s (channel full)\", dir)\n }\n }\n for _, done := range dones {\n select {\n case <-done:\n case <-time.After(30 * time.Second):\n cclog.Warn(\"[METRICSTORE]> WAL rotation timed out, continuing\")\n return\n }\n }\n}\n```\n\n---\n\n### 3. **The Actual Rotation Implementation**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go:244-256`\n\nThe WALStaging goroutines process rotation requests:\n\n```go\nprocessRotate := func(req walRotateReq) {\n ws, ok := hostFiles[req.hostDir]\n if ok && ws.f != nil {\n ws.w.Flush() // Flush any buffered data\n ws.f.Close() // Close the open file handle\n walPath := path.Join(req.hostDir, \"current.wal\")\n if err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n cclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n }\n delete(hostFiles, req.hostDir) // Remove from open files cache\n }\n close(req.done)\n}\n```\n\n**What happens:**\n1. Flushes the buffered writer to disk\n2. Closes the file handle\n3. **Deletes the current.wal file completely** (not rotated to a numbered file)\n4. Removes the entry from the open files cache\n5. Next write to that host will create a fresh `current.wal`\n\n---\n\n### 4. **Alternative Rotation: ToCheckpointWAL Workers**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go:699-703`\n\nThere's also **immediate deletion** of WAL files inside the checkpoint workers themselves:\n\n```go\n// Delete WAL immediately after successful snapshot.\nwalPath := path.Join(wi.hostDir, \"current.wal\")\nif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n cclog.Errorf(\"[METRICSTORE]> WAL remove %s: %v\", walPath, err)\n}\n```\n\nThis is a redundant cleanup—the file may have already been deleted by RotateWALFiles, but the code handles both cases gracefully with `!os.IsNotExist(err)`.\n\n---\n\n### 5. **What Triggers Checkpoints (and Thus WAL Rotation)?**\n\nThe Checkpointing goroutine (line 94-154 in checkpoint.go):\n\n- Runs on a **ticker interval** (default 12 hours, configurable)\n- Only calls `ToCheckpointWAL()` if format is \"wal\"\n- **Always updates `lastCheckpoint` timestamp** after success\n- Only calls `RotateWALFiles()` if checkpoint succeeded (`else` branch is skipped on error)\n\n---\n\n### 6. **Are There Error Paths Where Rotation Could Be Skipped?**\n\n**YES - Several critical scenarios:**\n\n| Scenario | Impact | Details |\n|----------|--------|---------|\n| **Binary checkpoint fails** | ❌ WAL NOT rotated | Lines 130-131: If `ToCheckpointWAL()` returns error, `RotateWALFiles()` is never called. WAL continues growing indefinitely. |\n| **Rotation channel full** | ⚠️ Specific hosts skipped | Lines 341-344: If rotation request buffer is full (capacity 64), that host's rotation is silently dropped. Warning logged but no retry. |\n| **Rotation times out** | ⚠️ Partial rotation | Lines 349-352: After 30s timeout, function returns without waiting for remaining rotations. Some hosts may still have their WAL files. |\n| **Shutdown in progress** | ✅ Handled gracefully | Line 331: Function returns early if `walShuttingDown` flag is set, preventing deadlock. |\n| **WAL staging goroutine hangs** | ⚠️ Timeout triggers | If goroutine isn't consuming rotation requests, 30s timeout allows recovery. |\n\n---\n\n### 7. **Is There a Size Limit on WAL Files?**\n\n**NO - WAL files can grow indefinitely.**\n\nEvidence:\n- **No size checking** in `writeWALRecordDirect()` (lines 379-435)\n- **No rotation trigger based on file size** (only time-based: 12-hour interval)\n- **No maximum file size enforcement** anywhere in the code\n- The only limits are:\n - Record payload sanity check: 1 MB max per record (line 458)\n - WAL message channel buffer size: ~65KB per shard (lines 166-167)\n\n**Consequence**: If checkpointing fails, the `current.wal` file grows unbounded until the next successful checkpoint.\n\n---\n\n### 8. **What Happens During Shutdown?**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/metricstore.go:273-320`\n\nThe shutdown sequence:\n\n```go\n// Signal producers to stop sending before closing channels\nwalShuttingDown.Store(true)\ntime.Sleep(100 * time.Millisecond) // Grace period\n\nfor _, ch := range walShardChs {\n close(ch) // Close message channels\n}\ndrainStart := time.Now()\nWaitForWALStagingDrain() // Wait for goroutines to exit\n\n// Write final checkpoint\nif Keys.Checkpoints.FileFormat == \"wal\" {\n files, _, err = ms.ToCheckpointWAL(...)\n}\n```\n\n**Key points:**\n- ✅ **WAL staging goroutines are allowed to exit** before final checkpoint (comment: lines 293-295)\n- ✅ **Buffered WAL messages are NOT drained** (intentional—final snapshot captures all in-memory data)\n- ✅ **Final checkpoint is written** (line 311)\n- ❌ **WAL files are NOT explicitly rotated after shutdown checkpoint**\n\nAfter shutdown, the WAL files remain on disk. On restart:\n1. Latest binary snapshots are loaded\n2. `current.wal` is replayed on top (lines 582-598 in checkpoint.go)\n3. WAL is NOT cleared—it persists until the next successful scheduled checkpoint\n\n---\n\n### 9. **What Happens If Checkpoint Writing Fails?**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/checkpoint.go:128-139`\n\n```go\nif Keys.Checkpoints.FileFormat == \"wal\" {\n n, hostDirs, err := ms.ToCheckpointWAL(...)\n if err != nil {\n cclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n // ❌ RotateWALFiles is NOT called\n } else {\n // ✅ Only on success:\n RotateWALFiles(hostDirs)\n }\n}\n```\n\n**Behavior on checkpoint failure:**\n- ❌ **WAL rotation is skipped**\n- ❌ **`lastCheckpoint` timestamp is NOT updated** (lines 134-136)\n- ✅ Next checkpoint attempt uses same time range (will retry those hosts)\n- ⚠️ **WAL files continue accumulating** until next successful checkpoint\n\n---\n\n### 10. **Orphaned WAL Files on Restart**\n\n**Location**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/metricstore.go:309-312`\n\nThere's a function `RotateWALFilesAfterShutdown()` (lines 367-374 in walCheckpoint.go) that's defined but **never called in the codebase**:\n\n```go\nfunc RotateWALFilesAfterShutdown(hostDirs []string) {\n for _, dir := range hostDirs {\n walPath := path.Join(dir, \"current.wal\")\n if err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n cclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n }\n }\n}\n```\n\nThis suggests there may have been an intent to clean up WAL files after restart, but it's not implemented.\n\n---\n\n### Summary Table\n\n| Question | Answer | Evidence |\n|----------|--------|----------|\n| **When rotated?** | After successful binary checkpoint every 12h | checkpoint.go:138 |\n| **Can they grow indefinitely?** | **YES** - if checkpoint fails | No size limits, rotation only on checkpoint success |\n| **Error path skips rotation?** | **YES** - checkpoint failure | checkpoint.go:130-131 |\n| **Size limits?** | Only per-record (1MB), not per-file | walCheckpoint.go:458 |\n| **Shutdown flushes/rotates WAL?** | Flushes only, no rotation | metricstore.go:293-295 |\n| **Checkpoint failure rotates?** | **NO** | checkpoint.go:130-131 |\n\n---\n\n### Critical Risk Assessment\n\n🔴 **HIGH RISK**: If checkpoints consistently fail (e.g., disk full, permission errors), WAL files will grow unbounded until:\n1. Disk space is exhausted, OR\n2. A checkpoint eventually succeeds\n\nThis could cause operational issues without explicit size monitoring."}],"totalDurationMs":32918,"totalTokens":53621,"totalToolUseCount":8,"usage":{"input_tokens":7,"cache_creation_input_tokens":834,"cache_read_input_tokens":49751,"output_tokens":3029,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":0,"ephemeral_5m_input_tokens":834},"inference_geo":"","iterations":[],"speed":"standard"}},"sourceToolAssistantUUID":"8243b46d-589a-45d9-97e5-87631e7b7533","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"0d9b5c77-fd10-4f90-bfc3-644859f065b6","isSidechain":false,"promptId":"17a0d398-e459-40df-8656-39fec4ba62e0","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_014v2nYmHPN2Ros7fUTKuwGX","type":"tool_result","content":"320\tfunc WaitForWALStagingDrain() {\n321\t\twalStagingWg.Wait()\n322\t}\n323\t\n324\t// RotateWALFiles sends rotation requests for the given host directories\n325\t// and blocks until all rotations complete. Each request is routed to the\n326\t// shard that owns the host directory.\n327\t//\n328\t// If shutdown is in progress (WAL staging goroutines may have exited),\n329\t// rotation is skipped to avoid deadlocking on abandoned channels.\n330\tfunc RotateWALFiles(hostDirs []string) {\n331\t\tif walShardRotateChs == nil || walShuttingDown.Load() {\n332\t\t\treturn\n333\t\t}\n334\t\tdones := make([]chan struct{}, 0, len(hostDirs))\n335\t\tfor _, dir := range hostDirs {\n336\t\t\tdone := make(chan struct{})\n337\t\t\tshard := walShardIndexFromDir(dir)\n338\t\t\tselect {\n339\t\t\tcase walShardRotateChs[shard] <- walRotateReq{hostDir: dir, done: done}:\n340\t\t\t\tdones = append(dones, done)\n341\t\t\tdefault:\n342\t\t\t\t// Channel full or goroutine not consuming — skip this host.\n343\t\t\t\tcclog.Warnf(\"[METRICSTORE]> WAL rotation skipped for %s (channel full)\", dir)\n344\t\t\t}\n345\t\t}\n346\t\tfor _, done := range dones {\n347\t\t\tselect {\n348\t\t\tcase <-done:\n349\t\t\tcase <-time.After(30 * time.Second):\n350\t\t\t\tcclog.Warn(\"[METRICSTORE]> WAL rotation timed out, continuing\")\n351\t\t\t\treturn\n352\t\t\t}\n353\t\t}\n354\t}\n355\t\n356\t// walShardIndexFromDir extracts cluster and node from a host directory path\n357\t// and returns the shard index. The path format is: rootDir/cluster/node\n358\tfunc walShardIndexFromDir(hostDir string) int {\n359\t\t// hostDir = .../cluster/node — extract last two path components\n360\t\tnode := path.Base(hostDir)\n361\t\tcluster := path.Base(path.Dir(hostDir))\n362\t\treturn walShardIndex(cluster, node)\n363\t}\n364\t\n365\t// RotateWALFiles sends rotation requests for the given host directories\n366\t// and blocks until all rotations complete.\n367\tfunc RotateWALFilesAfterShutdown(hostDirs []string) {\n368\t\tfor _, dir := range hostDirs {\n369\t\t\twalPath := path.Join(dir, \"current.wal\")\n370\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n371\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n372\t\t\t}\n373\t\t}\n374\t}\n375\t\n376\t// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\n377\t// then writes it to the bufio.Writer in a single call. This prevents partial\n378\t// records in the write buffer if a write error occurs mid-record (e.g. disk full).\n379\tfunc writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) error {"}]},"uuid":"e01c0879-0052-4943-a1e1-8cfd8d7f0c44","timestamp":"2026-03-28T05:12:41.304Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","content":"func WaitForWALStagingDrain() {\n\twalStagingWg.Wait()\n}\n\n// RotateWALFiles sends rotation requests for the given host directories\n// and blocks until all rotations complete. Each request is routed to the\n// shard that owns the host directory.\n//\n// If shutdown is in progress (WAL staging goroutines may have exited),\n// rotation is skipped to avoid deadlocking on abandoned channels.\nfunc RotateWALFiles(hostDirs []string) {\n\tif walShardRotateChs == nil || walShuttingDown.Load() {\n\t\treturn\n\t}\n\tdones := make([]chan struct{}, 0, len(hostDirs))\n\tfor _, dir := range hostDirs {\n\t\tdone := make(chan struct{})\n\t\tshard := walShardIndexFromDir(dir)\n\t\tselect {\n\t\tcase walShardRotateChs[shard] <- walRotateReq{hostDir: dir, done: done}:\n\t\t\tdones = append(dones, done)\n\t\tdefault:\n\t\t\t// Channel full or goroutine not consuming — skip this host.\n\t\t\tcclog.Warnf(\"[METRICSTORE]> WAL rotation skipped for %s (channel full)\", dir)\n\t\t}\n\t}\n\tfor _, done := range dones {\n\t\tselect {\n\t\tcase <-done:\n\t\tcase <-time.After(30 * time.Second):\n\t\t\tcclog.Warn(\"[METRICSTORE]> WAL rotation timed out, continuing\")\n\t\t\treturn\n\t\t}\n\t}\n}\n\n// walShardIndexFromDir extracts cluster and node from a host directory path\n// and returns the shard index. The path format is: rootDir/cluster/node\nfunc walShardIndexFromDir(hostDir string) int {\n\t// hostDir = .../cluster/node — extract last two path components\n\tnode := path.Base(hostDir)\n\tcluster := path.Base(path.Dir(hostDir))\n\treturn walShardIndex(cluster, node)\n}\n\n// RotateWALFiles sends rotation requests for the given host directories\n// and blocks until all rotations complete.\nfunc RotateWALFilesAfterShutdown(hostDirs []string) {\n\tfor _, dir := range hostDirs {\n\t\twalPath := path.Join(dir, \"current.wal\")\n\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t}\n\t}\n}\n\n// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\n// then writes it to the bufio.Writer in a single call. This prevents partial\n// records in the write buffer if a write error occurs mid-record (e.g. disk full).\nfunc writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) error {","numLines":60,"startLine":320,"totalLines":951}},"sourceToolAssistantUUID":"0d9b5c77-fd10-4f90-bfc3-644859f065b6","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"31fb4cb3-408e-4753-8db7-5f9be0a10702","isSidechain":false,"promptId":"17a0d398-e459-40df-8656-39fec4ba62e0","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01LratA5Q1jrWRQFjneVWzUa","type":"tool_result","content":"94\tfunc Checkpointing(wg *sync.WaitGroup, ctx context.Context) {\n95\t\tlastCheckpointMu.Lock()\n96\t\tlastCheckpoint = time.Now()\n97\t\tlastCheckpointMu.Unlock()\n98\t\n99\t\tms := GetMemoryStore()\n100\t\n101\t\twg.Go(func() {\n102\t\n103\t\t\td := 12 * time.Hour // default checkpoint interval\n104\t\t\tif Keys.CheckpointInterval != \"\" {\n105\t\t\t\tparsed, err := time.ParseDuration(Keys.CheckpointInterval)\n106\t\t\t\tif err != nil {\n107\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> invalid checkpoint-interval %q: %s, using default 12h\", Keys.CheckpointInterval, err)\n108\t\t\t\t} else {\n109\t\t\t\t\td = parsed\n110\t\t\t\t}\n111\t\t\t}\n112\t\n113\t\t\tticker := time.NewTicker(d)\n114\t\t\tdefer ticker.Stop()\n115\t\n116\t\t\tfor {\n117\t\t\t\tselect {\n118\t\t\t\tcase <-ctx.Done():\n119\t\t\t\t\treturn\n120\t\t\t\tcase <-ticker.C:\n121\t\t\t\t\tlastCheckpointMu.Lock()\n122\t\t\t\t\tfrom := lastCheckpoint\n123\t\t\t\t\tlastCheckpointMu.Unlock()\n124\t\n125\t\t\t\t\tnow := time.Now()\n126\t\t\t\t\tcclog.Infof(\"[METRICSTORE]> start checkpointing (starting at %s)...\", from.Format(time.RFC3339))\n127\t\n128\t\t\t\t\tif Keys.Checkpoints.FileFormat == \"wal\" {\n129\t\t\t\t\t\tn, hostDirs, err := ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())\n130\t\t\t\t\t\tif err != nil {\n131\t\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n132\t\t\t\t\t\t} else {\n133\t\t\t\t\t\t\tcclog.Infof(\"[METRICSTORE]> done: %d binary snapshot files created\", n)\n134\t\t\t\t\t\t\tlastCheckpointMu.Lock()\n135\t\t\t\t\t\t\tlastCheckpoint = now\n136\t\t\t\t\t\t\tlastCheckpointMu.Unlock()\n137\t\t\t\t\t\t\t// Rotate WAL files for successfully checkpointed hosts.\n138\t\t\t\t\t\t\tRotateWALFiles(hostDirs)\n139\t\t\t\t\t\t}\n140\t\t\t\t\t} else {\n141\t\t\t\t\t\tn, err := ms.ToCheckpoint(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())\n142\t\t\t\t\t\tif err != nil {\n143\t\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> checkpointing failed: %s\", err.Error())\n144\t\t\t\t\t\t} else {\n145\t\t\t\t\t\t\tcclog.Infof(\"[METRICSTORE]> done: %d checkpoint files created\", n)\n146\t\t\t\t\t\t\tlastCheckpointMu.Lock()\n147\t\t\t\t\t\t\tlastCheckpoint = now\n148\t\t\t\t\t\t\tlastCheckpointMu.Unlock()\n149\t\t\t\t\t\t}\n150\t\t\t\t\t}\n151\t\t\t\t}\n152\t\t\t}\n153\t\t})\n154\t}\n155\t\n156\t// MarshalJSON provides optimized JSON encoding for CheckpointMetrics.\n157\t//\n158\t// Since schema.Float has custom MarshalJSON, serializing []Float has significant overhead."}]},"uuid":"6486fa13-d551-49f0-b8f1-6a0e7ed05b9a","timestamp":"2026-03-28T05:12:45.093Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/checkpoint.go","content":"func Checkpointing(wg *sync.WaitGroup, ctx context.Context) {\n\tlastCheckpointMu.Lock()\n\tlastCheckpoint = time.Now()\n\tlastCheckpointMu.Unlock()\n\n\tms := GetMemoryStore()\n\n\twg.Go(func() {\n\n\t\td := 12 * time.Hour // default checkpoint interval\n\t\tif Keys.CheckpointInterval != \"\" {\n\t\t\tparsed, err := time.ParseDuration(Keys.CheckpointInterval)\n\t\t\tif err != nil {\n\t\t\t\tcclog.Errorf(\"[METRICSTORE]> invalid checkpoint-interval %q: %s, using default 12h\", Keys.CheckpointInterval, err)\n\t\t\t} else {\n\t\t\t\td = parsed\n\t\t\t}\n\t\t}\n\n\t\tticker := time.NewTicker(d)\n\t\tdefer ticker.Stop()\n\n\t\tfor {\n\t\t\tselect {\n\t\t\tcase <-ctx.Done():\n\t\t\t\treturn\n\t\t\tcase <-ticker.C:\n\t\t\t\tlastCheckpointMu.Lock()\n\t\t\t\tfrom := lastCheckpoint\n\t\t\t\tlastCheckpointMu.Unlock()\n\n\t\t\t\tnow := time.Now()\n\t\t\t\tcclog.Infof(\"[METRICSTORE]> start checkpointing (starting at %s)...\", from.Format(time.RFC3339))\n\n\t\t\t\tif Keys.Checkpoints.FileFormat == \"wal\" {\n\t\t\t\t\tn, hostDirs, err := ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())\n\t\t\t\t\tif err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n\t\t\t\t\t} else {\n\t\t\t\t\t\tcclog.Infof(\"[METRICSTORE]> done: %d binary snapshot files created\", n)\n\t\t\t\t\t\tlastCheckpointMu.Lock()\n\t\t\t\t\t\tlastCheckpoint = now\n\t\t\t\t\t\tlastCheckpointMu.Unlock()\n\t\t\t\t\t\t// Rotate WAL files for successfully checkpointed hosts.\n\t\t\t\t\t\tRotateWALFiles(hostDirs)\n\t\t\t\t\t}\n\t\t\t\t} else {\n\t\t\t\t\tn, err := ms.ToCheckpoint(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())\n\t\t\t\t\tif err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> checkpointing failed: %s\", err.Error())\n\t\t\t\t\t} else {\n\t\t\t\t\t\tcclog.Infof(\"[METRICSTORE]> done: %d checkpoint files created\", n)\n\t\t\t\t\t\tlastCheckpointMu.Lock()\n\t\t\t\t\t\tlastCheckpoint = now\n\t\t\t\t\t\tlastCheckpointMu.Unlock()\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\t})\n}\n\n// MarshalJSON provides optimized JSON encoding for CheckpointMetrics.\n//\n// Since schema.Float has custom MarshalJSON, serializing []Float has significant overhead.","numLines":65,"startLine":94,"totalLines":670}},"sourceToolAssistantUUID":"31fb4cb3-408e-4753-8db7-5f9be0a10702","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"6486fa13-d551-49f0-b8f1-6a0e7ed05b9a","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01V62Xm2Jj9KBWHwhGTyniHn","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01HMamv84eNh4FxG43xDH9z2","name":"Read","input":{"file_path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/metricstore.go","offset":270,"limit":55},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":885,"cache_read_input_tokens":24917,"output_tokens":115,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":885,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUuUAQFiW8AurZQp95SJ","type":"assistant","uuid":"9a0ae586-864b-4c29-b420-b7e51c5adbb2","timestamp":"2026-03-28T05:12:48.020Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"9a0ae586-864b-4c29-b420-b7e51c5adbb2","isSidechain":false,"promptId":"17a0d398-e459-40df-8656-39fec4ba62e0","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01HMamv84eNh4FxG43xDH9z2","type":"tool_result","content":"270\t// 4. Log any errors encountered during shutdown\n271\t//\n272\t// Note: This function blocks until the final checkpoint is written.\n273\tfunc Shutdown() {\n274\t\ttotalStart := time.Now()\n275\t\n276\t\tshutdownFuncMu.Lock()\n277\t\tdefer shutdownFuncMu.Unlock()\n278\t\tif shutdownFunc != nil {\n279\t\t\tshutdownFunc()\n280\t\t}\n281\t\tcclog.Infof(\"[METRICSTORE]> Background workers cancelled (%v)\", time.Since(totalStart))\n282\t\n283\t\tif Keys.Checkpoints.FileFormat == \"wal\" {\n284\t\t\t// Signal producers to stop sending before closing channels,\n285\t\t\t// preventing send-on-closed-channel panics from in-flight NATS workers.\n286\t\t\twalShuttingDown.Store(true)\n287\t\t\t// Brief grace period for in-flight DecodeLine calls to complete.\n288\t\t\ttime.Sleep(100 * time.Millisecond)\n289\t\n290\t\t\tfor _, ch := range walShardChs {\n291\t\t\t\tclose(ch)\n292\t\t\t}\n293\t\t\tdrainStart := time.Now()\n294\t\t\tWaitForWALStagingDrain()\n295\t\t\tcclog.Infof(\"[METRICSTORE]> WAL staging goroutines exited (%v)\", time.Since(drainStart))\n296\t\t}\n297\t\n298\t\tcclog.Infof(\"[METRICSTORE]> Writing checkpoint to '%s'...\", Keys.Checkpoints.RootDir)\n299\t\tcheckpointStart := time.Now()\n300\t\tvar files int\n301\t\tvar err error\n302\t\n303\t\tms := GetMemoryStore()\n304\t\n305\t\tlastCheckpointMu.Lock()\n306\t\tfrom := lastCheckpoint\n307\t\tlastCheckpointMu.Unlock()\n308\t\n309\t\tif Keys.Checkpoints.FileFormat == \"wal\" {\n310\t\t\t// WAL files are deleted per-host inside ToCheckpointWAL workers.\n311\t\t\tfiles, _, err = ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), time.Now().Unix())\n312\t\t} else {\n313\t\t\tfiles, err = ms.ToCheckpoint(Keys.Checkpoints.RootDir, from.Unix(), time.Now().Unix())\n314\t\t}\n315\t\n316\t\tif err != nil {\n317\t\t\tcclog.Errorf(\"[METRICSTORE]> Writing checkpoint failed: %s\", err.Error())\n318\t\t}\n319\t\tcclog.Infof(\"[METRICSTORE]> Done! (%d files written in %v, total shutdown: %v)\", files, time.Since(checkpointStart), time.Since(totalStart))\n320\t}\n321\t\n322\t// Retention starts a background goroutine that periodically frees old metric data.\n323\t//\n324\t// This worker runs at half the retention interval and calls Free() to remove buffers"}]},"uuid":"778a3f91-8e40-493c-90a9-d54c654a120e","timestamp":"2026-03-28T05:12:48.035Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/metricstore.go","content":"// 4. Log any errors encountered during shutdown\n//\n// Note: This function blocks until the final checkpoint is written.\nfunc Shutdown() {\n\ttotalStart := time.Now()\n\n\tshutdownFuncMu.Lock()\n\tdefer shutdownFuncMu.Unlock()\n\tif shutdownFunc != nil {\n\t\tshutdownFunc()\n\t}\n\tcclog.Infof(\"[METRICSTORE]> Background workers cancelled (%v)\", time.Since(totalStart))\n\n\tif Keys.Checkpoints.FileFormat == \"wal\" {\n\t\t// Signal producers to stop sending before closing channels,\n\t\t// preventing send-on-closed-channel panics from in-flight NATS workers.\n\t\twalShuttingDown.Store(true)\n\t\t// Brief grace period for in-flight DecodeLine calls to complete.\n\t\ttime.Sleep(100 * time.Millisecond)\n\n\t\tfor _, ch := range walShardChs {\n\t\t\tclose(ch)\n\t\t}\n\t\tdrainStart := time.Now()\n\t\tWaitForWALStagingDrain()\n\t\tcclog.Infof(\"[METRICSTORE]> WAL staging goroutines exited (%v)\", time.Since(drainStart))\n\t}\n\n\tcclog.Infof(\"[METRICSTORE]> Writing checkpoint to '%s'...\", Keys.Checkpoints.RootDir)\n\tcheckpointStart := time.Now()\n\tvar files int\n\tvar err error\n\n\tms := GetMemoryStore()\n\n\tlastCheckpointMu.Lock()\n\tfrom := lastCheckpoint\n\tlastCheckpointMu.Unlock()\n\n\tif Keys.Checkpoints.FileFormat == \"wal\" {\n\t\t// WAL files are deleted per-host inside ToCheckpointWAL workers.\n\t\tfiles, _, err = ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), time.Now().Unix())\n\t} else {\n\t\tfiles, err = ms.ToCheckpoint(Keys.Checkpoints.RootDir, from.Unix(), time.Now().Unix())\n\t}\n\n\tif err != nil {\n\t\tcclog.Errorf(\"[METRICSTORE]> Writing checkpoint failed: %s\", err.Error())\n\t}\n\tcclog.Infof(\"[METRICSTORE]> Done! (%d files written in %v, total shutdown: %v)\", files, time.Since(checkpointStart), time.Since(totalStart))\n}\n\n// Retention starts a background goroutine that periodically frees old metric data.\n//\n// This worker runs at half the retention interval and calls Free() to remove buffers","numLines":55,"startLine":270,"totalLines":814}},"sourceToolAssistantUUID":"9a0ae586-864b-4c29-b420-b7e51c5adbb2","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"778a3f91-8e40-493c-90a9-d54c654a120e","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_0164ub1KYanRJrHa4p2hB6MT","type":"message","role":"assistant","content":[{"type":"text","text":"Now let me check the WAL deletion inside `ToCheckpointWAL` workers."}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":835,"cache_read_input_tokens":25802,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":835},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUuUNgh2K1rBcXuAJkAh","type":"assistant","uuid":"48437c9b-52b0-45de-9c99-b49caa48164e","timestamp":"2026-03-28T05:12:51.109Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"48437c9b-52b0-45de-9c99-b49caa48164e","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_0164ub1KYanRJrHa4p2hB6MT","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01EQht4sS4JzfCHa3sBwJ6bo","name":"Grep","input":{"pattern":"os\\.Remove.*current\\.wal","path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","output_mode":"content"},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":835,"cache_read_input_tokens":25802,"output_tokens":144,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":835,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUuUNgh2K1rBcXuAJkAh","type":"assistant","uuid":"ab1b217d-480a-4966-8dfe-a31e2bef63d3","timestamp":"2026-03-28T05:12:52.002Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"ab1b217d-480a-4966-8dfe-a31e2bef63d3","isSidechain":false,"promptId":"17a0d398-e459-40df-8656-39fec4ba62e0","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01EQht4sS4JzfCHa3sBwJ6bo","type":"tool_result","content":"No matches found"}]},"uuid":"7bc37337-1401-4f6a-b49b-effacfbdd49b","timestamp":"2026-03-28T05:12:52.029Z","toolUseResult":{"mode":"content","numFiles":0,"filenames":[],"content":"","numLines":0},"sourceToolAssistantUUID":"ab1b217d-480a-4966-8dfe-a31e2bef63d3","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"7bc37337-1401-4f6a-b49b-effacfbdd49b","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01BRwKHLxRYKUPULokEbid79","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_0158vzHb6fQaQtLeCfSAxyXk","name":"Grep","input":{"pattern":"os\\.Remove.*wal","path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","output_mode":"content","-n":true},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":159,"cache_read_input_tokens":26637,"output_tokens":139,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":159,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUuUfu2vtSS4mP3E27GT","type":"assistant","uuid":"50e1d1d4-94ce-4c5b-a2da-46af8a822a75","timestamp":"2026-03-28T05:12:55.968Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"50e1d1d4-94ce-4c5b-a2da-46af8a822a75","isSidechain":false,"promptId":"17a0d398-e459-40df-8656-39fec4ba62e0","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_0158vzHb6fQaQtLeCfSAxyXk","type":"tool_result","content":"250:\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n370:\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n701:\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {"}]},"uuid":"f13181d8-1c89-4cd3-9cc3-e15ef3d19bff","timestamp":"2026-03-28T05:12:55.980Z","toolUseResult":{"mode":"content","numFiles":0,"filenames":[],"content":"250:\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n370:\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n701:\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {","numLines":3},"sourceToolAssistantUUID":"50e1d1d4-94ce-4c5b-a2da-46af8a822a75","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"f13181d8-1c89-4cd3-9cc3-e15ef3d19bff","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01Cbk6TRFjGbSSDvDBuHjBj3","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_018LmzxPZhC3NqQQxK1H56Ev","name":"Read","input":{"file_path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","offset":690,"limit":20},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":396,"cache_read_input_tokens":26637,"output_tokens":115,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":396,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUuUxg6KoFK6zYnt2HEv","type":"assistant","uuid":"ea6d49e9-a7e2-4d88-b5bc-36e71cd742ed","timestamp":"2026-03-28T05:12:59.362Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"ea6d49e9-a7e2-4d88-b5bc-36e71cd742ed","isSidechain":false,"promptId":"17a0d398-e459-40df-8656-39fec4ba62e0","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_018LmzxPZhC3NqQQxK1H56Ev","type":"tool_result","content":"690\t\t\t\t\tif err != nil {\n691\t\t\t\t\t\tif err == ErrNoNewArchiveData {\n692\t\t\t\t\t\t\tatomic.AddInt32(&completed, 1)\n693\t\t\t\t\t\t\tcontinue\n694\t\t\t\t\t\t}\n695\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> binary checkpoint error for %s: %v\", wi.hostDir, err)\n696\t\t\t\t\t\tatomic.AddInt32(&errs, 1)\n697\t\t\t\t\t} else {\n698\t\t\t\t\t\tatomic.AddInt32(&n, 1)\n699\t\t\t\t\t\t// Delete WAL immediately after successful snapshot.\n700\t\t\t\t\t\twalPath := path.Join(wi.hostDir, \"current.wal\")\n701\t\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n702\t\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL remove %s: %v\", walPath, err)\n703\t\t\t\t\t\t}\n704\t\t\t\t\t\tsuccessMu.Lock()\n705\t\t\t\t\t\tsuccessDirs = append(successDirs, wi.hostDir)\n706\t\t\t\t\t\tsuccessMu.Unlock()\n707\t\t\t\t\t}\n708\t\t\t\t\tatomic.AddInt32(&completed, 1)\n709\t\t\t\t}"}]},"uuid":"64dfeb83-5492-4d2e-8764-3e592a8f9285","timestamp":"2026-03-28T05:12:59.369Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","content":"\t\t\t\tif err != nil {\n\t\t\t\t\tif err == ErrNoNewArchiveData {\n\t\t\t\t\t\tatomic.AddInt32(&completed, 1)\n\t\t\t\t\t\tcontinue\n\t\t\t\t\t}\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> binary checkpoint error for %s: %v\", wi.hostDir, err)\n\t\t\t\t\tatomic.AddInt32(&errs, 1)\n\t\t\t\t} else {\n\t\t\t\t\tatomic.AddInt32(&n, 1)\n\t\t\t\t\t// Delete WAL immediately after successful snapshot.\n\t\t\t\t\twalPath := path.Join(wi.hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tsuccessMu.Lock()\n\t\t\t\t\tsuccessDirs = append(successDirs, wi.hostDir)\n\t\t\t\t\tsuccessMu.Unlock()\n\t\t\t\t}\n\t\t\t\tatomic.AddInt32(&completed, 1)\n\t\t\t}","numLines":20,"startLine":690,"totalLines":951}},"sourceToolAssistantUUID":"ea6d49e9-a7e2-4d88-b5bc-36e71cd742ed","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"64dfeb83-5492-4d2e-8764-3e592a8f9285","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_013KVQjgpUXKUEDP4sq1mhKm","type":"message","role":"assistant","content":[{"type":"text","text":"Now I have a clear picture. Let me write the plan."}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":391,"cache_read_input_tokens":27033,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":391},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUuVDAERZ2uYCySzoAVU","type":"assistant","uuid":"748e61ca-21da-4ef9-aa9f-e165f5732e9d","timestamp":"2026-03-28T05:13:02.653Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"afd8eeca-04ea-447a-995e-6f0c592dea1f","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01MqqtTkVZfR4xHDXbHjf2Yo","type":"message","role":"assistant","content":[{"type":"thinking","thinking":"","signature":"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"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":861,"cache_read_input_tokens":27424,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":861},"output_tokens":37,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUuVUjMTspoAJyge4wDf","type":"assistant","uuid":"d4e4c4d7-58be-4a76-a270-ab975a05c6a6","timestamp":"2026-03-28T05:13:06.973Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"d4e4c4d7-58be-4a76-a270-ab975a05c6a6","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01MqqtTkVZfR4xHDXbHjf2Yo","type":"message","role":"assistant","content":[{"type":"text","text":"Here's what I found from tracing the code:\n\n## When WAL files are reset\n\nWAL files (`current.wal`) are deleted in **two places**, both tied to successful checkpointing:\n\n1. **Inside `ToCheckpointWAL` workers** (`walCheckpoint.go:699-703`) — each worker deletes the host's `current.wal` immediately after writing a successful binary snapshot.\n\n2. **Via `RotateWALFiles`** (`walCheckpoint.go:330-354`) — called after `ToCheckpointWAL` returns successfully in the periodic `Checkpointing()` goroutine (`checkpoint.go:138`). The staging goroutines flush, close, and delete the file (`walCheckpoint.go:244-256`).\n\nSo effectively, WAL files are reset **every checkpoint interval** (default 12 hours, configurable via `CheckpointInterval`).\n\n3. **On shutdown** (`metricstore.go:309-311`) — `ToCheckpointWAL` is called, which deletes WAL files per-host inside its workers. However, `RotateWALFiles` is **not** called after the shutdown checkpoint (the staging goroutines have already exited). The comment at line 310 says \"WAL files are deleted per-host inside ToCheckpointWAL workers\" so this is intentional.\n\n## Situations where they can grow indefinitely\n\n**Yes, there are several:**\n\n1. **Checkpoint failure** (`checkpoint.go:130-131`): If `ToCheckpointWAL()` returns an error, `RotateWALFiles()` is never called and `lastCheckpoint` is not advanced. The WAL keeps accumulating until a checkpoint eventually succeeds. There is **no file size limit** — only a per-record sanity check of 1 MB.\n\n2. **Rotation channel full** (`walCheckpoint.go:341-344`): If a shard's rotation channel (capacity 64) is full, that host's rotation is skipped with a warning log. The WAL for that host persists until the next checkpoint cycle.\n\n3. **Rotation timeout** (`walCheckpoint.go:349-352`): If rotation doesn't complete within 30 seconds, the function returns early. Remaining hosts keep their WAL files.\n\n4. **Shutdown checkpoint failure** (`metricstore.go:316-318`): If the final checkpoint on shutdown fails, WAL files remain on disk. On restart they'll be replayed, but won't be cleaned up until the first successful scheduled checkpoint (up to 12 hours later).\n\n5. **`RotateWALFilesAfterShutdown`** (`walCheckpoint.go:367-374`) exists but is **never called anywhere** — it appears to be dead code that was intended for post-restart cleanup.\n\n## Bottom line\n\nThe main risk is scenario 1: if checkpoints keep failing (e.g., disk full, permissions), WAL files grow without bound. There's no size-based rotation or cap. Would you like me to plan a fix for any of these issues?"}],"stop_reason":"end_turn","stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":861,"cache_read_input_tokens":27424,"output_tokens":780,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":861,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUuVUjMTspoAJyge4wDf","type":"assistant","uuid":"bdfd6a9d-44e4-436d-b9d8-50f694854d05","timestamp":"2026-03-28T05:13:21.581Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"9699af32-b985-4537-ba93-0446e98e72a2","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01RuKwWQvYhg67Cic8Drx8kb","type":"message","role":"assistant","content":[{"type":"thinking","thinking":"","signature":"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"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":789,"cache_read_input_tokens":28285,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":789},"output_tokens":31,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUuftHiuadJm8pZ2Y7YV","type":"assistant","uuid":"f6896145-19eb-43e4-a82e-9efb1e116ec6","timestamp":"2026-03-28T05:15:27.927Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"f6896145-19eb-43e4-a82e-9efb1e116ec6","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01RuKwWQvYhg67Cic8Drx8kb","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_015Aqag9YqhNjZ2ns1L6WT9T","name":"Agent","input":{"subagent_type":"Explore","description":"Explore WAL size and checkpoint error handling","prompt":"I need to understand the WAL file writing and checkpoint error handling in detail to plan a fix for unbounded WAL growth when checkpoints fail.\n\nPlease examine these aspects thoroughly:\n\n1. In `pkg/metricstore/walCheckpoint.go`:\n - How are WAL files opened/written? Look at `writeWALRecordDirect` and the WALStaging goroutine's write path\n - Is there any existing tracking of WAL file size?\n - What's the structure of `hostFiles` map and the file state stored per host?\n - Look at the `walHostState` or similar struct that tracks open WAL file handles\n - How does `ToCheckpointWAL` work — does it return partial success (some hosts succeed, some fail)? What does the `hostDirs` return value contain — all hosts or only successful ones?\n\n2. In `pkg/metricstore/checkpoint.go`:\n - The full Checkpointing() goroutine — what information is available when checkpoint fails?\n - Is there any retry logic or backoff?\n\n3. In `pkg/metricstore/metricstore.go`:\n - Look at the Keys/config structure — what checkpoint-related config options exist?\n - Look at Init() to understand available config fields\n\n4. In `pkg/metricstore/lineprotocol.go`:\n - How WALMessages are created and sent — is there a place to intercept/skip if WAL is too large?\n\n5. Any existing config structures in `pkg/metricstore/` that define checkpoint settings (look for struct definitions with json tags related to checkpoints, wal, max-size, etc.)\n\nRead all relevant sections fully."},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":789,"cache_read_input_tokens":28285,"output_tokens":542,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":789,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUuftHiuadJm8pZ2Y7YV","type":"assistant","uuid":"f511980f-7788-4a7b-a391-347c879dddec","timestamp":"2026-03-28T05:15:38.310Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"f511980f-7788-4a7b-a391-347c879dddec","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_015Aqag9YqhNjZ2ns1L6WT9T","type":"tool_result","content":[{"type":"text","text":"Perfect! Now let me compile a comprehensive report. Let me create a summary document with all the key findings:\n\n## Comprehensive Analysis: WAL File Writing and Checkpoint Error Handling\n\nBased on my thorough examination of the codebase, here are the detailed findings:\n\n### 1. WAL File Opening/Writing and File State Tracking\n\n**File: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go`**\n\n**walFileState Structure (lines 120-125):**\n```go\ntype walFileState struct {\n\tf *os.File\n\tw *bufio.Writer\n\tdirty bool\n}\n```\n- Tracks open WAL file handle, buffered writer, and dirty flag per host directory\n- Stored in `hostFiles` map: `map[string]*walFileState` (line 184 in WALStaging)\n- Each shard owns a subset of hosts determined by FNV-1a hash of cluster+node\n\n**WAL File Opening (lines 195-230):**\n- `getOrOpenWAL()` lazily opens `current.wal` files on first write\n- Creates file with `os.O_CREATE|os.O_APPEND|os.O_WRONLY` flags\n- Writes file header magic (`walFileMagic = 0xCC1DA701`) only on new (empty) files\n- File size is checked via `info.Size()` but **NO tracking of cumulative WAL size**\n\n**WAL Record Writing (lines 378-435 - writeWALRecordDirect):**\n- Encodes record in buffer before writing to prevent partial writes on error\n- Uses stack buffer (256 bytes) for small records, heap allocates for larger ones\n- Single atomic write via `bufio.Writer.Write()`\n- **NO size limits checked before writing**\n- **NO per-file or per-host WAL size tracking**\n\n**Flush Strategy (lines 258-265):**\n```go\nflushDirty := func() {\n for _, ws := range hostFiles {\n if ws.dirty {\n ws.w.Flush()\n ws.dirty = false\n }\n }\n}\n```\n- Periodic flush every 1 second (`walFlushInterval`) or on rotation\n- Flushes **all** open files (no per-file size awareness)\n\n### 2. Checkpoint File Success/Failure Handling\n\n**File: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go`**\n\n**ToCheckpointWAL Function (lines 627-729):**\n```go\nfunc (m *MemoryStore) ToCheckpointWAL(dir string, from, to int64) (int, []string, error)\n```\n\n**Return Value Details:**\n- Returns: `(numFilesWritten int, successDirs []string, error)`\n- `successDirs` contains **only hosts that successfully wrote binary snapshots**\n- Hosts with checkpoint errors are **NOT included** in successDirs (line 705)\n- **Partial success is supported:** some hosts can fail while others succeed\n\n**Critical Issue - Error Handling (lines 689-707):**\n```go\nerr := wi.level.toCheckpointBinary(wi.hostDir, from, to, m)\nif err != nil {\n if err == ErrNoNewArchiveData {\n atomic.AddInt32(&completed, 1)\n continue\n }\n cclog.Errorf(\"[METRICSTORE]> binary checkpoint error for %s: %v\", wi.hostDir, err)\n atomic.AddInt32(&errs, 1)\n} else {\n atomic.AddInt32(&n, 1)\n // Delete WAL immediately after successful snapshot.\n walPath := path.Join(wi.hostDir, \"current.wal\")\n if err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n cclog.Errorf(\"[METRICSTORE]> WAL remove %s: %v\", walPath, err)\n }\n successMu.Lock()\n successDirs = append(successDirs, wi.hostDir)\n successMu.Unlock()\n}\n```\n\n**Key Finding:**\n- WAL deletion only occurs for hosts with **successful snapshots** (line 700)\n- Hosts with checkpoint errors keep growing WAL files indefinitely\n- WAL files are **never rotated if checkpoint fails**\n\n**Return Error (lines 725-728):**\n```go\nif errs > 0 {\n return int(n), successDirs, fmt.Errorf(\"[METRICSTORE]> %d errors during binary checkpoint (%d successes)\", errs, n)\n}\nreturn int(n), successDirs, nil\n```\n- Returns error even with partial success\n- Caller must check both the error AND the successDirs\n\n### 3. Checkpointing Worker Behavior\n\n**File: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/checkpoint.go`**\n\n**Checkpointing Function (lines 94-154):**\n```go\nfunc Checkpointing(wg *sync.WaitGroup, ctx context.Context) {\n // ... setup ticker (default 12 hours)\n case <-ticker.C:\n from := lastCheckpoint\n now := time.Now()\n \n if Keys.Checkpoints.FileFormat == \"wal\" {\n n, hostDirs, err := ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())\n if err != nil {\n cclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n } else {\n cclog.Infof(\"[METRICSTORE]> done: %d binary snapshot files created\", n)\n lastCheckpointMu.Lock()\n lastCheckpoint = now // Updated ONLY on success\n lastCheckpointMu.Unlock()\n RotateWALFiles(hostDirs) // Only rotates successfully checkpointed hosts\n }\n }\n}\n```\n\n**Critical Issue - Incomplete Error Handling:**\n1. **Error case (line 131):** When `err != nil`, lastCheckpoint is **NOT updated**\n - However, `lastCheckpoint` tracks the time of the last successful checkpoint\n - **Bug: If all hosts fail, the error is logged but nothing prevents retrying**\n\n2. **Next checkpoint attempt:**\n - Will try to checkpoint the same `from` time again\n - Will still fail (same underlying issue)\n - WAL files for failed hosts continue growing\n - **There is no backoff, no skip, no mechanism to prevent repeated failures**\n\n3. **Retry Logic:** **NONE** - failures are logged but not acted upon\n\n### 4. WAL Message Channel and Ingestion\n\n**File: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/lineprotocol.go`**\n\n**DecodeLine Function (lines 199-379):**\n- Creates `WALMessage` for each metric when format is \"wal\" (line 356)\n- Sends via `SendWALMessage()` (line 364)\n- **Dropped messages logged periodically if channel full** (lines 367-369)\n- **NO size check before sending** - messages sent regardless of WAL size\n\n**SendWALMessage (lines 144-155 in walCheckpoint.go):**\n```go\nfunc SendWALMessage(msg *WALMessage) bool {\n if walShardChs == nil || walShuttingDown.Load() {\n return false\n }\n shard := walShardIndex(msg.Cluster, msg.Node)\n select {\n case walShardChs[shard] <- msg:\n return true\n default:\n return false // Channel full, message dropped\n }\n}\n```\n- Returns false if channel is full (non-blocking send)\n- **No capacity check or backpressure mechanism**\n- Dropped messages are only logged, not acted upon\n\n### 5. Configuration Structures\n\n**File: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/config.go`**\n\n**MetricStoreConfig Structure (lines 121-132):**\n```go\ntype MetricStoreConfig struct {\n NumWorkers int `json:\"num-workers\"`\n RetentionInMemory string `json:\"retention-in-memory\"`\n CheckpointInterval string `json:\"checkpoint-interval,omitempty\"`\n MemoryCap int `json:\"memory-cap\"`\n Checkpoints Checkpoints `json:\"checkpoints\"`\n Debug *Debug `json:\"debug\"`\n Cleanup *Cleanup `json:\"cleanup\"`\n Subscriptions *Subscriptions `json:\"nats-subscriptions\"`\n}\n```\n\n**Checkpoints Structure (lines 64-67):**\n```go\ntype Checkpoints struct {\n FileFormat string `json:\"file-format\"` // \"json\" or \"wal\"\n RootDir string `json:\"directory\"`\n}\n```\n\n**Missing Configuration:**\n- **NO max WAL file size limit**\n- **NO max WAL directory size limit**\n- **NO checkpoint retry policy**\n- **NO checkpoint timeout**\n- **NO WAL rotation interval independent of checkpoint**\n\n### 6. Root Causes of Unbounded WAL Growth\n\n1. **No WAL size tracking:** `walFileState` doesn't track file size; `getOrOpenWAL()` never checks cumulative size\n2. **WAL rotation only on successful checkpoint:** Line 700 of walCheckpoint.go - WAL deleted only if snapshot succeeds\n3. **No checkpoint error recovery:** Failed checkpoints just logged; no retry mechanism\n4. **No independent WAL rotation:** WAL lifetime tied entirely to checkpoint success\n5. **Checkpoint errors don't prevent future writes:** Messages keep flowing to failed hosts' WAL files\n6. **No circuit breaker:** Repeated failures don't trigger any defensive action\n7. **No backoff or throttling:** Metrics written even when WAL growth indicates problems\n\n### 7. Detailed Data Flow on Checkpoint Failure\n\n**Scenario: One host fails checkpoint**\n\n1. `ToCheckpointBinary()` fails for host1 (e.g., disk error)\n2. Worker logs error, increments `errs` counter, **does NOT add to successDirs**\n3. `ToCheckpointWAL()` returns with `(2, [\"host2\", \"host3\"], error)`\n4. `Checkpointing()` receives error (line 130-131)\n5. Error logged; **lastCheckpoint NOT updated**\n6. `RotateWALFiles()` called only for `[\"host2\", \"host3\"]` (line 138)\n7. **host1's current.wal is never deleted**, continues growing\n8. Next checkpoint interval (12 hours later):\n - `lastCheckpoint` still points to previous successful time\n - Will retry same `from` timestamp\n - host1 checkpoint will likely fail again (same condition)\n - **WAL grows more**\n9. **Infinite loop potential:** Permanent error = permanent WAL growth\n\n---\n\n## Summary of Key Structures and Data Flow\n\n**WAL File State Per Host:**\n- Path: `checkpoints/cluster/host/current.wal`\n- Tracked by: `walFileState{f, w, dirty}` in per-shard `hostFiles` map\n- **No size awareness anywhere**\n\n**Checkpoint Success/Failure Tracking:**\n- `successDirs` = only hosts that succeeded (returned from `ToCheckpointWAL`)\n- Partial success is possible\n- Error doesn't prevent future checkpoint attempts\n- No metrics on failure rate or retry logic\n\n**Configuration Available:**\n- `Keys.Checkpoints.FileFormat`: \"json\" or \"wal\"\n- `Keys.Checkpoints.RootDir`: storage directory\n- `Keys.CheckpointInterval`: interval between checkpoints (default 12h)\n- **Nothing related to WAL size limits or rotation policy**\n\n**Critical Missing Pieces for Fix:**\n1. Per-host WAL file size tracking\n2. Per-shard or global WAL directory size tracking\n3. Configurable WAL rotation interval/size limits\n4. Independent WAL rotation mechanism not tied to checkpoint success\n5. Checkpoint error recovery strategy with backoff/skip logic\n6. Mechanism to handle failed hosts differently (e.g., pause writes, skip rotation)"}]}]},"uuid":"cd894b66-6738-450a-aa91-18094225deba","timestamp":"2026-03-28T05:16:20.793Z","toolUseResult":{"status":"completed","prompt":"I need to understand the WAL file writing and checkpoint error handling in detail to plan a fix for unbounded WAL growth when checkpoints fail.\n\nPlease examine these aspects thoroughly:\n\n1. In `pkg/metricstore/walCheckpoint.go`:\n - How are WAL files opened/written? Look at `writeWALRecordDirect` and the WALStaging goroutine's write path\n - Is there any existing tracking of WAL file size?\n - What's the structure of `hostFiles` map and the file state stored per host?\n - Look at the `walHostState` or similar struct that tracks open WAL file handles\n - How does `ToCheckpointWAL` work — does it return partial success (some hosts succeed, some fail)? What does the `hostDirs` return value contain — all hosts or only successful ones?\n\n2. In `pkg/metricstore/checkpoint.go`:\n - The full Checkpointing() goroutine — what information is available when checkpoint fails?\n - Is there any retry logic or backoff?\n\n3. In `pkg/metricstore/metricstore.go`:\n - Look at the Keys/config structure — what checkpoint-related config options exist?\n - Look at Init() to understand available config fields\n\n4. In `pkg/metricstore/lineprotocol.go`:\n - How WALMessages are created and sent — is there a place to intercept/skip if WAL is too large?\n\n5. Any existing config structures in `pkg/metricstore/` that define checkpoint settings (look for struct definitions with json tags related to checkpoints, wal, max-size, etc.)\n\nRead all relevant sections fully.","agentId":"a3077cfd8dd9fd95a","agentType":"Explore","content":[{"type":"text","text":"Perfect! Now let me compile a comprehensive report. Let me create a summary document with all the key findings:\n\n## Comprehensive Analysis: WAL File Writing and Checkpoint Error Handling\n\nBased on my thorough examination of the codebase, here are the detailed findings:\n\n### 1. WAL File Opening/Writing and File State Tracking\n\n**File: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go`**\n\n**walFileState Structure (lines 120-125):**\n```go\ntype walFileState struct {\n\tf *os.File\n\tw *bufio.Writer\n\tdirty bool\n}\n```\n- Tracks open WAL file handle, buffered writer, and dirty flag per host directory\n- Stored in `hostFiles` map: `map[string]*walFileState` (line 184 in WALStaging)\n- Each shard owns a subset of hosts determined by FNV-1a hash of cluster+node\n\n**WAL File Opening (lines 195-230):**\n- `getOrOpenWAL()` lazily opens `current.wal` files on first write\n- Creates file with `os.O_CREATE|os.O_APPEND|os.O_WRONLY` flags\n- Writes file header magic (`walFileMagic = 0xCC1DA701`) only on new (empty) files\n- File size is checked via `info.Size()` but **NO tracking of cumulative WAL size**\n\n**WAL Record Writing (lines 378-435 - writeWALRecordDirect):**\n- Encodes record in buffer before writing to prevent partial writes on error\n- Uses stack buffer (256 bytes) for small records, heap allocates for larger ones\n- Single atomic write via `bufio.Writer.Write()`\n- **NO size limits checked before writing**\n- **NO per-file or per-host WAL size tracking**\n\n**Flush Strategy (lines 258-265):**\n```go\nflushDirty := func() {\n for _, ws := range hostFiles {\n if ws.dirty {\n ws.w.Flush()\n ws.dirty = false\n }\n }\n}\n```\n- Periodic flush every 1 second (`walFlushInterval`) or on rotation\n- Flushes **all** open files (no per-file size awareness)\n\n### 2. Checkpoint File Success/Failure Handling\n\n**File: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go`**\n\n**ToCheckpointWAL Function (lines 627-729):**\n```go\nfunc (m *MemoryStore) ToCheckpointWAL(dir string, from, to int64) (int, []string, error)\n```\n\n**Return Value Details:**\n- Returns: `(numFilesWritten int, successDirs []string, error)`\n- `successDirs` contains **only hosts that successfully wrote binary snapshots**\n- Hosts with checkpoint errors are **NOT included** in successDirs (line 705)\n- **Partial success is supported:** some hosts can fail while others succeed\n\n**Critical Issue - Error Handling (lines 689-707):**\n```go\nerr := wi.level.toCheckpointBinary(wi.hostDir, from, to, m)\nif err != nil {\n if err == ErrNoNewArchiveData {\n atomic.AddInt32(&completed, 1)\n continue\n }\n cclog.Errorf(\"[METRICSTORE]> binary checkpoint error for %s: %v\", wi.hostDir, err)\n atomic.AddInt32(&errs, 1)\n} else {\n atomic.AddInt32(&n, 1)\n // Delete WAL immediately after successful snapshot.\n walPath := path.Join(wi.hostDir, \"current.wal\")\n if err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n cclog.Errorf(\"[METRICSTORE]> WAL remove %s: %v\", walPath, err)\n }\n successMu.Lock()\n successDirs = append(successDirs, wi.hostDir)\n successMu.Unlock()\n}\n```\n\n**Key Finding:**\n- WAL deletion only occurs for hosts with **successful snapshots** (line 700)\n- Hosts with checkpoint errors keep growing WAL files indefinitely\n- WAL files are **never rotated if checkpoint fails**\n\n**Return Error (lines 725-728):**\n```go\nif errs > 0 {\n return int(n), successDirs, fmt.Errorf(\"[METRICSTORE]> %d errors during binary checkpoint (%d successes)\", errs, n)\n}\nreturn int(n), successDirs, nil\n```\n- Returns error even with partial success\n- Caller must check both the error AND the successDirs\n\n### 3. Checkpointing Worker Behavior\n\n**File: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/checkpoint.go`**\n\n**Checkpointing Function (lines 94-154):**\n```go\nfunc Checkpointing(wg *sync.WaitGroup, ctx context.Context) {\n // ... setup ticker (default 12 hours)\n case <-ticker.C:\n from := lastCheckpoint\n now := time.Now()\n \n if Keys.Checkpoints.FileFormat == \"wal\" {\n n, hostDirs, err := ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())\n if err != nil {\n cclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n } else {\n cclog.Infof(\"[METRICSTORE]> done: %d binary snapshot files created\", n)\n lastCheckpointMu.Lock()\n lastCheckpoint = now // Updated ONLY on success\n lastCheckpointMu.Unlock()\n RotateWALFiles(hostDirs) // Only rotates successfully checkpointed hosts\n }\n }\n}\n```\n\n**Critical Issue - Incomplete Error Handling:**\n1. **Error case (line 131):** When `err != nil`, lastCheckpoint is **NOT updated**\n - However, `lastCheckpoint` tracks the time of the last successful checkpoint\n - **Bug: If all hosts fail, the error is logged but nothing prevents retrying**\n\n2. **Next checkpoint attempt:**\n - Will try to checkpoint the same `from` time again\n - Will still fail (same underlying issue)\n - WAL files for failed hosts continue growing\n - **There is no backoff, no skip, no mechanism to prevent repeated failures**\n\n3. **Retry Logic:** **NONE** - failures are logged but not acted upon\n\n### 4. WAL Message Channel and Ingestion\n\n**File: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/lineprotocol.go`**\n\n**DecodeLine Function (lines 199-379):**\n- Creates `WALMessage` for each metric when format is \"wal\" (line 356)\n- Sends via `SendWALMessage()` (line 364)\n- **Dropped messages logged periodically if channel full** (lines 367-369)\n- **NO size check before sending** - messages sent regardless of WAL size\n\n**SendWALMessage (lines 144-155 in walCheckpoint.go):**\n```go\nfunc SendWALMessage(msg *WALMessage) bool {\n if walShardChs == nil || walShuttingDown.Load() {\n return false\n }\n shard := walShardIndex(msg.Cluster, msg.Node)\n select {\n case walShardChs[shard] <- msg:\n return true\n default:\n return false // Channel full, message dropped\n }\n}\n```\n- Returns false if channel is full (non-blocking send)\n- **No capacity check or backpressure mechanism**\n- Dropped messages are only logged, not acted upon\n\n### 5. Configuration Structures\n\n**File: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/config.go`**\n\n**MetricStoreConfig Structure (lines 121-132):**\n```go\ntype MetricStoreConfig struct {\n NumWorkers int `json:\"num-workers\"`\n RetentionInMemory string `json:\"retention-in-memory\"`\n CheckpointInterval string `json:\"checkpoint-interval,omitempty\"`\n MemoryCap int `json:\"memory-cap\"`\n Checkpoints Checkpoints `json:\"checkpoints\"`\n Debug *Debug `json:\"debug\"`\n Cleanup *Cleanup `json:\"cleanup\"`\n Subscriptions *Subscriptions `json:\"nats-subscriptions\"`\n}\n```\n\n**Checkpoints Structure (lines 64-67):**\n```go\ntype Checkpoints struct {\n FileFormat string `json:\"file-format\"` // \"json\" or \"wal\"\n RootDir string `json:\"directory\"`\n}\n```\n\n**Missing Configuration:**\n- **NO max WAL file size limit**\n- **NO max WAL directory size limit**\n- **NO checkpoint retry policy**\n- **NO checkpoint timeout**\n- **NO WAL rotation interval independent of checkpoint**\n\n### 6. Root Causes of Unbounded WAL Growth\n\n1. **No WAL size tracking:** `walFileState` doesn't track file size; `getOrOpenWAL()` never checks cumulative size\n2. **WAL rotation only on successful checkpoint:** Line 700 of walCheckpoint.go - WAL deleted only if snapshot succeeds\n3. **No checkpoint error recovery:** Failed checkpoints just logged; no retry mechanism\n4. **No independent WAL rotation:** WAL lifetime tied entirely to checkpoint success\n5. **Checkpoint errors don't prevent future writes:** Messages keep flowing to failed hosts' WAL files\n6. **No circuit breaker:** Repeated failures don't trigger any defensive action\n7. **No backoff or throttling:** Metrics written even when WAL growth indicates problems\n\n### 7. Detailed Data Flow on Checkpoint Failure\n\n**Scenario: One host fails checkpoint**\n\n1. `ToCheckpointBinary()` fails for host1 (e.g., disk error)\n2. Worker logs error, increments `errs` counter, **does NOT add to successDirs**\n3. `ToCheckpointWAL()` returns with `(2, [\"host2\", \"host3\"], error)`\n4. `Checkpointing()` receives error (line 130-131)\n5. Error logged; **lastCheckpoint NOT updated**\n6. `RotateWALFiles()` called only for `[\"host2\", \"host3\"]` (line 138)\n7. **host1's current.wal is never deleted**, continues growing\n8. Next checkpoint interval (12 hours later):\n - `lastCheckpoint` still points to previous successful time\n - Will retry same `from` timestamp\n - host1 checkpoint will likely fail again (same condition)\n - **WAL grows more**\n9. **Infinite loop potential:** Permanent error = permanent WAL growth\n\n---\n\n## Summary of Key Structures and Data Flow\n\n**WAL File State Per Host:**\n- Path: `checkpoints/cluster/host/current.wal`\n- Tracked by: `walFileState{f, w, dirty}` in per-shard `hostFiles` map\n- **No size awareness anywhere**\n\n**Checkpoint Success/Failure Tracking:**\n- `successDirs` = only hosts that succeeded (returned from `ToCheckpointWAL`)\n- Partial success is possible\n- Error doesn't prevent future checkpoint attempts\n- No metrics on failure rate or retry logic\n\n**Configuration Available:**\n- `Keys.Checkpoints.FileFormat`: \"json\" or \"wal\"\n- `Keys.Checkpoints.RootDir`: storage directory\n- `Keys.CheckpointInterval`: interval between checkpoints (default 12h)\n- **Nothing related to WAL size limits or rotation policy**\n\n**Critical Missing Pieces for Fix:**\n1. Per-host WAL file size tracking\n2. Per-shard or global WAL directory size tracking\n3. Configurable WAL rotation interval/size limits\n4. Independent WAL rotation mechanism not tied to checkpoint success\n5. Checkpoint error recovery strategy with backoff/skip logic\n6. 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{"parentUuid":"817f2bea-5af0-40bb-b62c-6029cf7929e4","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01Cao3j8H7JyzDg8y8zChu27","type":"tool_result","content":"180\t\n181\t\t\twalStagingWg.Add(1)\n182\t\t\twg.Go(func() {\n183\t\t\t\tdefer walStagingWg.Done()\n184\t\t\t\thostFiles := make(map[string]*walFileState)\n185\t\n186\t\t\t\tdefer func() {\n187\t\t\t\t\tfor _, ws := range hostFiles {\n188\t\t\t\t\t\tif ws.f != nil {\n189\t\t\t\t\t\t\tws.w.Flush()\n190\t\t\t\t\t\t\tws.f.Close()\n191\t\t\t\t\t\t}\n192\t\t\t\t\t}\n193\t\t\t\t}()\n194\t\n195\t\t\t\tgetOrOpenWAL := func(hostDir string) *walFileState {\n196\t\t\t\t\tws, ok := hostFiles[hostDir]\n197\t\t\t\t\tif ok {\n198\t\t\t\t\t\treturn ws\n199\t\t\t\t\t}\n200\t\n201\t\t\t\t\tif err := os.MkdirAll(hostDir, CheckpointDirPerms); err != nil {\n202\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: mkdir %s: %v\", hostDir, err)\n203\t\t\t\t\t\treturn nil\n204\t\t\t\t\t}\n205\t\n206\t\t\t\t\twalPath := path.Join(hostDir, \"current.wal\")\n207\t\t\t\t\tf, err := os.OpenFile(walPath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, CheckpointFilePerms)\n208\t\t\t\t\tif err != nil {\n209\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: open %s: %v\", walPath, err)\n210\t\t\t\t\t\treturn nil\n211\t\t\t\t\t}\n212\t\n213\t\t\t\t\tw := bufio.NewWriter(f)\n214\t\n215\t\t\t\t\t// Write file header magic if file is new (empty).\n216\t\t\t\t\tinfo, err := f.Stat()\n217\t\t\t\t\tif err == nil && info.Size() == 0 {\n218\t\t\t\t\t\tvar hdr [4]byte\n219\t\t\t\t\t\tbinary.LittleEndian.PutUint32(hdr[:], walFileMagic)\n220\t\t\t\t\t\tif _, err := w.Write(hdr[:]); err != nil {\n221\t\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write header %s: %v\", walPath, err)\n222\t\t\t\t\t\t\tf.Close()\n223\t\t\t\t\t\t\treturn nil\n224\t\t\t\t\t\t}\n225\t\t\t\t\t}\n226\t\n227\t\t\t\t\tws = &walFileState{f: f, w: w}\n228\t\t\t\t\thostFiles[hostDir] = ws\n229\t\t\t\t\treturn ws\n230\t\t\t\t}\n231\t\n232\t\t\t\tprocessMsg := func(msg *WALMessage) {\n233\t\t\t\t\thostDir := path.Join(Keys.Checkpoints.RootDir, msg.Cluster, msg.Node)\n234\t\t\t\t\tws := getOrOpenWAL(hostDir)\n235\t\t\t\t\tif ws == nil {\n236\t\t\t\t\t\treturn\n237\t\t\t\t\t}\n238\t\t\t\t\tif err := writeWALRecordDirect(ws.w, msg); err != nil {\n239\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write record: %v\", err)\n240\t\t\t\t\t}\n241\t\t\t\t\tws.dirty = true\n242\t\t\t\t}\n243\t\n244\t\t\t\tprocessRotate := func(req walRotateReq) {\n245\t\t\t\t\tws, ok := hostFiles[req.hostDir]\n246\t\t\t\t\tif ok && ws.f != nil {\n247\t\t\t\t\t\tws.w.Flush()\n248\t\t\t\t\t\tws.f.Close()\n249\t\t\t\t\t\twalPath := path.Join(req.hostDir, \"current.wal\")\n250\t\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n251\t\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n252\t\t\t\t\t\t}\n253\t\t\t\t\t\tdelete(hostFiles, req.hostDir)\n254\t\t\t\t\t}\n255\t\t\t\t\tclose(req.done)\n256\t\t\t\t}\n257\t\n258\t\t\t\tflushDirty := func() {\n259\t\t\t\t\tfor _, ws := range hostFiles {\n260\t\t\t\t\t\tif ws.dirty {\n261\t\t\t\t\t\t\tws.w.Flush()\n262\t\t\t\t\t\t\tws.dirty = false\n263\t\t\t\t\t\t}\n264\t\t\t\t\t}"}]},"uuid":"cbde4d80-6b99-4f01-902b-9d743359dd07","timestamp":"2026-03-28T05:16:50.125Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","content":"\n\t\twalStagingWg.Add(1)\n\t\twg.Go(func() {\n\t\t\tdefer walStagingWg.Done()\n\t\t\thostFiles := make(map[string]*walFileState)\n\n\t\t\tdefer func() {\n\t\t\t\tfor _, ws := range hostFiles {\n\t\t\t\t\tif ws.f != nil {\n\t\t\t\t\t\tws.w.Flush()\n\t\t\t\t\t\tws.f.Close()\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}()\n\n\t\t\tgetOrOpenWAL := func(hostDir string) *walFileState {\n\t\t\t\tws, ok := hostFiles[hostDir]\n\t\t\t\tif ok {\n\t\t\t\t\treturn ws\n\t\t\t\t}\n\n\t\t\t\tif err := os.MkdirAll(hostDir, CheckpointDirPerms); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: mkdir %s: %v\", hostDir, err)\n\t\t\t\t\treturn nil\n\t\t\t\t}\n\n\t\t\t\twalPath := path.Join(hostDir, \"current.wal\")\n\t\t\t\tf, err := os.OpenFile(walPath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, CheckpointFilePerms)\n\t\t\t\tif err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: open %s: %v\", walPath, err)\n\t\t\t\t\treturn nil\n\t\t\t\t}\n\n\t\t\t\tw := bufio.NewWriter(f)\n\n\t\t\t\t// Write file header magic if file is new (empty).\n\t\t\t\tinfo, err := f.Stat()\n\t\t\t\tif err == nil && info.Size() == 0 {\n\t\t\t\t\tvar hdr [4]byte\n\t\t\t\t\tbinary.LittleEndian.PutUint32(hdr[:], walFileMagic)\n\t\t\t\t\tif _, err := w.Write(hdr[:]); err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write header %s: %v\", walPath, err)\n\t\t\t\t\t\tf.Close()\n\t\t\t\t\t\treturn nil\n\t\t\t\t\t}\n\t\t\t\t}\n\n\t\t\t\tws = &walFileState{f: f, w: w}\n\t\t\t\thostFiles[hostDir] = ws\n\t\t\t\treturn ws\n\t\t\t}\n\n\t\t\tprocessMsg := func(msg *WALMessage) {\n\t\t\t\thostDir := path.Join(Keys.Checkpoints.RootDir, msg.Cluster, msg.Node)\n\t\t\t\tws := getOrOpenWAL(hostDir)\n\t\t\t\tif ws == nil {\n\t\t\t\t\treturn\n\t\t\t\t}\n\t\t\t\tif err := writeWALRecordDirect(ws.w, msg); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write record: %v\", err)\n\t\t\t\t}\n\t\t\t\tws.dirty = true\n\t\t\t}\n\n\t\t\tprocessRotate := func(req walRotateReq) {\n\t\t\t\tws, ok := hostFiles[req.hostDir]\n\t\t\t\tif ok && ws.f != nil {\n\t\t\t\t\tws.w.Flush()\n\t\t\t\t\tws.f.Close()\n\t\t\t\t\twalPath := path.Join(req.hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tdelete(hostFiles, req.hostDir)\n\t\t\t\t}\n\t\t\t\tclose(req.done)\n\t\t\t}\n\n\t\t\tflushDirty := func() {\n\t\t\t\tfor _, ws := range hostFiles {\n\t\t\t\t\tif ws.dirty {\n\t\t\t\t\t\tws.w.Flush()\n\t\t\t\t\t\tws.dirty = false\n\t\t\t\t\t}\n\t\t\t\t}","numLines":85,"startLine":180,"totalLines":951}},"sourceToolAssistantUUID":"817f2bea-5af0-40bb-b62c-6029cf7929e4","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"cbde4d80-6b99-4f01-902b-9d743359dd07","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01C3ZTyNHdFnEzFkUnHD5hWW","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_013QfzNLwYqWVdsX65XQeTHa","name":"Read","input":{"file_path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/config.go","offset":60,"limit":15},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":1081,"cache_read_input_tokens":33934,"output_tokens":113,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":1081,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUunDnA2kmweCYUvDsxr","type":"assistant","uuid":"d9f8ab3d-140d-417d-ac76-2eea0423edd3","timestamp":"2026-03-28T05:16:53.580Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"d9f8ab3d-140d-417d-ac76-2eea0423edd3","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_013QfzNLwYqWVdsX65XQeTHa","type":"tool_result","content":"60\t//\n61\t// Fields:\n62\t// - FileFormat: \"json\" (human-readable, periodic) or \"wal\" (binary snapshot + WAL, crash-safe); default is \"wal\"\n63\t// - RootDir: Filesystem path for checkpoint files (created if missing)\n64\ttype Checkpoints struct {\n65\t\tFileFormat string `json:\"file-format\"`\n66\t\tRootDir string `json:\"directory\"`\n67\t}\n68\t\n69\t// Debug provides development and profiling options.\n70\t//\n71\t// Fields:\n72\t// - DumpToFile: Path to dump checkpoint data for inspection (empty = disabled)\n73\t// - EnableGops: Enable gops agent for live runtime debugging (https://github.com/google/gops)\n74\ttype Debug struct {"}]},"uuid":"41bc6412-f007-4073-ab9a-1cecfe8beb51","timestamp":"2026-03-28T05:16:53.602Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/config.go","content":"//\n// Fields:\n// - FileFormat: \"json\" (human-readable, periodic) or \"wal\" (binary snapshot + WAL, crash-safe); default is \"wal\"\n// - RootDir: Filesystem path for checkpoint files (created if missing)\ntype Checkpoints struct {\n\tFileFormat string `json:\"file-format\"`\n\tRootDir string `json:\"directory\"`\n}\n\n// Debug provides development and profiling options.\n//\n// Fields:\n// - DumpToFile: Path to dump checkpoint data for inspection (empty = disabled)\n// - EnableGops: Enable gops agent for live runtime debugging (https://github.com/google/gops)\ntype Debug struct {","numLines":15,"startLine":60,"totalLines":255}},"sourceToolAssistantUUID":"d9f8ab3d-140d-417d-ac76-2eea0423edd3","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"41bc6412-f007-4073-ab9a-1cecfe8beb51","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_011zB3ko7wNusNtThfxyi766","type":"message","role":"assistant","content":[{"type":"text","text":"Now I have everything I need. Let me write the plan."}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":321,"cache_read_input_tokens":35015,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":321},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUunUnJcn87LjyEBRWcr","type":"assistant","uuid":"8e0832f4-07f4-4bf7-8bfe-fada39ce8c77","timestamp":"2026-03-28T05:16:57.100Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"8e0832f4-07f4-4bf7-8bfe-fada39ce8c77","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_011zB3ko7wNusNtThfxyi766","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_017UaRrFUhkAwsHeXpkBCtnq","name":"Write","input":{"file_path":"/Users/jan/.claude/plans/atomic-giggling-gizmo.md","content":"# Fix: Unbounded WAL growth on checkpoint failure\n\n## Context\n\nWhen binary checkpointing fails (disk error, permission issue, etc.), WAL files are never rotated because `RotateWALFiles()` is only called on success. With a 12-hour checkpoint interval, a persistent failure means WAL files grow indefinitely until disk exhaustion. There are two distinct bugs:\n\n1. **Partial success is treated as total failure** (`checkpoint.go:128-139`): `ToCheckpointWAL` supports partial success (returns `successDirs` for hosts that wrote snapshots), but the caller ignores this — on any error, `lastCheckpoint` is not advanced and `RotateWALFiles` is not called. The inner workers already delete WAL files for successful hosts (line 700), but `lastCheckpoint` not advancing means the next run re-processes all hosts unnecessarily.\n\n2. **No WAL size limit**: There is no mechanism to cap WAL file size. If a host's checkpoint consistently fails, its `current.wal` grows without bound.\n\n## Fix\n\n### Part 1: Handle partial checkpoint success (`checkpoint.go`)\n\nIn `Checkpointing()`, when `ToCheckpointWAL` returns an error **and** successful hosts:\n- Still advance `lastCheckpoint` if there were any successes\n- Still call `RotateWALFiles(hostDirs)` for the successful hosts\n\nChange the `if err != nil` / `else` block (lines 128-139) to:\n\n```go\nn, hostDirs, err := ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())\nif err != nil {\n cclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n}\nif n > 0 {\n cclog.Infof(\"[METRICSTORE]> done: %d binary snapshot files created\", n)\n lastCheckpointMu.Lock()\n lastCheckpoint = now\n lastCheckpointMu.Unlock()\n RotateWALFiles(hostDirs)\n}\n```\n\nThis way partial success still advances the checkpoint timestamp and rotates WAL for successful hosts.\n\n### Part 2: Add max WAL file size with forced rotation (`walCheckpoint.go`)\n\n**Config** — add `MaxWALSize` to `Checkpoints` struct in `config.go`:\n```go\ntype Checkpoints struct {\n FileFormat string `json:\"file-format\"`\n RootDir string `json:\"directory\"`\n MaxWALSize int64 `json:\"max-wal-size,omitempty\"` // bytes, 0 = unlimited\n}\n```\n\nDefault to 0 (unlimited) for backward compatibility. Recommended value in docs: something like 512 MB.\n\n**Size tracking** — add `size` field to `walFileState`:\n```go\ntype walFileState struct {\n f *os.File\n w *bufio.Writer\n dirty bool\n size int64\n}\n```\n\nInitialize `size` from `info.Size()` in `getOrOpenWAL()` (the stat is already done at line 216-217).\n\n**Size enforcement** — in `processMsg()`, after `writeWALRecordDirect` succeeds, update `ws.size`. Before writing, check if `ws.size` would exceed `Keys.Checkpoints.MaxWALSize` (when > 0). If exceeded:\n1. Log a warning\n2. Flush, close, and delete the WAL file (same as `processRotate`)\n3. Remove from `hostFiles` so next write creates a fresh file\n\nThis accepts data loss for crash recovery of that host's gap, but the in-memory store still holds the data and will persist it at the next successful checkpoint. The alternative (letting the disk fill up) is worse.\n\n## Files to modify\n\n1. **`pkg/metricstore/config.go`** — add `MaxWALSize` field to `Checkpoints` struct\n2. **`pkg/metricstore/walCheckpoint.go`** — add `size` to `walFileState`, track size in `getOrOpenWAL` and `processMsg`, enforce limit in `processMsg`\n3. **`pkg/metricstore/checkpoint.go`** — fix partial success handling in `Checkpointing()`\n\n## Verification\n\n1. `go build ./...` — ensure it compiles\n2. `go test ./pkg/metricstore/...` — run existing tests\n3. Manual review: trace all callers of the changed code paths to confirm no behavioral regression\n4. Verify that the `processRotate` path still works correctly (it doesn't track size, but it deletes from `hostFiles` which resets tracking)\n"},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":321,"cache_read_input_tokens":35015,"output_tokens":1235,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":321,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUunUnJcn87LjyEBRWcr","type":"assistant","uuid":"481b04e9-b63e-4722-8097-42cf1a0b944c","timestamp":"2026-03-28T05:17:17.939Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"481b04e9-b63e-4722-8097-42cf1a0b944c","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_017UaRrFUhkAwsHeXpkBCtnq","type":"tool_result","content":"File created successfully at: /Users/jan/.claude/plans/atomic-giggling-gizmo.md"}]},"uuid":"d929572f-8ab3-45b2-8e76-4a6bea484db5","timestamp":"2026-03-28T05:17:17.960Z","toolUseResult":{"type":"create","filePath":"/Users/jan/.claude/plans/atomic-giggling-gizmo.md","content":"# Fix: Unbounded WAL growth on checkpoint failure\n\n## Context\n\nWhen binary checkpointing fails (disk error, permission issue, etc.), WAL files are never rotated because `RotateWALFiles()` is only called on success. With a 12-hour checkpoint interval, a persistent failure means WAL files grow indefinitely until disk exhaustion. There are two distinct bugs:\n\n1. **Partial success is treated as total failure** (`checkpoint.go:128-139`): `ToCheckpointWAL` supports partial success (returns `successDirs` for hosts that wrote snapshots), but the caller ignores this — on any error, `lastCheckpoint` is not advanced and `RotateWALFiles` is not called. The inner workers already delete WAL files for successful hosts (line 700), but `lastCheckpoint` not advancing means the next run re-processes all hosts unnecessarily.\n\n2. **No WAL size limit**: There is no mechanism to cap WAL file size. If a host's checkpoint consistently fails, its `current.wal` grows without bound.\n\n## Fix\n\n### Part 1: Handle partial checkpoint success (`checkpoint.go`)\n\nIn `Checkpointing()`, when `ToCheckpointWAL` returns an error **and** successful hosts:\n- Still advance `lastCheckpoint` if there were any successes\n- Still call `RotateWALFiles(hostDirs)` for the successful hosts\n\nChange the `if err != nil` / `else` block (lines 128-139) to:\n\n```go\nn, hostDirs, err := ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())\nif err != nil {\n cclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n}\nif n > 0 {\n cclog.Infof(\"[METRICSTORE]> done: %d binary snapshot files created\", n)\n lastCheckpointMu.Lock()\n lastCheckpoint = now\n lastCheckpointMu.Unlock()\n RotateWALFiles(hostDirs)\n}\n```\n\nThis way partial success still advances the checkpoint timestamp and rotates WAL for successful hosts.\n\n### Part 2: Add max WAL file size with forced rotation (`walCheckpoint.go`)\n\n**Config** — add `MaxWALSize` to `Checkpoints` struct in `config.go`:\n```go\ntype Checkpoints struct {\n FileFormat string `json:\"file-format\"`\n RootDir string `json:\"directory\"`\n MaxWALSize int64 `json:\"max-wal-size,omitempty\"` // bytes, 0 = unlimited\n}\n```\n\nDefault to 0 (unlimited) for backward compatibility. Recommended value in docs: something like 512 MB.\n\n**Size tracking** — add `size` field to `walFileState`:\n```go\ntype walFileState struct {\n f *os.File\n w *bufio.Writer\n dirty bool\n size int64\n}\n```\n\nInitialize `size` from `info.Size()` in `getOrOpenWAL()` (the stat is already done at line 216-217).\n\n**Size enforcement** — in `processMsg()`, after `writeWALRecordDirect` succeeds, update `ws.size`. Before writing, check if `ws.size` would exceed `Keys.Checkpoints.MaxWALSize` (when > 0). If exceeded:\n1. Log a warning\n2. Flush, close, and delete the WAL file (same as `processRotate`)\n3. Remove from `hostFiles` so next write creates a fresh file\n\nThis accepts data loss for crash recovery of that host's gap, but the in-memory store still holds the data and will persist it at the next successful checkpoint. The alternative (letting the disk fill up) is worse.\n\n## Files to modify\n\n1. **`pkg/metricstore/config.go`** — add `MaxWALSize` field to `Checkpoints` struct\n2. **`pkg/metricstore/walCheckpoint.go`** — add `size` to `walFileState`, track size in `getOrOpenWAL` and `processMsg`, enforce limit in `processMsg`\n3. **`pkg/metricstore/checkpoint.go`** — fix partial success handling in `Checkpointing()`\n\n## Verification\n\n1. `go build ./...` — ensure it compiles\n2. `go test ./pkg/metricstore/...` — run existing tests\n3. Manual review: trace all callers of the changed code paths to confirm no behavioral regression\n4. Verify that the `processRotate` path still works correctly (it doesn't track size, but it deletes from `hostFiles` which resets tracking)\n","structuredPatch":[],"originalFile":null},"sourceToolAssistantUUID":"481b04e9-b63e-4722-8097-42cf1a0b944c","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"d929572f-8ab3-45b2-8e76-4a6bea484db5","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01J7Kq2DzZVqH1MJewv9LsSP","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01GCAcABM2mn5krR5sozvb2T","name":"ExitPlanMode","input":{"plan":"# Fix: Unbounded WAL growth on checkpoint failure\n\n## Context\n\nWhen binary checkpointing fails (disk error, permission issue, etc.), WAL files are never rotated because `RotateWALFiles()` is only called on success. With a 12-hour checkpoint interval, a persistent failure means WAL files grow indefinitely until disk exhaustion. There are two distinct bugs:\n\n1. **Partial success is treated as total failure** (`checkpoint.go:128-139`): `ToCheckpointWAL` supports partial success (returns `successDirs` for hosts that wrote snapshots), but the caller ignores this — on any error, `lastCheckpoint` is not advanced and `RotateWALFiles` is not called. The inner workers already delete WAL files for successful hosts (line 700), but `lastCheckpoint` not advancing means the next run re-processes all hosts unnecessarily.\n\n2. **No WAL size limit**: There is no mechanism to cap WAL file size. If a host's checkpoint consistently fails, its `current.wal` grows without bound.\n\n## Fix\n\n### Part 1: Handle partial checkpoint success (`checkpoint.go`)\n\nIn `Checkpointing()`, when `ToCheckpointWAL` returns an error **and** successful hosts:\n- Still advance `lastCheckpoint` if there were any successes\n- Still call `RotateWALFiles(hostDirs)` for the successful hosts\n\nChange the `if err != nil` / `else` block (lines 128-139) to:\n\n```go\nn, hostDirs, err := ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())\nif err != nil {\n cclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n}\nif n > 0 {\n cclog.Infof(\"[METRICSTORE]> done: %d binary snapshot files created\", n)\n lastCheckpointMu.Lock()\n lastCheckpoint = now\n lastCheckpointMu.Unlock()\n RotateWALFiles(hostDirs)\n}\n```\n\nThis way partial success still advances the checkpoint timestamp and rotates WAL for successful hosts.\n\n### Part 2: Add max WAL file size with forced rotation (`walCheckpoint.go`)\n\n**Config** — add `MaxWALSize` to `Checkpoints` struct in `config.go`:\n```go\ntype Checkpoints struct {\n FileFormat string `json:\"file-format\"`\n RootDir string `json:\"directory\"`\n MaxWALSize int64 `json:\"max-wal-size,omitempty\"` // bytes, 0 = unlimited\n}\n```\n\nDefault to 0 (unlimited) for backward compatibility. Recommended value in docs: something like 512 MB.\n\n**Size tracking** — add `size` field to `walFileState`:\n```go\ntype walFileState struct {\n f *os.File\n w *bufio.Writer\n dirty bool\n size int64\n}\n```\n\nInitialize `size` from `info.Size()` in `getOrOpenWAL()` (the stat is already done at line 216-217).\n\n**Size enforcement** — in `processMsg()`, after `writeWALRecordDirect` succeeds, update `ws.size`. Before writing, check if `ws.size` would exceed `Keys.Checkpoints.MaxWALSize` (when > 0). If exceeded:\n1. Log a warning\n2. Flush, close, and delete the WAL file (same as `processRotate`)\n3. Remove from `hostFiles` so next write creates a fresh file\n\nThis accepts data loss for crash recovery of that host's gap, but the in-memory store still holds the data and will persist it at the next successful checkpoint. The alternative (letting the disk fill up) is worse.\n\n## Files to modify\n\n1. **`pkg/metricstore/config.go`** — add `MaxWALSize` field to `Checkpoints` struct\n2. **`pkg/metricstore/walCheckpoint.go`** — add `size` to `walFileState`, track size in `getOrOpenWAL` and `processMsg`, enforce limit in `processMsg`\n3. **`pkg/metricstore/checkpoint.go`** — fix partial success handling in `Checkpointing()`\n\n## Verification\n\n1. `go build ./...` — ensure it compiles\n2. `go test ./pkg/metricstore/...` — run existing tests\n3. Manual review: trace all callers of the changed code paths to confirm no behavioral regression\n4. Verify that the `processRotate` path still works correctly (it doesn't track size, but it deletes from `hostFiles` which resets tracking)\n","planFilePath":"/Users/jan/.claude/plans/atomic-giggling-gizmo.md"},"caller":{"type":"direct"}}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":1271,"cache_read_input_tokens":35336,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":1271},"output_tokens":38,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUupGm4GeEoSDfMXjiqc","type":"assistant","uuid":"2769ffd9-b29c-4e00-8cc1-50bb2d79318e","timestamp":"2026-03-28T05:17:21.255Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"2769ffd9-b29c-4e00-8cc1-50bb2d79318e","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"type":"tool_result","content":"User has approved your plan. You can now start coding. Start with updating your todo list if applicable\n\nYour plan has been saved to: /Users/jan/.claude/plans/atomic-giggling-gizmo.md\nYou can refer back to it if needed during implementation.\n\n## Approved Plan:\n# Fix: Unbounded WAL growth on checkpoint failure\n\n## Context\n\nWhen binary checkpointing fails (disk error, permission issue, etc.), WAL files are never rotated because `RotateWALFiles()` is only called on success. With a 12-hour checkpoint interval, a persistent failure means WAL files grow indefinitely until disk exhaustion. There are two distinct bugs:\n\n1. **Partial success is treated as total failure** (`checkpoint.go:128-139`): `ToCheckpointWAL` supports partial success (returns `successDirs` for hosts that wrote snapshots), but the caller ignores this — on any error, `lastCheckpoint` is not advanced and `RotateWALFiles` is not called. The inner workers already delete WAL files for successful hosts (line 700), but `lastCheckpoint` not advancing means the next run re-processes all hosts unnecessarily.\n\n2. **No WAL size limit**: There is no mechanism to cap WAL file size. If a host's checkpoint consistently fails, its `current.wal` grows without bound.\n\n## Fix\n\n### Part 1: Handle partial checkpoint success (`checkpoint.go`)\n\nIn `Checkpointing()`, when `ToCheckpointWAL` returns an error **and** successful hosts:\n- Still advance `lastCheckpoint` if there were any successes\n- Still call `RotateWALFiles(hostDirs)` for the successful hosts\n\nChange the `if err != nil` / `else` block (lines 128-139) to:\n\n```go\nn, hostDirs, err := ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())\nif err != nil {\n cclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n}\nif n > 0 {\n cclog.Infof(\"[METRICSTORE]> done: %d binary snapshot files created\", n)\n lastCheckpointMu.Lock()\n lastCheckpoint = now\n lastCheckpointMu.Unlock()\n RotateWALFiles(hostDirs)\n}\n```\n\nThis way partial success still advances the checkpoint timestamp and rotates WAL for successful hosts.\n\n### Part 2: Add max WAL file size with forced rotation (`walCheckpoint.go`)\n\n**Config** — add `MaxWALSize` to `Checkpoints` struct in `config.go`:\n```go\ntype Checkpoints struct {\n FileFormat string `json:\"file-format\"`\n RootDir string `json:\"directory\"`\n MaxWALSize int64 `json:\"max-wal-size,omitempty\"` // bytes, 0 = unlimited\n}\n```\n\nDefault to 0 (unlimited) for backward compatibility. Recommended value in docs: something like 512 MB.\n\n**Size tracking** — add `size` field to `walFileState`:\n```go\ntype walFileState struct {\n f *os.File\n w *bufio.Writer\n dirty bool\n size int64\n}\n```\n\nInitialize `size` from `info.Size()` in `getOrOpenWAL()` (the stat is already done at line 216-217).\n\n**Size enforcement** — in `processMsg()`, after `writeWALRecordDirect` succeeds, update `ws.size`. Before writing, check if `ws.size` would exceed `Keys.Checkpoints.MaxWALSize` (when > 0). If exceeded:\n1. Log a warning\n2. Flush, close, and delete the WAL file (same as `processRotate`)\n3. Remove from `hostFiles` so next write creates a fresh file\n\nThis accepts data loss for crash recovery of that host's gap, but the in-memory store still holds the data and will persist it at the next successful checkpoint. The alternative (letting the disk fill up) is worse.\n\n## Files to modify\n\n1. **`pkg/metricstore/config.go`** — add `MaxWALSize` field to `Checkpoints` struct\n2. **`pkg/metricstore/walCheckpoint.go`** — add `size` to `walFileState`, track size in `getOrOpenWAL` and `processMsg`, enforce limit in `processMsg`\n3. **`pkg/metricstore/checkpoint.go`** — fix partial success handling in `Checkpointing()`\n\n## Verification\n\n1. `go build ./...` — ensure it compiles\n2. `go test ./pkg/metricstore/...` — run existing tests\n3. Manual review: trace all callers of the changed code paths to confirm no behavioral regression\n4. Verify that the `processRotate` path still works correctly (it doesn't track size, but it deletes from `hostFiles` which resets tracking)\n","tool_use_id":"toolu_01GCAcABM2mn5krR5sozvb2T"}]},"uuid":"a67aeb6e-7731-499b-80ef-24e8e7a05866","timestamp":"2026-03-28T05:20:11.499Z","toolUseResult":{"plan":"# Fix: Unbounded WAL growth on checkpoint failure\n\n## Context\n\nWhen binary checkpointing fails (disk error, permission issue, etc.), WAL files are never rotated because `RotateWALFiles()` is only called on success. With a 12-hour checkpoint interval, a persistent failure means WAL files grow indefinitely until disk exhaustion. There are two distinct bugs:\n\n1. **Partial success is treated as total failure** (`checkpoint.go:128-139`): `ToCheckpointWAL` supports partial success (returns `successDirs` for hosts that wrote snapshots), but the caller ignores this — on any error, `lastCheckpoint` is not advanced and `RotateWALFiles` is not called. The inner workers already delete WAL files for successful hosts (line 700), but `lastCheckpoint` not advancing means the next run re-processes all hosts unnecessarily.\n\n2. **No WAL size limit**: There is no mechanism to cap WAL file size. If a host's checkpoint consistently fails, its `current.wal` grows without bound.\n\n## Fix\n\n### Part 1: Handle partial checkpoint success (`checkpoint.go`)\n\nIn `Checkpointing()`, when `ToCheckpointWAL` returns an error **and** successful hosts:\n- Still advance `lastCheckpoint` if there were any successes\n- Still call `RotateWALFiles(hostDirs)` for the successful hosts\n\nChange the `if err != nil` / `else` block (lines 128-139) to:\n\n```go\nn, hostDirs, err := ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())\nif err != nil {\n cclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n}\nif n > 0 {\n cclog.Infof(\"[METRICSTORE]> done: %d binary snapshot files created\", n)\n lastCheckpointMu.Lock()\n lastCheckpoint = now\n lastCheckpointMu.Unlock()\n RotateWALFiles(hostDirs)\n}\n```\n\nThis way partial success still advances the checkpoint timestamp and rotates WAL for successful hosts.\n\n### Part 2: Add max WAL file size with forced rotation (`walCheckpoint.go`)\n\n**Config** — add `MaxWALSize` to `Checkpoints` struct in `config.go`:\n```go\ntype Checkpoints struct {\n FileFormat string `json:\"file-format\"`\n RootDir string `json:\"directory\"`\n MaxWALSize int64 `json:\"max-wal-size,omitempty\"` // bytes, 0 = unlimited\n}\n```\n\nDefault to 0 (unlimited) for backward compatibility. Recommended value in docs: something like 512 MB.\n\n**Size tracking** — add `size` field to `walFileState`:\n```go\ntype walFileState struct {\n f *os.File\n w *bufio.Writer\n dirty bool\n size int64\n}\n```\n\nInitialize `size` from `info.Size()` in `getOrOpenWAL()` (the stat is already done at line 216-217).\n\n**Size enforcement** — in `processMsg()`, after `writeWALRecordDirect` succeeds, update `ws.size`. Before writing, check if `ws.size` would exceed `Keys.Checkpoints.MaxWALSize` (when > 0). If exceeded:\n1. Log a warning\n2. Flush, close, and delete the WAL file (same as `processRotate`)\n3. Remove from `hostFiles` so next write creates a fresh file\n\nThis accepts data loss for crash recovery of that host's gap, but the in-memory store still holds the data and will persist it at the next successful checkpoint. The alternative (letting the disk fill up) is worse.\n\n## Files to modify\n\n1. **`pkg/metricstore/config.go`** — add `MaxWALSize` field to `Checkpoints` struct\n2. **`pkg/metricstore/walCheckpoint.go`** — add `size` to `walFileState`, track size in `getOrOpenWAL` and `processMsg`, enforce limit in `processMsg`\n3. **`pkg/metricstore/checkpoint.go`** — fix partial success handling in `Checkpointing()`\n\n## Verification\n\n1. `go build ./...` — ensure it compiles\n2. `go test ./pkg/metricstore/...` — run existing tests\n3. Manual review: trace all callers of the changed code paths to confirm no behavioral regression\n4. Verify that the `processRotate` path still works correctly (it doesn't track size, but it deletes from `hostFiles` which resets tracking)\n","isAgent":false,"filePath":"/Users/jan/.claude/plans/atomic-giggling-gizmo.md"},"sourceToolAssistantUUID":"2769ffd9-b29c-4e00-8cc1-50bb2d79318e","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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This file is part of cc-backend.\n// Use of this source code is governed by a MIT-style\n// license that can be found in the LICENSE file.\n\n// This file implements checkpoint persistence for the in-memory metric store.\n//\n// Checkpoints enable graceful restarts by periodically saving in-memory metric\n// data to disk in JSON or binary format. The checkpoint system:\n//\n// Key Features:\n// - Periodic background checkpointing via the Checkpointing() worker\n// - Two format families: JSON (human-readable) and WAL+binary (compact, crash-safe)\n// - Parallel checkpoint creation and loading using worker pools\n// - Hierarchical file organization: checkpoint_dir/cluster/host/timestamp.{json|bin}\n// - WAL file: checkpoint_dir/cluster/host/current.wal (append-only, per-entry)\n// - Only saves unarchived data (archived data is already persisted elsewhere)\n// - GC optimization during loading to prevent excessive heap growth\n//\n// Checkpoint Workflow:\n// 1. Init() loads checkpoints within retention window at startup\n// 2. Checkpointing() worker periodically saves new data\n// 3. Shutdown() writes final checkpoint before exit\n//\n// File Organization:\n//\n//\tcheckpoints/\n//\t cluster1/\n//\t host001/\n//\t 1234567890.json (JSON format: full subtree snapshot)\n//\t 1234567890.bin (binary format: full subtree snapshot)\n//\t current.wal (WAL format: append-only per-entry log)\n//\t host002/\n//\t ...\npackage metricstore\n\nimport (\n\t\"bufio\"\n\t\"context\"\n\t\"encoding/json\"\n\t\"errors\"\n\t\"fmt\"\n\t\"io/fs\"\n\t\"os\"\n\t\"path\"\n\t\"path/filepath\"\n\t\"sort\"\n\t\"strconv\"\n\t\"strings\"\n\t\"sync\"\n\t\"sync/atomic\"\n\t\"time\"\n\n\tcclog \"github.com/ClusterCockpit/cc-lib/v2/ccLogger\"\n\t\"github.com/ClusterCockpit/cc-lib/v2/schema\"\n)\n\nconst (\n\tCheckpointFilePerms = 0o644 // File permissions for checkpoint files\n\tCheckpointDirPerms = 0o755 // Directory permissions for checkpoint directories\n\tGCTriggerInterval = DefaultGCTriggerInterval // Interval for triggering GC during checkpoint loading\n)\n\n// CheckpointMetrics represents metric data in a checkpoint file.\n// Whenever the structure changes, update MarshalJSON as well!\ntype CheckpointMetrics struct {\n\tData []schema.Float `json:\"data\"`\n\tFrequency int64 `json:\"frequency\"`\n\tStart int64 `json:\"start\"`\n}\n\n// CheckpointFile represents the hierarchical structure of a checkpoint file.\n// It mirrors the Level tree structure from the MemoryStore.\ntype CheckpointFile struct {\n\tMetrics map[string]*CheckpointMetrics `json:\"metrics\"`\n\tChildren map[string]*CheckpointFile `json:\"children\"`\n\tFrom int64 `json:\"from\"`\n\tTo int64 `json:\"to\"`\n}\n\n// lastCheckpoint tracks the timestamp of the last checkpoint creation.\nvar (\n\tlastCheckpoint time.Time\n\tlastCheckpointMu sync.Mutex\n)\n\n// Checkpointing starts a background worker that periodically saves metric data to disk.\n//\n// Checkpoints are written every 12 hours (hardcoded).\n//\n// Format behaviour:\n// - \"json\": Periodic checkpointing every checkpointInterval\n// - \"wal\": Periodic binary snapshots + WAL rotation every checkpointInterval\nfunc Checkpointing(wg *sync.WaitGroup, ctx context.Context) {\n\tlastCheckpointMu.Lock()\n\tlastCheckpoint = time.Now()\n\tlastCheckpointMu.Unlock()\n\n\tms := GetMemoryStore()\n\n\twg.Go(func() {\n\n\t\td := 12 * time.Hour // default checkpoint interval\n\t\tif Keys.CheckpointInterval != \"\" {\n\t\t\tparsed, err := time.ParseDuration(Keys.CheckpointInterval)\n\t\t\tif err != nil {\n\t\t\t\tcclog.Errorf(\"[METRICSTORE]> invalid checkpoint-interval %q: %s, using default 12h\", Keys.CheckpointInterval, err)\n\t\t\t} else {\n\t\t\t\td = parsed\n\t\t\t}\n\t\t}\n\n\t\tticker := time.NewTicker(d)\n\t\tdefer ticker.Stop()\n\n\t\tfor {\n\t\t\tselect {\n\t\t\tcase <-ctx.Done():\n\t\t\t\treturn\n\t\t\tcase <-ticker.C:\n\t\t\t\tlastCheckpointMu.Lock()\n\t\t\t\tfrom := lastCheckpoint\n\t\t\t\tlastCheckpointMu.Unlock()\n\n\t\t\t\tnow := time.Now()\n\t\t\t\tcclog.Infof(\"[METRICSTORE]> start checkpointing (starting at %s)...\", from.Format(time.RFC3339))\n\n\t\t\t\tif Keys.Checkpoints.FileFormat == \"wal\" {\n\t\t\t\t\tn, hostDirs, err := ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())\n\t\t\t\t\tif err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())\n\t\t\t\t\t} else {\n\t\t\t\t\t\tcclog.Infof(\"[METRICSTORE]> done: %d binary snapshot files created\", n)\n\t\t\t\t\t\tlastCheckpointMu.Lock()\n\t\t\t\t\t\tlastCheckpoint = now\n\t\t\t\t\t\tlastCheckpointMu.Unlock()\n\t\t\t\t\t\t// Rotate WAL files for successfully checkpointed hosts.\n\t\t\t\t\t\tRotateWALFiles(hostDirs)\n\t\t\t\t\t}\n\t\t\t\t} else {\n\t\t\t\t\tn, err := ms.ToCheckpoint(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())\n\t\t\t\t\tif err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> checkpointing failed: %s\", err.Error())\n\t\t\t\t\t} else {\n\t\t\t\t\t\tcclog.Infof(\"[METRICSTORE]> done: %d checkpoint files created\", n)\n\t\t\t\t\t\tlastCheckpointMu.Lock()\n\t\t\t\t\t\tlastCheckpoint = now\n\t\t\t\t\t\tlastCheckpointMu.Unlock()\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\t})\n}\n\n// MarshalJSON provides optimized JSON encoding for CheckpointMetrics.\n//\n// Since schema.Float has custom MarshalJSON, serializing []Float has significant overhead.\n// This method manually constructs JSON to avoid allocations and interface conversions.\nfunc (cm *CheckpointMetrics) MarshalJSON() ([]byte, error) {\n\tbuf := make([]byte, 0, 128+len(cm.Data)*8)\n\tbuf = append(buf, `{\"frequency\":`...)\n\tbuf = strconv.AppendInt(buf, cm.Frequency, 10)\n\tbuf = append(buf, `,\"start\":`...)\n\tbuf = strconv.AppendInt(buf, cm.Start, 10)\n\tbuf = append(buf, `,\"data\":[`...)\n\tfor i, x := range cm.Data {\n\t\tif i != 0 {\n\t\t\tbuf = append(buf, ',')\n\t\t}\n\t\tif x.IsNaN() {\n\t\t\tbuf = append(buf, `null`...)\n\t\t} else {\n\t\t\tbuf = strconv.AppendFloat(buf, float64(x), 'f', 1, 32)\n\t\t}\n\t}\n\tbuf = append(buf, `]}`...)\n\treturn buf, nil\n}\n\n// ToCheckpoint writes metric data to checkpoint files in parallel (JSON format).\n//\n// Metrics at root and cluster levels are skipped. One file per host is created.\n// Uses worker pool (Keys.NumWorkers) for parallel processing. Only locks one host\n// at a time, allowing concurrent writes/reads to other hosts.\n//\n// Returns the number of checkpoint files created and any errors encountered.\nfunc (m *MemoryStore) ToCheckpoint(dir string, from, to int64) (int, error) {\n\t// Pre-calculate capacity by counting cluster/host pairs\n\tm.root.lock.RLock()\n\ttotalHosts := 0\n\tfor _, l1 := range m.root.children {\n\t\tl1.lock.RLock()\n\t\ttotalHosts += len(l1.children)\n\t\tl1.lock.RUnlock()\n\t}\n\tm.root.lock.RUnlock()\n\n\tlevels := make([]*Level, 0, totalHosts)\n\tselectors := make([][]string, 0, totalHosts)\n\n\tm.root.lock.RLock()\n\tfor sel1, l1 := range m.root.children {\n\t\tl1.lock.RLock()\n\t\tfor sel2, l2 := range l1.children {\n\t\t\tlevels = append(levels, l2)\n\t\t\tselectors = append(selectors, []string{sel1, sel2})\n\t\t}\n\t\tl1.lock.RUnlock()\n\t}\n\tm.root.lock.RUnlock()\n\n\ttype workItem struct {\n\t\tlevel *Level\n\t\tdir string\n\t\tselector []string\n\t}\n\n\tn, errs := int32(0), int32(0)\n\n\tvar wg sync.WaitGroup\n\twg.Add(Keys.NumWorkers)\n\twork := make(chan workItem, Keys.NumWorkers*2)\n\tfor worker := 0; worker < Keys.NumWorkers; worker++ {\n\t\tgo func() {\n\t\t\tdefer wg.Done()\n\n\t\t\tfor workItem := range work {\n\t\t\t\tif err := workItem.level.toCheckpoint(workItem.dir, from, to, m); err != nil {\n\t\t\t\t\tif err == ErrNoNewArchiveData {\n\t\t\t\t\t\tcontinue\n\t\t\t\t\t}\n\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> error while checkpointing %#v: %s\", workItem.selector, err.Error())\n\t\t\t\t\tatomic.AddInt32(&errs, 1)\n\t\t\t\t} else {\n\t\t\t\t\tatomic.AddInt32(&n, 1)\n\t\t\t\t}\n\t\t\t}\n\t\t}()\n\t}\n\n\tfor i := 0; i < len(levels); i++ {\n\t\tdir := path.Join(dir, path.Join(selectors[i]...))\n\t\twork <- workItem{\n\t\t\tlevel: levels[i],\n\t\t\tdir: dir,\n\t\t\tselector: selectors[i],\n\t\t}\n\t}\n\n\tclose(work)\n\twg.Wait()\n\n\tif errs > 0 {\n\t\treturn int(n), fmt.Errorf(\"[METRICSTORE]> %d errors happened while creating checkpoints (%d successes)\", errs, n)\n\t}\n\treturn int(n), nil\n}\n\n// toCheckpointFile recursively converts a Level tree to CheckpointFile structure.\n// Skips metrics that are already archived. Returns nil if no unarchived data exists.\nfunc (l *Level) toCheckpointFile(from, to int64, m *MemoryStore) (*CheckpointFile, error) {\n\tl.lock.RLock()\n\tdefer l.lock.RUnlock()\n\n\tretval := &CheckpointFile{\n\t\tFrom: from,\n\t\tTo: to,\n\t\tMetrics: make(map[string]*CheckpointMetrics),\n\t\tChildren: make(map[string]*CheckpointFile),\n\t}\n\n\tfor metric, minfo := range m.Metrics {\n\t\tb := l.metrics[minfo.offset]\n\t\tif b == nil {\n\t\t\tcontinue\n\t\t}\n\n\t\tallArchived := true\n\t\tb.iterFromTo(from, to, func(b *buffer) error {\n\t\t\tif !b.archived {\n\t\t\t\tallArchived = false\n\t\t\t\treturn fmt.Errorf(\"stop\") // Early termination signal\n\t\t\t}\n\t\t\treturn nil\n\t\t})\n\n\t\tif allArchived {\n\t\t\tcontinue\n\t\t}\n\n\t\tdata := make([]schema.Float, (to-from)/b.frequency+1)\n\t\tdata, start, end, err := b.read(from, to, data)\n\t\tif err != nil {\n\t\t\treturn nil, err\n\t\t}\n\n\t\tfor i := int((end - start) / b.frequency); i < len(data); i++ {\n\t\t\tdata[i] = schema.NaN\n\t\t}\n\n\t\tretval.Metrics[metric] = &CheckpointMetrics{\n\t\t\tFrequency: b.frequency,\n\t\t\tStart: start,\n\t\t\tData: data,\n\t\t}\n\t}\n\n\tfor name, child := range l.children {\n\t\tval, err := child.toCheckpointFile(from, to, m)\n\t\tif err != nil {\n\t\t\treturn nil, err\n\t\t}\n\n\t\tif val != nil {\n\t\t\tretval.Children[name] = val\n\t\t}\n\t}\n\n\tif len(retval.Children) == 0 && len(retval.Metrics) == 0 {\n\t\treturn nil, nil\n\t}\n\n\treturn retval, nil\n}\n\n// toCheckpoint writes a Level's data to a JSON checkpoint file.\n// Creates directory if needed. Returns ErrNoNewArchiveData if nothing to save.\nfunc (l *Level) toCheckpoint(dir string, from, to int64, m *MemoryStore) error {\n\tcf, err := l.toCheckpointFile(from, to, m)\n\tif err != nil {\n\t\treturn err\n\t}\n\n\tif cf == nil {\n\t\treturn ErrNoNewArchiveData\n\t}\n\n\tfilepath := path.Join(dir, fmt.Sprintf(\"%d.json\", from))\n\tf, err := os.OpenFile(filepath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, CheckpointFilePerms)\n\tif err != nil && os.IsNotExist(err) {\n\t\terr = os.MkdirAll(dir, CheckpointDirPerms)\n\t\tif err == nil {\n\t\t\tf, err = os.OpenFile(filepath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, CheckpointFilePerms)\n\t\t}\n\t}\n\tif err != nil {\n\t\treturn err\n\t}\n\tdefer f.Close()\n\n\tbw := bufio.NewWriter(f)\n\tif err = json.NewEncoder(bw).Encode(cf); err != nil {\n\t\treturn err\n\t}\n\n\treturn bw.Flush()\n}\n\n// enqueueCheckpointHosts traverses checkpoint directory and enqueues cluster/host pairs.\n// Returns error if directory structure is invalid.\nfunc enqueueCheckpointHosts(dir string, work chan<- [2]string) error {\n\tclustersDir, err := os.ReadDir(dir)\n\tif err != nil {\n\t\treturn err\n\t}\n\n\tfor _, clusterDir := range clustersDir {\n\t\tif !clusterDir.IsDir() {\n\t\t\treturn errors.New(\"[METRICSTORE]> expected only directories at first level of checkpoints/ directory\")\n\t\t}\n\n\t\thostsDir, err := os.ReadDir(filepath.Join(dir, clusterDir.Name()))\n\t\tif err != nil {\n\t\t\treturn err\n\t\t}\n\n\t\tfor _, hostDir := range hostsDir {\n\t\t\tif !hostDir.IsDir() {\n\t\t\t\treturn errors.New(\"[METRICSTORE]> expected only directories at second level of checkpoints/ directory\")\n\t\t\t}\n\n\t\t\twork <- [2]string{clusterDir.Name(), hostDir.Name()}\n\t\t}\n\t}\n\n\treturn nil\n}\n\n// FromCheckpoint loads checkpoint files from disk into memory in parallel.\n//\n// Uses worker pool to load cluster/host combinations. Returns number of files\n// loaded and any errors.\nfunc (m *MemoryStore) FromCheckpoint(dir string, from int64) (int, error) {\n\tvar wg sync.WaitGroup\n\twork := make(chan [2]string, Keys.NumWorkers*4)\n\tn, errs := int32(0), int32(0)\n\n\twg.Add(Keys.NumWorkers)\n\tfor worker := 0; worker < Keys.NumWorkers; worker++ {\n\t\tgo func() {\n\t\t\tdefer wg.Done()\n\t\t\tfor host := range work {\n\t\t\t\tlvl := m.root.findLevelOrCreate(host[:], len(m.Metrics))\n\t\t\t\tnn, err := lvl.fromCheckpoint(m, filepath.Join(dir, host[0], host[1]), from)\n\t\t\t\tif err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> error while loading checkpoints for %s/%s: %s\", host[0], host[1], err.Error())\n\t\t\t\t\tatomic.AddInt32(&errs, 1)\n\t\t\t\t}\n\t\t\t\tatomic.AddInt32(&n, int32(nn))\n\t\t\t}\n\t\t}()\n\t}\n\n\terr := enqueueCheckpointHosts(dir, work)\n\tclose(work)\n\twg.Wait()\n\n\tif err != nil {\n\t\treturn int(n), err\n\t}\n\n\tif errs > 0 {\n\t\treturn int(n), fmt.Errorf(\"[METRICSTORE]> %d errors happened while creating checkpoints (%d successes)\", errs, n)\n\t}\n\treturn int(n), nil\n}\n\n// FromCheckpointFiles is the main entry point for loading checkpoints at startup.\n//\n// Creates checkpoint directory if it doesn't exist. This function must be called\n// before any writes or reads, and can only be called once.\nfunc (m *MemoryStore) FromCheckpointFiles(dir string, from int64) (int, error) {\n\tif _, err := os.Stat(dir); os.IsNotExist(err) {\n\t\terr := os.MkdirAll(dir, CheckpointDirPerms)\n\t\tif err != nil {\n\t\t\tcclog.Fatalf(\"[METRICSTORE]> Error creating directory: %#v\\n\", err)\n\t\t}\n\t\tcclog.Debugf(\"[METRICSTORE]> %#v Directory created successfully\", dir)\n\t}\n\n\treturn m.FromCheckpoint(dir, from)\n}\n\nfunc (l *Level) loadJSONFile(m *MemoryStore, f *os.File, from int64) error {\n\tbr := bufio.NewReader(f)\n\tcf := &CheckpointFile{}\n\tif err := json.NewDecoder(br).Decode(cf); err != nil {\n\t\treturn err\n\t}\n\n\tif cf.To != 0 && cf.To < from {\n\t\treturn nil\n\t}\n\n\tif err := l.loadFile(cf, m); err != nil {\n\t\treturn err\n\t}\n\n\treturn nil\n}\n\nfunc (l *Level) loadFile(cf *CheckpointFile, m *MemoryStore) error {\n\tfor name, metric := range cf.Metrics {\n\t\tn := len(metric.Data)\n\t\tb := &buffer{\n\t\t\tfrequency: metric.Frequency,\n\t\t\tstart: metric.Start,\n\t\t\tdata: metric.Data[0:n:n],\n\t\t\tprev: nil,\n\t\t\tnext: nil,\n\t\t\tarchived: true,\n\t\t}\n\n\t\tminfo, ok := m.Metrics[name]\n\t\tif !ok {\n\t\t\tcontinue\n\t\t}\n\n\t\tprev := l.metrics[minfo.offset]\n\t\tif prev == nil {\n\t\t\tl.metrics[minfo.offset] = b\n\t\t} else {\n\t\t\tif prev.start > b.start {\n\t\t\t\treturn fmt.Errorf(\"[METRICSTORE]> buffer start time %d is before previous buffer start %d\", b.start, prev.start)\n\t\t\t}\n\n\t\t\tb.prev = prev\n\t\t\tprev.next = b\n\t\t}\n\t\tl.metrics[minfo.offset] = b\n\t}\n\n\tif len(cf.Children) > 0 && l.children == nil {\n\t\tl.children = make(map[string]*Level)\n\t}\n\n\tfor sel, childCf := range cf.Children {\n\t\tchild, ok := l.children[sel]\n\t\tif !ok {\n\t\t\tchild = &Level{\n\t\t\t\tmetrics: make([]*buffer, len(m.Metrics)),\n\t\t\t\tchildren: nil,\n\t\t\t}\n\t\t\tl.children[sel] = child\n\t\t}\n\n\t\tif err := child.loadFile(childCf, m); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\n\treturn nil\n}\n\n// fromCheckpoint loads all checkpoint files (JSON, binary snapshot, WAL) for a\n// single host directory. Snapshot files are loaded first (sorted by timestamp),\n// then current.wal is replayed on top.\nfunc (l *Level) fromCheckpoint(m *MemoryStore, dir string, from int64) (int, error) {\n\tdirentries, err := os.ReadDir(dir)\n\tif err != nil {\n\t\tif os.IsNotExist(err) {\n\t\t\treturn 0, nil\n\t\t}\n\t\treturn 0, err\n\t}\n\n\tallFiles := make([]fs.DirEntry, 0)\n\tvar walEntry fs.DirEntry\n\tfilesLoaded := 0\n\n\tfor _, e := range direntries {\n\t\tif e.IsDir() {\n\t\t\t// Legacy: skip subdirectories (only used by old Avro format).\n\t\t\t// These are ignored; their data is not loaded.\n\t\t\tcclog.Debugf(\"[METRICSTORE]> skipping subdirectory %s in checkpoint dir %s\", e.Name(), dir)\n\t\t\tcontinue\n\t\t}\n\n\t\tname := e.Name()\n\t\tif strings.HasSuffix(name, \".json\") || strings.HasSuffix(name, \".bin\") {\n\t\t\tallFiles = append(allFiles, e)\n\t\t} else if name == \"current.wal\" {\n\t\t\twalEntry = e\n\t\t}\n\t\t// Silently ignore other files (e.g., .tmp, .bin.tmp from interrupted writes).\n\t}\n\n\tfiles, err := findFiles(allFiles, from, true)\n\tif err != nil {\n\t\treturn filesLoaded, err\n\t}\n\n\tloaders := map[string]func(*MemoryStore, *os.File, int64) error{\n\t\t\".json\": l.loadJSONFile,\n\t\t\".bin\": l.loadBinaryFile,\n\t}\n\n\tfor _, filename := range files {\n\t\text := filepath.Ext(filename)\n\t\tloader := loaders[ext]\n\t\tif loader == nil {\n\t\t\tcclog.Warnf(\"[METRICSTORE]> unknown extension for checkpoint file %s\", filename)\n\t\t\tcontinue\n\t\t}\n\n\t\terr := func() error {\n\t\t\tf, err := os.Open(path.Join(dir, filename))\n\t\t\tif err != nil {\n\t\t\t\treturn err\n\t\t\t}\n\t\t\tdefer f.Close()\n\t\t\treturn loader(m, f, from)\n\t\t}()\n\t\tif err != nil {\n\t\t\treturn filesLoaded, err\n\t\t}\n\t\tfilesLoaded++\n\t}\n\n\t// Replay WAL after all snapshot files so it fills in data since the last snapshot.\n\tif walEntry != nil {\n\t\terr := func() error {\n\t\t\tf, err := os.Open(path.Join(dir, walEntry.Name()))\n\t\t\tif err != nil {\n\t\t\t\treturn err\n\t\t\t}\n\t\t\tdefer f.Close()\n\t\t\treturn l.loadWALFile(m, f, from)\n\t\t}()\n\t\tif err != nil {\n\t\t\t// WAL errors are non-fatal: the snapshot already loaded the bulk of data.\n\t\t\tcclog.Warnf(\"[METRICSTORE]> WAL replay error for %s: %v (data since last snapshot may be missing)\", dir, err)\n\t\t} else {\n\t\t\tfilesLoaded++\n\t\t}\n\t}\n\n\treturn filesLoaded, nil\n}\n\n// parseTimestampFromFilename extracts a Unix timestamp from a checkpoint filename.\n// Supports \".json\" (format: \"<ts>.json\") and \".bin\" (format: \"<ts>.bin\").\nfunc parseTimestampFromFilename(name string) (int64, error) {\n\tswitch {\n\tcase strings.HasSuffix(name, \".json\"):\n\t\treturn strconv.ParseInt(name[:len(name)-5], 10, 64)\n\tcase strings.HasSuffix(name, \".bin\"):\n\t\treturn strconv.ParseInt(name[:len(name)-4], 10, 64)\n\tdefault:\n\t\treturn 0, fmt.Errorf(\"unknown checkpoint extension for file %q\", name)\n\t}\n}\n\n// findFiles returns filenames from direntries whose timestamps satisfy the filter.\n// If findMoreRecentFiles is true, returns files with timestamps >= t (plus the\n// last file before t if t falls between two files).\nfunc findFiles(direntries []fs.DirEntry, t int64, findMoreRecentFiles bool) ([]string, error) {\n\tnums := map[string]int64{}\n\tfor _, e := range direntries {\n\t\tname := e.Name()\n\t\tif !strings.HasSuffix(name, \".json\") && !strings.HasSuffix(name, \".bin\") {\n\t\t\tcontinue\n\t\t}\n\n\t\tts, err := parseTimestampFromFilename(name)\n\t\tif err != nil {\n\t\t\treturn nil, err\n\t\t}\n\t\tnums[name] = ts\n\t}\n\n\tsort.Slice(direntries, func(i, j int) bool {\n\t\ta, b := direntries[i], direntries[j]\n\t\treturn nums[a.Name()] < nums[b.Name()]\n\t})\n\n\tif len(nums) == 0 {\n\t\treturn nil, nil\n\t}\n\n\tfilenames := make([]string, 0)\n\n\tfor i, e := range direntries {\n\t\tts1 := nums[e.Name()]\n\n\t\tif findMoreRecentFiles && t <= ts1 {\n\t\t\tfilenames = append(filenames, e.Name())\n\t\t} else if !findMoreRecentFiles && ts1 <= t && ts1 != 0 {\n\t\t\tfilenames = append(filenames, e.Name())\n\t\t}\n\n\t\tif i == len(direntries)-1 {\n\t\t\tcontinue\n\t\t}\n\n\t\tenext := direntries[i+1]\n\t\tts2 := nums[enext.Name()]\n\n\t\tif findMoreRecentFiles {\n\t\t\tif ts1 < t && t < ts2 {\n\t\t\t\tfilenames = append(filenames, e.Name())\n\t\t\t}\n\t\t}\n\t}\n\n\treturn filenames, nil\n}\n","structuredPatch":[{"oldStart":129,"oldLines":7,"newStart":129,"newLines":8,"lines":[" n, hostDirs, err := ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), now.Unix())"," if err != nil {"," cclog.Errorf(\"[METRICSTORE]> binary checkpointing failed: %s\", err.Error())","- } else {","+ }","+ if n > 0 {"," cclog.Infof(\"[METRICSTORE]> done: %d binary snapshot files created\", n)"," lastCheckpointMu.Lock()"," lastCheckpoint = 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This file is part of cc-backend.\n// Use of this source code is governed by a MIT-style\n// license that can be found in the LICENSE file.\n\n// Package metricstore provides config.go: Configuration structures and metric management.\n//\n// # Configuration Hierarchy\n//\n// The metricstore package uses nested configuration structures:\n//\n//\tMetricStoreConfig (Keys)\n//\t├─ NumWorkers: Parallel checkpoint/archive workers\n//\t├─ RetentionInMemory: How long to keep data in RAM (also used as cleanup interval)\n//\t├─ MemoryCap: Memory limit in bytes (triggers forceFree)\n//\t├─ Checkpoints: Persistence configuration\n//\t│ ├─ FileFormat: \"json\" or \"wal\" (default: \"wal\")\n//\t│ └─ RootDir: Checkpoint storage path\n//\t├─ Cleanup: Long-term storage configuration (interval = RetentionInMemory)\n//\t│ ├─ RootDir: Archive storage path (archive mode only)\n//\t│ └─ Mode: \"delete\" or \"archive\"\n//\t├─ Debug: Development/debugging options\n//\t└─ Subscriptions: NATS topic subscriptions for metric ingestion\n//\n// # Metric Configuration\n//\n// Each metric (e.g., \"cpu_load\", \"mem_used\") has a MetricConfig entry in the global\n// Metrics map, defining:\n//\n// - Frequency: Measurement interval in seconds\n// - Aggregation: How to combine values (sum/avg/none) when transforming scopes\n// - offset: Internal index into Level.metrics slice (assigned during Init)\n//\n// # AggregationStrategy\n//\n// Determines how to combine metric values when aggregating from finer to coarser scopes:\n//\n// - NoAggregation: Do not combine (incompatible scopes)\n// - SumAggregation: Add values (e.g., power consumption: core→socket)\n// - AvgAggregation: Average values (e.g., temperature: core→socket)\npackage metricstore\n\nimport (\n\t\"fmt\"\n\t\"time\"\n\n\t\"github.com/ClusterCockpit/cc-backend/pkg/archive\"\n\tcclog \"github.com/ClusterCockpit/cc-lib/v2/ccLogger\"\n\t\"github.com/ClusterCockpit/cc-lib/v2/schema\"\n)\n\nconst (\n\tDefaultMaxWorkers = 10\n\tDefaultBufferCapacity = 512\n\tDefaultGCTriggerInterval = 100\n\tDefaultMemoryUsageTrackerInterval = 5 * time.Minute\n)\n\n// Checkpoints configures periodic persistence of in-memory metric data.\n//\n// Fields:\n// - FileFormat: \"json\" (human-readable, periodic) or \"wal\" (binary snapshot + WAL, crash-safe); default is \"wal\"\n// - RootDir: Filesystem path for checkpoint files (created if missing)\ntype Checkpoints struct {\n\tFileFormat string `json:\"file-format\"`\n\tRootDir string `json:\"directory\"`\n}\n\n// Debug provides development and profiling options.\n//\n// Fields:\n// - DumpToFile: Path to dump checkpoint data for inspection (empty = disabled)\n// - EnableGops: Enable gops agent for live runtime debugging (https://github.com/google/gops)\ntype Debug struct {\n\tDumpToFile string `json:\"dump-to-file\"`\n\tEnableGops bool `json:\"gops\"`\n}\n\n// Cleanup configures long-term storage of old metric data.\n//\n// Data older than RetentionInMemory is archived to disk or deleted.\n// The cleanup interval is always RetentionInMemory.\n//\n// Fields:\n// - RootDir: Filesystem path for archived data (used in \"archive\" mode)\n// - Mode: \"delete\" (discard old data) or \"archive\" (write to RootDir)\ntype Cleanup struct {\n\tRootDir string `json:\"directory\"`\n\tMode string `json:\"mode\"`\n}\n\n// Subscriptions defines NATS topics to subscribe to for metric ingestion.\n//\n// Each subscription receives metrics via NATS messaging, enabling real-time\n// data collection from compute nodes.\n//\n// Fields:\n// - SubscribeTo: NATS subject/channel name (e.g., \"metrics.compute.*\")\n// - ClusterTag: Default cluster name for metrics without cluster tag (optional)\ntype Subscriptions []struct {\n\t// Channel name\n\tSubscribeTo string `json:\"subscribe-to\"`\n\n\t// Allow lines without a cluster tag, use this as default, optional\n\tClusterTag string `json:\"cluster-tag\"`\n}\n\n// MetricStoreConfig defines the main configuration for the metricstore.\n//\n// Loaded from cc-backend's config.json \"metricstore\" section. Controls memory usage,\n// persistence, archiving, and metric ingestion.\n//\n// Fields:\n// - NumWorkers: Parallel workers for checkpoint/archive (0 = auto: min(NumCPU/2+1, 10))\n// - RetentionInMemory: Duration string (e.g., \"48h\") for in-memory data retention\n// - MemoryCap: Max memory in GB for buffer data (0 = unlimited); triggers forceFree when exceeded\n// - Checkpoints: Periodic persistence configuration\n// - Debug: Development/profiling options (nil = disabled)\n// - Archive: Long-term storage configuration (nil = disabled)\n// - Subscriptions: NATS topics for metric ingestion (nil = polling only)\ntype MetricStoreConfig struct {\n\t// Number of concurrent workers for checkpoint and archive operations.\n\t// If not set or 0, defaults to min(runtime.NumCPU()/2+1, 10)\n\tNumWorkers int `json:\"num-workers\"`\n\tRetentionInMemory string `json:\"retention-in-memory\"`\n\tCheckpointInterval string `json:\"checkpoint-interval,omitempty\"`\n\tMemoryCap int `json:\"memory-cap\"`\n\tCheckpoints Checkpoints `json:\"checkpoints\"`\n\tDebug *Debug `json:\"debug\"`\n\tCleanup *Cleanup `json:\"cleanup\"`\n\tSubscriptions *Subscriptions `json:\"nats-subscriptions\"`\n}\n\n// Keys is the global metricstore configuration instance.\n//\n// Initialized with defaults, then overwritten by cc-backend's config.json.\n// Accessed by Init(), Checkpointing(), and other lifecycle functions.\nvar Keys MetricStoreConfig = MetricStoreConfig{\n\tCheckpoints: Checkpoints{\n\t\tFileFormat: \"wal\",\n\t\tRootDir: \"./var/checkpoints\",\n\t},\n\tCleanup: &Cleanup{\n\t\tMode: \"delete\",\n\t},\n}\n\n// AggregationStrategy defines how to combine metric values across hierarchy levels.\n//\n// Used when transforming data from finer-grained scopes (e.g., core) to coarser scopes\n// (e.g., socket). This is SPATIAL aggregation, not TEMPORAL (time-based) aggregation.\n//\n// Values:\n// - NoAggregation: Do not aggregate (incompatible scopes or non-aggregatable metrics)\n// - SumAggregation: Add values (e.g., power: sum core power → socket power)\n// - AvgAggregation: Average values (e.g., temperature: average core temps → socket temp)\ntype AggregationStrategy int\n\nconst (\n\tNoAggregation AggregationStrategy = iota // Do not aggregate\n\tSumAggregation // Sum values (e.g., power, energy)\n\tAvgAggregation // Average values (e.g., temperature, utilization)\n)\n\n// AssignAggregationStrategy parses a string into an AggregationStrategy value.\n//\n// Used when loading metric configurations from JSON/YAML files.\n//\n// Parameters:\n// - str: \"sum\", \"avg\", or \"\" (empty string for NoAggregation)\n//\n// Returns:\n// - AggregationStrategy: Parsed value\n// - error: Non-nil if str is unrecognized\nfunc AssignAggregationStrategy(str string) (AggregationStrategy, error) {\n\tswitch str {\n\tcase \"\":\n\t\treturn NoAggregation, nil\n\tcase \"sum\":\n\t\treturn SumAggregation, nil\n\tcase \"avg\":\n\t\treturn AvgAggregation, nil\n\tdefault:\n\t\treturn NoAggregation, fmt.Errorf(\"[METRICSTORE]> unknown aggregation strategy: %s\", str)\n\t}\n}\n\n// MetricConfig defines configuration for a single metric type.\n//\n// Stored in the global Metrics map, keyed by metric name (e.g., \"cpu_load\").\n//\n// Fields:\n// - Frequency: Measurement interval in seconds (e.g., 60 for 1-minute granularity)\n// - Aggregation: How to combine values across hierarchy levels (sum/avg/none)\n// - offset: Internal index into Level.metrics slice (assigned during Init)\ntype MetricConfig struct {\n\t// Interval in seconds at which measurements are stored\n\tFrequency int64\n\n\t// Can be 'sum', 'avg' or null. Describes how to aggregate metrics from the same timestep over the hierarchy.\n\tAggregation AggregationStrategy\n\n\t// Private, used internally...\n\toffset int\n}\n\nfunc BuildMetricList() map[string]MetricConfig {\n\tvar metrics map[string]MetricConfig = make(map[string]MetricConfig)\n\n\taddMetric := func(name string, metric MetricConfig) error {\n\t\tif metrics == nil {\n\t\t\tmetrics = make(map[string]MetricConfig, 0)\n\t\t}\n\n\t\tif existingMetric, ok := metrics[name]; ok {\n\t\t\tif existingMetric.Frequency != metric.Frequency {\n\t\t\t\tif existingMetric.Frequency < metric.Frequency {\n\t\t\t\t\texistingMetric.Frequency = metric.Frequency\n\t\t\t\t\tmetrics[name] = existingMetric\n\t\t\t\t}\n\t\t\t}\n\t\t} else {\n\t\t\tmetrics[name] = metric\n\t\t}\n\n\t\treturn nil\n\t}\n\n\t// Helper function to add metric configuration\n\taddMetricConfig := func(mc *schema.MetricConfig) {\n\t\tagg, err := AssignAggregationStrategy(mc.Aggregation)\n\t\tif err != nil {\n\t\t\tcclog.Warnf(\"Could not find aggregation strategy for metric config '%s': %s\", mc.Name, err.Error())\n\t\t}\n\n\t\taddMetric(mc.Name, MetricConfig{\n\t\t\tFrequency: int64(mc.Timestep),\n\t\t\tAggregation: agg,\n\t\t})\n\t}\n\tfor _, c := range archive.Clusters {\n\t\tfor _, mc := range c.MetricConfig {\n\t\t\taddMetricConfig(mc)\n\t\t}\n\n\t\tfor _, sc := range c.SubClusters {\n\t\t\tfor _, mc := range sc.MetricConfig {\n\t\t\t\taddMetricConfig(mc)\n\t\t\t}\n\t\t}\n\t}\n\n\treturn metrics\n}\n","structuredPatch":[{"oldStart":59,"oldLines":11,"newStart":59,"newLines":14,"lines":[" // Checkpoints configures periodic persistence of in-memory metric data."," //"," // Fields:","-// - FileFormat: \"json\" (human-readable, periodic) or \"wal\" (binary snapshot + WAL, crash-safe); default is \"wal\"","-// - RootDir: Filesystem path for checkpoint files (created if missing)","+// - FileFormat: \"json\" (human-readable, periodic) or \"wal\" (binary snapshot + WAL, crash-safe); default is \"wal\"","+// - RootDir: Filesystem path for checkpoint files (created if missing)","+// - MaxWALSize: Maximum size in bytes for a single host's WAL file; 0 = unlimited (default).","+// When exceeded the WAL is force-rotated to prevent unbounded disk growth."," type Checkpoints struct {"," FileFormat string `json:\"file-format\"`"," RootDir string `json:\"directory\"`","+ MaxWALSize int64 `json:\"max-wal-size,omitempty\"`"," }"," "," // Debug provides development and profiling options."]}],"userModified":false,"replaceAll":false},"sourceToolAssistantUUID":"2f8b6505-4164-49e5-8f42-c376d3a84d28","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"b41004ed-5eef-4c67-b5eb-c9571ea41a27","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01D19J2wE9cbwyu3KeZWeGrz","type":"tool_result","content":"The file /Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go has been updated successfully."}]},"uuid":"3f3bf098-af0f-4da8-b7b3-13e173195d3e","timestamp":"2026-03-28T05:20:58.343Z","toolUseResult":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","oldString":"// walFileState holds an open WAL file handle and buffered writer for one host directory.\ntype walFileState struct {\n\tf *os.File\n\tw *bufio.Writer\n\tdirty bool\n}","newString":"// walFileState holds an open WAL file handle and buffered writer for one host directory.\ntype walFileState struct {\n\tf *os.File\n\tw *bufio.Writer\n\tdirty bool\n\tsize int64 // approximate bytes written (tracked from open + writes)\n}","originalFile":"// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.\n// All rights reserved. This file is part of cc-backend.\n// Use of this source code is governed by a MIT-style\n// license that can be found in the LICENSE file.\n\n// Package metricstore provides walCheckpoint.go: WAL-based checkpoint implementation.\n//\n// This replaces the Avro shadow tree with an append-only Write-Ahead Log (WAL)\n// per host, eliminating the extra memory overhead of the AvroStore and providing\n// truly continuous (per-write) crash safety.\n//\n// # Architecture\n//\n//\tMetric write (DecodeLine)\n//\t │\n//\t ├─► WriteToLevel() → main MemoryStore (unchanged)\n//\t │\n//\t └─► WALMessages channel\n//\t │\n//\t ▼\n//\t WALStaging goroutine\n//\t │\n//\t ▼\n//\t checkpoints/cluster/host/current.wal (append-only, binary)\n//\n//\tPeriodic checkpoint (Checkpointing goroutine):\n//\t 1. Write <timestamp>.bin snapshot (column-oriented, from main tree)\n//\t 2. Signal WALStaging to truncate current.wal per host\n//\n//\tOn restart (FromCheckpoint):\n//\t 1. Load most recent <timestamp>.bin snapshot\n//\t 2. Replay current.wal (overwrite-safe: buffer.write handles duplicate timestamps)\n//\n// # WAL Record Format\n//\n//\t[4B magic 0xCC1DA7A1][4B payload_len][payload][4B CRC32]\n//\n//\tpayload:\n//\t [8B timestamp int64]\n//\t [2B metric_name_len uint16][N metric name bytes]\n//\t [1B selector_count uint8]\n//\t per selector: [1B selector_len uint8][M selector bytes]\n//\t [4B value float32 bits]\n//\n// # Binary Snapshot Format\n//\n//\t[4B magic 0xCC5B0001][8B from int64][8B to int64]\n//\tLevel tree (recursive):\n//\t [4B num_metrics uint32]\n//\t per metric:\n//\t [2B name_len uint16][N name bytes]\n//\t [8B frequency int64][8B start int64]\n//\t [4B num_values uint32][num_values × 4B float32]\n//\t [4B num_children uint32]\n//\t per child: [2B name_len uint16][N name bytes] + Level (recursive)\npackage metricstore\n\nimport (\n\t\"bufio\"\n\t\"context\"\n\t\"encoding/binary\"\n\t\"fmt\"\n\t\"hash/crc32\"\n\t\"hash/fnv\"\n\t\"io\"\n\t\"math\"\n\t\"os\"\n\t\"path\"\n\t\"strings\"\n\t\"sync\"\n\t\"sync/atomic\"\n\t\"time\"\n\n\tcclog \"github.com/ClusterCockpit/cc-lib/v2/ccLogger\"\n\t\"github.com/ClusterCockpit/cc-lib/v2/schema\"\n)\n\n// Magic numbers for binary formats.\nconst (\n\twalFileMagic = uint32(0xCC1DA701) // WAL file header magic\n\twalRecordMagic = uint32(0xCC1DA7A1) // WAL record magic\n\tsnapFileMagic = uint32(0xCC5B0001) // Binary snapshot magic\n)\n\n// walShardChs holds per-shard channels for WAL messages.\n// Initialized by WALStaging; nil when WAL is not active.\nvar walShardChs []chan *WALMessage\n\n// walShardRotateChs holds per-shard channels for WAL rotation requests.\nvar walShardRotateChs []chan walRotateReq\n\n// walNumShards stores the number of shards (set during WALStaging init).\nvar walNumShards int\n\n// walStagingWg tracks WALStaging goroutine exits for shutdown synchronization.\nvar walStagingWg sync.WaitGroup\n\n// walShuttingDown is set before closing shard channels to prevent\n// SendWALMessage from sending on a closed channel (which panics in Go).\nvar walShuttingDown atomic.Bool\n\n// WALMessage represents a single metric write to be appended to the WAL.\n// Cluster and Node are NOT stored in the WAL record (inferred from file path).\ntype WALMessage struct {\n\tMetricName string\n\tCluster string\n\tNode string\n\tSelector []string\n\tValue schema.Float\n\tTimestamp int64\n}\n\n// walRotateReq requests WAL file rotation for a specific host directory.\n// The done channel is closed by the WAL goroutine when rotation is complete.\ntype walRotateReq struct {\n\thostDir string\n\tdone chan struct{}\n}\n\n// walFileState holds an open WAL file handle and buffered writer for one host directory.\ntype walFileState struct {\n\tf *os.File\n\tw *bufio.Writer\n\tdirty bool\n}\n\n// walFlushInterval controls how often dirty WAL files are flushed to disk.\n// Decoupling flushes from message processing lets the consumer run at memory\n// speed, amortizing syscall overhead across many writes.\nconst walFlushInterval = 1 * time.Second\n\n// walShardIndex computes which shard a message belongs to based on cluster+node.\n// Uses FNV-1a hash for fast, well-distributed mapping.\nfunc walShardIndex(cluster, node string) int {\n\th := fnv.New32a()\n\th.Write([]byte(cluster))\n\th.Write([]byte{0})\n\th.Write([]byte(node))\n\treturn int(h.Sum32()) % walNumShards\n}\n\n// SendWALMessage routes a WAL message to the appropriate shard channel.\n// Returns false if the channel is full or shutdown is in progress.\nfunc SendWALMessage(msg *WALMessage) bool {\n\tif walShardChs == nil || walShuttingDown.Load() {\n\t\treturn false\n\t}\n\tshard := walShardIndex(msg.Cluster, msg.Node)\n\tselect {\n\tcase walShardChs[shard] <- msg:\n\t\treturn true\n\tdefault:\n\t\treturn false\n\t}\n}\n\n// WALStaging starts N sharded background goroutines that receive WALMessage items\n// and append binary WAL records to per-host current.wal files.\n// Each shard owns a subset of hosts (determined by hash of cluster+node),\n// parallelizing serialization and I/O while keeping per-host writes serial.\nfunc WALStaging(wg *sync.WaitGroup, ctx context.Context) {\n\tif Keys.Checkpoints.FileFormat == \"json\" {\n\t\treturn\n\t}\n\n\twalNumShards = max(Keys.NumWorkers, 1)\n\tchBufSize := max(65536/walNumShards, 1024)\n\n\twalShardChs = make([]chan *WALMessage, walNumShards)\n\twalShardRotateChs = make([]chan walRotateReq, walNumShards)\n\n\tfor i := range walNumShards {\n\t\twalShardChs[i] = make(chan *WALMessage, chBufSize)\n\t\twalShardRotateChs[i] = make(chan walRotateReq, 64)\n\t}\n\n\tfor i := range walNumShards {\n\t\tmsgCh := walShardChs[i]\n\t\trotateCh := walShardRotateChs[i]\n\n\t\twalStagingWg.Add(1)\n\t\twg.Go(func() {\n\t\t\tdefer walStagingWg.Done()\n\t\t\thostFiles := make(map[string]*walFileState)\n\n\t\t\tdefer func() {\n\t\t\t\tfor _, ws := range hostFiles {\n\t\t\t\t\tif ws.f != nil {\n\t\t\t\t\t\tws.w.Flush()\n\t\t\t\t\t\tws.f.Close()\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}()\n\n\t\t\tgetOrOpenWAL := func(hostDir string) *walFileState {\n\t\t\t\tws, ok := hostFiles[hostDir]\n\t\t\t\tif ok {\n\t\t\t\t\treturn ws\n\t\t\t\t}\n\n\t\t\t\tif err := os.MkdirAll(hostDir, CheckpointDirPerms); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: mkdir %s: %v\", hostDir, err)\n\t\t\t\t\treturn nil\n\t\t\t\t}\n\n\t\t\t\twalPath := path.Join(hostDir, \"current.wal\")\n\t\t\t\tf, err := os.OpenFile(walPath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, CheckpointFilePerms)\n\t\t\t\tif err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: open %s: %v\", walPath, err)\n\t\t\t\t\treturn nil\n\t\t\t\t}\n\n\t\t\t\tw := bufio.NewWriter(f)\n\n\t\t\t\t// Write file header magic if file is new (empty).\n\t\t\t\tinfo, err := f.Stat()\n\t\t\t\tif err == nil && info.Size() == 0 {\n\t\t\t\t\tvar hdr [4]byte\n\t\t\t\t\tbinary.LittleEndian.PutUint32(hdr[:], walFileMagic)\n\t\t\t\t\tif _, err := w.Write(hdr[:]); err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write header %s: %v\", walPath, err)\n\t\t\t\t\t\tf.Close()\n\t\t\t\t\t\treturn nil\n\t\t\t\t\t}\n\t\t\t\t}\n\n\t\t\t\tws = &walFileState{f: f, w: w}\n\t\t\t\thostFiles[hostDir] = ws\n\t\t\t\treturn ws\n\t\t\t}\n\n\t\t\tprocessMsg := func(msg *WALMessage) {\n\t\t\t\thostDir := path.Join(Keys.Checkpoints.RootDir, msg.Cluster, msg.Node)\n\t\t\t\tws := getOrOpenWAL(hostDir)\n\t\t\t\tif ws == nil {\n\t\t\t\t\treturn\n\t\t\t\t}\n\t\t\t\tif err := writeWALRecordDirect(ws.w, msg); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write record: %v\", err)\n\t\t\t\t}\n\t\t\t\tws.dirty = true\n\t\t\t}\n\n\t\t\tprocessRotate := func(req walRotateReq) {\n\t\t\t\tws, ok := hostFiles[req.hostDir]\n\t\t\t\tif ok && ws.f != nil {\n\t\t\t\t\tws.w.Flush()\n\t\t\t\t\tws.f.Close()\n\t\t\t\t\twalPath := path.Join(req.hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tdelete(hostFiles, req.hostDir)\n\t\t\t\t}\n\t\t\t\tclose(req.done)\n\t\t\t}\n\n\t\t\tflushDirty := func() {\n\t\t\t\tfor _, ws := range hostFiles {\n\t\t\t\t\tif ws.dirty {\n\t\t\t\t\t\tws.w.Flush()\n\t\t\t\t\t\tws.dirty = false\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}\n\n\t\t\tticker := time.NewTicker(walFlushInterval)\n\t\t\tdefer ticker.Stop()\n\n\t\t\t// drainBatch processes up to 4096 pending messages without blocking.\n\t\t\t// Returns false if the channel was closed.\n\t\t\tdrainBatch := func() bool {\n\t\t\t\tfor range 4096 {\n\t\t\t\t\tselect {\n\t\t\t\t\tcase msg, ok := <-msgCh:\n\t\t\t\t\t\tif !ok {\n\t\t\t\t\t\t\tflushDirty()\n\t\t\t\t\t\t\treturn false\n\t\t\t\t\t\t}\n\t\t\t\t\t\tprocessMsg(msg)\n\t\t\t\t\tcase req := <-rotateCh:\n\t\t\t\t\t\tprocessRotate(req)\n\t\t\t\t\tdefault:\n\t\t\t\t\t\treturn true\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\treturn true\n\t\t\t}\n\n\t\t\tfor {\n\t\t\t\tselect {\n\t\t\t\tcase <-ctx.Done():\n\t\t\t\t\t// On shutdown, skip draining buffered messages — a full binary\n\t\t\t\t\t// checkpoint will be written from in-memory state, making\n\t\t\t\t\t// buffered WAL records redundant.\n\t\t\t\t\tflushDirty()\n\t\t\t\t\treturn\n\t\t\t\tcase msg, ok := <-msgCh:\n\t\t\t\t\tif !ok {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t\tprocessMsg(msg)\n\t\t\t\t\tif !drainBatch() {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t\t// No flush here — timer handles periodic flushing.\n\t\t\t\tcase <-ticker.C:\n\t\t\t\t\tflushDirty()\n\t\t\t\tcase req := <-rotateCh:\n\t\t\t\t\tprocessRotate(req)\n\t\t\t\t}\n\t\t\t}\n\t\t})\n\t}\n}\n\n// WaitForWALStagingDrain blocks until all WALStaging goroutines have exited.\n// Must be called after closing walShardChs to ensure all file handles are\n// flushed and closed before checkpoint writes begin.\nfunc WaitForWALStagingDrain() {\n\twalStagingWg.Wait()\n}\n\n// RotateWALFiles sends rotation requests for the given host directories\n// and blocks until all rotations complete. Each request is routed to the\n// shard that owns the host directory.\n//\n// If shutdown is in progress (WAL staging goroutines may have exited),\n// rotation is skipped to avoid deadlocking on abandoned channels.\nfunc RotateWALFiles(hostDirs []string) {\n\tif walShardRotateChs == nil || walShuttingDown.Load() {\n\t\treturn\n\t}\n\tdones := make([]chan struct{}, 0, len(hostDirs))\n\tfor _, dir := range hostDirs {\n\t\tdone := make(chan struct{})\n\t\tshard := walShardIndexFromDir(dir)\n\t\tselect {\n\t\tcase walShardRotateChs[shard] <- walRotateReq{hostDir: dir, done: done}:\n\t\t\tdones = append(dones, done)\n\t\tdefault:\n\t\t\t// Channel full or goroutine not consuming — skip this host.\n\t\t\tcclog.Warnf(\"[METRICSTORE]> WAL rotation skipped for %s (channel full)\", dir)\n\t\t}\n\t}\n\tfor _, done := range dones {\n\t\tselect {\n\t\tcase <-done:\n\t\tcase <-time.After(30 * time.Second):\n\t\t\tcclog.Warn(\"[METRICSTORE]> WAL rotation timed out, continuing\")\n\t\t\treturn\n\t\t}\n\t}\n}\n\n// walShardIndexFromDir extracts cluster and node from a host directory path\n// and returns the shard index. The path format is: rootDir/cluster/node\nfunc walShardIndexFromDir(hostDir string) int {\n\t// hostDir = .../cluster/node — extract last two path components\n\tnode := path.Base(hostDir)\n\tcluster := path.Base(path.Dir(hostDir))\n\treturn walShardIndex(cluster, node)\n}\n\n// RotateWALFiles sends rotation requests for the given host directories\n// and blocks until all rotations complete.\nfunc RotateWALFilesAfterShutdown(hostDirs []string) {\n\tfor _, dir := range hostDirs {\n\t\twalPath := path.Join(dir, \"current.wal\")\n\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t}\n\t}\n}\n\n// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\n// then writes it to the bufio.Writer in a single call. This prevents partial\n// records in the write buffer if a write error occurs mid-record (e.g. disk full).\nfunc writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) error {\n\t// Compute payload and total record size.\n\tpayloadSize := 8 + 2 + len(msg.MetricName) + 1 + 4\n\tfor _, s := range msg.Selector {\n\t\tpayloadSize += 1 + len(s)\n\t}\n\t// Total: 8 (header) + payload + 4 (CRC).\n\ttotalSize := 8 + payloadSize + 4\n\n\t// Use stack buffer for typical small records, heap-allocate only for large ones.\n\tvar stackBuf [256]byte\n\tvar buf []byte\n\tif totalSize <= len(stackBuf) {\n\t\tbuf = stackBuf[:totalSize]\n\t} else {\n\t\tbuf = make([]byte, totalSize)\n\t}\n\n\t// Header: magic + payload length.\n\tbinary.LittleEndian.PutUint32(buf[0:4], walRecordMagic)\n\tbinary.LittleEndian.PutUint32(buf[4:8], uint32(payloadSize))\n\n\t// Payload starts at offset 8.\n\tp := 8\n\n\t// Timestamp (8 bytes).\n\tbinary.LittleEndian.PutUint64(buf[p:p+8], uint64(msg.Timestamp))\n\tp += 8\n\n\t// Metric name length (2 bytes) + metric name.\n\tbinary.LittleEndian.PutUint16(buf[p:p+2], uint16(len(msg.MetricName)))\n\tp += 2\n\tp += copy(buf[p:], msg.MetricName)\n\n\t// Selector count (1 byte).\n\tbuf[p] = byte(len(msg.Selector))\n\tp++\n\n\t// Selectors (1-byte length + bytes each).\n\tfor _, sel := range msg.Selector {\n\t\tbuf[p] = byte(len(sel))\n\t\tp++\n\t\tp += copy(buf[p:], sel)\n\t}\n\n\t// Value (4 bytes, float32 bits).\n\tbinary.LittleEndian.PutUint32(buf[p:p+4], math.Float32bits(float32(msg.Value)))\n\tp += 4\n\n\t// CRC32 over payload (bytes 8..8+payloadSize).\n\tcrc := crc32.ChecksumIEEE(buf[8 : 8+payloadSize])\n\tbinary.LittleEndian.PutUint32(buf[p:p+4], crc)\n\n\t// Single atomic write to the buffered writer.\n\t_, err := w.Write(buf)\n\treturn err\n}\n\n// readWALRecord reads one WAL record from the reader.\n// Returns (nil, nil) on clean EOF. Returns error on data corruption.\n// A CRC mismatch indicates a truncated trailing record (expected on crash).\nfunc readWALRecord(r io.Reader) (*WALMessage, error) {\n\tvar magic uint32\n\tif err := binary.Read(r, binary.LittleEndian, &magic); err != nil {\n\t\tif err == io.EOF {\n\t\t\treturn nil, nil // Clean EOF\n\t\t}\n\t\treturn nil, fmt.Errorf(\"read record magic: %w\", err)\n\t}\n\n\tif magic != walRecordMagic {\n\t\treturn nil, fmt.Errorf(\"invalid record magic 0x%08X (expected 0x%08X)\", magic, walRecordMagic)\n\t}\n\n\tvar payloadLen uint32\n\tif err := binary.Read(r, binary.LittleEndian, &payloadLen); err != nil {\n\t\treturn nil, fmt.Errorf(\"read payload length: %w\", err)\n\t}\n\n\tif payloadLen > 1<<20 { // 1 MB sanity limit\n\t\treturn nil, fmt.Errorf(\"record payload too large: %d bytes\", payloadLen)\n\t}\n\n\tpayload := make([]byte, payloadLen)\n\tif _, err := io.ReadFull(r, payload); err != nil {\n\t\treturn nil, fmt.Errorf(\"read payload: %w\", err)\n\t}\n\n\tvar storedCRC uint32\n\tif err := binary.Read(r, binary.LittleEndian, &storedCRC); err != nil {\n\t\treturn nil, fmt.Errorf(\"read CRC: %w\", err)\n\t}\n\n\tif crc32.ChecksumIEEE(payload) != storedCRC {\n\t\treturn nil, fmt.Errorf(\"CRC mismatch (truncated write or corruption)\")\n\t}\n\n\treturn parseWALPayload(payload)\n}\n\n// parseWALPayload decodes a binary payload into a WALMessage.\nfunc parseWALPayload(payload []byte) (*WALMessage, error) {\n\tif len(payload) < 8+2+1+4 {\n\t\treturn nil, fmt.Errorf(\"payload too short: %d bytes\", len(payload))\n\t}\n\n\toffset := 0\n\n\t// Timestamp (8 bytes)\n\tts := int64(binary.LittleEndian.Uint64(payload[offset : offset+8]))\n\toffset += 8\n\n\t// Metric name (2-byte length + bytes)\n\tif offset+2 > len(payload) {\n\t\treturn nil, fmt.Errorf(\"metric name length overflows payload\")\n\t}\n\tmLen := int(binary.LittleEndian.Uint16(payload[offset : offset+2]))\n\toffset += 2\n\n\tif offset+mLen > len(payload) {\n\t\treturn nil, fmt.Errorf(\"metric name overflows payload\")\n\t}\n\tmetricName := string(payload[offset : offset+mLen])\n\toffset += mLen\n\n\t// Selector count (1 byte)\n\tif offset >= len(payload) {\n\t\treturn nil, fmt.Errorf(\"selector count overflows payload\")\n\t}\n\tselCount := int(payload[offset])\n\toffset++\n\n\tselectors := make([]string, selCount)\n\tfor i := range selCount {\n\t\tif offset >= len(payload) {\n\t\t\treturn nil, fmt.Errorf(\"selector[%d] length overflows payload\", i)\n\t\t}\n\t\tsLen := int(payload[offset])\n\t\toffset++\n\n\t\tif offset+sLen > len(payload) {\n\t\t\treturn nil, fmt.Errorf(\"selector[%d] data overflows payload\", i)\n\t\t}\n\t\tselectors[i] = string(payload[offset : offset+sLen])\n\t\toffset += sLen\n\t}\n\n\t// Value (4 bytes, float32 bits)\n\tif offset+4 > len(payload) {\n\t\treturn nil, fmt.Errorf(\"value overflows payload\")\n\t}\n\tbits := binary.LittleEndian.Uint32(payload[offset : offset+4])\n\tvalue := schema.Float(math.Float32frombits(bits))\n\n\treturn &WALMessage{\n\t\tMetricName: metricName,\n\t\tTimestamp: ts,\n\t\tSelector: selectors,\n\t\tValue: value,\n\t}, nil\n}\n\n// loadWALFile reads a WAL file and replays all valid records into the Level tree.\n// l is the host-level node. Corrupt or partial trailing records are silently skipped\n// (expected on crash). Records older than 'from' are skipped.\nfunc (l *Level) loadWALFile(m *MemoryStore, f *os.File, from int64) error {\n\tbr := bufio.NewReader(f)\n\n\t// Verify file header magic.\n\tvar fileMagic uint32\n\tif err := binary.Read(br, binary.LittleEndian, &fileMagic); err != nil {\n\t\tif err == io.EOF {\n\t\t\treturn nil // Empty file, no data\n\t\t}\n\t\treturn fmt.Errorf(\"[METRICSTORE]> WAL: read file header: %w\", err)\n\t}\n\n\tif fileMagic != walFileMagic {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> WAL: invalid file magic 0x%08X (expected 0x%08X)\", fileMagic, walFileMagic)\n\t}\n\n\t// Cache level lookups to avoid repeated tree traversal.\n\tlvlCache := make(map[string]*Level)\n\n\tfor {\n\t\tmsg, err := readWALRecord(br)\n\t\tif err != nil {\n\t\t\t// Truncated trailing record is expected after a crash; stop replaying.\n\t\t\tcclog.Debugf(\"[METRICSTORE]> WAL: stopping replay at corrupted/partial record: %v\", err)\n\t\t\tbreak\n\t\t}\n\t\tif msg == nil {\n\t\t\tbreak // Clean EOF\n\t\t}\n\n\t\tif msg.Timestamp < from {\n\t\t\tcontinue // Older than retention window\n\t\t}\n\n\t\tminfo, ok := m.Metrics[msg.MetricName]\n\t\tif !ok {\n\t\t\tcontinue // Unknown metric (config may have changed)\n\t\t}\n\n\t\t// Cache key is the null-separated selector path.\n\t\tcacheKey := joinSelector(msg.Selector)\n\t\tlvl, ok := lvlCache[cacheKey]\n\t\tif !ok {\n\t\t\tlvl = l.findLevelOrCreate(msg.Selector, len(m.Metrics))\n\t\t\tlvlCache[cacheKey] = lvl\n\t\t}\n\n\t\t// Write directly to the buffer, same as WriteToLevel but without the\n\t\t// global level lookup (we already have the right level).\n\t\tlvl.lock.Lock()\n\t\tb := lvl.metrics[minfo.offset]\n\t\tif b == nil {\n\t\t\tb = newBuffer(msg.Timestamp, minfo.Frequency)\n\t\t\tlvl.metrics[minfo.offset] = b\n\t\t}\n\t\tnb, writeErr := b.write(msg.Timestamp, msg.Value)\n\t\tif writeErr == nil && b != nb {\n\t\t\tlvl.metrics[minfo.offset] = nb\n\t\t}\n\t\t// Ignore write errors for timestamps before buffer start (can happen when\n\t\t// replaying WAL entries that predate a loaded snapshot's start time).\n\t\tlvl.lock.Unlock()\n\t}\n\n\treturn nil\n}\n\n// joinSelector builds a cache key from a selector slice using null bytes as separators.\nfunc joinSelector(sel []string) string {\n\tif len(sel) == 0 {\n\t\treturn \"\"\n\t}\n\tvar result strings.Builder\n\tresult.WriteString(sel[0])\n\tfor i := 1; i < len(sel); i++ {\n\t\tresult.WriteString(\"\\x00\" + sel[i])\n\t}\n\treturn result.String()\n}\n\n// ToCheckpointWAL writes binary snapshot files for all hosts in parallel.\n// Returns the number of files written, the list of host directories that were\n// successfully checkpointed (for WAL rotation), and any errors.\nfunc (m *MemoryStore) ToCheckpointWAL(dir string, from, to int64) (int, []string, error) {\n\t// Collect all cluster/host pairs.\n\tm.root.lock.RLock()\n\ttotalHosts := 0\n\tfor _, l1 := range m.root.children {\n\t\tl1.lock.RLock()\n\t\ttotalHosts += len(l1.children)\n\t\tl1.lock.RUnlock()\n\t}\n\tm.root.lock.RUnlock()\n\n\tlevels := make([]*Level, 0, totalHosts)\n\tselectors := make([][]string, 0, totalHosts)\n\n\tm.root.lock.RLock()\n\tfor sel1, l1 := range m.root.children {\n\t\tl1.lock.RLock()\n\t\tfor sel2, l2 := range l1.children {\n\t\t\tlevels = append(levels, l2)\n\t\t\tselectors = append(selectors, []string{sel1, sel2})\n\t\t}\n\t\tl1.lock.RUnlock()\n\t}\n\tm.root.lock.RUnlock()\n\n\ttype workItem struct {\n\t\tlevel *Level\n\t\thostDir string\n\t\tselector []string\n\t}\n\n\ttotalWork := len(levels)\n\tcclog.Infof(\"[METRICSTORE]> Starting binary checkpoint for %d hosts with %d workers\", totalWork, Keys.NumWorkers)\n\n\tn, errs, completed := int32(0), int32(0), int32(0)\n\tvar successDirs []string\n\tvar successMu sync.Mutex\n\n\tvar wg sync.WaitGroup\n\twg.Add(Keys.NumWorkers)\n\twork := make(chan workItem, Keys.NumWorkers*2)\n\n\t// Progress logging goroutine.\n\tstopProgress := make(chan struct{})\n\tgo func() {\n\t\tticker := time.NewTicker(10 * time.Second)\n\t\tdefer ticker.Stop()\n\t\tfor {\n\t\t\tselect {\n\t\t\tcase <-ticker.C:\n\t\t\t\tcclog.Infof(\"[METRICSTORE]> Checkpoint progress: %d/%d hosts (%d written, %d errors)\",\n\t\t\t\t\tatomic.LoadInt32(&completed), totalWork, atomic.LoadInt32(&n), atomic.LoadInt32(&errs))\n\t\t\tcase <-stopProgress:\n\t\t\t\treturn\n\t\t\t}\n\t\t}\n\t}()\n\n\tfor range Keys.NumWorkers {\n\t\tgo func() {\n\t\t\tdefer wg.Done()\n\t\t\tfor wi := range work {\n\t\t\t\terr := wi.level.toCheckpointBinary(wi.hostDir, from, to, m)\n\t\t\t\tif err != nil {\n\t\t\t\t\tif err == ErrNoNewArchiveData {\n\t\t\t\t\t\tatomic.AddInt32(&completed, 1)\n\t\t\t\t\t\tcontinue\n\t\t\t\t\t}\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> binary checkpoint error for %s: %v\", wi.hostDir, err)\n\t\t\t\t\tatomic.AddInt32(&errs, 1)\n\t\t\t\t} else {\n\t\t\t\t\tatomic.AddInt32(&n, 1)\n\t\t\t\t\t// Delete WAL immediately after successful snapshot.\n\t\t\t\t\twalPath := path.Join(wi.hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tsuccessMu.Lock()\n\t\t\t\t\tsuccessDirs = append(successDirs, wi.hostDir)\n\t\t\t\t\tsuccessMu.Unlock()\n\t\t\t\t}\n\t\t\t\tatomic.AddInt32(&completed, 1)\n\t\t\t}\n\t\t}()\n\t}\n\n\tfor i := range levels {\n\t\thostDir := path.Join(dir, path.Join(selectors[i]...))\n\t\twork <- workItem{\n\t\t\tlevel: levels[i],\n\t\t\thostDir: hostDir,\n\t\t\tselector: selectors[i],\n\t\t}\n\t}\n\tclose(work)\n\twg.Wait()\n\tclose(stopProgress)\n\n\tif errs > 0 {\n\t\treturn int(n), successDirs, fmt.Errorf(\"[METRICSTORE]> %d errors during binary checkpoint (%d successes)\", errs, n)\n\t}\n\treturn int(n), successDirs, nil\n}\n\n// toCheckpointBinary writes a binary snapshot file for a single host-level node.\n// Uses atomic rename (write to .tmp then rename) to avoid partial reads on crash.\nfunc (l *Level) toCheckpointBinary(dir string, from, to int64, m *MemoryStore) error {\n\tcf, err := l.toCheckpointFile(from, to, m)\n\tif err != nil {\n\t\treturn err\n\t}\n\tif cf == nil {\n\t\treturn ErrNoNewArchiveData\n\t}\n\n\tif err := os.MkdirAll(dir, CheckpointDirPerms); err != nil {\n\t\treturn fmt.Errorf(\"mkdir %s: %w\", dir, err)\n\t}\n\n\t// Write to a temp file first, then rename (atomic on POSIX).\n\ttmpPath := path.Join(dir, fmt.Sprintf(\"%d.bin.tmp\", from))\n\tfinalPath := path.Join(dir, fmt.Sprintf(\"%d.bin\", from))\n\n\tf, err := os.OpenFile(tmpPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, CheckpointFilePerms)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"open binary snapshot %s: %w\", tmpPath, err)\n\t}\n\n\tbw := bufio.NewWriter(f)\n\tif err := writeBinarySnapshotFile(bw, cf); err != nil {\n\t\tf.Close()\n\t\tos.Remove(tmpPath)\n\t\treturn fmt.Errorf(\"write binary snapshot: %w\", err)\n\t}\n\tif err := bw.Flush(); err != nil {\n\t\tf.Close()\n\t\tos.Remove(tmpPath)\n\t\treturn err\n\t}\n\tf.Close()\n\n\treturn os.Rename(tmpPath, finalPath)\n}\n\n// writeBinarySnapshotFile writes the binary snapshot file header and level tree.\nfunc writeBinarySnapshotFile(w io.Writer, cf *CheckpointFile) error {\n\tif err := binary.Write(w, binary.LittleEndian, snapFileMagic); err != nil {\n\t\treturn err\n\t}\n\tif err := binary.Write(w, binary.LittleEndian, cf.From); err != nil {\n\t\treturn err\n\t}\n\tif err := binary.Write(w, binary.LittleEndian, cf.To); err != nil {\n\t\treturn err\n\t}\n\treturn writeBinaryLevel(w, cf)\n}\n\n// writeBinaryLevel recursively writes a CheckpointFile level in binary format.\nfunc writeBinaryLevel(w io.Writer, cf *CheckpointFile) error {\n\tif err := binary.Write(w, binary.LittleEndian, uint32(len(cf.Metrics))); err != nil {\n\t\treturn err\n\t}\n\n\tfor name, metric := range cf.Metrics {\n\t\tif err := writeString16(w, name); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, metric.Frequency); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, metric.Start); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, uint32(len(metric.Data))); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tfor _, v := range metric.Data {\n\t\t\tif err := binary.Write(w, binary.LittleEndian, math.Float32bits(float32(v))); err != nil {\n\t\t\t\treturn err\n\t\t\t}\n\t\t}\n\t}\n\n\tif err := binary.Write(w, binary.LittleEndian, uint32(len(cf.Children))); err != nil {\n\t\treturn err\n\t}\n\n\tfor name, child := range cf.Children {\n\t\tif err := writeString16(w, name); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := writeBinaryLevel(w, child); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\n\treturn nil\n}\n\n// writeString16 writes a 2-byte length-prefixed string to w.\nfunc writeString16(w io.Writer, s string) error {\n\tif err := binary.Write(w, binary.LittleEndian, uint16(len(s))); err != nil {\n\t\treturn err\n\t}\n\t_, err := io.WriteString(w, s)\n\treturn err\n}\n\n// loadBinaryFile reads a binary snapshot file and loads data into the Level tree.\n// The retention check (from) is applied to the file's 'to' timestamp.\nfunc (l *Level) loadBinaryFile(m *MemoryStore, f *os.File, from int64) error {\n\tbr := bufio.NewReader(f)\n\n\tvar magic uint32\n\tif err := binary.Read(br, binary.LittleEndian, &magic); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read magic: %w\", err)\n\t}\n\tif magic != snapFileMagic {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: invalid magic 0x%08X (expected 0x%08X)\", magic, snapFileMagic)\n\t}\n\n\tvar fileFrom, fileTo int64\n\tif err := binary.Read(br, binary.LittleEndian, &fileFrom); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read from: %w\", err)\n\t}\n\tif err := binary.Read(br, binary.LittleEndian, &fileTo); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read to: %w\", err)\n\t}\n\n\tif fileTo != 0 && fileTo < from {\n\t\treturn nil // File is older than retention window, skip it\n\t}\n\n\tcf, err := readBinaryLevel(br)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read level tree: %w\", err)\n\t}\n\tcf.From = fileFrom\n\tcf.To = fileTo\n\n\treturn l.loadFile(cf, m)\n}\n\n// readBinaryLevel recursively reads a level from the binary snapshot format.\nfunc readBinaryLevel(r io.Reader) (*CheckpointFile, error) {\n\tcf := &CheckpointFile{\n\t\tMetrics: make(map[string]*CheckpointMetrics),\n\t\tChildren: make(map[string]*CheckpointFile),\n\t}\n\n\tvar numMetrics uint32\n\tif err := binary.Read(r, binary.LittleEndian, &numMetrics); err != nil {\n\t\treturn nil, fmt.Errorf(\"read num_metrics: %w\", err)\n\t}\n\n\tfor range numMetrics {\n\t\tname, err := readString16(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read metric name: %w\", err)\n\t\t}\n\n\t\tvar freq, start int64\n\t\tif err := binary.Read(r, binary.LittleEndian, &freq); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read frequency for %s: %w\", name, err)\n\t\t}\n\t\tif err := binary.Read(r, binary.LittleEndian, &start); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read start for %s: %w\", name, err)\n\t\t}\n\n\t\tvar numValues uint32\n\t\tif err := binary.Read(r, binary.LittleEndian, &numValues); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read num_values for %s: %w\", name, err)\n\t\t}\n\n\t\tdata := make([]schema.Float, numValues)\n\t\tfor i := range numValues {\n\t\t\tvar bits uint32\n\t\t\tif err := binary.Read(r, binary.LittleEndian, &bits); err != nil {\n\t\t\t\treturn nil, fmt.Errorf(\"read value[%d] for %s: %w\", i, name, err)\n\t\t\t}\n\t\t\tdata[i] = schema.Float(math.Float32frombits(bits))\n\t\t}\n\n\t\tcf.Metrics[name] = &CheckpointMetrics{\n\t\t\tFrequency: freq,\n\t\t\tStart: start,\n\t\t\tData: data,\n\t\t}\n\t}\n\n\tvar numChildren uint32\n\tif err := binary.Read(r, binary.LittleEndian, &numChildren); err != nil {\n\t\treturn nil, fmt.Errorf(\"read num_children: %w\", err)\n\t}\n\n\tfor range numChildren {\n\t\tchildName, err := readString16(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read child name: %w\", err)\n\t\t}\n\n\t\tchild, err := readBinaryLevel(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read child %s: %w\", childName, err)\n\t\t}\n\t\tcf.Children[childName] = child\n\t}\n\n\treturn cf, nil\n}\n\n// readString16 reads a 2-byte length-prefixed string from r.\nfunc readString16(r io.Reader) (string, error) {\n\tvar sLen uint16\n\tif err := binary.Read(r, binary.LittleEndian, &sLen); err != nil {\n\t\treturn \"\", err\n\t}\n\tbuf := make([]byte, sLen)\n\tif _, err := io.ReadFull(r, buf); err != nil {\n\t\treturn \"\", err\n\t}\n\treturn string(buf), nil\n}\n","structuredPatch":[{"oldStart":122,"oldLines":6,"newStart":122,"newLines":7,"lines":[" f *os.File"," w *bufio.Writer"," dirty bool","+ size int64 // approximate bytes written (tracked from open + writes)"," }"," "," // walFlushInterval controls how often dirty WAL files are flushed to disk."]}],"userModified":false,"replaceAll":false},"sourceToolAssistantUUID":"b41004ed-5eef-4c67-b5eb-c9571ea41a27","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"3f3bf098-af0f-4da8-b7b3-13e173195d3e","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01FXskaNHuK5LFbJbAE3gmhS","type":"message","role":"assistant","content":[{"type":"text","text":"Now initialize `size` in `getOrOpenWAL`:"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":317,"cache_read_input_tokens":42195,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":317},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUv6X7TLCPG3z26LV99e","type":"assistant","uuid":"d8bd7bc7-a341-4809-9ecb-0e083d6e89ef","timestamp":"2026-03-28T05:21:01.136Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"d8bd7bc7-a341-4809-9ecb-0e083d6e89ef","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01FXskaNHuK5LFbJbAE3gmhS","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_015fKSySddMAq82MvHFtjbHH","name":"Edit","input":{"replace_all":false,"file_path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","old_string":"\t\t\t\tw := bufio.NewWriter(f)\n\n\t\t\t\t// Write file header magic if file is new (empty).\n\t\t\t\tinfo, err := f.Stat()\n\t\t\t\tif err == nil && info.Size() == 0 {\n\t\t\t\t\tvar hdr [4]byte\n\t\t\t\t\tbinary.LittleEndian.PutUint32(hdr[:], walFileMagic)\n\t\t\t\t\tif _, err := w.Write(hdr[:]); err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write header %s: %v\", walPath, err)\n\t\t\t\t\t\tf.Close()\n\t\t\t\t\t\treturn nil\n\t\t\t\t\t}\n\t\t\t\t}\n\n\t\t\t\tws = &walFileState{f: f, w: w}","new_string":"\t\t\t\tw := bufio.NewWriter(f)\n\n\t\t\t\t// Write file header magic if file is new (empty).\n\t\t\t\tinfo, err := f.Stat()\n\t\t\t\tvar fileSize int64\n\t\t\t\tif err == nil {\n\t\t\t\t\tfileSize = info.Size()\n\t\t\t\t}\n\t\t\t\tif err == nil && fileSize == 0 {\n\t\t\t\t\tvar hdr [4]byte\n\t\t\t\t\tbinary.LittleEndian.PutUint32(hdr[:], walFileMagic)\n\t\t\t\t\tif _, err := w.Write(hdr[:]); err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write header %s: %v\", walPath, err)\n\t\t\t\t\t\tf.Close()\n\t\t\t\t\t\treturn nil\n\t\t\t\t\t}\n\t\t\t\t\tfileSize = 4\n\t\t\t\t}\n\n\t\t\t\tws = &walFileState{f: f, w: w, size: fileSize}"},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":317,"cache_read_input_tokens":42195,"output_tokens":525,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":317,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUv6X7TLCPG3z26LV99e","type":"assistant","uuid":"2e741356-af8f-45a8-bb2a-9078bed4328c","timestamp":"2026-03-28T05:21:05.838Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"2e741356-af8f-45a8-bb2a-9078bed4328c","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_015fKSySddMAq82MvHFtjbHH","type":"tool_result","content":"The file /Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go has been updated successfully."}]},"uuid":"d2a537fc-3819-4284-add9-4c102531da49","timestamp":"2026-03-28T05:21:05.867Z","toolUseResult":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","oldString":"\t\t\t\tw := bufio.NewWriter(f)\n\n\t\t\t\t// Write file header magic if file is new (empty).\n\t\t\t\tinfo, err := f.Stat()\n\t\t\t\tif err == nil && info.Size() == 0 {\n\t\t\t\t\tvar hdr [4]byte\n\t\t\t\t\tbinary.LittleEndian.PutUint32(hdr[:], walFileMagic)\n\t\t\t\t\tif _, err := w.Write(hdr[:]); err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write header %s: %v\", walPath, err)\n\t\t\t\t\t\tf.Close()\n\t\t\t\t\t\treturn nil\n\t\t\t\t\t}\n\t\t\t\t}\n\n\t\t\t\tws = &walFileState{f: f, w: w}","newString":"\t\t\t\tw := bufio.NewWriter(f)\n\n\t\t\t\t// Write file header magic if file is new (empty).\n\t\t\t\tinfo, err := f.Stat()\n\t\t\t\tvar fileSize int64\n\t\t\t\tif err == nil {\n\t\t\t\t\tfileSize = info.Size()\n\t\t\t\t}\n\t\t\t\tif err == nil && fileSize == 0 {\n\t\t\t\t\tvar hdr [4]byte\n\t\t\t\t\tbinary.LittleEndian.PutUint32(hdr[:], walFileMagic)\n\t\t\t\t\tif _, err := w.Write(hdr[:]); err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write header %s: %v\", walPath, err)\n\t\t\t\t\t\tf.Close()\n\t\t\t\t\t\treturn nil\n\t\t\t\t\t}\n\t\t\t\t\tfileSize = 4\n\t\t\t\t}\n\n\t\t\t\tws = &walFileState{f: f, w: w, size: fileSize}","originalFile":"// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.\n// All rights reserved. This file is part of cc-backend.\n// Use of this source code is governed by a MIT-style\n// license that can be found in the LICENSE file.\n\n// Package metricstore provides walCheckpoint.go: WAL-based checkpoint implementation.\n//\n// This replaces the Avro shadow tree with an append-only Write-Ahead Log (WAL)\n// per host, eliminating the extra memory overhead of the AvroStore and providing\n// truly continuous (per-write) crash safety.\n//\n// # Architecture\n//\n//\tMetric write (DecodeLine)\n//\t │\n//\t ├─► WriteToLevel() → main MemoryStore (unchanged)\n//\t │\n//\t └─► WALMessages channel\n//\t │\n//\t ▼\n//\t WALStaging goroutine\n//\t │\n//\t ▼\n//\t checkpoints/cluster/host/current.wal (append-only, binary)\n//\n//\tPeriodic checkpoint (Checkpointing goroutine):\n//\t 1. Write <timestamp>.bin snapshot (column-oriented, from main tree)\n//\t 2. Signal WALStaging to truncate current.wal per host\n//\n//\tOn restart (FromCheckpoint):\n//\t 1. Load most recent <timestamp>.bin snapshot\n//\t 2. Replay current.wal (overwrite-safe: buffer.write handles duplicate timestamps)\n//\n// # WAL Record Format\n//\n//\t[4B magic 0xCC1DA7A1][4B payload_len][payload][4B CRC32]\n//\n//\tpayload:\n//\t [8B timestamp int64]\n//\t [2B metric_name_len uint16][N metric name bytes]\n//\t [1B selector_count uint8]\n//\t per selector: [1B selector_len uint8][M selector bytes]\n//\t [4B value float32 bits]\n//\n// # Binary Snapshot Format\n//\n//\t[4B magic 0xCC5B0001][8B from int64][8B to int64]\n//\tLevel tree (recursive):\n//\t [4B num_metrics uint32]\n//\t per metric:\n//\t [2B name_len uint16][N name bytes]\n//\t [8B frequency int64][8B start int64]\n//\t [4B num_values uint32][num_values × 4B float32]\n//\t [4B num_children uint32]\n//\t per child: [2B name_len uint16][N name bytes] + Level (recursive)\npackage metricstore\n\nimport (\n\t\"bufio\"\n\t\"context\"\n\t\"encoding/binary\"\n\t\"fmt\"\n\t\"hash/crc32\"\n\t\"hash/fnv\"\n\t\"io\"\n\t\"math\"\n\t\"os\"\n\t\"path\"\n\t\"strings\"\n\t\"sync\"\n\t\"sync/atomic\"\n\t\"time\"\n\n\tcclog \"github.com/ClusterCockpit/cc-lib/v2/ccLogger\"\n\t\"github.com/ClusterCockpit/cc-lib/v2/schema\"\n)\n\n// Magic numbers for binary formats.\nconst (\n\twalFileMagic = uint32(0xCC1DA701) // WAL file header magic\n\twalRecordMagic = uint32(0xCC1DA7A1) // WAL record magic\n\tsnapFileMagic = uint32(0xCC5B0001) // Binary snapshot magic\n)\n\n// walShardChs holds per-shard channels for WAL messages.\n// Initialized by WALStaging; nil when WAL is not active.\nvar walShardChs []chan *WALMessage\n\n// walShardRotateChs holds per-shard channels for WAL rotation requests.\nvar walShardRotateChs []chan walRotateReq\n\n// walNumShards stores the number of shards (set during WALStaging init).\nvar walNumShards int\n\n// walStagingWg tracks WALStaging goroutine exits for shutdown synchronization.\nvar walStagingWg sync.WaitGroup\n\n// walShuttingDown is set before closing shard channels to prevent\n// SendWALMessage from sending on a closed channel (which panics in Go).\nvar walShuttingDown atomic.Bool\n\n// WALMessage represents a single metric write to be appended to the WAL.\n// Cluster and Node are NOT stored in the WAL record (inferred from file path).\ntype WALMessage struct {\n\tMetricName string\n\tCluster string\n\tNode string\n\tSelector []string\n\tValue schema.Float\n\tTimestamp int64\n}\n\n// walRotateReq requests WAL file rotation for a specific host directory.\n// The done channel is closed by the WAL goroutine when rotation is complete.\ntype walRotateReq struct {\n\thostDir string\n\tdone chan struct{}\n}\n\n// walFileState holds an open WAL file handle and buffered writer for one host directory.\ntype walFileState struct {\n\tf *os.File\n\tw *bufio.Writer\n\tdirty bool\n\tsize int64 // approximate bytes written (tracked from open + writes)\n}\n\n// walFlushInterval controls how often dirty WAL files are flushed to disk.\n// Decoupling flushes from message processing lets the consumer run at memory\n// speed, amortizing syscall overhead across many writes.\nconst walFlushInterval = 1 * time.Second\n\n// walShardIndex computes which shard a message belongs to based on cluster+node.\n// Uses FNV-1a hash for fast, well-distributed mapping.\nfunc walShardIndex(cluster, node string) int {\n\th := fnv.New32a()\n\th.Write([]byte(cluster))\n\th.Write([]byte{0})\n\th.Write([]byte(node))\n\treturn int(h.Sum32()) % walNumShards\n}\n\n// SendWALMessage routes a WAL message to the appropriate shard channel.\n// Returns false if the channel is full or shutdown is in progress.\nfunc SendWALMessage(msg *WALMessage) bool {\n\tif walShardChs == nil || walShuttingDown.Load() {\n\t\treturn false\n\t}\n\tshard := walShardIndex(msg.Cluster, msg.Node)\n\tselect {\n\tcase walShardChs[shard] <- msg:\n\t\treturn true\n\tdefault:\n\t\treturn false\n\t}\n}\n\n// WALStaging starts N sharded background goroutines that receive WALMessage items\n// and append binary WAL records to per-host current.wal files.\n// Each shard owns a subset of hosts (determined by hash of cluster+node),\n// parallelizing serialization and I/O while keeping per-host writes serial.\nfunc WALStaging(wg *sync.WaitGroup, ctx context.Context) {\n\tif Keys.Checkpoints.FileFormat == \"json\" {\n\t\treturn\n\t}\n\n\twalNumShards = max(Keys.NumWorkers, 1)\n\tchBufSize := max(65536/walNumShards, 1024)\n\n\twalShardChs = make([]chan *WALMessage, walNumShards)\n\twalShardRotateChs = make([]chan walRotateReq, walNumShards)\n\n\tfor i := range walNumShards {\n\t\twalShardChs[i] = make(chan *WALMessage, chBufSize)\n\t\twalShardRotateChs[i] = make(chan walRotateReq, 64)\n\t}\n\n\tfor i := range walNumShards {\n\t\tmsgCh := walShardChs[i]\n\t\trotateCh := walShardRotateChs[i]\n\n\t\twalStagingWg.Add(1)\n\t\twg.Go(func() {\n\t\t\tdefer walStagingWg.Done()\n\t\t\thostFiles := make(map[string]*walFileState)\n\n\t\t\tdefer func() {\n\t\t\t\tfor _, ws := range hostFiles {\n\t\t\t\t\tif ws.f != nil {\n\t\t\t\t\t\tws.w.Flush()\n\t\t\t\t\t\tws.f.Close()\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}()\n\n\t\t\tgetOrOpenWAL := func(hostDir string) *walFileState {\n\t\t\t\tws, ok := hostFiles[hostDir]\n\t\t\t\tif ok {\n\t\t\t\t\treturn ws\n\t\t\t\t}\n\n\t\t\t\tif err := os.MkdirAll(hostDir, CheckpointDirPerms); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: mkdir %s: %v\", hostDir, err)\n\t\t\t\t\treturn nil\n\t\t\t\t}\n\n\t\t\t\twalPath := path.Join(hostDir, \"current.wal\")\n\t\t\t\tf, err := os.OpenFile(walPath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, CheckpointFilePerms)\n\t\t\t\tif err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: open %s: %v\", walPath, err)\n\t\t\t\t\treturn nil\n\t\t\t\t}\n\n\t\t\t\tw := bufio.NewWriter(f)\n\n\t\t\t\t// Write file header magic if file is new (empty).\n\t\t\t\tinfo, err := f.Stat()\n\t\t\t\tif err == nil && info.Size() == 0 {\n\t\t\t\t\tvar hdr [4]byte\n\t\t\t\t\tbinary.LittleEndian.PutUint32(hdr[:], walFileMagic)\n\t\t\t\t\tif _, err := w.Write(hdr[:]); err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write header %s: %v\", walPath, err)\n\t\t\t\t\t\tf.Close()\n\t\t\t\t\t\treturn nil\n\t\t\t\t\t}\n\t\t\t\t}\n\n\t\t\t\tws = &walFileState{f: f, w: w}\n\t\t\t\thostFiles[hostDir] = ws\n\t\t\t\treturn ws\n\t\t\t}\n\n\t\t\tprocessMsg := func(msg *WALMessage) {\n\t\t\t\thostDir := path.Join(Keys.Checkpoints.RootDir, msg.Cluster, msg.Node)\n\t\t\t\tws := getOrOpenWAL(hostDir)\n\t\t\t\tif ws == nil {\n\t\t\t\t\treturn\n\t\t\t\t}\n\t\t\t\tif err := writeWALRecordDirect(ws.w, msg); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write record: %v\", err)\n\t\t\t\t}\n\t\t\t\tws.dirty = true\n\t\t\t}\n\n\t\t\tprocessRotate := func(req walRotateReq) {\n\t\t\t\tws, ok := hostFiles[req.hostDir]\n\t\t\t\tif ok && ws.f != nil {\n\t\t\t\t\tws.w.Flush()\n\t\t\t\t\tws.f.Close()\n\t\t\t\t\twalPath := path.Join(req.hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tdelete(hostFiles, req.hostDir)\n\t\t\t\t}\n\t\t\t\tclose(req.done)\n\t\t\t}\n\n\t\t\tflushDirty := func() {\n\t\t\t\tfor _, ws := range hostFiles {\n\t\t\t\t\tif ws.dirty {\n\t\t\t\t\t\tws.w.Flush()\n\t\t\t\t\t\tws.dirty = false\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}\n\n\t\t\tticker := time.NewTicker(walFlushInterval)\n\t\t\tdefer ticker.Stop()\n\n\t\t\t// drainBatch processes up to 4096 pending messages without blocking.\n\t\t\t// Returns false if the channel was closed.\n\t\t\tdrainBatch := func() bool {\n\t\t\t\tfor range 4096 {\n\t\t\t\t\tselect {\n\t\t\t\t\tcase msg, ok := <-msgCh:\n\t\t\t\t\t\tif !ok {\n\t\t\t\t\t\t\tflushDirty()\n\t\t\t\t\t\t\treturn false\n\t\t\t\t\t\t}\n\t\t\t\t\t\tprocessMsg(msg)\n\t\t\t\t\tcase req := <-rotateCh:\n\t\t\t\t\t\tprocessRotate(req)\n\t\t\t\t\tdefault:\n\t\t\t\t\t\treturn true\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\treturn true\n\t\t\t}\n\n\t\t\tfor {\n\t\t\t\tselect {\n\t\t\t\tcase <-ctx.Done():\n\t\t\t\t\t// On shutdown, skip draining buffered messages — a full binary\n\t\t\t\t\t// checkpoint will be written from in-memory state, making\n\t\t\t\t\t// buffered WAL records redundant.\n\t\t\t\t\tflushDirty()\n\t\t\t\t\treturn\n\t\t\t\tcase msg, ok := <-msgCh:\n\t\t\t\t\tif !ok {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t\tprocessMsg(msg)\n\t\t\t\t\tif !drainBatch() {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t\t// No flush here — timer handles periodic flushing.\n\t\t\t\tcase <-ticker.C:\n\t\t\t\t\tflushDirty()\n\t\t\t\tcase req := <-rotateCh:\n\t\t\t\t\tprocessRotate(req)\n\t\t\t\t}\n\t\t\t}\n\t\t})\n\t}\n}\n\n// WaitForWALStagingDrain blocks until all WALStaging goroutines have exited.\n// Must be called after closing walShardChs to ensure all file handles are\n// flushed and closed before checkpoint writes begin.\nfunc WaitForWALStagingDrain() {\n\twalStagingWg.Wait()\n}\n\n// RotateWALFiles sends rotation requests for the given host directories\n// and blocks until all rotations complete. Each request is routed to the\n// shard that owns the host directory.\n//\n// If shutdown is in progress (WAL staging goroutines may have exited),\n// rotation is skipped to avoid deadlocking on abandoned channels.\nfunc RotateWALFiles(hostDirs []string) {\n\tif walShardRotateChs == nil || walShuttingDown.Load() {\n\t\treturn\n\t}\n\tdones := make([]chan struct{}, 0, len(hostDirs))\n\tfor _, dir := range hostDirs {\n\t\tdone := make(chan struct{})\n\t\tshard := walShardIndexFromDir(dir)\n\t\tselect {\n\t\tcase walShardRotateChs[shard] <- walRotateReq{hostDir: dir, done: done}:\n\t\t\tdones = append(dones, done)\n\t\tdefault:\n\t\t\t// Channel full or goroutine not consuming — skip this host.\n\t\t\tcclog.Warnf(\"[METRICSTORE]> WAL rotation skipped for %s (channel full)\", dir)\n\t\t}\n\t}\n\tfor _, done := range dones {\n\t\tselect {\n\t\tcase <-done:\n\t\tcase <-time.After(30 * time.Second):\n\t\t\tcclog.Warn(\"[METRICSTORE]> WAL rotation timed out, continuing\")\n\t\t\treturn\n\t\t}\n\t}\n}\n\n// walShardIndexFromDir extracts cluster and node from a host directory path\n// and returns the shard index. The path format is: rootDir/cluster/node\nfunc walShardIndexFromDir(hostDir string) int {\n\t// hostDir = .../cluster/node — extract last two path components\n\tnode := path.Base(hostDir)\n\tcluster := path.Base(path.Dir(hostDir))\n\treturn walShardIndex(cluster, node)\n}\n\n// RotateWALFiles sends rotation requests for the given host directories\n// and blocks until all rotations complete.\nfunc RotateWALFilesAfterShutdown(hostDirs []string) {\n\tfor _, dir := range hostDirs {\n\t\twalPath := path.Join(dir, \"current.wal\")\n\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t}\n\t}\n}\n\n// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\n// then writes it to the bufio.Writer in a single call. This prevents partial\n// records in the write buffer if a write error occurs mid-record (e.g. disk full).\nfunc writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) error {\n\t// Compute payload and total record size.\n\tpayloadSize := 8 + 2 + len(msg.MetricName) + 1 + 4\n\tfor _, s := range msg.Selector {\n\t\tpayloadSize += 1 + len(s)\n\t}\n\t// Total: 8 (header) + payload + 4 (CRC).\n\ttotalSize := 8 + payloadSize + 4\n\n\t// Use stack buffer for typical small records, heap-allocate only for large ones.\n\tvar stackBuf [256]byte\n\tvar buf []byte\n\tif totalSize <= len(stackBuf) {\n\t\tbuf = stackBuf[:totalSize]\n\t} else {\n\t\tbuf = make([]byte, totalSize)\n\t}\n\n\t// Header: magic + payload length.\n\tbinary.LittleEndian.PutUint32(buf[0:4], walRecordMagic)\n\tbinary.LittleEndian.PutUint32(buf[4:8], uint32(payloadSize))\n\n\t// Payload starts at offset 8.\n\tp := 8\n\n\t// Timestamp (8 bytes).\n\tbinary.LittleEndian.PutUint64(buf[p:p+8], uint64(msg.Timestamp))\n\tp += 8\n\n\t// Metric name length (2 bytes) + metric name.\n\tbinary.LittleEndian.PutUint16(buf[p:p+2], uint16(len(msg.MetricName)))\n\tp += 2\n\tp += copy(buf[p:], msg.MetricName)\n\n\t// Selector count (1 byte).\n\tbuf[p] = byte(len(msg.Selector))\n\tp++\n\n\t// Selectors (1-byte length + bytes each).\n\tfor _, sel := range msg.Selector {\n\t\tbuf[p] = byte(len(sel))\n\t\tp++\n\t\tp += copy(buf[p:], sel)\n\t}\n\n\t// Value (4 bytes, float32 bits).\n\tbinary.LittleEndian.PutUint32(buf[p:p+4], math.Float32bits(float32(msg.Value)))\n\tp += 4\n\n\t// CRC32 over payload (bytes 8..8+payloadSize).\n\tcrc := crc32.ChecksumIEEE(buf[8 : 8+payloadSize])\n\tbinary.LittleEndian.PutUint32(buf[p:p+4], crc)\n\n\t// Single atomic write to the buffered writer.\n\t_, err := w.Write(buf)\n\treturn err\n}\n\n// readWALRecord reads one WAL record from the reader.\n// Returns (nil, nil) on clean EOF. Returns error on data corruption.\n// A CRC mismatch indicates a truncated trailing record (expected on crash).\nfunc readWALRecord(r io.Reader) (*WALMessage, error) {\n\tvar magic uint32\n\tif err := binary.Read(r, binary.LittleEndian, &magic); err != nil {\n\t\tif err == io.EOF {\n\t\t\treturn nil, nil // Clean EOF\n\t\t}\n\t\treturn nil, fmt.Errorf(\"read record magic: %w\", err)\n\t}\n\n\tif magic != walRecordMagic {\n\t\treturn nil, fmt.Errorf(\"invalid record magic 0x%08X (expected 0x%08X)\", magic, walRecordMagic)\n\t}\n\n\tvar payloadLen uint32\n\tif err := binary.Read(r, binary.LittleEndian, &payloadLen); err != nil {\n\t\treturn nil, fmt.Errorf(\"read payload length: %w\", err)\n\t}\n\n\tif payloadLen > 1<<20 { // 1 MB sanity limit\n\t\treturn nil, fmt.Errorf(\"record payload too large: %d bytes\", payloadLen)\n\t}\n\n\tpayload := make([]byte, payloadLen)\n\tif _, err := io.ReadFull(r, payload); err != nil {\n\t\treturn nil, fmt.Errorf(\"read payload: %w\", err)\n\t}\n\n\tvar storedCRC uint32\n\tif err := binary.Read(r, binary.LittleEndian, &storedCRC); err != nil {\n\t\treturn nil, fmt.Errorf(\"read CRC: %w\", err)\n\t}\n\n\tif crc32.ChecksumIEEE(payload) != storedCRC {\n\t\treturn nil, fmt.Errorf(\"CRC mismatch (truncated write or corruption)\")\n\t}\n\n\treturn parseWALPayload(payload)\n}\n\n// parseWALPayload decodes a binary payload into a WALMessage.\nfunc parseWALPayload(payload []byte) (*WALMessage, error) {\n\tif len(payload) < 8+2+1+4 {\n\t\treturn nil, fmt.Errorf(\"payload too short: %d bytes\", len(payload))\n\t}\n\n\toffset := 0\n\n\t// Timestamp (8 bytes)\n\tts := int64(binary.LittleEndian.Uint64(payload[offset : offset+8]))\n\toffset += 8\n\n\t// Metric name (2-byte length + bytes)\n\tif offset+2 > len(payload) {\n\t\treturn nil, fmt.Errorf(\"metric name length overflows payload\")\n\t}\n\tmLen := int(binary.LittleEndian.Uint16(payload[offset : offset+2]))\n\toffset += 2\n\n\tif offset+mLen > len(payload) {\n\t\treturn nil, fmt.Errorf(\"metric name overflows payload\")\n\t}\n\tmetricName := string(payload[offset : offset+mLen])\n\toffset += mLen\n\n\t// Selector count (1 byte)\n\tif offset >= len(payload) {\n\t\treturn nil, fmt.Errorf(\"selector count overflows payload\")\n\t}\n\tselCount := int(payload[offset])\n\toffset++\n\n\tselectors := make([]string, selCount)\n\tfor i := range selCount {\n\t\tif offset >= len(payload) {\n\t\t\treturn nil, fmt.Errorf(\"selector[%d] length overflows payload\", i)\n\t\t}\n\t\tsLen := int(payload[offset])\n\t\toffset++\n\n\t\tif offset+sLen > len(payload) {\n\t\t\treturn nil, fmt.Errorf(\"selector[%d] data overflows payload\", i)\n\t\t}\n\t\tselectors[i] = string(payload[offset : offset+sLen])\n\t\toffset += sLen\n\t}\n\n\t// Value (4 bytes, float32 bits)\n\tif offset+4 > len(payload) {\n\t\treturn nil, fmt.Errorf(\"value overflows payload\")\n\t}\n\tbits := binary.LittleEndian.Uint32(payload[offset : offset+4])\n\tvalue := schema.Float(math.Float32frombits(bits))\n\n\treturn &WALMessage{\n\t\tMetricName: metricName,\n\t\tTimestamp: ts,\n\t\tSelector: selectors,\n\t\tValue: value,\n\t}, nil\n}\n\n// loadWALFile reads a WAL file and replays all valid records into the Level tree.\n// l is the host-level node. Corrupt or partial trailing records are silently skipped\n// (expected on crash). Records older than 'from' are skipped.\nfunc (l *Level) loadWALFile(m *MemoryStore, f *os.File, from int64) error {\n\tbr := bufio.NewReader(f)\n\n\t// Verify file header magic.\n\tvar fileMagic uint32\n\tif err := binary.Read(br, binary.LittleEndian, &fileMagic); err != nil {\n\t\tif err == io.EOF {\n\t\t\treturn nil // Empty file, no data\n\t\t}\n\t\treturn fmt.Errorf(\"[METRICSTORE]> WAL: read file header: %w\", err)\n\t}\n\n\tif fileMagic != walFileMagic {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> WAL: invalid file magic 0x%08X (expected 0x%08X)\", fileMagic, walFileMagic)\n\t}\n\n\t// Cache level lookups to avoid repeated tree traversal.\n\tlvlCache := make(map[string]*Level)\n\n\tfor {\n\t\tmsg, err := readWALRecord(br)\n\t\tif err != nil {\n\t\t\t// Truncated trailing record is expected after a crash; stop replaying.\n\t\t\tcclog.Debugf(\"[METRICSTORE]> WAL: stopping replay at corrupted/partial record: %v\", err)\n\t\t\tbreak\n\t\t}\n\t\tif msg == nil {\n\t\t\tbreak // Clean EOF\n\t\t}\n\n\t\tif msg.Timestamp < from {\n\t\t\tcontinue // Older than retention window\n\t\t}\n\n\t\tminfo, ok := m.Metrics[msg.MetricName]\n\t\tif !ok {\n\t\t\tcontinue // Unknown metric (config may have changed)\n\t\t}\n\n\t\t// Cache key is the null-separated selector path.\n\t\tcacheKey := joinSelector(msg.Selector)\n\t\tlvl, ok := lvlCache[cacheKey]\n\t\tif !ok {\n\t\t\tlvl = l.findLevelOrCreate(msg.Selector, len(m.Metrics))\n\t\t\tlvlCache[cacheKey] = lvl\n\t\t}\n\n\t\t// Write directly to the buffer, same as WriteToLevel but without the\n\t\t// global level lookup (we already have the right level).\n\t\tlvl.lock.Lock()\n\t\tb := lvl.metrics[minfo.offset]\n\t\tif b == nil {\n\t\t\tb = newBuffer(msg.Timestamp, minfo.Frequency)\n\t\t\tlvl.metrics[minfo.offset] = b\n\t\t}\n\t\tnb, writeErr := b.write(msg.Timestamp, msg.Value)\n\t\tif writeErr == nil && b != nb {\n\t\t\tlvl.metrics[minfo.offset] = nb\n\t\t}\n\t\t// Ignore write errors for timestamps before buffer start (can happen when\n\t\t// replaying WAL entries that predate a loaded snapshot's start time).\n\t\tlvl.lock.Unlock()\n\t}\n\n\treturn nil\n}\n\n// joinSelector builds a cache key from a selector slice using null bytes as separators.\nfunc joinSelector(sel []string) string {\n\tif len(sel) == 0 {\n\t\treturn \"\"\n\t}\n\tvar result strings.Builder\n\tresult.WriteString(sel[0])\n\tfor i := 1; i < len(sel); i++ {\n\t\tresult.WriteString(\"\\x00\" + sel[i])\n\t}\n\treturn result.String()\n}\n\n// ToCheckpointWAL writes binary snapshot files for all hosts in parallel.\n// Returns the number of files written, the list of host directories that were\n// successfully checkpointed (for WAL rotation), and any errors.\nfunc (m *MemoryStore) ToCheckpointWAL(dir string, from, to int64) (int, []string, error) {\n\t// Collect all cluster/host pairs.\n\tm.root.lock.RLock()\n\ttotalHosts := 0\n\tfor _, l1 := range m.root.children {\n\t\tl1.lock.RLock()\n\t\ttotalHosts += len(l1.children)\n\t\tl1.lock.RUnlock()\n\t}\n\tm.root.lock.RUnlock()\n\n\tlevels := make([]*Level, 0, totalHosts)\n\tselectors := make([][]string, 0, totalHosts)\n\n\tm.root.lock.RLock()\n\tfor sel1, l1 := range m.root.children {\n\t\tl1.lock.RLock()\n\t\tfor sel2, l2 := range l1.children {\n\t\t\tlevels = append(levels, l2)\n\t\t\tselectors = append(selectors, []string{sel1, sel2})\n\t\t}\n\t\tl1.lock.RUnlock()\n\t}\n\tm.root.lock.RUnlock()\n\n\ttype workItem struct {\n\t\tlevel *Level\n\t\thostDir string\n\t\tselector []string\n\t}\n\n\ttotalWork := len(levels)\n\tcclog.Infof(\"[METRICSTORE]> Starting binary checkpoint for %d hosts with %d workers\", totalWork, Keys.NumWorkers)\n\n\tn, errs, completed := int32(0), int32(0), int32(0)\n\tvar successDirs []string\n\tvar successMu sync.Mutex\n\n\tvar wg sync.WaitGroup\n\twg.Add(Keys.NumWorkers)\n\twork := make(chan workItem, Keys.NumWorkers*2)\n\n\t// Progress logging goroutine.\n\tstopProgress := make(chan struct{})\n\tgo func() {\n\t\tticker := time.NewTicker(10 * time.Second)\n\t\tdefer ticker.Stop()\n\t\tfor {\n\t\t\tselect {\n\t\t\tcase <-ticker.C:\n\t\t\t\tcclog.Infof(\"[METRICSTORE]> Checkpoint progress: %d/%d hosts (%d written, %d errors)\",\n\t\t\t\t\tatomic.LoadInt32(&completed), totalWork, atomic.LoadInt32(&n), atomic.LoadInt32(&errs))\n\t\t\tcase <-stopProgress:\n\t\t\t\treturn\n\t\t\t}\n\t\t}\n\t}()\n\n\tfor range Keys.NumWorkers {\n\t\tgo func() {\n\t\t\tdefer wg.Done()\n\t\t\tfor wi := range work {\n\t\t\t\terr := wi.level.toCheckpointBinary(wi.hostDir, from, to, m)\n\t\t\t\tif err != nil {\n\t\t\t\t\tif err == ErrNoNewArchiveData {\n\t\t\t\t\t\tatomic.AddInt32(&completed, 1)\n\t\t\t\t\t\tcontinue\n\t\t\t\t\t}\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> binary checkpoint error for %s: %v\", wi.hostDir, err)\n\t\t\t\t\tatomic.AddInt32(&errs, 1)\n\t\t\t\t} else {\n\t\t\t\t\tatomic.AddInt32(&n, 1)\n\t\t\t\t\t// Delete WAL immediately after successful snapshot.\n\t\t\t\t\twalPath := path.Join(wi.hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tsuccessMu.Lock()\n\t\t\t\t\tsuccessDirs = append(successDirs, wi.hostDir)\n\t\t\t\t\tsuccessMu.Unlock()\n\t\t\t\t}\n\t\t\t\tatomic.AddInt32(&completed, 1)\n\t\t\t}\n\t\t}()\n\t}\n\n\tfor i := range levels {\n\t\thostDir := path.Join(dir, path.Join(selectors[i]...))\n\t\twork <- workItem{\n\t\t\tlevel: levels[i],\n\t\t\thostDir: hostDir,\n\t\t\tselector: selectors[i],\n\t\t}\n\t}\n\tclose(work)\n\twg.Wait()\n\tclose(stopProgress)\n\n\tif errs > 0 {\n\t\treturn int(n), successDirs, fmt.Errorf(\"[METRICSTORE]> %d errors during binary checkpoint (%d successes)\", errs, n)\n\t}\n\treturn int(n), successDirs, nil\n}\n\n// toCheckpointBinary writes a binary snapshot file for a single host-level node.\n// Uses atomic rename (write to .tmp then rename) to avoid partial reads on crash.\nfunc (l *Level) toCheckpointBinary(dir string, from, to int64, m *MemoryStore) error {\n\tcf, err := l.toCheckpointFile(from, to, m)\n\tif err != nil {\n\t\treturn err\n\t}\n\tif cf == nil {\n\t\treturn ErrNoNewArchiveData\n\t}\n\n\tif err := os.MkdirAll(dir, CheckpointDirPerms); err != nil {\n\t\treturn fmt.Errorf(\"mkdir %s: %w\", dir, err)\n\t}\n\n\t// Write to a temp file first, then rename (atomic on POSIX).\n\ttmpPath := path.Join(dir, fmt.Sprintf(\"%d.bin.tmp\", from))\n\tfinalPath := path.Join(dir, fmt.Sprintf(\"%d.bin\", from))\n\n\tf, err := os.OpenFile(tmpPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, CheckpointFilePerms)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"open binary snapshot %s: %w\", tmpPath, err)\n\t}\n\n\tbw := bufio.NewWriter(f)\n\tif err := writeBinarySnapshotFile(bw, cf); err != nil {\n\t\tf.Close()\n\t\tos.Remove(tmpPath)\n\t\treturn fmt.Errorf(\"write binary snapshot: %w\", err)\n\t}\n\tif err := bw.Flush(); err != nil {\n\t\tf.Close()\n\t\tos.Remove(tmpPath)\n\t\treturn err\n\t}\n\tf.Close()\n\n\treturn os.Rename(tmpPath, finalPath)\n}\n\n// writeBinarySnapshotFile writes the binary snapshot file header and level tree.\nfunc writeBinarySnapshotFile(w io.Writer, cf *CheckpointFile) error {\n\tif err := binary.Write(w, binary.LittleEndian, snapFileMagic); err != nil {\n\t\treturn err\n\t}\n\tif err := binary.Write(w, binary.LittleEndian, cf.From); err != nil {\n\t\treturn err\n\t}\n\tif err := binary.Write(w, binary.LittleEndian, cf.To); err != nil {\n\t\treturn err\n\t}\n\treturn writeBinaryLevel(w, cf)\n}\n\n// writeBinaryLevel recursively writes a CheckpointFile level in binary format.\nfunc writeBinaryLevel(w io.Writer, cf *CheckpointFile) error {\n\tif err := binary.Write(w, binary.LittleEndian, uint32(len(cf.Metrics))); err != nil {\n\t\treturn err\n\t}\n\n\tfor name, metric := range cf.Metrics {\n\t\tif err := writeString16(w, name); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, metric.Frequency); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, metric.Start); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, uint32(len(metric.Data))); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tfor _, v := range metric.Data {\n\t\t\tif err := binary.Write(w, binary.LittleEndian, math.Float32bits(float32(v))); err != nil {\n\t\t\t\treturn err\n\t\t\t}\n\t\t}\n\t}\n\n\tif err := binary.Write(w, binary.LittleEndian, uint32(len(cf.Children))); err != nil {\n\t\treturn err\n\t}\n\n\tfor name, child := range cf.Children {\n\t\tif err := writeString16(w, name); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := writeBinaryLevel(w, child); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\n\treturn nil\n}\n\n// writeString16 writes a 2-byte length-prefixed string to w.\nfunc writeString16(w io.Writer, s string) error {\n\tif err := binary.Write(w, binary.LittleEndian, uint16(len(s))); err != nil {\n\t\treturn err\n\t}\n\t_, err := io.WriteString(w, s)\n\treturn err\n}\n\n// loadBinaryFile reads a binary snapshot file and loads data into the Level tree.\n// The retention check (from) is applied to the file's 'to' timestamp.\nfunc (l *Level) loadBinaryFile(m *MemoryStore, f *os.File, from int64) error {\n\tbr := bufio.NewReader(f)\n\n\tvar magic uint32\n\tif err := binary.Read(br, binary.LittleEndian, &magic); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read magic: %w\", err)\n\t}\n\tif magic != snapFileMagic {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: invalid magic 0x%08X (expected 0x%08X)\", magic, snapFileMagic)\n\t}\n\n\tvar fileFrom, fileTo int64\n\tif err := binary.Read(br, binary.LittleEndian, &fileFrom); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read from: %w\", err)\n\t}\n\tif err := binary.Read(br, binary.LittleEndian, &fileTo); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read to: %w\", err)\n\t}\n\n\tif fileTo != 0 && fileTo < from {\n\t\treturn nil // File is older than retention window, skip it\n\t}\n\n\tcf, err := readBinaryLevel(br)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read level tree: %w\", err)\n\t}\n\tcf.From = fileFrom\n\tcf.To = fileTo\n\n\treturn l.loadFile(cf, m)\n}\n\n// readBinaryLevel recursively reads a level from the binary snapshot format.\nfunc readBinaryLevel(r io.Reader) (*CheckpointFile, error) {\n\tcf := &CheckpointFile{\n\t\tMetrics: make(map[string]*CheckpointMetrics),\n\t\tChildren: make(map[string]*CheckpointFile),\n\t}\n\n\tvar numMetrics uint32\n\tif err := binary.Read(r, binary.LittleEndian, &numMetrics); err != nil {\n\t\treturn nil, fmt.Errorf(\"read num_metrics: %w\", err)\n\t}\n\n\tfor range numMetrics {\n\t\tname, err := readString16(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read metric name: %w\", err)\n\t\t}\n\n\t\tvar freq, start int64\n\t\tif err := binary.Read(r, binary.LittleEndian, &freq); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read frequency for %s: %w\", name, err)\n\t\t}\n\t\tif err := binary.Read(r, binary.LittleEndian, &start); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read start for %s: %w\", name, err)\n\t\t}\n\n\t\tvar numValues uint32\n\t\tif err := binary.Read(r, binary.LittleEndian, &numValues); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read num_values for %s: %w\", name, err)\n\t\t}\n\n\t\tdata := make([]schema.Float, numValues)\n\t\tfor i := range numValues {\n\t\t\tvar bits uint32\n\t\t\tif err := binary.Read(r, binary.LittleEndian, &bits); err != nil {\n\t\t\t\treturn nil, fmt.Errorf(\"read value[%d] for %s: %w\", i, name, err)\n\t\t\t}\n\t\t\tdata[i] = schema.Float(math.Float32frombits(bits))\n\t\t}\n\n\t\tcf.Metrics[name] = &CheckpointMetrics{\n\t\t\tFrequency: freq,\n\t\t\tStart: start,\n\t\t\tData: data,\n\t\t}\n\t}\n\n\tvar numChildren uint32\n\tif err := binary.Read(r, binary.LittleEndian, &numChildren); err != nil {\n\t\treturn nil, fmt.Errorf(\"read num_children: %w\", err)\n\t}\n\n\tfor range numChildren {\n\t\tchildName, err := readString16(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read child name: %w\", err)\n\t\t}\n\n\t\tchild, err := readBinaryLevel(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read child %s: %w\", childName, err)\n\t\t}\n\t\tcf.Children[childName] = child\n\t}\n\n\treturn cf, nil\n}\n\n// readString16 reads a 2-byte length-prefixed string from r.\nfunc readString16(r io.Reader) (string, error) {\n\tvar sLen uint16\n\tif err := binary.Read(r, binary.LittleEndian, &sLen); err != nil {\n\t\treturn \"\", err\n\t}\n\tbuf := make([]byte, sLen)\n\tif _, err := io.ReadFull(r, buf); err != nil {\n\t\treturn \"\", err\n\t}\n\treturn string(buf), nil\n}\n","structuredPatch":[{"oldStart":215,"oldLines":7,"newStart":215,"newLines":11,"lines":[" "," // Write file header magic if file is new (empty)."," info, err := f.Stat()","- if err == nil && info.Size() == 0 {","+ var fileSize int64","+ if err == nil {","+ fileSize = info.Size()","+ }","+ if err == nil && fileSize == 0 {"," var hdr [4]byte"," binary.LittleEndian.PutUint32(hdr[:], walFileMagic)"," if _, err := w.Write(hdr[:]); err != nil {"]},{"oldStart":223,"oldLines":9,"newStart":227,"newLines":10,"lines":[" f.Close()"," return nil"," }","+ fileSize = 4"," }"," ","- ws = &walFileState{f: f, w: w}","+ ws = &walFileState{f: f, w: w, size: fileSize}"," hostFiles[hostDir] = ws"," return ws"," }"]}],"userModified":false,"replaceAll":false},"sourceToolAssistantUUID":"2e741356-af8f-45a8-bb2a-9078bed4328c","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"9a686108-54c3-4c67-9aa4-3a5879f4fe82","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01WNCJCv7Sn5ps9rgsAQf76y","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01A5kvGzRdhxvVUnyEL8fynh","name":"Read","input":{"file_path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","offset":246,"limit":5},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":320,"cache_read_input_tokens":43084,"output_tokens":115,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":320,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUv7MfxJUsbwCJBYDu1P","type":"assistant","uuid":"ace4012f-fc7c-4d38-871a-d45af8402448","timestamp":"2026-03-28T05:21:13.849Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"ace4012f-fc7c-4d38-871a-d45af8402448","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01A5kvGzRdhxvVUnyEL8fynh","type":"tool_result","content":"246\t\t\t\t\t}\n247\t\t\t\t\tws.dirty = true\n248\t\t\t\t}\n249\t\n250\t\t\t\tprocessRotate := func(req walRotateReq) {"}]},"uuid":"7d3f9da8-48d5-488d-a6e6-daf331cf988c","timestamp":"2026-03-28T05:21:13.864Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","content":"\t\t\t\t}\n\t\t\t\tws.dirty = true\n\t\t\t}\n\n\t\t\tprocessRotate := func(req walRotateReq) {","numLines":5,"startLine":246,"totalLines":957}},"sourceToolAssistantUUID":"ace4012f-fc7c-4d38-871a-d45af8402448","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"7d3f9da8-48d5-488d-a6e6-daf331cf988c","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_013vYQGXn5sSSsD5WWBZaymB","type":"message","role":"assistant","content":[{"type":"text","text":"I need to understand how `writeWALRecordDirect` works to know the record size. Let me check if it returns the number of bytes written."}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":482,"cache_read_input_tokens":43084,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":482},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUv7fUmRfqu1EE6JnH5o","type":"assistant","uuid":"9419b69e-5ed0-4a3d-88f4-8ca9133beffe","timestamp":"2026-03-28T05:21:18.633Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"9419b69e-5ed0-4a3d-88f4-8ca9133beffe","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_013vYQGXn5sSSsD5WWBZaymB","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01WJuK9QgQUVU9TvDyHiZgJG","name":"Read","input":{"file_path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","offset":382,"limit":60},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":482,"cache_read_input_tokens":43084,"output_tokens":150,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":482,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUv7fUmRfqu1EE6JnH5o","type":"assistant","uuid":"81dfd337-a43f-4e4c-8bb0-5c8c399e92c3","timestamp":"2026-03-28T05:21:19.242Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"81dfd337-a43f-4e4c-8bb0-5c8c399e92c3","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01WJuK9QgQUVU9TvDyHiZgJG","type":"tool_result","content":"382\t// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\n383\t// then writes it to the bufio.Writer in a single call. This prevents partial\n384\t// records in the write buffer if a write error occurs mid-record (e.g. disk full).\n385\tfunc writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) error {\n386\t\t// Compute payload and total record size.\n387\t\tpayloadSize := 8 + 2 + len(msg.MetricName) + 1 + 4\n388\t\tfor _, s := range msg.Selector {\n389\t\t\tpayloadSize += 1 + len(s)\n390\t\t}\n391\t\t// Total: 8 (header) + payload + 4 (CRC).\n392\t\ttotalSize := 8 + payloadSize + 4\n393\t\n394\t\t// Use stack buffer for typical small records, heap-allocate only for large ones.\n395\t\tvar stackBuf [256]byte\n396\t\tvar buf []byte\n397\t\tif totalSize <= len(stackBuf) {\n398\t\t\tbuf = stackBuf[:totalSize]\n399\t\t} else {\n400\t\t\tbuf = make([]byte, totalSize)\n401\t\t}\n402\t\n403\t\t// Header: magic + payload length.\n404\t\tbinary.LittleEndian.PutUint32(buf[0:4], walRecordMagic)\n405\t\tbinary.LittleEndian.PutUint32(buf[4:8], uint32(payloadSize))\n406\t\n407\t\t// Payload starts at offset 8.\n408\t\tp := 8\n409\t\n410\t\t// Timestamp (8 bytes).\n411\t\tbinary.LittleEndian.PutUint64(buf[p:p+8], uint64(msg.Timestamp))\n412\t\tp += 8\n413\t\n414\t\t// Metric name length (2 bytes) + metric name.\n415\t\tbinary.LittleEndian.PutUint16(buf[p:p+2], uint16(len(msg.MetricName)))\n416\t\tp += 2\n417\t\tp += copy(buf[p:], msg.MetricName)\n418\t\n419\t\t// Selector count (1 byte).\n420\t\tbuf[p] = byte(len(msg.Selector))\n421\t\tp++\n422\t\n423\t\t// Selectors (1-byte length + bytes each).\n424\t\tfor _, sel := range msg.Selector {\n425\t\t\tbuf[p] = byte(len(sel))\n426\t\t\tp++\n427\t\t\tp += copy(buf[p:], sel)\n428\t\t}\n429\t\n430\t\t// Value (4 bytes, float32 bits).\n431\t\tbinary.LittleEndian.PutUint32(buf[p:p+4], math.Float32bits(float32(msg.Value)))\n432\t\tp += 4\n433\t\n434\t\t// CRC32 over payload (bytes 8..8+payloadSize).\n435\t\tcrc := crc32.ChecksumIEEE(buf[8 : 8+payloadSize])\n436\t\tbinary.LittleEndian.PutUint32(buf[p:p+4], crc)\n437\t\n438\t\t// Single atomic write to the buffered writer.\n439\t\t_, err := w.Write(buf)\n440\t\treturn err\n441\t}"}]},"uuid":"60e1007f-0afd-444c-8f4c-8ee570395dec","timestamp":"2026-03-28T05:21:19.261Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","content":"// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\n// then writes it to the bufio.Writer in a single call. This prevents partial\n// records in the write buffer if a write error occurs mid-record (e.g. disk full).\nfunc writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) error {\n\t// Compute payload and total record size.\n\tpayloadSize := 8 + 2 + len(msg.MetricName) + 1 + 4\n\tfor _, s := range msg.Selector {\n\t\tpayloadSize += 1 + len(s)\n\t}\n\t// Total: 8 (header) + payload + 4 (CRC).\n\ttotalSize := 8 + payloadSize + 4\n\n\t// Use stack buffer for typical small records, heap-allocate only for large ones.\n\tvar stackBuf [256]byte\n\tvar buf []byte\n\tif totalSize <= len(stackBuf) {\n\t\tbuf = stackBuf[:totalSize]\n\t} else {\n\t\tbuf = make([]byte, totalSize)\n\t}\n\n\t// Header: magic + payload length.\n\tbinary.LittleEndian.PutUint32(buf[0:4], walRecordMagic)\n\tbinary.LittleEndian.PutUint32(buf[4:8], uint32(payloadSize))\n\n\t// Payload starts at offset 8.\n\tp := 8\n\n\t// Timestamp (8 bytes).\n\tbinary.LittleEndian.PutUint64(buf[p:p+8], uint64(msg.Timestamp))\n\tp += 8\n\n\t// Metric name length (2 bytes) + metric name.\n\tbinary.LittleEndian.PutUint16(buf[p:p+2], uint16(len(msg.MetricName)))\n\tp += 2\n\tp += copy(buf[p:], msg.MetricName)\n\n\t// Selector count (1 byte).\n\tbuf[p] = byte(len(msg.Selector))\n\tp++\n\n\t// Selectors (1-byte length + bytes each).\n\tfor _, sel := range msg.Selector {\n\t\tbuf[p] = byte(len(sel))\n\t\tp++\n\t\tp += copy(buf[p:], sel)\n\t}\n\n\t// Value (4 bytes, float32 bits).\n\tbinary.LittleEndian.PutUint32(buf[p:p+4], math.Float32bits(float32(msg.Value)))\n\tp += 4\n\n\t// CRC32 over payload (bytes 8..8+payloadSize).\n\tcrc := crc32.ChecksumIEEE(buf[8 : 8+payloadSize])\n\tbinary.LittleEndian.PutUint32(buf[p:p+4], crc)\n\n\t// Single atomic write to the buffered writer.\n\t_, err := w.Write(buf)\n\treturn err\n}","numLines":60,"startLine":382,"totalLines":957}},"sourceToolAssistantUUID":"81dfd337-a43f-4e4c-8bb0-5c8c399e92c3","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"60e1007f-0afd-444c-8f4c-8ee570395dec","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_0184KS1VRjcnvpDcL54P6pnR","type":"message","role":"assistant","content":[{"type":"text","text":"The function doesn't return size, but `totalSize` is computable. The simplest approach: estimate record size after the write using the same formula, or just change `writeWALRecordDirect` to return the bytes written. Actually, even simpler — I can just compute it the same way, or change the function signature. Let me change `writeWALRecordDirect` to return `(int, error)`:"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":981,"cache_read_input_tokens":43566,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":981},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUv84kF2fbCs43SzEihe","type":"assistant","uuid":"d7a5b8f1-7425-4045-992e-b3dcb6a59a67","timestamp":"2026-03-28T05:21:24.436Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"d7a5b8f1-7425-4045-992e-b3dcb6a59a67","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_0184KS1VRjcnvpDcL54P6pnR","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01XAHXFeieNNaXsLC3Huw3p2","name":"Edit","input":{"replace_all":false,"file_path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","old_string":"// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\n// then writes it to the bufio.Writer in a single call. This prevents partial\n// records in the write buffer if a write error occurs mid-record (e.g. disk full).\nfunc writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) error {","new_string":"// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\n// then writes it to the bufio.Writer in a single call. This prevents partial\n// records in the write buffer if a write error occurs mid-record (e.g. disk full).\n// Returns the number of bytes written and any error.\nfunc writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) (int, error) {"},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":981,"cache_read_input_tokens":43566,"output_tokens":427,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":981,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUv84kF2fbCs43SzEihe","type":"assistant","uuid":"e93afdf8-6b29-437b-b0ee-67952dd06498","timestamp":"2026-03-28T05:21:26.545Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"e93afdf8-6b29-437b-b0ee-67952dd06498","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01XAHXFeieNNaXsLC3Huw3p2","type":"tool_result","content":"The file /Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go has been updated successfully."}]},"uuid":"ca37853d-41f9-4cbd-bf8f-86594b402459","timestamp":"2026-03-28T05:21:26.585Z","toolUseResult":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","oldString":"// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\n// then writes it to the bufio.Writer in a single call. This prevents partial\n// records in the write buffer if a write error occurs mid-record (e.g. disk full).\nfunc writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) error {","newString":"// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\n// then writes it to the bufio.Writer in a single call. This prevents partial\n// records in the write buffer if a write error occurs mid-record (e.g. disk full).\n// Returns the number of bytes written and any error.\nfunc writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) (int, error) {","originalFile":"// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.\n// All rights reserved. This file is part of cc-backend.\n// Use of this source code is governed by a MIT-style\n// license that can be found in the LICENSE file.\n\n// Package metricstore provides walCheckpoint.go: WAL-based checkpoint implementation.\n//\n// This replaces the Avro shadow tree with an append-only Write-Ahead Log (WAL)\n// per host, eliminating the extra memory overhead of the AvroStore and providing\n// truly continuous (per-write) crash safety.\n//\n// # Architecture\n//\n//\tMetric write (DecodeLine)\n//\t │\n//\t ├─► WriteToLevel() → main MemoryStore (unchanged)\n//\t │\n//\t └─► WALMessages channel\n//\t │\n//\t ▼\n//\t WALStaging goroutine\n//\t │\n//\t ▼\n//\t checkpoints/cluster/host/current.wal (append-only, binary)\n//\n//\tPeriodic checkpoint (Checkpointing goroutine):\n//\t 1. Write <timestamp>.bin snapshot (column-oriented, from main tree)\n//\t 2. Signal WALStaging to truncate current.wal per host\n//\n//\tOn restart (FromCheckpoint):\n//\t 1. Load most recent <timestamp>.bin snapshot\n//\t 2. Replay current.wal (overwrite-safe: buffer.write handles duplicate timestamps)\n//\n// # WAL Record Format\n//\n//\t[4B magic 0xCC1DA7A1][4B payload_len][payload][4B CRC32]\n//\n//\tpayload:\n//\t [8B timestamp int64]\n//\t [2B metric_name_len uint16][N metric name bytes]\n//\t [1B selector_count uint8]\n//\t per selector: [1B selector_len uint8][M selector bytes]\n//\t [4B value float32 bits]\n//\n// # Binary Snapshot Format\n//\n//\t[4B magic 0xCC5B0001][8B from int64][8B to int64]\n//\tLevel tree (recursive):\n//\t [4B num_metrics uint32]\n//\t per metric:\n//\t [2B name_len uint16][N name bytes]\n//\t [8B frequency int64][8B start int64]\n//\t [4B num_values uint32][num_values × 4B float32]\n//\t [4B num_children uint32]\n//\t per child: [2B name_len uint16][N name bytes] + Level (recursive)\npackage metricstore\n\nimport (\n\t\"bufio\"\n\t\"context\"\n\t\"encoding/binary\"\n\t\"fmt\"\n\t\"hash/crc32\"\n\t\"hash/fnv\"\n\t\"io\"\n\t\"math\"\n\t\"os\"\n\t\"path\"\n\t\"strings\"\n\t\"sync\"\n\t\"sync/atomic\"\n\t\"time\"\n\n\tcclog \"github.com/ClusterCockpit/cc-lib/v2/ccLogger\"\n\t\"github.com/ClusterCockpit/cc-lib/v2/schema\"\n)\n\n// Magic numbers for binary formats.\nconst (\n\twalFileMagic = uint32(0xCC1DA701) // WAL file header magic\n\twalRecordMagic = uint32(0xCC1DA7A1) // WAL record magic\n\tsnapFileMagic = uint32(0xCC5B0001) // Binary snapshot magic\n)\n\n// walShardChs holds per-shard channels for WAL messages.\n// Initialized by WALStaging; nil when WAL is not active.\nvar walShardChs []chan *WALMessage\n\n// walShardRotateChs holds per-shard channels for WAL rotation requests.\nvar walShardRotateChs []chan walRotateReq\n\n// walNumShards stores the number of shards (set during WALStaging init).\nvar walNumShards int\n\n// walStagingWg tracks WALStaging goroutine exits for shutdown synchronization.\nvar walStagingWg sync.WaitGroup\n\n// walShuttingDown is set before closing shard channels to prevent\n// SendWALMessage from sending on a closed channel (which panics in Go).\nvar walShuttingDown atomic.Bool\n\n// WALMessage represents a single metric write to be appended to the WAL.\n// Cluster and Node are NOT stored in the WAL record (inferred from file path).\ntype WALMessage struct {\n\tMetricName string\n\tCluster string\n\tNode string\n\tSelector []string\n\tValue schema.Float\n\tTimestamp int64\n}\n\n// walRotateReq requests WAL file rotation for a specific host directory.\n// The done channel is closed by the WAL goroutine when rotation is complete.\ntype walRotateReq struct {\n\thostDir string\n\tdone chan struct{}\n}\n\n// walFileState holds an open WAL file handle and buffered writer for one host directory.\ntype walFileState struct {\n\tf *os.File\n\tw *bufio.Writer\n\tdirty bool\n\tsize int64 // approximate bytes written (tracked from open + writes)\n}\n\n// walFlushInterval controls how often dirty WAL files are flushed to disk.\n// Decoupling flushes from message processing lets the consumer run at memory\n// speed, amortizing syscall overhead across many writes.\nconst walFlushInterval = 1 * time.Second\n\n// walShardIndex computes which shard a message belongs to based on cluster+node.\n// Uses FNV-1a hash for fast, well-distributed mapping.\nfunc walShardIndex(cluster, node string) int {\n\th := fnv.New32a()\n\th.Write([]byte(cluster))\n\th.Write([]byte{0})\n\th.Write([]byte(node))\n\treturn int(h.Sum32()) % walNumShards\n}\n\n// SendWALMessage routes a WAL message to the appropriate shard channel.\n// Returns false if the channel is full or shutdown is in progress.\nfunc SendWALMessage(msg *WALMessage) bool {\n\tif walShardChs == nil || walShuttingDown.Load() {\n\t\treturn false\n\t}\n\tshard := walShardIndex(msg.Cluster, msg.Node)\n\tselect {\n\tcase walShardChs[shard] <- msg:\n\t\treturn true\n\tdefault:\n\t\treturn false\n\t}\n}\n\n// WALStaging starts N sharded background goroutines that receive WALMessage items\n// and append binary WAL records to per-host current.wal files.\n// Each shard owns a subset of hosts (determined by hash of cluster+node),\n// parallelizing serialization and I/O while keeping per-host writes serial.\nfunc WALStaging(wg *sync.WaitGroup, ctx context.Context) {\n\tif Keys.Checkpoints.FileFormat == \"json\" {\n\t\treturn\n\t}\n\n\twalNumShards = max(Keys.NumWorkers, 1)\n\tchBufSize := max(65536/walNumShards, 1024)\n\n\twalShardChs = make([]chan *WALMessage, walNumShards)\n\twalShardRotateChs = make([]chan walRotateReq, walNumShards)\n\n\tfor i := range walNumShards {\n\t\twalShardChs[i] = make(chan *WALMessage, chBufSize)\n\t\twalShardRotateChs[i] = make(chan walRotateReq, 64)\n\t}\n\n\tfor i := range walNumShards {\n\t\tmsgCh := walShardChs[i]\n\t\trotateCh := walShardRotateChs[i]\n\n\t\twalStagingWg.Add(1)\n\t\twg.Go(func() {\n\t\t\tdefer walStagingWg.Done()\n\t\t\thostFiles := make(map[string]*walFileState)\n\n\t\t\tdefer func() {\n\t\t\t\tfor _, ws := range hostFiles {\n\t\t\t\t\tif ws.f != nil {\n\t\t\t\t\t\tws.w.Flush()\n\t\t\t\t\t\tws.f.Close()\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}()\n\n\t\t\tgetOrOpenWAL := func(hostDir string) *walFileState {\n\t\t\t\tws, ok := hostFiles[hostDir]\n\t\t\t\tif ok {\n\t\t\t\t\treturn ws\n\t\t\t\t}\n\n\t\t\t\tif err := os.MkdirAll(hostDir, CheckpointDirPerms); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: mkdir %s: %v\", hostDir, err)\n\t\t\t\t\treturn nil\n\t\t\t\t}\n\n\t\t\t\twalPath := path.Join(hostDir, \"current.wal\")\n\t\t\t\tf, err := os.OpenFile(walPath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, CheckpointFilePerms)\n\t\t\t\tif err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: open %s: %v\", walPath, err)\n\t\t\t\t\treturn nil\n\t\t\t\t}\n\n\t\t\t\tw := bufio.NewWriter(f)\n\n\t\t\t\t// Write file header magic if file is new (empty).\n\t\t\t\tinfo, err := f.Stat()\n\t\t\t\tvar fileSize int64\n\t\t\t\tif err == nil {\n\t\t\t\t\tfileSize = info.Size()\n\t\t\t\t}\n\t\t\t\tif err == nil && fileSize == 0 {\n\t\t\t\t\tvar hdr [4]byte\n\t\t\t\t\tbinary.LittleEndian.PutUint32(hdr[:], walFileMagic)\n\t\t\t\t\tif _, err := w.Write(hdr[:]); err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write header %s: %v\", walPath, err)\n\t\t\t\t\t\tf.Close()\n\t\t\t\t\t\treturn nil\n\t\t\t\t\t}\n\t\t\t\t\tfileSize = 4\n\t\t\t\t}\n\n\t\t\t\tws = &walFileState{f: f, w: w, size: fileSize}\n\t\t\t\thostFiles[hostDir] = ws\n\t\t\t\treturn ws\n\t\t\t}\n\n\t\t\tprocessMsg := func(msg *WALMessage) {\n\t\t\t\thostDir := path.Join(Keys.Checkpoints.RootDir, msg.Cluster, msg.Node)\n\t\t\t\tws := getOrOpenWAL(hostDir)\n\t\t\t\tif ws == nil {\n\t\t\t\t\treturn\n\t\t\t\t}\n\t\t\t\tif err := writeWALRecordDirect(ws.w, msg); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write record: %v\", err)\n\t\t\t\t}\n\t\t\t\tws.dirty = true\n\t\t\t}\n\n\t\t\tprocessRotate := func(req walRotateReq) {\n\t\t\t\tws, ok := hostFiles[req.hostDir]\n\t\t\t\tif ok && ws.f != nil {\n\t\t\t\t\tws.w.Flush()\n\t\t\t\t\tws.f.Close()\n\t\t\t\t\twalPath := path.Join(req.hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tdelete(hostFiles, req.hostDir)\n\t\t\t\t}\n\t\t\t\tclose(req.done)\n\t\t\t}\n\n\t\t\tflushDirty := func() {\n\t\t\t\tfor _, ws := range hostFiles {\n\t\t\t\t\tif ws.dirty {\n\t\t\t\t\t\tws.w.Flush()\n\t\t\t\t\t\tws.dirty = false\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}\n\n\t\t\tticker := time.NewTicker(walFlushInterval)\n\t\t\tdefer ticker.Stop()\n\n\t\t\t// drainBatch processes up to 4096 pending messages without blocking.\n\t\t\t// Returns false if the channel was closed.\n\t\t\tdrainBatch := func() bool {\n\t\t\t\tfor range 4096 {\n\t\t\t\t\tselect {\n\t\t\t\t\tcase msg, ok := <-msgCh:\n\t\t\t\t\t\tif !ok {\n\t\t\t\t\t\t\tflushDirty()\n\t\t\t\t\t\t\treturn false\n\t\t\t\t\t\t}\n\t\t\t\t\t\tprocessMsg(msg)\n\t\t\t\t\tcase req := <-rotateCh:\n\t\t\t\t\t\tprocessRotate(req)\n\t\t\t\t\tdefault:\n\t\t\t\t\t\treturn true\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\treturn true\n\t\t\t}\n\n\t\t\tfor {\n\t\t\t\tselect {\n\t\t\t\tcase <-ctx.Done():\n\t\t\t\t\t// On shutdown, skip draining buffered messages — a full binary\n\t\t\t\t\t// checkpoint will be written from in-memory state, making\n\t\t\t\t\t// buffered WAL records redundant.\n\t\t\t\t\tflushDirty()\n\t\t\t\t\treturn\n\t\t\t\tcase msg, ok := <-msgCh:\n\t\t\t\t\tif !ok {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t\tprocessMsg(msg)\n\t\t\t\t\tif !drainBatch() {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t\t// No flush here — timer handles periodic flushing.\n\t\t\t\tcase <-ticker.C:\n\t\t\t\t\tflushDirty()\n\t\t\t\tcase req := <-rotateCh:\n\t\t\t\t\tprocessRotate(req)\n\t\t\t\t}\n\t\t\t}\n\t\t})\n\t}\n}\n\n// WaitForWALStagingDrain blocks until all WALStaging goroutines have exited.\n// Must be called after closing walShardChs to ensure all file handles are\n// flushed and closed before checkpoint writes begin.\nfunc WaitForWALStagingDrain() {\n\twalStagingWg.Wait()\n}\n\n// RotateWALFiles sends rotation requests for the given host directories\n// and blocks until all rotations complete. Each request is routed to the\n// shard that owns the host directory.\n//\n// If shutdown is in progress (WAL staging goroutines may have exited),\n// rotation is skipped to avoid deadlocking on abandoned channels.\nfunc RotateWALFiles(hostDirs []string) {\n\tif walShardRotateChs == nil || walShuttingDown.Load() {\n\t\treturn\n\t}\n\tdones := make([]chan struct{}, 0, len(hostDirs))\n\tfor _, dir := range hostDirs {\n\t\tdone := make(chan struct{})\n\t\tshard := walShardIndexFromDir(dir)\n\t\tselect {\n\t\tcase walShardRotateChs[shard] <- walRotateReq{hostDir: dir, done: done}:\n\t\t\tdones = append(dones, done)\n\t\tdefault:\n\t\t\t// Channel full or goroutine not consuming — skip this host.\n\t\t\tcclog.Warnf(\"[METRICSTORE]> WAL rotation skipped for %s (channel full)\", dir)\n\t\t}\n\t}\n\tfor _, done := range dones {\n\t\tselect {\n\t\tcase <-done:\n\t\tcase <-time.After(30 * time.Second):\n\t\t\tcclog.Warn(\"[METRICSTORE]> WAL rotation timed out, continuing\")\n\t\t\treturn\n\t\t}\n\t}\n}\n\n// walShardIndexFromDir extracts cluster and node from a host directory path\n// and returns the shard index. The path format is: rootDir/cluster/node\nfunc walShardIndexFromDir(hostDir string) int {\n\t// hostDir = .../cluster/node — extract last two path components\n\tnode := path.Base(hostDir)\n\tcluster := path.Base(path.Dir(hostDir))\n\treturn walShardIndex(cluster, node)\n}\n\n// RotateWALFiles sends rotation requests for the given host directories\n// and blocks until all rotations complete.\nfunc RotateWALFilesAfterShutdown(hostDirs []string) {\n\tfor _, dir := range hostDirs {\n\t\twalPath := path.Join(dir, \"current.wal\")\n\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t}\n\t}\n}\n\n// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\n// then writes it to the bufio.Writer in a single call. This prevents partial\n// records in the write buffer if a write error occurs mid-record (e.g. disk full).\nfunc writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) error {\n\t// Compute payload and total record size.\n\tpayloadSize := 8 + 2 + len(msg.MetricName) + 1 + 4\n\tfor _, s := range msg.Selector {\n\t\tpayloadSize += 1 + len(s)\n\t}\n\t// Total: 8 (header) + payload + 4 (CRC).\n\ttotalSize := 8 + payloadSize + 4\n\n\t// Use stack buffer for typical small records, heap-allocate only for large ones.\n\tvar stackBuf [256]byte\n\tvar buf []byte\n\tif totalSize <= len(stackBuf) {\n\t\tbuf = stackBuf[:totalSize]\n\t} else {\n\t\tbuf = make([]byte, totalSize)\n\t}\n\n\t// Header: magic + payload length.\n\tbinary.LittleEndian.PutUint32(buf[0:4], walRecordMagic)\n\tbinary.LittleEndian.PutUint32(buf[4:8], uint32(payloadSize))\n\n\t// Payload starts at offset 8.\n\tp := 8\n\n\t// Timestamp (8 bytes).\n\tbinary.LittleEndian.PutUint64(buf[p:p+8], uint64(msg.Timestamp))\n\tp += 8\n\n\t// Metric name length (2 bytes) + metric name.\n\tbinary.LittleEndian.PutUint16(buf[p:p+2], uint16(len(msg.MetricName)))\n\tp += 2\n\tp += copy(buf[p:], msg.MetricName)\n\n\t// Selector count (1 byte).\n\tbuf[p] = byte(len(msg.Selector))\n\tp++\n\n\t// Selectors (1-byte length + bytes each).\n\tfor _, sel := range msg.Selector {\n\t\tbuf[p] = byte(len(sel))\n\t\tp++\n\t\tp += copy(buf[p:], sel)\n\t}\n\n\t// Value (4 bytes, float32 bits).\n\tbinary.LittleEndian.PutUint32(buf[p:p+4], math.Float32bits(float32(msg.Value)))\n\tp += 4\n\n\t// CRC32 over payload (bytes 8..8+payloadSize).\n\tcrc := crc32.ChecksumIEEE(buf[8 : 8+payloadSize])\n\tbinary.LittleEndian.PutUint32(buf[p:p+4], crc)\n\n\t// Single atomic write to the buffered writer.\n\t_, err := w.Write(buf)\n\treturn err\n}\n\n// readWALRecord reads one WAL record from the reader.\n// Returns (nil, nil) on clean EOF. Returns error on data corruption.\n// A CRC mismatch indicates a truncated trailing record (expected on crash).\nfunc readWALRecord(r io.Reader) (*WALMessage, error) {\n\tvar magic uint32\n\tif err := binary.Read(r, binary.LittleEndian, &magic); err != nil {\n\t\tif err == io.EOF {\n\t\t\treturn nil, nil // Clean EOF\n\t\t}\n\t\treturn nil, fmt.Errorf(\"read record magic: %w\", err)\n\t}\n\n\tif magic != walRecordMagic {\n\t\treturn nil, fmt.Errorf(\"invalid record magic 0x%08X (expected 0x%08X)\", magic, walRecordMagic)\n\t}\n\n\tvar payloadLen uint32\n\tif err := binary.Read(r, binary.LittleEndian, &payloadLen); err != nil {\n\t\treturn nil, fmt.Errorf(\"read payload length: %w\", err)\n\t}\n\n\tif payloadLen > 1<<20 { // 1 MB sanity limit\n\t\treturn nil, fmt.Errorf(\"record payload too large: %d bytes\", payloadLen)\n\t}\n\n\tpayload := make([]byte, payloadLen)\n\tif _, err := io.ReadFull(r, payload); err != nil {\n\t\treturn nil, fmt.Errorf(\"read payload: %w\", err)\n\t}\n\n\tvar storedCRC uint32\n\tif err := binary.Read(r, binary.LittleEndian, &storedCRC); err != nil {\n\t\treturn nil, fmt.Errorf(\"read CRC: %w\", err)\n\t}\n\n\tif crc32.ChecksumIEEE(payload) != storedCRC {\n\t\treturn nil, fmt.Errorf(\"CRC mismatch (truncated write or corruption)\")\n\t}\n\n\treturn parseWALPayload(payload)\n}\n\n// parseWALPayload decodes a binary payload into a WALMessage.\nfunc parseWALPayload(payload []byte) (*WALMessage, error) {\n\tif len(payload) < 8+2+1+4 {\n\t\treturn nil, fmt.Errorf(\"payload too short: %d bytes\", len(payload))\n\t}\n\n\toffset := 0\n\n\t// Timestamp (8 bytes)\n\tts := int64(binary.LittleEndian.Uint64(payload[offset : offset+8]))\n\toffset += 8\n\n\t// Metric name (2-byte length + bytes)\n\tif offset+2 > len(payload) {\n\t\treturn nil, fmt.Errorf(\"metric name length overflows payload\")\n\t}\n\tmLen := int(binary.LittleEndian.Uint16(payload[offset : offset+2]))\n\toffset += 2\n\n\tif offset+mLen > len(payload) {\n\t\treturn nil, fmt.Errorf(\"metric name overflows payload\")\n\t}\n\tmetricName := string(payload[offset : offset+mLen])\n\toffset += mLen\n\n\t// Selector count (1 byte)\n\tif offset >= len(payload) {\n\t\treturn nil, fmt.Errorf(\"selector count overflows payload\")\n\t}\n\tselCount := int(payload[offset])\n\toffset++\n\n\tselectors := make([]string, selCount)\n\tfor i := range selCount {\n\t\tif offset >= len(payload) {\n\t\t\treturn nil, fmt.Errorf(\"selector[%d] length overflows payload\", i)\n\t\t}\n\t\tsLen := int(payload[offset])\n\t\toffset++\n\n\t\tif offset+sLen > len(payload) {\n\t\t\treturn nil, fmt.Errorf(\"selector[%d] data overflows payload\", i)\n\t\t}\n\t\tselectors[i] = string(payload[offset : offset+sLen])\n\t\toffset += sLen\n\t}\n\n\t// Value (4 bytes, float32 bits)\n\tif offset+4 > len(payload) {\n\t\treturn nil, fmt.Errorf(\"value overflows payload\")\n\t}\n\tbits := binary.LittleEndian.Uint32(payload[offset : offset+4])\n\tvalue := schema.Float(math.Float32frombits(bits))\n\n\treturn &WALMessage{\n\t\tMetricName: metricName,\n\t\tTimestamp: ts,\n\t\tSelector: selectors,\n\t\tValue: value,\n\t}, nil\n}\n\n// loadWALFile reads a WAL file and replays all valid records into the Level tree.\n// l is the host-level node. Corrupt or partial trailing records are silently skipped\n// (expected on crash). Records older than 'from' are skipped.\nfunc (l *Level) loadWALFile(m *MemoryStore, f *os.File, from int64) error {\n\tbr := bufio.NewReader(f)\n\n\t// Verify file header magic.\n\tvar fileMagic uint32\n\tif err := binary.Read(br, binary.LittleEndian, &fileMagic); err != nil {\n\t\tif err == io.EOF {\n\t\t\treturn nil // Empty file, no data\n\t\t}\n\t\treturn fmt.Errorf(\"[METRICSTORE]> WAL: read file header: %w\", err)\n\t}\n\n\tif fileMagic != walFileMagic {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> WAL: invalid file magic 0x%08X (expected 0x%08X)\", fileMagic, walFileMagic)\n\t}\n\n\t// Cache level lookups to avoid repeated tree traversal.\n\tlvlCache := make(map[string]*Level)\n\n\tfor {\n\t\tmsg, err := readWALRecord(br)\n\t\tif err != nil {\n\t\t\t// Truncated trailing record is expected after a crash; stop replaying.\n\t\t\tcclog.Debugf(\"[METRICSTORE]> WAL: stopping replay at corrupted/partial record: %v\", err)\n\t\t\tbreak\n\t\t}\n\t\tif msg == nil {\n\t\t\tbreak // Clean EOF\n\t\t}\n\n\t\tif msg.Timestamp < from {\n\t\t\tcontinue // Older than retention window\n\t\t}\n\n\t\tminfo, ok := m.Metrics[msg.MetricName]\n\t\tif !ok {\n\t\t\tcontinue // Unknown metric (config may have changed)\n\t\t}\n\n\t\t// Cache key is the null-separated selector path.\n\t\tcacheKey := joinSelector(msg.Selector)\n\t\tlvl, ok := lvlCache[cacheKey]\n\t\tif !ok {\n\t\t\tlvl = l.findLevelOrCreate(msg.Selector, len(m.Metrics))\n\t\t\tlvlCache[cacheKey] = lvl\n\t\t}\n\n\t\t// Write directly to the buffer, same as WriteToLevel but without the\n\t\t// global level lookup (we already have the right level).\n\t\tlvl.lock.Lock()\n\t\tb := lvl.metrics[minfo.offset]\n\t\tif b == nil {\n\t\t\tb = newBuffer(msg.Timestamp, minfo.Frequency)\n\t\t\tlvl.metrics[minfo.offset] = b\n\t\t}\n\t\tnb, writeErr := b.write(msg.Timestamp, msg.Value)\n\t\tif writeErr == nil && b != nb {\n\t\t\tlvl.metrics[minfo.offset] = nb\n\t\t}\n\t\t// Ignore write errors for timestamps before buffer start (can happen when\n\t\t// replaying WAL entries that predate a loaded snapshot's start time).\n\t\tlvl.lock.Unlock()\n\t}\n\n\treturn nil\n}\n\n// joinSelector builds a cache key from a selector slice using null bytes as separators.\nfunc joinSelector(sel []string) string {\n\tif len(sel) == 0 {\n\t\treturn \"\"\n\t}\n\tvar result strings.Builder\n\tresult.WriteString(sel[0])\n\tfor i := 1; i < len(sel); i++ {\n\t\tresult.WriteString(\"\\x00\" + sel[i])\n\t}\n\treturn result.String()\n}\n\n// ToCheckpointWAL writes binary snapshot files for all hosts in parallel.\n// Returns the number of files written, the list of host directories that were\n// successfully checkpointed (for WAL rotation), and any errors.\nfunc (m *MemoryStore) ToCheckpointWAL(dir string, from, to int64) (int, []string, error) {\n\t// Collect all cluster/host pairs.\n\tm.root.lock.RLock()\n\ttotalHosts := 0\n\tfor _, l1 := range m.root.children {\n\t\tl1.lock.RLock()\n\t\ttotalHosts += len(l1.children)\n\t\tl1.lock.RUnlock()\n\t}\n\tm.root.lock.RUnlock()\n\n\tlevels := make([]*Level, 0, totalHosts)\n\tselectors := make([][]string, 0, totalHosts)\n\n\tm.root.lock.RLock()\n\tfor sel1, l1 := range m.root.children {\n\t\tl1.lock.RLock()\n\t\tfor sel2, l2 := range l1.children {\n\t\t\tlevels = append(levels, l2)\n\t\t\tselectors = append(selectors, []string{sel1, sel2})\n\t\t}\n\t\tl1.lock.RUnlock()\n\t}\n\tm.root.lock.RUnlock()\n\n\ttype workItem struct {\n\t\tlevel *Level\n\t\thostDir string\n\t\tselector []string\n\t}\n\n\ttotalWork := len(levels)\n\tcclog.Infof(\"[METRICSTORE]> Starting binary checkpoint for %d hosts with %d workers\", totalWork, Keys.NumWorkers)\n\n\tn, errs, completed := int32(0), int32(0), int32(0)\n\tvar successDirs []string\n\tvar successMu sync.Mutex\n\n\tvar wg sync.WaitGroup\n\twg.Add(Keys.NumWorkers)\n\twork := make(chan workItem, Keys.NumWorkers*2)\n\n\t// Progress logging goroutine.\n\tstopProgress := make(chan struct{})\n\tgo func() {\n\t\tticker := time.NewTicker(10 * time.Second)\n\t\tdefer ticker.Stop()\n\t\tfor {\n\t\t\tselect {\n\t\t\tcase <-ticker.C:\n\t\t\t\tcclog.Infof(\"[METRICSTORE]> Checkpoint progress: %d/%d hosts (%d written, %d errors)\",\n\t\t\t\t\tatomic.LoadInt32(&completed), totalWork, atomic.LoadInt32(&n), atomic.LoadInt32(&errs))\n\t\t\tcase <-stopProgress:\n\t\t\t\treturn\n\t\t\t}\n\t\t}\n\t}()\n\n\tfor range Keys.NumWorkers {\n\t\tgo func() {\n\t\t\tdefer wg.Done()\n\t\t\tfor wi := range work {\n\t\t\t\terr := wi.level.toCheckpointBinary(wi.hostDir, from, to, m)\n\t\t\t\tif err != nil {\n\t\t\t\t\tif err == ErrNoNewArchiveData {\n\t\t\t\t\t\tatomic.AddInt32(&completed, 1)\n\t\t\t\t\t\tcontinue\n\t\t\t\t\t}\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> binary checkpoint error for %s: %v\", wi.hostDir, err)\n\t\t\t\t\tatomic.AddInt32(&errs, 1)\n\t\t\t\t} else {\n\t\t\t\t\tatomic.AddInt32(&n, 1)\n\t\t\t\t\t// Delete WAL immediately after successful snapshot.\n\t\t\t\t\twalPath := path.Join(wi.hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tsuccessMu.Lock()\n\t\t\t\t\tsuccessDirs = append(successDirs, wi.hostDir)\n\t\t\t\t\tsuccessMu.Unlock()\n\t\t\t\t}\n\t\t\t\tatomic.AddInt32(&completed, 1)\n\t\t\t}\n\t\t}()\n\t}\n\n\tfor i := range levels {\n\t\thostDir := path.Join(dir, path.Join(selectors[i]...))\n\t\twork <- workItem{\n\t\t\tlevel: levels[i],\n\t\t\thostDir: hostDir,\n\t\t\tselector: selectors[i],\n\t\t}\n\t}\n\tclose(work)\n\twg.Wait()\n\tclose(stopProgress)\n\n\tif errs > 0 {\n\t\treturn int(n), successDirs, fmt.Errorf(\"[METRICSTORE]> %d errors during binary checkpoint (%d successes)\", errs, n)\n\t}\n\treturn int(n), successDirs, nil\n}\n\n// toCheckpointBinary writes a binary snapshot file for a single host-level node.\n// Uses atomic rename (write to .tmp then rename) to avoid partial reads on crash.\nfunc (l *Level) toCheckpointBinary(dir string, from, to int64, m *MemoryStore) error {\n\tcf, err := l.toCheckpointFile(from, to, m)\n\tif err != nil {\n\t\treturn err\n\t}\n\tif cf == nil {\n\t\treturn ErrNoNewArchiveData\n\t}\n\n\tif err := os.MkdirAll(dir, CheckpointDirPerms); err != nil {\n\t\treturn fmt.Errorf(\"mkdir %s: %w\", dir, err)\n\t}\n\n\t// Write to a temp file first, then rename (atomic on POSIX).\n\ttmpPath := path.Join(dir, fmt.Sprintf(\"%d.bin.tmp\", from))\n\tfinalPath := path.Join(dir, fmt.Sprintf(\"%d.bin\", from))\n\n\tf, err := os.OpenFile(tmpPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, CheckpointFilePerms)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"open binary snapshot %s: %w\", tmpPath, err)\n\t}\n\n\tbw := bufio.NewWriter(f)\n\tif err := writeBinarySnapshotFile(bw, cf); err != nil {\n\t\tf.Close()\n\t\tos.Remove(tmpPath)\n\t\treturn fmt.Errorf(\"write binary snapshot: %w\", err)\n\t}\n\tif err := bw.Flush(); err != nil {\n\t\tf.Close()\n\t\tos.Remove(tmpPath)\n\t\treturn err\n\t}\n\tf.Close()\n\n\treturn os.Rename(tmpPath, finalPath)\n}\n\n// writeBinarySnapshotFile writes the binary snapshot file header and level tree.\nfunc writeBinarySnapshotFile(w io.Writer, cf *CheckpointFile) error {\n\tif err := binary.Write(w, binary.LittleEndian, snapFileMagic); err != nil {\n\t\treturn err\n\t}\n\tif err := binary.Write(w, binary.LittleEndian, cf.From); err != nil {\n\t\treturn err\n\t}\n\tif err := binary.Write(w, binary.LittleEndian, cf.To); err != nil {\n\t\treturn err\n\t}\n\treturn writeBinaryLevel(w, cf)\n}\n\n// writeBinaryLevel recursively writes a CheckpointFile level in binary format.\nfunc writeBinaryLevel(w io.Writer, cf *CheckpointFile) error {\n\tif err := binary.Write(w, binary.LittleEndian, uint32(len(cf.Metrics))); err != nil {\n\t\treturn err\n\t}\n\n\tfor name, metric := range cf.Metrics {\n\t\tif err := writeString16(w, name); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, metric.Frequency); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, metric.Start); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, uint32(len(metric.Data))); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tfor _, v := range metric.Data {\n\t\t\tif err := binary.Write(w, binary.LittleEndian, math.Float32bits(float32(v))); err != nil {\n\t\t\t\treturn err\n\t\t\t}\n\t\t}\n\t}\n\n\tif err := binary.Write(w, binary.LittleEndian, uint32(len(cf.Children))); err != nil {\n\t\treturn err\n\t}\n\n\tfor name, child := range cf.Children {\n\t\tif err := writeString16(w, name); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := writeBinaryLevel(w, child); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\n\treturn nil\n}\n\n// writeString16 writes a 2-byte length-prefixed string to w.\nfunc writeString16(w io.Writer, s string) error {\n\tif err := binary.Write(w, binary.LittleEndian, uint16(len(s))); err != nil {\n\t\treturn err\n\t}\n\t_, err := io.WriteString(w, s)\n\treturn err\n}\n\n// loadBinaryFile reads a binary snapshot file and loads data into the Level tree.\n// The retention check (from) is applied to the file's 'to' timestamp.\nfunc (l *Level) loadBinaryFile(m *MemoryStore, f *os.File, from int64) error {\n\tbr := bufio.NewReader(f)\n\n\tvar magic uint32\n\tif err := binary.Read(br, binary.LittleEndian, &magic); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read magic: %w\", err)\n\t}\n\tif magic != snapFileMagic {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: invalid magic 0x%08X (expected 0x%08X)\", magic, snapFileMagic)\n\t}\n\n\tvar fileFrom, fileTo int64\n\tif err := binary.Read(br, binary.LittleEndian, &fileFrom); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read from: %w\", err)\n\t}\n\tif err := binary.Read(br, binary.LittleEndian, &fileTo); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read to: %w\", err)\n\t}\n\n\tif fileTo != 0 && fileTo < from {\n\t\treturn nil // File is older than retention window, skip it\n\t}\n\n\tcf, err := readBinaryLevel(br)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read level tree: %w\", err)\n\t}\n\tcf.From = fileFrom\n\tcf.To = fileTo\n\n\treturn l.loadFile(cf, m)\n}\n\n// readBinaryLevel recursively reads a level from the binary snapshot format.\nfunc readBinaryLevel(r io.Reader) (*CheckpointFile, error) {\n\tcf := &CheckpointFile{\n\t\tMetrics: make(map[string]*CheckpointMetrics),\n\t\tChildren: make(map[string]*CheckpointFile),\n\t}\n\n\tvar numMetrics uint32\n\tif err := binary.Read(r, binary.LittleEndian, &numMetrics); err != nil {\n\t\treturn nil, fmt.Errorf(\"read num_metrics: %w\", err)\n\t}\n\n\tfor range numMetrics {\n\t\tname, err := readString16(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read metric name: %w\", err)\n\t\t}\n\n\t\tvar freq, start int64\n\t\tif err := binary.Read(r, binary.LittleEndian, &freq); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read frequency for %s: %w\", name, err)\n\t\t}\n\t\tif err := binary.Read(r, binary.LittleEndian, &start); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read start for %s: %w\", name, err)\n\t\t}\n\n\t\tvar numValues uint32\n\t\tif err := binary.Read(r, binary.LittleEndian, &numValues); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read num_values for %s: %w\", name, err)\n\t\t}\n\n\t\tdata := make([]schema.Float, numValues)\n\t\tfor i := range numValues {\n\t\t\tvar bits uint32\n\t\t\tif err := binary.Read(r, binary.LittleEndian, &bits); err != nil {\n\t\t\t\treturn nil, fmt.Errorf(\"read value[%d] for %s: %w\", i, name, err)\n\t\t\t}\n\t\t\tdata[i] = schema.Float(math.Float32frombits(bits))\n\t\t}\n\n\t\tcf.Metrics[name] = &CheckpointMetrics{\n\t\t\tFrequency: freq,\n\t\t\tStart: start,\n\t\t\tData: data,\n\t\t}\n\t}\n\n\tvar numChildren uint32\n\tif err := binary.Read(r, binary.LittleEndian, &numChildren); err != nil {\n\t\treturn nil, fmt.Errorf(\"read num_children: %w\", err)\n\t}\n\n\tfor range numChildren {\n\t\tchildName, err := readString16(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read child name: %w\", err)\n\t\t}\n\n\t\tchild, err := readBinaryLevel(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read child %s: %w\", childName, err)\n\t\t}\n\t\tcf.Children[childName] = child\n\t}\n\n\treturn cf, nil\n}\n\n// readString16 reads a 2-byte length-prefixed string from r.\nfunc readString16(r io.Reader) (string, error) {\n\tvar sLen uint16\n\tif err := binary.Read(r, binary.LittleEndian, &sLen); err != nil {\n\t\treturn \"\", err\n\t}\n\tbuf := make([]byte, sLen)\n\tif _, err := io.ReadFull(r, buf); err != nil {\n\t\treturn \"\", err\n\t}\n\treturn string(buf), nil\n}\n","structuredPatch":[{"oldStart":382,"oldLines":7,"newStart":382,"newLines":8,"lines":[" // writeWALRecordDirect encodes a WAL record into a contiguous buffer first,"," // then writes it to the bufio.Writer in a single call. This prevents partial"," // records in the write buffer if a write error occurs mid-record (e.g. disk full).","-func writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) error {","+// Returns the number of bytes written and any error.","+func writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) (int, error) {"," // Compute payload and total record size."," payloadSize := 8 + 2 + len(msg.MetricName) + 1 + 4"," for _, s := range msg.Selector {"]}],"userModified":false,"replaceAll":false},"sourceToolAssistantUUID":"e93afdf8-6b29-437b-b0ee-67952dd06498","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"3521bdc4-973a-44cf-b485-f8698fb8bd85","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01Va88S1Uh1ARuVSGGtWR5ff","type":"tool_result","content":"The file /Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go has been updated successfully."}]},"uuid":"cc99d38b-a539-45ae-8fc3-36eac429f3f4","timestamp":"2026-03-28T05:21:30.913Z","toolUseResult":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","oldString":"\t// Single atomic write to the buffered writer.\n\t_, err := w.Write(buf)\n\treturn err\n}","newString":"\t// Single atomic write to the buffered writer.\n\tn, err := w.Write(buf)\n\treturn n, err\n}","originalFile":"// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.\n// All rights reserved. This file is part of cc-backend.\n// Use of this source code is governed by a MIT-style\n// license that can be found in the LICENSE file.\n\n// Package metricstore provides walCheckpoint.go: WAL-based checkpoint implementation.\n//\n// This replaces the Avro shadow tree with an append-only Write-Ahead Log (WAL)\n// per host, eliminating the extra memory overhead of the AvroStore and providing\n// truly continuous (per-write) crash safety.\n//\n// # Architecture\n//\n//\tMetric write (DecodeLine)\n//\t │\n//\t ├─► WriteToLevel() → main MemoryStore (unchanged)\n//\t │\n//\t └─► WALMessages channel\n//\t │\n//\t ▼\n//\t WALStaging goroutine\n//\t │\n//\t ▼\n//\t checkpoints/cluster/host/current.wal (append-only, binary)\n//\n//\tPeriodic checkpoint (Checkpointing goroutine):\n//\t 1. Write <timestamp>.bin snapshot (column-oriented, from main tree)\n//\t 2. Signal WALStaging to truncate current.wal per host\n//\n//\tOn restart (FromCheckpoint):\n//\t 1. Load most recent <timestamp>.bin snapshot\n//\t 2. Replay current.wal (overwrite-safe: buffer.write handles duplicate timestamps)\n//\n// # WAL Record Format\n//\n//\t[4B magic 0xCC1DA7A1][4B payload_len][payload][4B CRC32]\n//\n//\tpayload:\n//\t [8B timestamp int64]\n//\t [2B metric_name_len uint16][N metric name bytes]\n//\t [1B selector_count uint8]\n//\t per selector: [1B selector_len uint8][M selector bytes]\n//\t [4B value float32 bits]\n//\n// # Binary Snapshot Format\n//\n//\t[4B magic 0xCC5B0001][8B from int64][8B to int64]\n//\tLevel tree (recursive):\n//\t [4B num_metrics uint32]\n//\t per metric:\n//\t [2B name_len uint16][N name bytes]\n//\t [8B frequency int64][8B start int64]\n//\t [4B num_values uint32][num_values × 4B float32]\n//\t [4B num_children uint32]\n//\t per child: [2B name_len uint16][N name bytes] + Level (recursive)\npackage metricstore\n\nimport (\n\t\"bufio\"\n\t\"context\"\n\t\"encoding/binary\"\n\t\"fmt\"\n\t\"hash/crc32\"\n\t\"hash/fnv\"\n\t\"io\"\n\t\"math\"\n\t\"os\"\n\t\"path\"\n\t\"strings\"\n\t\"sync\"\n\t\"sync/atomic\"\n\t\"time\"\n\n\tcclog \"github.com/ClusterCockpit/cc-lib/v2/ccLogger\"\n\t\"github.com/ClusterCockpit/cc-lib/v2/schema\"\n)\n\n// Magic numbers for binary formats.\nconst (\n\twalFileMagic = uint32(0xCC1DA701) // WAL file header magic\n\twalRecordMagic = uint32(0xCC1DA7A1) // WAL record magic\n\tsnapFileMagic = uint32(0xCC5B0001) // Binary snapshot magic\n)\n\n// walShardChs holds per-shard channels for WAL messages.\n// Initialized by WALStaging; nil when WAL is not active.\nvar walShardChs []chan *WALMessage\n\n// walShardRotateChs holds per-shard channels for WAL rotation requests.\nvar walShardRotateChs []chan walRotateReq\n\n// walNumShards stores the number of shards (set during WALStaging init).\nvar walNumShards int\n\n// walStagingWg tracks WALStaging goroutine exits for shutdown synchronization.\nvar walStagingWg sync.WaitGroup\n\n// walShuttingDown is set before closing shard channels to prevent\n// SendWALMessage from sending on a closed channel (which panics in Go).\nvar walShuttingDown atomic.Bool\n\n// WALMessage represents a single metric write to be appended to the WAL.\n// Cluster and Node are NOT stored in the WAL record (inferred from file path).\ntype WALMessage struct {\n\tMetricName string\n\tCluster string\n\tNode string\n\tSelector []string\n\tValue schema.Float\n\tTimestamp int64\n}\n\n// walRotateReq requests WAL file rotation for a specific host directory.\n// The done channel is closed by the WAL goroutine when rotation is complete.\ntype walRotateReq struct {\n\thostDir string\n\tdone chan struct{}\n}\n\n// walFileState holds an open WAL file handle and buffered writer for one host directory.\ntype walFileState struct {\n\tf *os.File\n\tw *bufio.Writer\n\tdirty bool\n\tsize int64 // approximate bytes written (tracked from open + writes)\n}\n\n// walFlushInterval controls how often dirty WAL files are flushed to disk.\n// Decoupling flushes from message processing lets the consumer run at memory\n// speed, amortizing syscall overhead across many writes.\nconst walFlushInterval = 1 * time.Second\n\n// walShardIndex computes which shard a message belongs to based on cluster+node.\n// Uses FNV-1a hash for fast, well-distributed mapping.\nfunc walShardIndex(cluster, node string) int {\n\th := fnv.New32a()\n\th.Write([]byte(cluster))\n\th.Write([]byte{0})\n\th.Write([]byte(node))\n\treturn int(h.Sum32()) % walNumShards\n}\n\n// SendWALMessage routes a WAL message to the appropriate shard channel.\n// Returns false if the channel is full or shutdown is in progress.\nfunc SendWALMessage(msg *WALMessage) bool {\n\tif walShardChs == nil || walShuttingDown.Load() {\n\t\treturn false\n\t}\n\tshard := walShardIndex(msg.Cluster, msg.Node)\n\tselect {\n\tcase walShardChs[shard] <- msg:\n\t\treturn true\n\tdefault:\n\t\treturn false\n\t}\n}\n\n// WALStaging starts N sharded background goroutines that receive WALMessage items\n// and append binary WAL records to per-host current.wal files.\n// Each shard owns a subset of hosts (determined by hash of cluster+node),\n// parallelizing serialization and I/O while keeping per-host writes serial.\nfunc WALStaging(wg *sync.WaitGroup, ctx context.Context) {\n\tif Keys.Checkpoints.FileFormat == \"json\" {\n\t\treturn\n\t}\n\n\twalNumShards = max(Keys.NumWorkers, 1)\n\tchBufSize := max(65536/walNumShards, 1024)\n\n\twalShardChs = make([]chan *WALMessage, walNumShards)\n\twalShardRotateChs = make([]chan walRotateReq, walNumShards)\n\n\tfor i := range walNumShards {\n\t\twalShardChs[i] = make(chan *WALMessage, chBufSize)\n\t\twalShardRotateChs[i] = make(chan walRotateReq, 64)\n\t}\n\n\tfor i := range walNumShards {\n\t\tmsgCh := walShardChs[i]\n\t\trotateCh := walShardRotateChs[i]\n\n\t\twalStagingWg.Add(1)\n\t\twg.Go(func() {\n\t\t\tdefer walStagingWg.Done()\n\t\t\thostFiles := make(map[string]*walFileState)\n\n\t\t\tdefer func() {\n\t\t\t\tfor _, ws := range hostFiles {\n\t\t\t\t\tif ws.f != nil {\n\t\t\t\t\t\tws.w.Flush()\n\t\t\t\t\t\tws.f.Close()\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}()\n\n\t\t\tgetOrOpenWAL := func(hostDir string) *walFileState {\n\t\t\t\tws, ok := hostFiles[hostDir]\n\t\t\t\tif ok {\n\t\t\t\t\treturn ws\n\t\t\t\t}\n\n\t\t\t\tif err := os.MkdirAll(hostDir, CheckpointDirPerms); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: mkdir %s: %v\", hostDir, err)\n\t\t\t\t\treturn nil\n\t\t\t\t}\n\n\t\t\t\twalPath := path.Join(hostDir, \"current.wal\")\n\t\t\t\tf, err := os.OpenFile(walPath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, CheckpointFilePerms)\n\t\t\t\tif err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: open %s: %v\", walPath, err)\n\t\t\t\t\treturn nil\n\t\t\t\t}\n\n\t\t\t\tw := bufio.NewWriter(f)\n\n\t\t\t\t// Write file header magic if file is new (empty).\n\t\t\t\tinfo, err := f.Stat()\n\t\t\t\tvar fileSize int64\n\t\t\t\tif err == nil {\n\t\t\t\t\tfileSize = info.Size()\n\t\t\t\t}\n\t\t\t\tif err == nil && fileSize == 0 {\n\t\t\t\t\tvar hdr [4]byte\n\t\t\t\t\tbinary.LittleEndian.PutUint32(hdr[:], walFileMagic)\n\t\t\t\t\tif _, err := w.Write(hdr[:]); err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write header %s: %v\", walPath, err)\n\t\t\t\t\t\tf.Close()\n\t\t\t\t\t\treturn nil\n\t\t\t\t\t}\n\t\t\t\t\tfileSize = 4\n\t\t\t\t}\n\n\t\t\t\tws = &walFileState{f: f, w: w, size: fileSize}\n\t\t\t\thostFiles[hostDir] = ws\n\t\t\t\treturn ws\n\t\t\t}\n\n\t\t\tprocessMsg := func(msg *WALMessage) {\n\t\t\t\thostDir := path.Join(Keys.Checkpoints.RootDir, msg.Cluster, msg.Node)\n\t\t\t\tws := getOrOpenWAL(hostDir)\n\t\t\t\tif ws == nil {\n\t\t\t\t\treturn\n\t\t\t\t}\n\t\t\t\tif err := writeWALRecordDirect(ws.w, msg); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write record: %v\", err)\n\t\t\t\t}\n\t\t\t\tws.dirty = true\n\t\t\t}\n\n\t\t\tprocessRotate := func(req walRotateReq) {\n\t\t\t\tws, ok := hostFiles[req.hostDir]\n\t\t\t\tif ok && ws.f != nil {\n\t\t\t\t\tws.w.Flush()\n\t\t\t\t\tws.f.Close()\n\t\t\t\t\twalPath := path.Join(req.hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tdelete(hostFiles, req.hostDir)\n\t\t\t\t}\n\t\t\t\tclose(req.done)\n\t\t\t}\n\n\t\t\tflushDirty := func() {\n\t\t\t\tfor _, ws := range hostFiles {\n\t\t\t\t\tif ws.dirty {\n\t\t\t\t\t\tws.w.Flush()\n\t\t\t\t\t\tws.dirty = false\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}\n\n\t\t\tticker := time.NewTicker(walFlushInterval)\n\t\t\tdefer ticker.Stop()\n\n\t\t\t// drainBatch processes up to 4096 pending messages without blocking.\n\t\t\t// Returns false if the channel was closed.\n\t\t\tdrainBatch := func() bool {\n\t\t\t\tfor range 4096 {\n\t\t\t\t\tselect {\n\t\t\t\t\tcase msg, ok := <-msgCh:\n\t\t\t\t\t\tif !ok {\n\t\t\t\t\t\t\tflushDirty()\n\t\t\t\t\t\t\treturn false\n\t\t\t\t\t\t}\n\t\t\t\t\t\tprocessMsg(msg)\n\t\t\t\t\tcase req := <-rotateCh:\n\t\t\t\t\t\tprocessRotate(req)\n\t\t\t\t\tdefault:\n\t\t\t\t\t\treturn true\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\treturn true\n\t\t\t}\n\n\t\t\tfor {\n\t\t\t\tselect {\n\t\t\t\tcase <-ctx.Done():\n\t\t\t\t\t// On shutdown, skip draining buffered messages — a full binary\n\t\t\t\t\t// checkpoint will be written from in-memory state, making\n\t\t\t\t\t// buffered WAL records redundant.\n\t\t\t\t\tflushDirty()\n\t\t\t\t\treturn\n\t\t\t\tcase msg, ok := <-msgCh:\n\t\t\t\t\tif !ok {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t\tprocessMsg(msg)\n\t\t\t\t\tif !drainBatch() {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t\t// No flush here — timer handles periodic flushing.\n\t\t\t\tcase <-ticker.C:\n\t\t\t\t\tflushDirty()\n\t\t\t\tcase req := <-rotateCh:\n\t\t\t\t\tprocessRotate(req)\n\t\t\t\t}\n\t\t\t}\n\t\t})\n\t}\n}\n\n// WaitForWALStagingDrain blocks until all WALStaging goroutines have exited.\n// Must be called after closing walShardChs to ensure all file handles are\n// flushed and closed before checkpoint writes begin.\nfunc WaitForWALStagingDrain() {\n\twalStagingWg.Wait()\n}\n\n// RotateWALFiles sends rotation requests for the given host directories\n// and blocks until all rotations complete. Each request is routed to the\n// shard that owns the host directory.\n//\n// If shutdown is in progress (WAL staging goroutines may have exited),\n// rotation is skipped to avoid deadlocking on abandoned channels.\nfunc RotateWALFiles(hostDirs []string) {\n\tif walShardRotateChs == nil || walShuttingDown.Load() {\n\t\treturn\n\t}\n\tdones := make([]chan struct{}, 0, len(hostDirs))\n\tfor _, dir := range hostDirs {\n\t\tdone := make(chan struct{})\n\t\tshard := walShardIndexFromDir(dir)\n\t\tselect {\n\t\tcase walShardRotateChs[shard] <- walRotateReq{hostDir: dir, done: done}:\n\t\t\tdones = append(dones, done)\n\t\tdefault:\n\t\t\t// Channel full or goroutine not consuming — skip this host.\n\t\t\tcclog.Warnf(\"[METRICSTORE]> WAL rotation skipped for %s (channel full)\", dir)\n\t\t}\n\t}\n\tfor _, done := range dones {\n\t\tselect {\n\t\tcase <-done:\n\t\tcase <-time.After(30 * time.Second):\n\t\t\tcclog.Warn(\"[METRICSTORE]> WAL rotation timed out, continuing\")\n\t\t\treturn\n\t\t}\n\t}\n}\n\n// walShardIndexFromDir extracts cluster and node from a host directory path\n// and returns the shard index. The path format is: rootDir/cluster/node\nfunc walShardIndexFromDir(hostDir string) int {\n\t// hostDir = .../cluster/node — extract last two path components\n\tnode := path.Base(hostDir)\n\tcluster := path.Base(path.Dir(hostDir))\n\treturn walShardIndex(cluster, node)\n}\n\n// RotateWALFiles sends rotation requests for the given host directories\n// and blocks until all rotations complete.\nfunc RotateWALFilesAfterShutdown(hostDirs []string) {\n\tfor _, dir := range hostDirs {\n\t\twalPath := path.Join(dir, \"current.wal\")\n\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t}\n\t}\n}\n\n// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\n// then writes it to the bufio.Writer in a single call. This prevents partial\n// records in the write buffer if a write error occurs mid-record (e.g. disk full).\n// Returns the number of bytes written and any error.\nfunc writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) (int, error) {\n\t// Compute payload and total record size.\n\tpayloadSize := 8 + 2 + len(msg.MetricName) + 1 + 4\n\tfor _, s := range msg.Selector {\n\t\tpayloadSize += 1 + len(s)\n\t}\n\t// Total: 8 (header) + payload + 4 (CRC).\n\ttotalSize := 8 + payloadSize + 4\n\n\t// Use stack buffer for typical small records, heap-allocate only for large ones.\n\tvar stackBuf [256]byte\n\tvar buf []byte\n\tif totalSize <= len(stackBuf) {\n\t\tbuf = stackBuf[:totalSize]\n\t} else {\n\t\tbuf = make([]byte, totalSize)\n\t}\n\n\t// Header: magic + payload length.\n\tbinary.LittleEndian.PutUint32(buf[0:4], walRecordMagic)\n\tbinary.LittleEndian.PutUint32(buf[4:8], uint32(payloadSize))\n\n\t// Payload starts at offset 8.\n\tp := 8\n\n\t// Timestamp (8 bytes).\n\tbinary.LittleEndian.PutUint64(buf[p:p+8], uint64(msg.Timestamp))\n\tp += 8\n\n\t// Metric name length (2 bytes) + metric name.\n\tbinary.LittleEndian.PutUint16(buf[p:p+2], uint16(len(msg.MetricName)))\n\tp += 2\n\tp += copy(buf[p:], msg.MetricName)\n\n\t// Selector count (1 byte).\n\tbuf[p] = byte(len(msg.Selector))\n\tp++\n\n\t// Selectors (1-byte length + bytes each).\n\tfor _, sel := range msg.Selector {\n\t\tbuf[p] = byte(len(sel))\n\t\tp++\n\t\tp += copy(buf[p:], sel)\n\t}\n\n\t// Value (4 bytes, float32 bits).\n\tbinary.LittleEndian.PutUint32(buf[p:p+4], math.Float32bits(float32(msg.Value)))\n\tp += 4\n\n\t// CRC32 over payload (bytes 8..8+payloadSize).\n\tcrc := crc32.ChecksumIEEE(buf[8 : 8+payloadSize])\n\tbinary.LittleEndian.PutUint32(buf[p:p+4], crc)\n\n\t// Single atomic write to the buffered writer.\n\t_, err := w.Write(buf)\n\treturn err\n}\n\n// readWALRecord reads one WAL record from the reader.\n// Returns (nil, nil) on clean EOF. Returns error on data corruption.\n// A CRC mismatch indicates a truncated trailing record (expected on crash).\nfunc readWALRecord(r io.Reader) (*WALMessage, error) {\n\tvar magic uint32\n\tif err := binary.Read(r, binary.LittleEndian, &magic); err != nil {\n\t\tif err == io.EOF {\n\t\t\treturn nil, nil // Clean EOF\n\t\t}\n\t\treturn nil, fmt.Errorf(\"read record magic: %w\", err)\n\t}\n\n\tif magic != walRecordMagic {\n\t\treturn nil, fmt.Errorf(\"invalid record magic 0x%08X (expected 0x%08X)\", magic, walRecordMagic)\n\t}\n\n\tvar payloadLen uint32\n\tif err := binary.Read(r, binary.LittleEndian, &payloadLen); err != nil {\n\t\treturn nil, fmt.Errorf(\"read payload length: %w\", err)\n\t}\n\n\tif payloadLen > 1<<20 { // 1 MB sanity limit\n\t\treturn nil, fmt.Errorf(\"record payload too large: %d bytes\", payloadLen)\n\t}\n\n\tpayload := make([]byte, payloadLen)\n\tif _, err := io.ReadFull(r, payload); err != nil {\n\t\treturn nil, fmt.Errorf(\"read payload: %w\", err)\n\t}\n\n\tvar storedCRC uint32\n\tif err := binary.Read(r, binary.LittleEndian, &storedCRC); err != nil {\n\t\treturn nil, fmt.Errorf(\"read CRC: %w\", err)\n\t}\n\n\tif crc32.ChecksumIEEE(payload) != storedCRC {\n\t\treturn nil, fmt.Errorf(\"CRC mismatch (truncated write or corruption)\")\n\t}\n\n\treturn parseWALPayload(payload)\n}\n\n// parseWALPayload decodes a binary payload into a WALMessage.\nfunc parseWALPayload(payload []byte) (*WALMessage, error) {\n\tif len(payload) < 8+2+1+4 {\n\t\treturn nil, fmt.Errorf(\"payload too short: %d bytes\", len(payload))\n\t}\n\n\toffset := 0\n\n\t// Timestamp (8 bytes)\n\tts := int64(binary.LittleEndian.Uint64(payload[offset : offset+8]))\n\toffset += 8\n\n\t// Metric name (2-byte length + bytes)\n\tif offset+2 > len(payload) {\n\t\treturn nil, fmt.Errorf(\"metric name length overflows payload\")\n\t}\n\tmLen := int(binary.LittleEndian.Uint16(payload[offset : offset+2]))\n\toffset += 2\n\n\tif offset+mLen > len(payload) {\n\t\treturn nil, fmt.Errorf(\"metric name overflows payload\")\n\t}\n\tmetricName := string(payload[offset : offset+mLen])\n\toffset += mLen\n\n\t// Selector count (1 byte)\n\tif offset >= len(payload) {\n\t\treturn nil, fmt.Errorf(\"selector count overflows payload\")\n\t}\n\tselCount := int(payload[offset])\n\toffset++\n\n\tselectors := make([]string, selCount)\n\tfor i := range selCount {\n\t\tif offset >= len(payload) {\n\t\t\treturn nil, fmt.Errorf(\"selector[%d] length overflows payload\", i)\n\t\t}\n\t\tsLen := int(payload[offset])\n\t\toffset++\n\n\t\tif offset+sLen > len(payload) {\n\t\t\treturn nil, fmt.Errorf(\"selector[%d] data overflows payload\", i)\n\t\t}\n\t\tselectors[i] = string(payload[offset : offset+sLen])\n\t\toffset += sLen\n\t}\n\n\t// Value (4 bytes, float32 bits)\n\tif offset+4 > len(payload) {\n\t\treturn nil, fmt.Errorf(\"value overflows payload\")\n\t}\n\tbits := binary.LittleEndian.Uint32(payload[offset : offset+4])\n\tvalue := schema.Float(math.Float32frombits(bits))\n\n\treturn &WALMessage{\n\t\tMetricName: metricName,\n\t\tTimestamp: ts,\n\t\tSelector: selectors,\n\t\tValue: value,\n\t}, nil\n}\n\n// loadWALFile reads a WAL file and replays all valid records into the Level tree.\n// l is the host-level node. Corrupt or partial trailing records are silently skipped\n// (expected on crash). Records older than 'from' are skipped.\nfunc (l *Level) loadWALFile(m *MemoryStore, f *os.File, from int64) error {\n\tbr := bufio.NewReader(f)\n\n\t// Verify file header magic.\n\tvar fileMagic uint32\n\tif err := binary.Read(br, binary.LittleEndian, &fileMagic); err != nil {\n\t\tif err == io.EOF {\n\t\t\treturn nil // Empty file, no data\n\t\t}\n\t\treturn fmt.Errorf(\"[METRICSTORE]> WAL: read file header: %w\", err)\n\t}\n\n\tif fileMagic != walFileMagic {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> WAL: invalid file magic 0x%08X (expected 0x%08X)\", fileMagic, walFileMagic)\n\t}\n\n\t// Cache level lookups to avoid repeated tree traversal.\n\tlvlCache := make(map[string]*Level)\n\n\tfor {\n\t\tmsg, err := readWALRecord(br)\n\t\tif err != nil {\n\t\t\t// Truncated trailing record is expected after a crash; stop replaying.\n\t\t\tcclog.Debugf(\"[METRICSTORE]> WAL: stopping replay at corrupted/partial record: %v\", err)\n\t\t\tbreak\n\t\t}\n\t\tif msg == nil {\n\t\t\tbreak // Clean EOF\n\t\t}\n\n\t\tif msg.Timestamp < from {\n\t\t\tcontinue // Older than retention window\n\t\t}\n\n\t\tminfo, ok := m.Metrics[msg.MetricName]\n\t\tif !ok {\n\t\t\tcontinue // Unknown metric (config may have changed)\n\t\t}\n\n\t\t// Cache key is the null-separated selector path.\n\t\tcacheKey := joinSelector(msg.Selector)\n\t\tlvl, ok := lvlCache[cacheKey]\n\t\tif !ok {\n\t\t\tlvl = l.findLevelOrCreate(msg.Selector, len(m.Metrics))\n\t\t\tlvlCache[cacheKey] = lvl\n\t\t}\n\n\t\t// Write directly to the buffer, same as WriteToLevel but without the\n\t\t// global level lookup (we already have the right level).\n\t\tlvl.lock.Lock()\n\t\tb := lvl.metrics[minfo.offset]\n\t\tif b == nil {\n\t\t\tb = newBuffer(msg.Timestamp, minfo.Frequency)\n\t\t\tlvl.metrics[minfo.offset] = b\n\t\t}\n\t\tnb, writeErr := b.write(msg.Timestamp, msg.Value)\n\t\tif writeErr == nil && b != nb {\n\t\t\tlvl.metrics[minfo.offset] = nb\n\t\t}\n\t\t// Ignore write errors for timestamps before buffer start (can happen when\n\t\t// replaying WAL entries that predate a loaded snapshot's start time).\n\t\tlvl.lock.Unlock()\n\t}\n\n\treturn nil\n}\n\n// joinSelector builds a cache key from a selector slice using null bytes as separators.\nfunc joinSelector(sel []string) string {\n\tif len(sel) == 0 {\n\t\treturn \"\"\n\t}\n\tvar result strings.Builder\n\tresult.WriteString(sel[0])\n\tfor i := 1; i < len(sel); i++ {\n\t\tresult.WriteString(\"\\x00\" + sel[i])\n\t}\n\treturn result.String()\n}\n\n// ToCheckpointWAL writes binary snapshot files for all hosts in parallel.\n// Returns the number of files written, the list of host directories that were\n// successfully checkpointed (for WAL rotation), and any errors.\nfunc (m *MemoryStore) ToCheckpointWAL(dir string, from, to int64) (int, []string, error) {\n\t// Collect all cluster/host pairs.\n\tm.root.lock.RLock()\n\ttotalHosts := 0\n\tfor _, l1 := range m.root.children {\n\t\tl1.lock.RLock()\n\t\ttotalHosts += len(l1.children)\n\t\tl1.lock.RUnlock()\n\t}\n\tm.root.lock.RUnlock()\n\n\tlevels := make([]*Level, 0, totalHosts)\n\tselectors := make([][]string, 0, totalHosts)\n\n\tm.root.lock.RLock()\n\tfor sel1, l1 := range m.root.children {\n\t\tl1.lock.RLock()\n\t\tfor sel2, l2 := range l1.children {\n\t\t\tlevels = append(levels, l2)\n\t\t\tselectors = append(selectors, []string{sel1, sel2})\n\t\t}\n\t\tl1.lock.RUnlock()\n\t}\n\tm.root.lock.RUnlock()\n\n\ttype workItem struct {\n\t\tlevel *Level\n\t\thostDir string\n\t\tselector []string\n\t}\n\n\ttotalWork := len(levels)\n\tcclog.Infof(\"[METRICSTORE]> Starting binary checkpoint for %d hosts with %d workers\", totalWork, Keys.NumWorkers)\n\n\tn, errs, completed := int32(0), int32(0), int32(0)\n\tvar successDirs []string\n\tvar successMu sync.Mutex\n\n\tvar wg sync.WaitGroup\n\twg.Add(Keys.NumWorkers)\n\twork := make(chan workItem, Keys.NumWorkers*2)\n\n\t// Progress logging goroutine.\n\tstopProgress := make(chan struct{})\n\tgo func() {\n\t\tticker := time.NewTicker(10 * time.Second)\n\t\tdefer ticker.Stop()\n\t\tfor {\n\t\t\tselect {\n\t\t\tcase <-ticker.C:\n\t\t\t\tcclog.Infof(\"[METRICSTORE]> Checkpoint progress: %d/%d hosts (%d written, %d errors)\",\n\t\t\t\t\tatomic.LoadInt32(&completed), totalWork, atomic.LoadInt32(&n), atomic.LoadInt32(&errs))\n\t\t\tcase <-stopProgress:\n\t\t\t\treturn\n\t\t\t}\n\t\t}\n\t}()\n\n\tfor range Keys.NumWorkers {\n\t\tgo func() {\n\t\t\tdefer wg.Done()\n\t\t\tfor wi := range work {\n\t\t\t\terr := wi.level.toCheckpointBinary(wi.hostDir, from, to, m)\n\t\t\t\tif err != nil {\n\t\t\t\t\tif err == ErrNoNewArchiveData {\n\t\t\t\t\t\tatomic.AddInt32(&completed, 1)\n\t\t\t\t\t\tcontinue\n\t\t\t\t\t}\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> binary checkpoint error for %s: %v\", wi.hostDir, err)\n\t\t\t\t\tatomic.AddInt32(&errs, 1)\n\t\t\t\t} else {\n\t\t\t\t\tatomic.AddInt32(&n, 1)\n\t\t\t\t\t// Delete WAL immediately after successful snapshot.\n\t\t\t\t\twalPath := path.Join(wi.hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tsuccessMu.Lock()\n\t\t\t\t\tsuccessDirs = append(successDirs, wi.hostDir)\n\t\t\t\t\tsuccessMu.Unlock()\n\t\t\t\t}\n\t\t\t\tatomic.AddInt32(&completed, 1)\n\t\t\t}\n\t\t}()\n\t}\n\n\tfor i := range levels {\n\t\thostDir := path.Join(dir, path.Join(selectors[i]...))\n\t\twork <- workItem{\n\t\t\tlevel: levels[i],\n\t\t\thostDir: hostDir,\n\t\t\tselector: selectors[i],\n\t\t}\n\t}\n\tclose(work)\n\twg.Wait()\n\tclose(stopProgress)\n\n\tif errs > 0 {\n\t\treturn int(n), successDirs, fmt.Errorf(\"[METRICSTORE]> %d errors during binary checkpoint (%d successes)\", errs, n)\n\t}\n\treturn int(n), successDirs, nil\n}\n\n// toCheckpointBinary writes a binary snapshot file for a single host-level node.\n// Uses atomic rename (write to .tmp then rename) to avoid partial reads on crash.\nfunc (l *Level) toCheckpointBinary(dir string, from, to int64, m *MemoryStore) error {\n\tcf, err := l.toCheckpointFile(from, to, m)\n\tif err != nil {\n\t\treturn err\n\t}\n\tif cf == nil {\n\t\treturn ErrNoNewArchiveData\n\t}\n\n\tif err := os.MkdirAll(dir, CheckpointDirPerms); err != nil {\n\t\treturn fmt.Errorf(\"mkdir %s: %w\", dir, err)\n\t}\n\n\t// Write to a temp file first, then rename (atomic on POSIX).\n\ttmpPath := path.Join(dir, fmt.Sprintf(\"%d.bin.tmp\", from))\n\tfinalPath := path.Join(dir, fmt.Sprintf(\"%d.bin\", from))\n\n\tf, err := os.OpenFile(tmpPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, CheckpointFilePerms)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"open binary snapshot %s: %w\", tmpPath, err)\n\t}\n\n\tbw := bufio.NewWriter(f)\n\tif err := writeBinarySnapshotFile(bw, cf); err != nil {\n\t\tf.Close()\n\t\tos.Remove(tmpPath)\n\t\treturn fmt.Errorf(\"write binary snapshot: %w\", err)\n\t}\n\tif err := bw.Flush(); err != nil {\n\t\tf.Close()\n\t\tos.Remove(tmpPath)\n\t\treturn err\n\t}\n\tf.Close()\n\n\treturn os.Rename(tmpPath, finalPath)\n}\n\n// writeBinarySnapshotFile writes the binary snapshot file header and level tree.\nfunc writeBinarySnapshotFile(w io.Writer, cf *CheckpointFile) error {\n\tif err := binary.Write(w, binary.LittleEndian, snapFileMagic); err != nil {\n\t\treturn err\n\t}\n\tif err := binary.Write(w, binary.LittleEndian, cf.From); err != nil {\n\t\treturn err\n\t}\n\tif err := binary.Write(w, binary.LittleEndian, cf.To); err != nil {\n\t\treturn err\n\t}\n\treturn writeBinaryLevel(w, cf)\n}\n\n// writeBinaryLevel recursively writes a CheckpointFile level in binary format.\nfunc writeBinaryLevel(w io.Writer, cf *CheckpointFile) error {\n\tif err := binary.Write(w, binary.LittleEndian, uint32(len(cf.Metrics))); err != nil {\n\t\treturn err\n\t}\n\n\tfor name, metric := range cf.Metrics {\n\t\tif err := writeString16(w, name); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, metric.Frequency); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, metric.Start); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, uint32(len(metric.Data))); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tfor _, v := range metric.Data {\n\t\t\tif err := binary.Write(w, binary.LittleEndian, math.Float32bits(float32(v))); err != nil {\n\t\t\t\treturn err\n\t\t\t}\n\t\t}\n\t}\n\n\tif err := binary.Write(w, binary.LittleEndian, uint32(len(cf.Children))); err != nil {\n\t\treturn err\n\t}\n\n\tfor name, child := range cf.Children {\n\t\tif err := writeString16(w, name); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := writeBinaryLevel(w, child); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\n\treturn nil\n}\n\n// writeString16 writes a 2-byte length-prefixed string to w.\nfunc writeString16(w io.Writer, s string) error {\n\tif err := binary.Write(w, binary.LittleEndian, uint16(len(s))); err != nil {\n\t\treturn err\n\t}\n\t_, err := io.WriteString(w, s)\n\treturn err\n}\n\n// loadBinaryFile reads a binary snapshot file and loads data into the Level tree.\n// The retention check (from) is applied to the file's 'to' timestamp.\nfunc (l *Level) loadBinaryFile(m *MemoryStore, f *os.File, from int64) error {\n\tbr := bufio.NewReader(f)\n\n\tvar magic uint32\n\tif err := binary.Read(br, binary.LittleEndian, &magic); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read magic: %w\", err)\n\t}\n\tif magic != snapFileMagic {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: invalid magic 0x%08X (expected 0x%08X)\", magic, snapFileMagic)\n\t}\n\n\tvar fileFrom, fileTo int64\n\tif err := binary.Read(br, binary.LittleEndian, &fileFrom); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read from: %w\", err)\n\t}\n\tif err := binary.Read(br, binary.LittleEndian, &fileTo); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read to: %w\", err)\n\t}\n\n\tif fileTo != 0 && fileTo < from {\n\t\treturn nil // File is older than retention window, skip it\n\t}\n\n\tcf, err := readBinaryLevel(br)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read level tree: %w\", err)\n\t}\n\tcf.From = fileFrom\n\tcf.To = fileTo\n\n\treturn l.loadFile(cf, m)\n}\n\n// readBinaryLevel recursively reads a level from the binary snapshot format.\nfunc readBinaryLevel(r io.Reader) (*CheckpointFile, error) {\n\tcf := &CheckpointFile{\n\t\tMetrics: make(map[string]*CheckpointMetrics),\n\t\tChildren: make(map[string]*CheckpointFile),\n\t}\n\n\tvar numMetrics uint32\n\tif err := binary.Read(r, binary.LittleEndian, &numMetrics); err != nil {\n\t\treturn nil, fmt.Errorf(\"read num_metrics: %w\", err)\n\t}\n\n\tfor range numMetrics {\n\t\tname, err := readString16(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read metric name: %w\", err)\n\t\t}\n\n\t\tvar freq, start int64\n\t\tif err := binary.Read(r, binary.LittleEndian, &freq); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read frequency for %s: %w\", name, err)\n\t\t}\n\t\tif err := binary.Read(r, binary.LittleEndian, &start); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read start for %s: %w\", name, err)\n\t\t}\n\n\t\tvar numValues uint32\n\t\tif err := binary.Read(r, binary.LittleEndian, &numValues); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read num_values for %s: %w\", name, err)\n\t\t}\n\n\t\tdata := make([]schema.Float, numValues)\n\t\tfor i := range numValues {\n\t\t\tvar bits uint32\n\t\t\tif err := binary.Read(r, binary.LittleEndian, &bits); err != nil {\n\t\t\t\treturn nil, fmt.Errorf(\"read value[%d] for %s: %w\", i, name, err)\n\t\t\t}\n\t\t\tdata[i] = schema.Float(math.Float32frombits(bits))\n\t\t}\n\n\t\tcf.Metrics[name] = &CheckpointMetrics{\n\t\t\tFrequency: freq,\n\t\t\tStart: start,\n\t\t\tData: data,\n\t\t}\n\t}\n\n\tvar numChildren uint32\n\tif err := binary.Read(r, binary.LittleEndian, &numChildren); err != nil {\n\t\treturn nil, fmt.Errorf(\"read num_children: %w\", err)\n\t}\n\n\tfor range numChildren {\n\t\tchildName, err := readString16(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read child name: %w\", err)\n\t\t}\n\n\t\tchild, err := readBinaryLevel(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read child %s: %w\", childName, err)\n\t\t}\n\t\tcf.Children[childName] = child\n\t}\n\n\treturn cf, nil\n}\n\n// readString16 reads a 2-byte length-prefixed string from r.\nfunc readString16(r io.Reader) (string, error) {\n\tvar sLen uint16\n\tif err := binary.Read(r, binary.LittleEndian, &sLen); err != nil {\n\t\treturn \"\", err\n\t}\n\tbuf := make([]byte, sLen)\n\tif _, err := io.ReadFull(r, buf); err != nil {\n\t\treturn \"\", err\n\t}\n\treturn string(buf), nil\n}\n","structuredPatch":[{"oldStart":437,"oldLines":8,"newStart":437,"newLines":8,"lines":[" binary.LittleEndian.PutUint32(buf[p:p+4], crc)"," "," // Single atomic write to the buffered writer.","- _, err := w.Write(buf)","- return err","+ n, err := w.Write(buf)","+ return n, err"," }"," "," // readWALRecord reads one WAL record from the reader."]}],"userModified":false,"replaceAll":false},"sourceToolAssistantUUID":"3521bdc4-973a-44cf-b485-f8698fb8bd85","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"cc99d38b-a539-45ae-8fc3-36eac429f3f4","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01B1yGuDfizb62zSpCvbB3fE","type":"message","role":"assistant","content":[{"type":"text","text":"Let me check if there are other callers of `writeWALRecordDirect`:"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":365,"cache_read_input_tokens":45204,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":365},"output_tokens":3,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUv8vNz1RsrjV8dgQJXX","type":"assistant","uuid":"a674f251-7fe3-4af1-943b-6640c9f06e13","timestamp":"2026-03-28T05:21:34.343Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"a674f251-7fe3-4af1-943b-6640c9f06e13","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01B1yGuDfizb62zSpCvbB3fE","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01LpGTS88YMkxco3MECCaGx9","name":"Grep","input":{"pattern":"writeWALRecordDirect","path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore","output_mode":"content","-n":true},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":365,"cache_read_input_tokens":45204,"output_tokens":156,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":365,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUv8vNz1RsrjV8dgQJXX","type":"assistant","uuid":"b7ed4570-4c83-426b-ac21-5b582f94cac4","timestamp":"2026-03-28T05:21:35.126Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"b7ed4570-4c83-426b-ac21-5b582f94cac4","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01LpGTS88YMkxco3MECCaGx9","type":"tool_result","content":"pkg/metricstore/walCheckpoint.go:244:\t\t\t\tif err := writeWALRecordDirect(ws.w, msg); err != nil {\npkg/metricstore/walCheckpoint.go:382:// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\npkg/metricstore/walCheckpoint.go:386:func writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) (int, error) {"}]},"uuid":"cf7f73b1-c614-470a-a3d6-5194fc80b62e","timestamp":"2026-03-28T05:21:35.170Z","toolUseResult":{"mode":"content","numFiles":0,"filenames":[],"content":"pkg/metricstore/walCheckpoint.go:244:\t\t\t\tif err := writeWALRecordDirect(ws.w, msg); err != nil {\npkg/metricstore/walCheckpoint.go:382:// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\npkg/metricstore/walCheckpoint.go:386:func writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) (int, error) {","numLines":3},"sourceToolAssistantUUID":"b7ed4570-4c83-426b-ac21-5b582f94cac4","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"cf7f73b1-c614-470a-a3d6-5194fc80b62e","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_017umKnjZT9FS2JwiD83Kw5y","type":"message","role":"assistant","content":[{"type":"text","text":"Good, only one caller. Let me also check line 441 — there may be an early return that still returns only error:"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":286,"cache_read_input_tokens":45569,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":286},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUv9EW9ZccXdFeHKy3Yx","type":"assistant","uuid":"bd0e11b9-79d3-472e-9e71-176bfd1134d1","timestamp":"2026-03-28T05:21:38.452Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"bd0e11b9-79d3-472e-9e71-176bfd1134d1","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_017umKnjZT9FS2JwiD83Kw5y","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01TPByCQjXEbccogqLk17iMc","name":"Read","input":{"file_path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","offset":438,"limit":15},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":286,"cache_read_input_tokens":45569,"output_tokens":143,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":286,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUv9EW9ZccXdFeHKy3Yx","type":"assistant","uuid":"2e8284c0-60b4-44ac-b12b-09b897d88c20","timestamp":"2026-03-28T05:21:39.033Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"2e8284c0-60b4-44ac-b12b-09b897d88c20","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01TPByCQjXEbccogqLk17iMc","type":"tool_result","content":"438\t\n439\t\t// Single atomic write to the buffered writer.\n440\t\tn, err := w.Write(buf)\n441\t\treturn n, err\n442\t}\n443\t\n444\t// readWALRecord reads one WAL record from the reader.\n445\t// Returns (nil, nil) on clean EOF. Returns error on data corruption.\n446\t// A CRC mismatch indicates a truncated trailing record (expected on crash).\n447\tfunc readWALRecord(r io.Reader) (*WALMessage, error) {\n448\t\tvar magic uint32\n449\t\tif err := binary.Read(r, binary.LittleEndian, &magic); err != nil {\n450\t\t\tif err == io.EOF {\n451\t\t\t\treturn nil, nil // Clean EOF\n452\t\t\t}"}]},"uuid":"7e1baaaa-76ec-4586-9608-ed9971930e1a","timestamp":"2026-03-28T05:21:39.055Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","content":"\n\t// Single atomic write to the buffered writer.\n\tn, err := w.Write(buf)\n\treturn n, err\n}\n\n// readWALRecord reads one WAL record from the reader.\n// Returns (nil, nil) on clean EOF. Returns error on data corruption.\n// A CRC mismatch indicates a truncated trailing record (expected on crash).\nfunc readWALRecord(r io.Reader) (*WALMessage, error) {\n\tvar magic uint32\n\tif err := binary.Read(r, binary.LittleEndian, &magic); err != nil {\n\t\tif err == io.EOF {\n\t\t\treturn nil, nil // Clean EOF\n\t\t}","numLines":15,"startLine":438,"totalLines":958}},"sourceToolAssistantUUID":"2e8284c0-60b4-44ac-b12b-09b897d88c20","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"7e1baaaa-76ec-4586-9608-ed9971930e1a","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_014qRwgbo7Zd8v6B3814SYYY","type":"message","role":"assistant","content":[{"type":"text","text":"The diagnostic at line 441 was stale — let me check if there's a `return err` somewhere in the function body I missed:"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":336,"cache_read_input_tokens":45855,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":336},"output_tokens":2,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUv9XBW86bEZQuhEVS2h","type":"assistant","uuid":"c1539a41-21d8-4e98-b397-1c6b88603f9b","timestamp":"2026-03-28T05:21:42.317Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"c1539a41-21d8-4e98-b397-1c6b88603f9b","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_014qRwgbo7Zd8v6B3814SYYY","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01Xg7VGWbDhuJAWmHcQ25C88","name":"Grep","input":{"pattern":"return.*err","path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","output_mode":"content","-n":true,"-B":0,"-A":0,"head_limit":30},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":336,"cache_read_input_tokens":45855,"output_tokens":222,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":336,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUv9XBW86bEZQuhEVS2h","type":"assistant","uuid":"0763a379-fed3-4346-83be-73a5cd04b275","timestamp":"2026-03-28T05:21:43.759Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"0763a379-fed3-4346-83be-73a5cd04b275","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01Xg7VGWbDhuJAWmHcQ25C88","type":"tool_result","content":"441:\treturn n, err\n453:\t\treturn nil, fmt.Errorf(\"read record magic: %w\", err)\n462:\t\treturn nil, fmt.Errorf(\"read payload length: %w\", err)\n471:\t\treturn nil, fmt.Errorf(\"read payload: %w\", err)\n476:\t\treturn nil, fmt.Errorf(\"read CRC: %w\", err)\n560:\t\treturn fmt.Errorf(\"[METRICSTORE]> WAL: read file header: %w\", err)\n733:\t\treturn int(n), successDirs, fmt.Errorf(\"[METRICSTORE]> %d errors during binary checkpoint (%d successes)\", errs, n)\n743:\t\treturn err\n750:\t\treturn fmt.Errorf(\"mkdir %s: %w\", dir, err)\n759:\t\treturn fmt.Errorf(\"open binary snapshot %s: %w\", tmpPath, err)\n766:\t\treturn fmt.Errorf(\"write binary snapshot: %w\", err)\n771:\t\treturn err\n781:\t\treturn err\n784:\t\treturn err\n787:\t\treturn err\n795:\t\treturn err\n800:\t\t\treturn err\n803:\t\t\treturn err\n806:\t\t\treturn err\n809:\t\t\treturn err\n813:\t\t\t\treturn err\n819:\t\treturn err\n824:\t\t\treturn err\n827:\t\t\treturn err\n837:\t\treturn err\n840:\treturn err\n850:\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read magic: %w\", err)\n858:\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read from: %w\", err)\n861:\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read to: %w\", err)\n870:\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read level tree: %w\", err)\n\n[Showing results with pagination = limit: 30]"}]},"uuid":"fb719a92-eedf-40b7-a6e1-ca88ccc47969","timestamp":"2026-03-28T05:21:43.792Z","toolUseResult":{"mode":"content","numFiles":0,"filenames":[],"content":"441:\treturn n, err\n453:\t\treturn nil, fmt.Errorf(\"read record magic: %w\", err)\n462:\t\treturn nil, fmt.Errorf(\"read payload length: %w\", err)\n471:\t\treturn nil, fmt.Errorf(\"read payload: %w\", err)\n476:\t\treturn nil, fmt.Errorf(\"read CRC: %w\", err)\n560:\t\treturn fmt.Errorf(\"[METRICSTORE]> WAL: read file header: %w\", err)\n733:\t\treturn int(n), successDirs, fmt.Errorf(\"[METRICSTORE]> %d errors during binary checkpoint (%d successes)\", errs, n)\n743:\t\treturn err\n750:\t\treturn fmt.Errorf(\"mkdir %s: %w\", dir, err)\n759:\t\treturn fmt.Errorf(\"open binary snapshot %s: %w\", tmpPath, err)\n766:\t\treturn fmt.Errorf(\"write binary snapshot: %w\", err)\n771:\t\treturn err\n781:\t\treturn err\n784:\t\treturn err\n787:\t\treturn err\n795:\t\treturn err\n800:\t\t\treturn err\n803:\t\t\treturn err\n806:\t\t\treturn err\n809:\t\t\treturn err\n813:\t\t\t\treturn err\n819:\t\treturn err\n824:\t\t\treturn err\n827:\t\t\treturn err\n837:\t\treturn err\n840:\treturn err\n850:\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read magic: %w\", err)\n858:\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read from: %w\", err)\n861:\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read to: %w\", err)\n870:\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read level tree: %w\", err)","numLines":30,"appliedLimit":30},"sourceToolAssistantUUID":"0763a379-fed3-4346-83be-73a5cd04b275","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"fb719a92-eedf-40b7-a6e1-ca88ccc47969","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_015fjWDC772xcYq5FMVK1tJa","type":"message","role":"assistant","content":[{"type":"text","text":"OK, that diagnostic was likely stale from before my edit. Now update the caller in `processMsg`:"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":688,"cache_read_input_tokens":46191,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":688},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUv9sPvrY4sZkcL3KyYG","type":"assistant","uuid":"4ea6da0f-fb1c-4f29-9777-f9fa1902b607","timestamp":"2026-03-28T05:21:47.835Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"4ea6da0f-fb1c-4f29-9777-f9fa1902b607","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_015fjWDC772xcYq5FMVK1tJa","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01CD26mJsQ58W3xz2CHFUQrR","name":"Edit","input":{"replace_all":false,"file_path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","old_string":"\t\t\tprocessMsg := func(msg *WALMessage) {\n\t\t\t\thostDir := path.Join(Keys.Checkpoints.RootDir, msg.Cluster, msg.Node)\n\t\t\t\tws := getOrOpenWAL(hostDir)\n\t\t\t\tif ws == nil {\n\t\t\t\t\treturn\n\t\t\t\t}\n\t\t\t\tif err := writeWALRecordDirect(ws.w, msg); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write record: %v\", err)\n\t\t\t\t}\n\t\t\t\tws.dirty = true\n\t\t\t}","new_string":"\t\t\tprocessMsg := func(msg *WALMessage) {\n\t\t\t\thostDir := path.Join(Keys.Checkpoints.RootDir, msg.Cluster, msg.Node)\n\t\t\t\tws := getOrOpenWAL(hostDir)\n\t\t\t\tif ws == nil {\n\t\t\t\t\treturn\n\t\t\t\t}\n\n\t\t\t\t// Enforce max WAL size: force-rotate before writing if limit is exceeded.\n\t\t\t\t// The in-memory store still holds the data; only crash-recovery coverage is lost.\n\t\t\t\tif maxSize := Keys.Checkpoints.MaxWALSize; maxSize > 0 && ws.size >= maxSize {\n\t\t\t\t\tcclog.Warnf(\"[METRICSTORE]> WAL: force-rotating %s (size %d >= limit %d)\",\n\t\t\t\t\t\thostDir, ws.size, maxSize)\n\t\t\t\t\tws.w.Flush()\n\t\t\t\t\tws.f.Close()\n\t\t\t\t\twalPath := path.Join(hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tdelete(hostFiles, hostDir)\n\t\t\t\t\tws = getOrOpenWAL(hostDir)\n\t\t\t\t\tif ws == nil {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t}\n\n\t\t\t\tn, err := writeWALRecordDirect(ws.w, msg)\n\t\t\t\tif err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write record: %v\", err)\n\t\t\t\t}\n\t\t\t\tws.size += int64(n)\n\t\t\t\tws.dirty = true\n\t\t\t}"},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":688,"cache_read_input_tokens":46191,"output_tokens":687,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":688,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUv9sPvrY4sZkcL3KyYG","type":"assistant","uuid":"05d54134-4ce0-47e2-acea-a3c3123da1eb","timestamp":"2026-03-28T05:21:54.467Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"05d54134-4ce0-47e2-acea-a3c3123da1eb","isSidechain":false,"promptId":"43b42c1c-d21b-4a8e-9dc9-e1c671f830bb","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01CD26mJsQ58W3xz2CHFUQrR","type":"tool_result","content":"The file /Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go has been updated successfully."}]},"uuid":"306106ca-ffdd-416e-9e5f-876ee716ccee","timestamp":"2026-03-28T05:21:54.504Z","toolUseResult":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","oldString":"\t\t\tprocessMsg := func(msg *WALMessage) {\n\t\t\t\thostDir := path.Join(Keys.Checkpoints.RootDir, msg.Cluster, msg.Node)\n\t\t\t\tws := getOrOpenWAL(hostDir)\n\t\t\t\tif ws == nil {\n\t\t\t\t\treturn\n\t\t\t\t}\n\t\t\t\tif err := writeWALRecordDirect(ws.w, msg); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write record: %v\", err)\n\t\t\t\t}\n\t\t\t\tws.dirty = true\n\t\t\t}","newString":"\t\t\tprocessMsg := func(msg *WALMessage) {\n\t\t\t\thostDir := path.Join(Keys.Checkpoints.RootDir, msg.Cluster, msg.Node)\n\t\t\t\tws := getOrOpenWAL(hostDir)\n\t\t\t\tif ws == nil {\n\t\t\t\t\treturn\n\t\t\t\t}\n\n\t\t\t\t// Enforce max WAL size: force-rotate before writing if limit is exceeded.\n\t\t\t\t// The in-memory store still holds the data; only crash-recovery coverage is lost.\n\t\t\t\tif maxSize := Keys.Checkpoints.MaxWALSize; maxSize > 0 && ws.size >= maxSize {\n\t\t\t\t\tcclog.Warnf(\"[METRICSTORE]> WAL: force-rotating %s (size %d >= limit %d)\",\n\t\t\t\t\t\thostDir, ws.size, maxSize)\n\t\t\t\t\tws.w.Flush()\n\t\t\t\t\tws.f.Close()\n\t\t\t\t\twalPath := path.Join(hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tdelete(hostFiles, hostDir)\n\t\t\t\t\tws = getOrOpenWAL(hostDir)\n\t\t\t\t\tif ws == nil {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t}\n\n\t\t\t\tn, err := writeWALRecordDirect(ws.w, msg)\n\t\t\t\tif err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write record: %v\", err)\n\t\t\t\t}\n\t\t\t\tws.size += int64(n)\n\t\t\t\tws.dirty = true\n\t\t\t}","originalFile":"// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.\n// All rights reserved. This file is part of cc-backend.\n// Use of this source code is governed by a MIT-style\n// license that can be found in the LICENSE file.\n\n// Package metricstore provides walCheckpoint.go: WAL-based checkpoint implementation.\n//\n// This replaces the Avro shadow tree with an append-only Write-Ahead Log (WAL)\n// per host, eliminating the extra memory overhead of the AvroStore and providing\n// truly continuous (per-write) crash safety.\n//\n// # Architecture\n//\n//\tMetric write (DecodeLine)\n//\t │\n//\t ├─► WriteToLevel() → main MemoryStore (unchanged)\n//\t │\n//\t └─► WALMessages channel\n//\t │\n//\t ▼\n//\t WALStaging goroutine\n//\t │\n//\t ▼\n//\t checkpoints/cluster/host/current.wal (append-only, binary)\n//\n//\tPeriodic checkpoint (Checkpointing goroutine):\n//\t 1. Write <timestamp>.bin snapshot (column-oriented, from main tree)\n//\t 2. Signal WALStaging to truncate current.wal per host\n//\n//\tOn restart (FromCheckpoint):\n//\t 1. Load most recent <timestamp>.bin snapshot\n//\t 2. Replay current.wal (overwrite-safe: buffer.write handles duplicate timestamps)\n//\n// # WAL Record Format\n//\n//\t[4B magic 0xCC1DA7A1][4B payload_len][payload][4B CRC32]\n//\n//\tpayload:\n//\t [8B timestamp int64]\n//\t [2B metric_name_len uint16][N metric name bytes]\n//\t [1B selector_count uint8]\n//\t per selector: [1B selector_len uint8][M selector bytes]\n//\t [4B value float32 bits]\n//\n// # Binary Snapshot Format\n//\n//\t[4B magic 0xCC5B0001][8B from int64][8B to int64]\n//\tLevel tree (recursive):\n//\t [4B num_metrics uint32]\n//\t per metric:\n//\t [2B name_len uint16][N name bytes]\n//\t [8B frequency int64][8B start int64]\n//\t [4B num_values uint32][num_values × 4B float32]\n//\t [4B num_children uint32]\n//\t per child: [2B name_len uint16][N name bytes] + Level (recursive)\npackage metricstore\n\nimport (\n\t\"bufio\"\n\t\"context\"\n\t\"encoding/binary\"\n\t\"fmt\"\n\t\"hash/crc32\"\n\t\"hash/fnv\"\n\t\"io\"\n\t\"math\"\n\t\"os\"\n\t\"path\"\n\t\"strings\"\n\t\"sync\"\n\t\"sync/atomic\"\n\t\"time\"\n\n\tcclog \"github.com/ClusterCockpit/cc-lib/v2/ccLogger\"\n\t\"github.com/ClusterCockpit/cc-lib/v2/schema\"\n)\n\n// Magic numbers for binary formats.\nconst (\n\twalFileMagic = uint32(0xCC1DA701) // WAL file header magic\n\twalRecordMagic = uint32(0xCC1DA7A1) // WAL record magic\n\tsnapFileMagic = uint32(0xCC5B0001) // Binary snapshot magic\n)\n\n// walShardChs holds per-shard channels for WAL messages.\n// Initialized by WALStaging; nil when WAL is not active.\nvar walShardChs []chan *WALMessage\n\n// walShardRotateChs holds per-shard channels for WAL rotation requests.\nvar walShardRotateChs []chan walRotateReq\n\n// walNumShards stores the number of shards (set during WALStaging init).\nvar walNumShards int\n\n// walStagingWg tracks WALStaging goroutine exits for shutdown synchronization.\nvar walStagingWg sync.WaitGroup\n\n// walShuttingDown is set before closing shard channels to prevent\n// SendWALMessage from sending on a closed channel (which panics in Go).\nvar walShuttingDown atomic.Bool\n\n// WALMessage represents a single metric write to be appended to the WAL.\n// Cluster and Node are NOT stored in the WAL record (inferred from file path).\ntype WALMessage struct {\n\tMetricName string\n\tCluster string\n\tNode string\n\tSelector []string\n\tValue schema.Float\n\tTimestamp int64\n}\n\n// walRotateReq requests WAL file rotation for a specific host directory.\n// The done channel is closed by the WAL goroutine when rotation is complete.\ntype walRotateReq struct {\n\thostDir string\n\tdone chan struct{}\n}\n\n// walFileState holds an open WAL file handle and buffered writer for one host directory.\ntype walFileState struct {\n\tf *os.File\n\tw *bufio.Writer\n\tdirty bool\n\tsize int64 // approximate bytes written (tracked from open + writes)\n}\n\n// walFlushInterval controls how often dirty WAL files are flushed to disk.\n// Decoupling flushes from message processing lets the consumer run at memory\n// speed, amortizing syscall overhead across many writes.\nconst walFlushInterval = 1 * time.Second\n\n// walShardIndex computes which shard a message belongs to based on cluster+node.\n// Uses FNV-1a hash for fast, well-distributed mapping.\nfunc walShardIndex(cluster, node string) int {\n\th := fnv.New32a()\n\th.Write([]byte(cluster))\n\th.Write([]byte{0})\n\th.Write([]byte(node))\n\treturn int(h.Sum32()) % walNumShards\n}\n\n// SendWALMessage routes a WAL message to the appropriate shard channel.\n// Returns false if the channel is full or shutdown is in progress.\nfunc SendWALMessage(msg *WALMessage) bool {\n\tif walShardChs == nil || walShuttingDown.Load() {\n\t\treturn false\n\t}\n\tshard := walShardIndex(msg.Cluster, msg.Node)\n\tselect {\n\tcase walShardChs[shard] <- msg:\n\t\treturn true\n\tdefault:\n\t\treturn false\n\t}\n}\n\n// WALStaging starts N sharded background goroutines that receive WALMessage items\n// and append binary WAL records to per-host current.wal files.\n// Each shard owns a subset of hosts (determined by hash of cluster+node),\n// parallelizing serialization and I/O while keeping per-host writes serial.\nfunc WALStaging(wg *sync.WaitGroup, ctx context.Context) {\n\tif Keys.Checkpoints.FileFormat == \"json\" {\n\t\treturn\n\t}\n\n\twalNumShards = max(Keys.NumWorkers, 1)\n\tchBufSize := max(65536/walNumShards, 1024)\n\n\twalShardChs = make([]chan *WALMessage, walNumShards)\n\twalShardRotateChs = make([]chan walRotateReq, walNumShards)\n\n\tfor i := range walNumShards {\n\t\twalShardChs[i] = make(chan *WALMessage, chBufSize)\n\t\twalShardRotateChs[i] = make(chan walRotateReq, 64)\n\t}\n\n\tfor i := range walNumShards {\n\t\tmsgCh := walShardChs[i]\n\t\trotateCh := walShardRotateChs[i]\n\n\t\twalStagingWg.Add(1)\n\t\twg.Go(func() {\n\t\t\tdefer walStagingWg.Done()\n\t\t\thostFiles := make(map[string]*walFileState)\n\n\t\t\tdefer func() {\n\t\t\t\tfor _, ws := range hostFiles {\n\t\t\t\t\tif ws.f != nil {\n\t\t\t\t\t\tws.w.Flush()\n\t\t\t\t\t\tws.f.Close()\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}()\n\n\t\t\tgetOrOpenWAL := func(hostDir string) *walFileState {\n\t\t\t\tws, ok := hostFiles[hostDir]\n\t\t\t\tif ok {\n\t\t\t\t\treturn ws\n\t\t\t\t}\n\n\t\t\t\tif err := os.MkdirAll(hostDir, CheckpointDirPerms); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: mkdir %s: %v\", hostDir, err)\n\t\t\t\t\treturn nil\n\t\t\t\t}\n\n\t\t\t\twalPath := path.Join(hostDir, \"current.wal\")\n\t\t\t\tf, err := os.OpenFile(walPath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, CheckpointFilePerms)\n\t\t\t\tif err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: open %s: %v\", walPath, err)\n\t\t\t\t\treturn nil\n\t\t\t\t}\n\n\t\t\t\tw := bufio.NewWriter(f)\n\n\t\t\t\t// Write file header magic if file is new (empty).\n\t\t\t\tinfo, err := f.Stat()\n\t\t\t\tvar fileSize int64\n\t\t\t\tif err == nil {\n\t\t\t\t\tfileSize = info.Size()\n\t\t\t\t}\n\t\t\t\tif err == nil && fileSize == 0 {\n\t\t\t\t\tvar hdr [4]byte\n\t\t\t\t\tbinary.LittleEndian.PutUint32(hdr[:], walFileMagic)\n\t\t\t\t\tif _, err := w.Write(hdr[:]); err != nil {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write header %s: %v\", walPath, err)\n\t\t\t\t\t\tf.Close()\n\t\t\t\t\t\treturn nil\n\t\t\t\t\t}\n\t\t\t\t\tfileSize = 4\n\t\t\t\t}\n\n\t\t\t\tws = &walFileState{f: f, w: w, size: fileSize}\n\t\t\t\thostFiles[hostDir] = ws\n\t\t\t\treturn ws\n\t\t\t}\n\n\t\t\tprocessMsg := func(msg *WALMessage) {\n\t\t\t\thostDir := path.Join(Keys.Checkpoints.RootDir, msg.Cluster, msg.Node)\n\t\t\t\tws := getOrOpenWAL(hostDir)\n\t\t\t\tif ws == nil {\n\t\t\t\t\treturn\n\t\t\t\t}\n\t\t\t\tif err := writeWALRecordDirect(ws.w, msg); err != nil {\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: write record: %v\", err)\n\t\t\t\t}\n\t\t\t\tws.dirty = true\n\t\t\t}\n\n\t\t\tprocessRotate := func(req walRotateReq) {\n\t\t\t\tws, ok := hostFiles[req.hostDir]\n\t\t\t\tif ok && ws.f != nil {\n\t\t\t\t\tws.w.Flush()\n\t\t\t\t\tws.f.Close()\n\t\t\t\t\twalPath := path.Join(req.hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tdelete(hostFiles, req.hostDir)\n\t\t\t\t}\n\t\t\t\tclose(req.done)\n\t\t\t}\n\n\t\t\tflushDirty := func() {\n\t\t\t\tfor _, ws := range hostFiles {\n\t\t\t\t\tif ws.dirty {\n\t\t\t\t\t\tws.w.Flush()\n\t\t\t\t\t\tws.dirty = false\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}\n\n\t\t\tticker := time.NewTicker(walFlushInterval)\n\t\t\tdefer ticker.Stop()\n\n\t\t\t// drainBatch processes up to 4096 pending messages without blocking.\n\t\t\t// Returns false if the channel was closed.\n\t\t\tdrainBatch := func() bool {\n\t\t\t\tfor range 4096 {\n\t\t\t\t\tselect {\n\t\t\t\t\tcase msg, ok := <-msgCh:\n\t\t\t\t\t\tif !ok {\n\t\t\t\t\t\t\tflushDirty()\n\t\t\t\t\t\t\treturn false\n\t\t\t\t\t\t}\n\t\t\t\t\t\tprocessMsg(msg)\n\t\t\t\t\tcase req := <-rotateCh:\n\t\t\t\t\t\tprocessRotate(req)\n\t\t\t\t\tdefault:\n\t\t\t\t\t\treturn true\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\treturn true\n\t\t\t}\n\n\t\t\tfor {\n\t\t\t\tselect {\n\t\t\t\tcase <-ctx.Done():\n\t\t\t\t\t// On shutdown, skip draining buffered messages — a full binary\n\t\t\t\t\t// checkpoint will be written from in-memory state, making\n\t\t\t\t\t// buffered WAL records redundant.\n\t\t\t\t\tflushDirty()\n\t\t\t\t\treturn\n\t\t\t\tcase msg, ok := <-msgCh:\n\t\t\t\t\tif !ok {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t\tprocessMsg(msg)\n\t\t\t\t\tif !drainBatch() {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t\t// No flush here — timer handles periodic flushing.\n\t\t\t\tcase <-ticker.C:\n\t\t\t\t\tflushDirty()\n\t\t\t\tcase req := <-rotateCh:\n\t\t\t\t\tprocessRotate(req)\n\t\t\t\t}\n\t\t\t}\n\t\t})\n\t}\n}\n\n// WaitForWALStagingDrain blocks until all WALStaging goroutines have exited.\n// Must be called after closing walShardChs to ensure all file handles are\n// flushed and closed before checkpoint writes begin.\nfunc WaitForWALStagingDrain() {\n\twalStagingWg.Wait()\n}\n\n// RotateWALFiles sends rotation requests for the given host directories\n// and blocks until all rotations complete. Each request is routed to the\n// shard that owns the host directory.\n//\n// If shutdown is in progress (WAL staging goroutines may have exited),\n// rotation is skipped to avoid deadlocking on abandoned channels.\nfunc RotateWALFiles(hostDirs []string) {\n\tif walShardRotateChs == nil || walShuttingDown.Load() {\n\t\treturn\n\t}\n\tdones := make([]chan struct{}, 0, len(hostDirs))\n\tfor _, dir := range hostDirs {\n\t\tdone := make(chan struct{})\n\t\tshard := walShardIndexFromDir(dir)\n\t\tselect {\n\t\tcase walShardRotateChs[shard] <- walRotateReq{hostDir: dir, done: done}:\n\t\t\tdones = append(dones, done)\n\t\tdefault:\n\t\t\t// Channel full or goroutine not consuming — skip this host.\n\t\t\tcclog.Warnf(\"[METRICSTORE]> WAL rotation skipped for %s (channel full)\", dir)\n\t\t}\n\t}\n\tfor _, done := range dones {\n\t\tselect {\n\t\tcase <-done:\n\t\tcase <-time.After(30 * time.Second):\n\t\t\tcclog.Warn(\"[METRICSTORE]> WAL rotation timed out, continuing\")\n\t\t\treturn\n\t\t}\n\t}\n}\n\n// walShardIndexFromDir extracts cluster and node from a host directory path\n// and returns the shard index. The path format is: rootDir/cluster/node\nfunc walShardIndexFromDir(hostDir string) int {\n\t// hostDir = .../cluster/node — extract last two path components\n\tnode := path.Base(hostDir)\n\tcluster := path.Base(path.Dir(hostDir))\n\treturn walShardIndex(cluster, node)\n}\n\n// RotateWALFiles sends rotation requests for the given host directories\n// and blocks until all rotations complete.\nfunc RotateWALFilesAfterShutdown(hostDirs []string) {\n\tfor _, dir := range hostDirs {\n\t\twalPath := path.Join(dir, \"current.wal\")\n\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)\n\t\t}\n\t}\n}\n\n// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,\n// then writes it to the bufio.Writer in a single call. This prevents partial\n// records in the write buffer if a write error occurs mid-record (e.g. disk full).\n// Returns the number of bytes written and any error.\nfunc writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) (int, error) {\n\t// Compute payload and total record size.\n\tpayloadSize := 8 + 2 + len(msg.MetricName) + 1 + 4\n\tfor _, s := range msg.Selector {\n\t\tpayloadSize += 1 + len(s)\n\t}\n\t// Total: 8 (header) + payload + 4 (CRC).\n\ttotalSize := 8 + payloadSize + 4\n\n\t// Use stack buffer for typical small records, heap-allocate only for large ones.\n\tvar stackBuf [256]byte\n\tvar buf []byte\n\tif totalSize <= len(stackBuf) {\n\t\tbuf = stackBuf[:totalSize]\n\t} else {\n\t\tbuf = make([]byte, totalSize)\n\t}\n\n\t// Header: magic + payload length.\n\tbinary.LittleEndian.PutUint32(buf[0:4], walRecordMagic)\n\tbinary.LittleEndian.PutUint32(buf[4:8], uint32(payloadSize))\n\n\t// Payload starts at offset 8.\n\tp := 8\n\n\t// Timestamp (8 bytes).\n\tbinary.LittleEndian.PutUint64(buf[p:p+8], uint64(msg.Timestamp))\n\tp += 8\n\n\t// Metric name length (2 bytes) + metric name.\n\tbinary.LittleEndian.PutUint16(buf[p:p+2], uint16(len(msg.MetricName)))\n\tp += 2\n\tp += copy(buf[p:], msg.MetricName)\n\n\t// Selector count (1 byte).\n\tbuf[p] = byte(len(msg.Selector))\n\tp++\n\n\t// Selectors (1-byte length + bytes each).\n\tfor _, sel := range msg.Selector {\n\t\tbuf[p] = byte(len(sel))\n\t\tp++\n\t\tp += copy(buf[p:], sel)\n\t}\n\n\t// Value (4 bytes, float32 bits).\n\tbinary.LittleEndian.PutUint32(buf[p:p+4], math.Float32bits(float32(msg.Value)))\n\tp += 4\n\n\t// CRC32 over payload (bytes 8..8+payloadSize).\n\tcrc := crc32.ChecksumIEEE(buf[8 : 8+payloadSize])\n\tbinary.LittleEndian.PutUint32(buf[p:p+4], crc)\n\n\t// Single atomic write to the buffered writer.\n\tn, err := w.Write(buf)\n\treturn n, err\n}\n\n// readWALRecord reads one WAL record from the reader.\n// Returns (nil, nil) on clean EOF. Returns error on data corruption.\n// A CRC mismatch indicates a truncated trailing record (expected on crash).\nfunc readWALRecord(r io.Reader) (*WALMessage, error) {\n\tvar magic uint32\n\tif err := binary.Read(r, binary.LittleEndian, &magic); err != nil {\n\t\tif err == io.EOF {\n\t\t\treturn nil, nil // Clean EOF\n\t\t}\n\t\treturn nil, fmt.Errorf(\"read record magic: %w\", err)\n\t}\n\n\tif magic != walRecordMagic {\n\t\treturn nil, fmt.Errorf(\"invalid record magic 0x%08X (expected 0x%08X)\", magic, walRecordMagic)\n\t}\n\n\tvar payloadLen uint32\n\tif err := binary.Read(r, binary.LittleEndian, &payloadLen); err != nil {\n\t\treturn nil, fmt.Errorf(\"read payload length: %w\", err)\n\t}\n\n\tif payloadLen > 1<<20 { // 1 MB sanity limit\n\t\treturn nil, fmt.Errorf(\"record payload too large: %d bytes\", payloadLen)\n\t}\n\n\tpayload := make([]byte, payloadLen)\n\tif _, err := io.ReadFull(r, payload); err != nil {\n\t\treturn nil, fmt.Errorf(\"read payload: %w\", err)\n\t}\n\n\tvar storedCRC uint32\n\tif err := binary.Read(r, binary.LittleEndian, &storedCRC); err != nil {\n\t\treturn nil, fmt.Errorf(\"read CRC: %w\", err)\n\t}\n\n\tif crc32.ChecksumIEEE(payload) != storedCRC {\n\t\treturn nil, fmt.Errorf(\"CRC mismatch (truncated write or corruption)\")\n\t}\n\n\treturn parseWALPayload(payload)\n}\n\n// parseWALPayload decodes a binary payload into a WALMessage.\nfunc parseWALPayload(payload []byte) (*WALMessage, error) {\n\tif len(payload) < 8+2+1+4 {\n\t\treturn nil, fmt.Errorf(\"payload too short: %d bytes\", len(payload))\n\t}\n\n\toffset := 0\n\n\t// Timestamp (8 bytes)\n\tts := int64(binary.LittleEndian.Uint64(payload[offset : offset+8]))\n\toffset += 8\n\n\t// Metric name (2-byte length + bytes)\n\tif offset+2 > len(payload) {\n\t\treturn nil, fmt.Errorf(\"metric name length overflows payload\")\n\t}\n\tmLen := int(binary.LittleEndian.Uint16(payload[offset : offset+2]))\n\toffset += 2\n\n\tif offset+mLen > len(payload) {\n\t\treturn nil, fmt.Errorf(\"metric name overflows payload\")\n\t}\n\tmetricName := string(payload[offset : offset+mLen])\n\toffset += mLen\n\n\t// Selector count (1 byte)\n\tif offset >= len(payload) {\n\t\treturn nil, fmt.Errorf(\"selector count overflows payload\")\n\t}\n\tselCount := int(payload[offset])\n\toffset++\n\n\tselectors := make([]string, selCount)\n\tfor i := range selCount {\n\t\tif offset >= len(payload) {\n\t\t\treturn nil, fmt.Errorf(\"selector[%d] length overflows payload\", i)\n\t\t}\n\t\tsLen := int(payload[offset])\n\t\toffset++\n\n\t\tif offset+sLen > len(payload) {\n\t\t\treturn nil, fmt.Errorf(\"selector[%d] data overflows payload\", i)\n\t\t}\n\t\tselectors[i] = string(payload[offset : offset+sLen])\n\t\toffset += sLen\n\t}\n\n\t// Value (4 bytes, float32 bits)\n\tif offset+4 > len(payload) {\n\t\treturn nil, fmt.Errorf(\"value overflows payload\")\n\t}\n\tbits := binary.LittleEndian.Uint32(payload[offset : offset+4])\n\tvalue := schema.Float(math.Float32frombits(bits))\n\n\treturn &WALMessage{\n\t\tMetricName: metricName,\n\t\tTimestamp: ts,\n\t\tSelector: selectors,\n\t\tValue: value,\n\t}, nil\n}\n\n// loadWALFile reads a WAL file and replays all valid records into the Level tree.\n// l is the host-level node. Corrupt or partial trailing records are silently skipped\n// (expected on crash). Records older than 'from' are skipped.\nfunc (l *Level) loadWALFile(m *MemoryStore, f *os.File, from int64) error {\n\tbr := bufio.NewReader(f)\n\n\t// Verify file header magic.\n\tvar fileMagic uint32\n\tif err := binary.Read(br, binary.LittleEndian, &fileMagic); err != nil {\n\t\tif err == io.EOF {\n\t\t\treturn nil // Empty file, no data\n\t\t}\n\t\treturn fmt.Errorf(\"[METRICSTORE]> WAL: read file header: %w\", err)\n\t}\n\n\tif fileMagic != walFileMagic {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> WAL: invalid file magic 0x%08X (expected 0x%08X)\", fileMagic, walFileMagic)\n\t}\n\n\t// Cache level lookups to avoid repeated tree traversal.\n\tlvlCache := make(map[string]*Level)\n\n\tfor {\n\t\tmsg, err := readWALRecord(br)\n\t\tif err != nil {\n\t\t\t// Truncated trailing record is expected after a crash; stop replaying.\n\t\t\tcclog.Debugf(\"[METRICSTORE]> WAL: stopping replay at corrupted/partial record: %v\", err)\n\t\t\tbreak\n\t\t}\n\t\tif msg == nil {\n\t\t\tbreak // Clean EOF\n\t\t}\n\n\t\tif msg.Timestamp < from {\n\t\t\tcontinue // Older than retention window\n\t\t}\n\n\t\tminfo, ok := m.Metrics[msg.MetricName]\n\t\tif !ok {\n\t\t\tcontinue // Unknown metric (config may have changed)\n\t\t}\n\n\t\t// Cache key is the null-separated selector path.\n\t\tcacheKey := joinSelector(msg.Selector)\n\t\tlvl, ok := lvlCache[cacheKey]\n\t\tif !ok {\n\t\t\tlvl = l.findLevelOrCreate(msg.Selector, len(m.Metrics))\n\t\t\tlvlCache[cacheKey] = lvl\n\t\t}\n\n\t\t// Write directly to the buffer, same as WriteToLevel but without the\n\t\t// global level lookup (we already have the right level).\n\t\tlvl.lock.Lock()\n\t\tb := lvl.metrics[minfo.offset]\n\t\tif b == nil {\n\t\t\tb = newBuffer(msg.Timestamp, minfo.Frequency)\n\t\t\tlvl.metrics[minfo.offset] = b\n\t\t}\n\t\tnb, writeErr := b.write(msg.Timestamp, msg.Value)\n\t\tif writeErr == nil && b != nb {\n\t\t\tlvl.metrics[minfo.offset] = nb\n\t\t}\n\t\t// Ignore write errors for timestamps before buffer start (can happen when\n\t\t// replaying WAL entries that predate a loaded snapshot's start time).\n\t\tlvl.lock.Unlock()\n\t}\n\n\treturn nil\n}\n\n// joinSelector builds a cache key from a selector slice using null bytes as separators.\nfunc joinSelector(sel []string) string {\n\tif len(sel) == 0 {\n\t\treturn \"\"\n\t}\n\tvar result strings.Builder\n\tresult.WriteString(sel[0])\n\tfor i := 1; i < len(sel); i++ {\n\t\tresult.WriteString(\"\\x00\" + sel[i])\n\t}\n\treturn result.String()\n}\n\n// ToCheckpointWAL writes binary snapshot files for all hosts in parallel.\n// Returns the number of files written, the list of host directories that were\n// successfully checkpointed (for WAL rotation), and any errors.\nfunc (m *MemoryStore) ToCheckpointWAL(dir string, from, to int64) (int, []string, error) {\n\t// Collect all cluster/host pairs.\n\tm.root.lock.RLock()\n\ttotalHosts := 0\n\tfor _, l1 := range m.root.children {\n\t\tl1.lock.RLock()\n\t\ttotalHosts += len(l1.children)\n\t\tl1.lock.RUnlock()\n\t}\n\tm.root.lock.RUnlock()\n\n\tlevels := make([]*Level, 0, totalHosts)\n\tselectors := make([][]string, 0, totalHosts)\n\n\tm.root.lock.RLock()\n\tfor sel1, l1 := range m.root.children {\n\t\tl1.lock.RLock()\n\t\tfor sel2, l2 := range l1.children {\n\t\t\tlevels = append(levels, l2)\n\t\t\tselectors = append(selectors, []string{sel1, sel2})\n\t\t}\n\t\tl1.lock.RUnlock()\n\t}\n\tm.root.lock.RUnlock()\n\n\ttype workItem struct {\n\t\tlevel *Level\n\t\thostDir string\n\t\tselector []string\n\t}\n\n\ttotalWork := len(levels)\n\tcclog.Infof(\"[METRICSTORE]> Starting binary checkpoint for %d hosts with %d workers\", totalWork, Keys.NumWorkers)\n\n\tn, errs, completed := int32(0), int32(0), int32(0)\n\tvar successDirs []string\n\tvar successMu sync.Mutex\n\n\tvar wg sync.WaitGroup\n\twg.Add(Keys.NumWorkers)\n\twork := make(chan workItem, Keys.NumWorkers*2)\n\n\t// Progress logging goroutine.\n\tstopProgress := make(chan struct{})\n\tgo func() {\n\t\tticker := time.NewTicker(10 * time.Second)\n\t\tdefer ticker.Stop()\n\t\tfor {\n\t\t\tselect {\n\t\t\tcase <-ticker.C:\n\t\t\t\tcclog.Infof(\"[METRICSTORE]> Checkpoint progress: %d/%d hosts (%d written, %d errors)\",\n\t\t\t\t\tatomic.LoadInt32(&completed), totalWork, atomic.LoadInt32(&n), atomic.LoadInt32(&errs))\n\t\t\tcase <-stopProgress:\n\t\t\t\treturn\n\t\t\t}\n\t\t}\n\t}()\n\n\tfor range Keys.NumWorkers {\n\t\tgo func() {\n\t\t\tdefer wg.Done()\n\t\t\tfor wi := range work {\n\t\t\t\terr := wi.level.toCheckpointBinary(wi.hostDir, from, to, m)\n\t\t\t\tif err != nil {\n\t\t\t\t\tif err == ErrNoNewArchiveData {\n\t\t\t\t\t\tatomic.AddInt32(&completed, 1)\n\t\t\t\t\t\tcontinue\n\t\t\t\t\t}\n\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> binary checkpoint error for %s: %v\", wi.hostDir, err)\n\t\t\t\t\tatomic.AddInt32(&errs, 1)\n\t\t\t\t} else {\n\t\t\t\t\tatomic.AddInt32(&n, 1)\n\t\t\t\t\t// Delete WAL immediately after successful snapshot.\n\t\t\t\t\twalPath := path.Join(wi.hostDir, \"current.wal\")\n\t\t\t\t\tif err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {\n\t\t\t\t\t\tcclog.Errorf(\"[METRICSTORE]> WAL remove %s: %v\", walPath, err)\n\t\t\t\t\t}\n\t\t\t\t\tsuccessMu.Lock()\n\t\t\t\t\tsuccessDirs = append(successDirs, wi.hostDir)\n\t\t\t\t\tsuccessMu.Unlock()\n\t\t\t\t}\n\t\t\t\tatomic.AddInt32(&completed, 1)\n\t\t\t}\n\t\t}()\n\t}\n\n\tfor i := range levels {\n\t\thostDir := path.Join(dir, path.Join(selectors[i]...))\n\t\twork <- workItem{\n\t\t\tlevel: levels[i],\n\t\t\thostDir: hostDir,\n\t\t\tselector: selectors[i],\n\t\t}\n\t}\n\tclose(work)\n\twg.Wait()\n\tclose(stopProgress)\n\n\tif errs > 0 {\n\t\treturn int(n), successDirs, fmt.Errorf(\"[METRICSTORE]> %d errors during binary checkpoint (%d successes)\", errs, n)\n\t}\n\treturn int(n), successDirs, nil\n}\n\n// toCheckpointBinary writes a binary snapshot file for a single host-level node.\n// Uses atomic rename (write to .tmp then rename) to avoid partial reads on crash.\nfunc (l *Level) toCheckpointBinary(dir string, from, to int64, m *MemoryStore) error {\n\tcf, err := l.toCheckpointFile(from, to, m)\n\tif err != nil {\n\t\treturn err\n\t}\n\tif cf == nil {\n\t\treturn ErrNoNewArchiveData\n\t}\n\n\tif err := os.MkdirAll(dir, CheckpointDirPerms); err != nil {\n\t\treturn fmt.Errorf(\"mkdir %s: %w\", dir, err)\n\t}\n\n\t// Write to a temp file first, then rename (atomic on POSIX).\n\ttmpPath := path.Join(dir, fmt.Sprintf(\"%d.bin.tmp\", from))\n\tfinalPath := path.Join(dir, fmt.Sprintf(\"%d.bin\", from))\n\n\tf, err := os.OpenFile(tmpPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, CheckpointFilePerms)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"open binary snapshot %s: %w\", tmpPath, err)\n\t}\n\n\tbw := bufio.NewWriter(f)\n\tif err := writeBinarySnapshotFile(bw, cf); err != nil {\n\t\tf.Close()\n\t\tos.Remove(tmpPath)\n\t\treturn fmt.Errorf(\"write binary snapshot: %w\", err)\n\t}\n\tif err := bw.Flush(); err != nil {\n\t\tf.Close()\n\t\tos.Remove(tmpPath)\n\t\treturn err\n\t}\n\tf.Close()\n\n\treturn os.Rename(tmpPath, finalPath)\n}\n\n// writeBinarySnapshotFile writes the binary snapshot file header and level tree.\nfunc writeBinarySnapshotFile(w io.Writer, cf *CheckpointFile) error {\n\tif err := binary.Write(w, binary.LittleEndian, snapFileMagic); err != nil {\n\t\treturn err\n\t}\n\tif err := binary.Write(w, binary.LittleEndian, cf.From); err != nil {\n\t\treturn err\n\t}\n\tif err := binary.Write(w, binary.LittleEndian, cf.To); err != nil {\n\t\treturn err\n\t}\n\treturn writeBinaryLevel(w, cf)\n}\n\n// writeBinaryLevel recursively writes a CheckpointFile level in binary format.\nfunc writeBinaryLevel(w io.Writer, cf *CheckpointFile) error {\n\tif err := binary.Write(w, binary.LittleEndian, uint32(len(cf.Metrics))); err != nil {\n\t\treturn err\n\t}\n\n\tfor name, metric := range cf.Metrics {\n\t\tif err := writeString16(w, name); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, metric.Frequency); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, metric.Start); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := binary.Write(w, binary.LittleEndian, uint32(len(metric.Data))); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tfor _, v := range metric.Data {\n\t\t\tif err := binary.Write(w, binary.LittleEndian, math.Float32bits(float32(v))); err != nil {\n\t\t\t\treturn err\n\t\t\t}\n\t\t}\n\t}\n\n\tif err := binary.Write(w, binary.LittleEndian, uint32(len(cf.Children))); err != nil {\n\t\treturn err\n\t}\n\n\tfor name, child := range cf.Children {\n\t\tif err := writeString16(w, name); err != nil {\n\t\t\treturn err\n\t\t}\n\t\tif err := writeBinaryLevel(w, child); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\n\treturn nil\n}\n\n// writeString16 writes a 2-byte length-prefixed string to w.\nfunc writeString16(w io.Writer, s string) error {\n\tif err := binary.Write(w, binary.LittleEndian, uint16(len(s))); err != nil {\n\t\treturn err\n\t}\n\t_, err := io.WriteString(w, s)\n\treturn err\n}\n\n// loadBinaryFile reads a binary snapshot file and loads data into the Level tree.\n// The retention check (from) is applied to the file's 'to' timestamp.\nfunc (l *Level) loadBinaryFile(m *MemoryStore, f *os.File, from int64) error {\n\tbr := bufio.NewReader(f)\n\n\tvar magic uint32\n\tif err := binary.Read(br, binary.LittleEndian, &magic); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read magic: %w\", err)\n\t}\n\tif magic != snapFileMagic {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: invalid magic 0x%08X (expected 0x%08X)\", magic, snapFileMagic)\n\t}\n\n\tvar fileFrom, fileTo int64\n\tif err := binary.Read(br, binary.LittleEndian, &fileFrom); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read from: %w\", err)\n\t}\n\tif err := binary.Read(br, binary.LittleEndian, &fileTo); err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read to: %w\", err)\n\t}\n\n\tif fileTo != 0 && fileTo < from {\n\t\treturn nil // File is older than retention window, skip it\n\t}\n\n\tcf, err := readBinaryLevel(br)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"[METRICSTORE]> binary snapshot: read level tree: %w\", err)\n\t}\n\tcf.From = fileFrom\n\tcf.To = fileTo\n\n\treturn l.loadFile(cf, m)\n}\n\n// readBinaryLevel recursively reads a level from the binary snapshot format.\nfunc readBinaryLevel(r io.Reader) (*CheckpointFile, error) {\n\tcf := &CheckpointFile{\n\t\tMetrics: make(map[string]*CheckpointMetrics),\n\t\tChildren: make(map[string]*CheckpointFile),\n\t}\n\n\tvar numMetrics uint32\n\tif err := binary.Read(r, binary.LittleEndian, &numMetrics); err != nil {\n\t\treturn nil, fmt.Errorf(\"read num_metrics: %w\", err)\n\t}\n\n\tfor range numMetrics {\n\t\tname, err := readString16(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read metric name: %w\", err)\n\t\t}\n\n\t\tvar freq, start int64\n\t\tif err := binary.Read(r, binary.LittleEndian, &freq); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read frequency for %s: %w\", name, err)\n\t\t}\n\t\tif err := binary.Read(r, binary.LittleEndian, &start); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read start for %s: %w\", name, err)\n\t\t}\n\n\t\tvar numValues uint32\n\t\tif err := binary.Read(r, binary.LittleEndian, &numValues); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read num_values for %s: %w\", name, err)\n\t\t}\n\n\t\tdata := make([]schema.Float, numValues)\n\t\tfor i := range numValues {\n\t\t\tvar bits uint32\n\t\t\tif err := binary.Read(r, binary.LittleEndian, &bits); err != nil {\n\t\t\t\treturn nil, fmt.Errorf(\"read value[%d] for %s: %w\", i, name, err)\n\t\t\t}\n\t\t\tdata[i] = schema.Float(math.Float32frombits(bits))\n\t\t}\n\n\t\tcf.Metrics[name] = &CheckpointMetrics{\n\t\t\tFrequency: freq,\n\t\t\tStart: start,\n\t\t\tData: data,\n\t\t}\n\t}\n\n\tvar numChildren uint32\n\tif err := binary.Read(r, binary.LittleEndian, &numChildren); err != nil {\n\t\treturn nil, fmt.Errorf(\"read num_children: %w\", err)\n\t}\n\n\tfor range numChildren {\n\t\tchildName, err := readString16(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read child name: %w\", err)\n\t\t}\n\n\t\tchild, err := readBinaryLevel(r)\n\t\tif err != nil {\n\t\t\treturn nil, fmt.Errorf(\"read child %s: %w\", childName, err)\n\t\t}\n\t\tcf.Children[childName] = child\n\t}\n\n\treturn cf, nil\n}\n\n// readString16 reads a 2-byte length-prefixed string from r.\nfunc readString16(r io.Reader) (string, error) {\n\tvar sLen uint16\n\tif err := binary.Read(r, binary.LittleEndian, &sLen); err != nil {\n\t\treturn \"\", err\n\t}\n\tbuf := make([]byte, sLen)\n\tif _, err := io.ReadFull(r, buf); err != nil {\n\t\treturn \"\", err\n\t}\n\treturn string(buf), nil\n}\n","structuredPatch":[{"oldStart":241,"oldLines":9,"newStart":241,"newLines":30,"lines":[" if ws == nil {"," return"," }","- if err := writeWALRecordDirect(ws.w, msg); err != nil {","+","+ // Enforce max WAL size: force-rotate before writing if limit is exceeded.","+ // The in-memory store still holds the data; only crash-recovery coverage is lost.","+ if maxSize := Keys.Checkpoints.MaxWALSize; maxSize > 0 && ws.size >= maxSize {","+ cclog.Warnf(\"[METRICSTORE]> WAL: force-rotating %s (size %d >= limit %d)\",","+ hostDir, ws.size, maxSize)","+ ws.w.Flush()","+ ws.f.Close()","+ walPath := path.Join(hostDir, \"current.wal\")","+ if err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {","+ cclog.Errorf(\"[METRICSTORE]> WAL: remove %s: %v\", walPath, err)","+ }","+ delete(hostFiles, hostDir)","+ ws = getOrOpenWAL(hostDir)","+ if ws == nil {","+ return","+ }","+ }","+","+ n, err := writeWALRecordDirect(ws.w, msg)","+ if err != nil {"," cclog.Errorf(\"[METRICSTORE]> WAL: write record: %v\", err)"," }","+ ws.size += int64(n)"," ws.dirty = true"," }"," "]}],"userModified":false,"replaceAll":false},"sourceToolAssistantUUID":"05d54134-4ce0-47e2-acea-a3c3123da1eb","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"43a1bceb-09a2-44fb-8dc8-21c4500f65d4","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01PxDWDtNPgcfz8depRUbEqj","type":"message","role":"assistant","content":[{"type":"text","text":"All done. Here's a summary of the changes:\n\n**`pkg/metricstore/checkpoint.go`** — Fixed partial checkpoint success handling. Previously, if `ToCheckpointWAL` returned any error (even with some hosts succeeding), `lastCheckpoint` was never advanced and `RotateWALFiles` was never called. Now, if `n > 0` snapshots were written, the timestamp advances and WAL rotation runs for the successful hosts, independent of whether other hosts failed.\n\n**`pkg/metricstore/config.go`** — Added `MaxWALSize int64` field to `Checkpoints` struct. Configurable via `\"max-wal-size\"` in JSON (bytes). Default 0 = unlimited (backward compatible).\n\n**`pkg/metricstore/walCheckpoint.go`** — Three changes:\n1. Added `size int64` field to `walFileState` to track approximate file size\n2. Initialized size from `Stat()` in `getOrOpenWAL()` (reusing the existing stat call)\n3. Added size enforcement in `processMsg()`: when a host's WAL exceeds `MaxWALSize`, it's force-rotated (flush, close, delete, re-open). This accepts loss of crash-recovery coverage for that interval, but the in-memory store still holds the data for the next successful checkpoint.\n4. Changed `writeWALRecordDirect` to return `(int, error)` so the caller can track bytes written."}],"stop_reason":"end_turn","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":94,"cache_read_input_tokens":48058,"output_tokens":351,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":94,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUvCPDMk6m8bH32oXZs6","type":"assistant","uuid":"03cdadef-284c-44b9-bb66-1cdf1e98bc5a","timestamp":"2026-03-28T05:22:28.985Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"bdac98be-9fbd-4814-b381-e35c8cc0b0c5","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01RnrMyBSpfhj6dcNyN3Utq7","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01FJk1fh6UvtbFji7RjFkqg7","name":"Agent","input":{"subagent_type":"Explore","description":"Find checkpoint config docs/schema","prompt":"Find all files that document the checkpoint configuration, specifically the \"checkpoints\" JSON config block with \"file-format\" and \"directory\" fields. Look for:\n\n1. Any JSON schema files (*.json with \"$schema\" or \"properties\" mentioning \"checkpoints\")\n2. Documentation files mentioning checkpoint configuration (e.g. in docs/, configs/, README)\n3. Example config files (config.json, *.example.json, etc.)\n4. CLAUDE.md or any markdown that documents the checkpoints config structure\n5. The config.go file itself (already known: pkg/metricstore/config.go)\n\nSearch broadly — glob for *.md, *.json, *.yml, *.yaml in the project root and key subdirectories. Use grep for \"max-wal-size\", \"file-format\", \"checkpoints\" in config-related contexts."},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":421,"cache_read_input_tokens":48152,"output_tokens":288,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":421,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUvFf2wyPCEbgsWszSP1","type":"assistant","uuid":"787e86f1-518b-47c0-9deb-e4cfdf88065b","timestamp":"2026-03-28T05:23:12.062Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"787e86f1-518b-47c0-9deb-e4cfdf88065b","isSidechain":false,"promptId":"d76a4a46-7268-4bc4-bb76-fc66c7547f28","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01FJk1fh6UvtbFji7RjFkqg7","type":"tool_result","content":[{"type":"text","text":"Excellent! Now I have all the information needed. Let me compile the comprehensive report.\n\n## Summary: Checkpoint Configuration Documentation\n\nI found comprehensive documentation about the checkpoint configuration scattered across multiple files in the project. Here's what documents the \"checkpoints\" JSON config block with \"file-format\" and \"directory\" fields:\n\n### Primary Documentation Files\n\n**1. Configuration Schema (Most authoritative):**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/configSchema.go`\n - Contains embedded JSON schema defining the checkpoints block structure\n - Defines `file-format` field: \"Specify the format for checkpoint files. Two variants: 'json' (human-readable, periodic) and 'wal' (binary snapshot + Write-Ahead Log, crash-safe). Default is 'wal'.\"\n - Defines `directory` field: \"Path in which the checkpointed files should be placed.\"\n - Also documents `max-wal-size` field (not visible in basic schema but referenced in code)\n\n**2. Configuration Structure Documentation (Go Code):**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/config.go` (lines 59-70)\n - Defines the `Checkpoints` struct with detailed docstring comments\n - Documents fields:\n - `FileFormat`: \"json\" (human-readable, periodic) or \"wal\" (binary snapshot + WAL, crash-safe); default is \"wal\"\n - `RootDir`: Filesystem path for checkpoint files (created if missing)\n - `MaxWALSize`: Maximum size in bytes for a single host's WAL file; 0 = unlimited (default)\n\n**3. Checkpoint Implementation Documentation:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/checkpoint.go` (lines 6-34)\n - Documents file organization and checkpoint workflow\n - Describes file structure:\n ```\n checkpoints/\n cluster1/\n host001/\n 1234567890.json (JSON format: full subtree snapshot)\n 1234567890.bin (binary format: full subtree snapshot)\n current.wal (WAL format: append-only per-entry log)\n ```\n\n**4. WAL Implementation Details:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go` (lines 6-50)\n - Documents WAL record format and binary snapshot format\n - Explains the crash-safety mechanism\n\n### Example Configuration Files\n\n**5. Example Configuration with Checkpoints:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/configs/config.json` (lines 76-78)\n - Example:\n ```json\n \"metric-store\": {\n \"checkpoints\": {\n \"directory\": \"./var/checkpoints\"\n },\n ...\n }\n ```\n\n**6. Minimal Demo Configuration:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/configs/config-demo.json`\n - Minimal example (uses defaults for checkpoint fields)\n\n### Developer Guidance\n\n**7. CLAUDE.md (Developer Guidelines):**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/CLAUDE.md` (lines 99-101)\n - Brief mention: \"In-memory metric storage with checkpointing\"\n\n**8. Release Notes:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/ReleaseNotes.md`\n - Documents checkpoint archiving changes and cleanup features\n - References the `-cleanup-checkpoints` CLI flag\n\n**9. CLI Documentation:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/cmd/cc-backend/cli.go` (line 32)\n - Flag: `-cleanup-checkpoints`: \"Clean up old checkpoint files (delete or archive) based on retention settings, then exit\"\n\n### README Documentation\n\n**10. Main README:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/README.md`\n - General project overview (no specific checkpoint config details)\n\n### Configuration Hierarchy\n\nThe checkpoint configuration is nested as:\n```json\n{\n \"metric-store\": {\n \"checkpoints\": {\n \"file-format\": \"wal|json\",\n \"directory\": \"/path/to/checkpoints\",\n \"max-wal-size\": 0\n }\n }\n}\n```\n\nAll files are located in the `/Users/jan/prg/ClusterCockpit/cc-backend` repository. The most authoritative sources are the config schema and the config.go Go file with its docstrings."}]}]},"uuid":"6ad52f25-a345-4527-b9d5-7a078c1975c7","timestamp":"2026-03-28T05:23:46.550Z","toolUseResult":{"status":"completed","prompt":"Find all files that document the checkpoint configuration, specifically the \"checkpoints\" JSON config block with \"file-format\" and \"directory\" fields. Look for:\n\n1. Any JSON schema files (*.json with \"$schema\" or \"properties\" mentioning \"checkpoints\")\n2. Documentation files mentioning checkpoint configuration (e.g. in docs/, configs/, README)\n3. Example config files (config.json, *.example.json, etc.)\n4. CLAUDE.md or any markdown that documents the checkpoints config structure\n5. The config.go file itself (already known: pkg/metricstore/config.go)\n\nSearch broadly — glob for *.md, *.json, *.yml, *.yaml in the project root and key subdirectories. Use grep for \"max-wal-size\", \"file-format\", \"checkpoints\" in config-related contexts.","agentId":"a136f3d875099254d","agentType":"Explore","content":[{"type":"text","text":"Excellent! Now I have all the information needed. Let me compile the comprehensive report.\n\n## Summary: Checkpoint Configuration Documentation\n\nI found comprehensive documentation about the checkpoint configuration scattered across multiple files in the project. Here's what documents the \"checkpoints\" JSON config block with \"file-format\" and \"directory\" fields:\n\n### Primary Documentation Files\n\n**1. Configuration Schema (Most authoritative):**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/configSchema.go`\n - Contains embedded JSON schema defining the checkpoints block structure\n - Defines `file-format` field: \"Specify the format for checkpoint files. Two variants: 'json' (human-readable, periodic) and 'wal' (binary snapshot + Write-Ahead Log, crash-safe). Default is 'wal'.\"\n - Defines `directory` field: \"Path in which the checkpointed files should be placed.\"\n - Also documents `max-wal-size` field (not visible in basic schema but referenced in code)\n\n**2. Configuration Structure Documentation (Go Code):**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/config.go` (lines 59-70)\n - Defines the `Checkpoints` struct with detailed docstring comments\n - Documents fields:\n - `FileFormat`: \"json\" (human-readable, periodic) or \"wal\" (binary snapshot + WAL, crash-safe); default is \"wal\"\n - `RootDir`: Filesystem path for checkpoint files (created if missing)\n - `MaxWALSize`: Maximum size in bytes for a single host's WAL file; 0 = unlimited (default)\n\n**3. Checkpoint Implementation Documentation:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/checkpoint.go` (lines 6-34)\n - Documents file organization and checkpoint workflow\n - Describes file structure:\n ```\n checkpoints/\n cluster1/\n host001/\n 1234567890.json (JSON format: full subtree snapshot)\n 1234567890.bin (binary format: full subtree snapshot)\n current.wal (WAL format: append-only per-entry log)\n ```\n\n**4. WAL Implementation Details:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go` (lines 6-50)\n - Documents WAL record format and binary snapshot format\n - Explains the crash-safety mechanism\n\n### Example Configuration Files\n\n**5. Example Configuration with Checkpoints:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/configs/config.json` (lines 76-78)\n - Example:\n ```json\n \"metric-store\": {\n \"checkpoints\": {\n \"directory\": \"./var/checkpoints\"\n },\n ...\n }\n ```\n\n**6. Minimal Demo Configuration:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/configs/config-demo.json`\n - Minimal example (uses defaults for checkpoint fields)\n\n### Developer Guidance\n\n**7. CLAUDE.md (Developer Guidelines):**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/CLAUDE.md` (lines 99-101)\n - Brief mention: \"In-memory metric storage with checkpointing\"\n\n**8. Release Notes:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/ReleaseNotes.md`\n - Documents checkpoint archiving changes and cleanup features\n - References the `-cleanup-checkpoints` CLI flag\n\n**9. CLI Documentation:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/cmd/cc-backend/cli.go` (line 32)\n - Flag: `-cleanup-checkpoints`: \"Clean up old checkpoint files (delete or archive) based on retention settings, then exit\"\n\n### README Documentation\n\n**10. Main README:**\n- **File**: `/Users/jan/prg/ClusterCockpit/cc-backend/README.md`\n - General project overview (no specific checkpoint config details)\n\n### Configuration Hierarchy\n\nThe checkpoint configuration is nested as:\n```json\n{\n \"metric-store\": {\n \"checkpoints\": {\n \"file-format\": \"wal|json\",\n \"directory\": \"/path/to/checkpoints\",\n \"max-wal-size\": 0\n }\n }\n}\n```\n\nAll files are located in the `/Users/jan/prg/ClusterCockpit/cc-backend` repository. The most authoritative sources are the config schema and the config.go Go file with its docstrings."}],"totalDurationMs":34221,"totalTokens":45213,"totalToolUseCount":20,"usage":{"input_tokens":4,"cache_creation_input_tokens":863,"cache_read_input_tokens":43181,"output_tokens":1165,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":0,"ephemeral_5m_input_tokens":863},"inference_geo":"","iterations":[],"speed":"standard"}},"sourceToolAssistantUUID":"787e86f1-518b-47c0-9deb-e4cfdf88065b","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"34edbb59-da16-4c75-8387-0f19ce0c1b05","isSidechain":false,"promptId":"d76a4a46-7268-4bc4-bb76-fc66c7547f28","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_011WXsyAmqeEGRXtZhk5quFL","type":"tool_result","content":"1\t// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.\n2\t// All rights reserved. This file is part of cc-backend.\n3\t// Use of this source code is governed by a MIT-style\n4\t// license that can be found in the LICENSE file.\n5\t\n6\tpackage metricstore\n7\t\n8\tconst configSchema = `{\n9\t \"type\": \"object\",\n10\t \"description\": \"Configuration specific to built-in metric-store.\",\n11\t \"properties\": {\n12\t \"num-workers\": {\n13\t \"description\": \"Number of concurrent workers for checkpoint and archive operations\",\n14\t \"type\": \"integer\"\n15\t },\n16\t \"checkpoints\": {\n17\t \"description\": \"Configuration for checkpointing the metrics buffers\",\n18\t \"type\": \"object\",\n19\t \"properties\": {\n20\t \"file-format\": {\n21\t \"description\": \"Specify the format for checkpoint files. Two variants: 'json' (human-readable, periodic) and 'wal' (binary snapshot + Write-Ahead Log, crash-safe). Default is 'wal'.\",\n22\t \"type\": \"string\"\n23\t },\n24\t \"directory\": {\n25\t \"description\": \"Path in which the checkpointed files should be placed.\",\n26\t \"type\": \"string\"\n27\t }\n28\t }\n29\t },\n30\t \"cleanup\": {\n31\t \"description\": \"Configuration for the cleanup process. The cleanup interval is always 'retention-in-memory'.\",\n32\t \"type\": \"object\",\n33\t \"properties\": {\n34\t \"mode\": {\n35\t \"description\": \"The operation mode (e.g., 'archive' or 'delete').\",\n36\t \"type\": \"string\",\n37\t \"enum\": [\"archive\", \"delete\"]\n38\t },\n39\t \"directory\": {\n40\t \"description\": \"Target directory for archive operations.\",\n41\t \"type\": \"string\"\n42\t }\n43\t },\n44\t \"if\": {\n45\t \"properties\": {\n46\t \"mode\": { \"const\": \"archive\" }\n47\t }\n48\t },\n49\t \"then\": {\n50\t \"required\": [\"directory\"]\n51\t }\n52\t },\n53\t \"retention-in-memory\": {\n54\t \"description\": \"Keep the metrics within memory for given time interval. Retention for X hours, then the metrics would be freed.\",\n55\t \"type\": \"string\"\n56\t },\n57\t \"checkpoint-interval\": {\n58\t \"description\": \"Interval between checkpoints as a Go duration string (e.g., '12h', '6h', '30m'). Default is '12h'.\",\n59\t \"type\": \"string\"\n60\t },\n61\t \"memory-cap\": {\n62\t \"description\": \"Upper memory capacity limit used by metricstore in GB\",\n63\t \"type\": \"integer\"\n64\t },\n65\t \"nats-subscriptions\": {\n66\t \"description\": \"Array of various subscriptions. Allows to subscribe to different subjects and publishers.\",\n67\t \"type\": \"array\",\n68\t \"items\": {\n69\t \"type\": \"object\",\n70\t \"properties\": {\n71\t \"subscribe-to\": {\n72\t \"description\": \"Subject name\",\n73\t \"type\": \"string\"\n74\t },\n75\t \"cluster-tag\": {\n76\t \"description\": \"Optional: Allow lines without a cluster tag, use this as default\",\n77\t \"type\": \"string\"\n78\t }\n79\t },\n80\t\t\t\t\t\"required\": [\"subscribe-to\"]\n81\t }\n82\t }\n83\t },\n84\t \"required\": [\"retention-in-memory\", \"memory-cap\"]\n85\t}`\n86\t"}]},"uuid":"1b72ffa8-a03a-41d1-a7d7-4165b71a7057","timestamp":"2026-03-28T05:23:50.400Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/configSchema.go","content":"// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.\n// All rights reserved. This file is part of cc-backend.\n// Use of this source code is governed by a MIT-style\n// license that can be found in the LICENSE file.\n\npackage metricstore\n\nconst configSchema = `{\n \"type\": \"object\",\n \"description\": \"Configuration specific to built-in metric-store.\",\n \"properties\": {\n \"num-workers\": {\n \"description\": \"Number of concurrent workers for checkpoint and archive operations\",\n \"type\": \"integer\"\n },\n \"checkpoints\": {\n \"description\": \"Configuration for checkpointing the metrics buffers\",\n \"type\": \"object\",\n \"properties\": {\n \"file-format\": {\n \"description\": \"Specify the format for checkpoint files. Two variants: 'json' (human-readable, periodic) and 'wal' (binary snapshot + Write-Ahead Log, crash-safe). Default is 'wal'.\",\n \"type\": \"string\"\n },\n \"directory\": {\n \"description\": \"Path in which the checkpointed files should be placed.\",\n \"type\": \"string\"\n }\n }\n },\n \"cleanup\": {\n \"description\": \"Configuration for the cleanup process. The cleanup interval is always 'retention-in-memory'.\",\n \"type\": \"object\",\n \"properties\": {\n \"mode\": {\n \"description\": \"The operation mode (e.g., 'archive' or 'delete').\",\n \"type\": \"string\",\n \"enum\": [\"archive\", \"delete\"]\n },\n \"directory\": {\n \"description\": \"Target directory for archive operations.\",\n \"type\": \"string\"\n }\n },\n \"if\": {\n \"properties\": {\n \"mode\": { \"const\": \"archive\" }\n }\n },\n \"then\": {\n \"required\": [\"directory\"]\n }\n },\n \"retention-in-memory\": {\n \"description\": \"Keep the metrics within memory for given time interval. Retention for X hours, then the metrics would be freed.\",\n \"type\": \"string\"\n },\n \"checkpoint-interval\": {\n \"description\": \"Interval between checkpoints as a Go duration string (e.g., '12h', '6h', '30m'). Default is '12h'.\",\n \"type\": \"string\"\n },\n \"memory-cap\": {\n \"description\": \"Upper memory capacity limit used by metricstore in GB\",\n \"type\": \"integer\"\n },\n \"nats-subscriptions\": {\n \"description\": \"Array of various subscriptions. Allows to subscribe to different subjects and publishers.\",\n \"type\": \"array\",\n \"items\": {\n \"type\": \"object\",\n \"properties\": {\n \"subscribe-to\": {\n \"description\": \"Subject name\",\n \"type\": \"string\"\n },\n \"cluster-tag\": {\n \"description\": \"Optional: Allow lines without a cluster tag, use this as default\",\n \"type\": \"string\"\n }\n },\n\t\t\t\t\"required\": [\"subscribe-to\"]\n }\n }\n },\n \"required\": [\"retention-in-memory\", \"memory-cap\"]\n}`\n","numLines":86,"startLine":1,"totalLines":86}},"sourceToolAssistantUUID":"34edbb59-da16-4c75-8387-0f19ce0c1b05","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"1b72ffa8-a03a-41d1-a7d7-4165b71a7057","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01614xVKcDfr5JR7k1N448ZL","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01T2JzjfzUWQchDjQ4X8nETu","name":"Read","input":{"file_path":"/Users/jan/prg/ClusterCockpit/cc-backend/configs/config.json","offset":70,"limit":20},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":1054,"cache_read_input_tokens":50036,"output_tokens":109,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":1054,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUvKCk1uRt6s3BggXyJ9","type":"assistant","uuid":"12e61c10-1730-47ca-845b-33d9af53959e","timestamp":"2026-03-28T05:23:54.024Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"12e61c10-1730-47ca-845b-33d9af53959e","isSidechain":false,"promptId":"d76a4a46-7268-4bc4-bb76-fc66c7547f28","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01T2JzjfzUWQchDjQ4X8nETu","type":"tool_result","content":"70\t \"scope\": \"alex\",\n71\t \"url\": \"http://x.x.x.x:8084\",\n72\t \"token\": \"MySecret\"\n73\t }\n74\t ],\n75\t \"metric-store\": {\n76\t \"checkpoints\": {\n77\t \"directory\": \"./var/checkpoints\"\n78\t },\n79\t \"memory-cap\": 100,\n80\t \"retention-in-memory\": \"24h\",\n81\t \"cleanup\": {\n82\t \"mode\": \"archive\",\n83\t \"directory\": \"./var/archive\"\n84\t },\n85\t \"nats-subscriptions\": [\n86\t {\n87\t \"subscribe-to\": \"hpc-nats\",\n88\t \"cluster-tag\": \"fritz\"\n89\t },"}]},"uuid":"e257cb0f-4e70-472e-a736-073c49d3619d","timestamp":"2026-03-28T05:23:54.051Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/configs/config.json","content":" \"scope\": \"alex\",\n \"url\": \"http://x.x.x.x:8084\",\n \"token\": \"MySecret\"\n }\n ],\n \"metric-store\": {\n \"checkpoints\": {\n \"directory\": \"./var/checkpoints\"\n },\n \"memory-cap\": 100,\n \"retention-in-memory\": \"24h\",\n \"cleanup\": {\n \"mode\": \"archive\",\n \"directory\": \"./var/archive\"\n },\n \"nats-subscriptions\": [\n {\n \"subscribe-to\": \"hpc-nats\",\n \"cluster-tag\": \"fritz\"\n },","numLines":20,"startLine":70,"totalLines":98}},"sourceToolAssistantUUID":"12e61c10-1730-47ca-845b-33d9af53959e","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"e257cb0f-4e70-472e-a736-073c49d3619d","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01G4dfcW4MUencNSqwGZNmcf","type":"message","role":"assistant","content":[{"type":"text","text":"Now I'll update the config schema and the example config."}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":1375,"cache_read_input_tokens":50036,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":1375},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUvKUQM1V6ZUeyRqFYRW","type":"assistant","uuid":"adc30250-12cd-4c53-9a0c-a0d07a2b1f1f","timestamp":"2026-03-28T05:23:57.874Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"adc30250-12cd-4c53-9a0c-a0d07a2b1f1f","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01G4dfcW4MUencNSqwGZNmcf","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01NhmZU2b6um6DcBA9rssJKR","name":"Edit","input":{"replace_all":false,"file_path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/configSchema.go","old_string":" \"directory\": {\n \"description\": \"Path in which the checkpointed files should be placed.\",\n \"type\": \"string\"\n }\n }","new_string":" \"directory\": {\n \"description\": \"Path in which the checkpointed files should be placed.\",\n \"type\": \"string\"\n },\n \"max-wal-size\": {\n \"description\": \"Maximum size in bytes for a single host's WAL file. When exceeded the WAL is force-rotated to prevent unbounded disk growth. Only applies when file-format is 'wal'. 0 means unlimited (default).\",\n \"type\": \"integer\",\n \"minimum\": 0\n }\n }"},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":1375,"cache_read_input_tokens":50036,"output_tokens":308,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":1375,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUvKUQM1V6ZUeyRqFYRW","type":"assistant","uuid":"3e518d7c-0be7-41d1-97fd-ac003a5138bc","timestamp":"2026-03-28T05:24:00.762Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"type":"file-history-snapshot","messageId":"3e518d7c-0be7-41d1-97fd-ac003a5138bc","snapshot":{"messageId":"bdac98be-9fbd-4814-b381-e35c8cc0b0c5","trackedFileBackups":{"/Users/jan/.claude/plans/atomic-giggling-gizmo.md":{"backupFileName":"3c4dde4e7dd55fd5@v2","version":2,"backupTime":"2026-03-28T05:23:02.323Z"},"pkg/metricstore/config.go":{"backupFileName":"614b3f053f832cad@v2","version":2,"backupTime":"2026-03-28T05:23:02.324Z"},"pkg/metricstore/walCheckpoint.go":{"backupFileName":"f5b5b4bac0274f50@v2","version":2,"backupTime":"2026-03-28T05:23:02.324Z"},"pkg/metricstore/checkpoint.go":{"backupFileName":"6cd2cc2f9fa35484@v2","version":2,"backupTime":"2026-03-28T05:23:02.324Z"},"pkg/metricstore/configSchema.go":{"backupFileName":"5a1be5ca7fda54fe@v1","version":1,"backupTime":"2026-03-28T05:24:04.617Z"}},"timestamp":"2026-03-28T05:23:02.324Z"},"isSnapshotUpdate":true}
{"parentUuid":"3e518d7c-0be7-41d1-97fd-ac003a5138bc","isSidechain":false,"promptId":"d76a4a46-7268-4bc4-bb76-fc66c7547f28","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01NhmZU2b6um6DcBA9rssJKR","type":"tool_result","content":"The file /Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/configSchema.go has been updated successfully."}]},"uuid":"fd204dfd-3d3c-4069-91f6-5d5ab37749c6","timestamp":"2026-03-28T05:24:04.619Z","toolUseResult":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/configSchema.go","oldString":" \"directory\": {\n \"description\": \"Path in which the checkpointed files should be placed.\",\n \"type\": \"string\"\n }\n }","newString":" \"directory\": {\n \"description\": \"Path in which the checkpointed files should be placed.\",\n \"type\": \"string\"\n },\n \"max-wal-size\": {\n \"description\": \"Maximum size in bytes for a single host's WAL file. When exceeded the WAL is force-rotated to prevent unbounded disk growth. Only applies when file-format is 'wal'. 0 means unlimited (default).\",\n \"type\": \"integer\",\n \"minimum\": 0\n }\n }","originalFile":"// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.\n// All rights reserved. This file is part of cc-backend.\n// Use of this source code is governed by a MIT-style\n// license that can be found in the LICENSE file.\n\npackage metricstore\n\nconst configSchema = `{\n \"type\": \"object\",\n \"description\": \"Configuration specific to built-in metric-store.\",\n \"properties\": {\n \"num-workers\": {\n \"description\": \"Number of concurrent workers for checkpoint and archive operations\",\n \"type\": \"integer\"\n },\n \"checkpoints\": {\n \"description\": \"Configuration for checkpointing the metrics buffers\",\n \"type\": \"object\",\n \"properties\": {\n \"file-format\": {\n \"description\": \"Specify the format for checkpoint files. Two variants: 'json' (human-readable, periodic) and 'wal' (binary snapshot + Write-Ahead Log, crash-safe). Default is 'wal'.\",\n \"type\": \"string\"\n },\n \"directory\": {\n \"description\": \"Path in which the checkpointed files should be placed.\",\n \"type\": \"string\"\n }\n }\n },\n \"cleanup\": {\n \"description\": \"Configuration for the cleanup process. The cleanup interval is always 'retention-in-memory'.\",\n \"type\": \"object\",\n \"properties\": {\n \"mode\": {\n \"description\": \"The operation mode (e.g., 'archive' or 'delete').\",\n \"type\": \"string\",\n \"enum\": [\"archive\", \"delete\"]\n },\n \"directory\": {\n \"description\": \"Target directory for archive operations.\",\n \"type\": \"string\"\n }\n },\n \"if\": {\n \"properties\": {\n \"mode\": { \"const\": \"archive\" }\n }\n },\n \"then\": {\n \"required\": [\"directory\"]\n }\n },\n \"retention-in-memory\": {\n \"description\": \"Keep the metrics within memory for given time interval. Retention for X hours, then the metrics would be freed.\",\n \"type\": \"string\"\n },\n \"checkpoint-interval\": {\n \"description\": \"Interval between checkpoints as a Go duration string (e.g., '12h', '6h', '30m'). Default is '12h'.\",\n \"type\": \"string\"\n },\n \"memory-cap\": {\n \"description\": \"Upper memory capacity limit used by metricstore in GB\",\n \"type\": \"integer\"\n },\n \"nats-subscriptions\": {\n \"description\": \"Array of various subscriptions. Allows to subscribe to different subjects and publishers.\",\n \"type\": \"array\",\n \"items\": {\n \"type\": \"object\",\n \"properties\": {\n \"subscribe-to\": {\n \"description\": \"Subject name\",\n \"type\": \"string\"\n },\n \"cluster-tag\": {\n \"description\": \"Optional: Allow lines without a cluster tag, use this as default\",\n \"type\": \"string\"\n }\n },\n\t\t\t\t\"required\": [\"subscribe-to\"]\n }\n }\n },\n \"required\": [\"retention-in-memory\", \"memory-cap\"]\n}`\n","structuredPatch":[{"oldStart":24,"oldLines":6,"newStart":24,"newLines":11,"lines":[" \"directory\": {"," \"description\": \"Path in which the checkpointed files should be placed.\","," \"type\": \"string\"","+ },","+ \"max-wal-size\": {","+ \"description\": \"Maximum size in bytes for a single host's WAL file. When exceeded the WAL is force-rotated to prevent unbounded disk growth. Only applies when file-format is 'wal'. 0 means unlimited (default).\",","+ \"type\": \"integer\",","+ \"minimum\": 0"," }"," }"," },"]}],"userModified":false,"replaceAll":false},"sourceToolAssistantUUID":"3e518d7c-0be7-41d1-97fd-ac003a5138bc","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"fd204dfd-3d3c-4069-91f6-5d5ab37749c6","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01VsD1vT2qzVyHnSkTReDaxK","type":"message","role":"assistant","content":[{"type":"text","text":"Now let me check if there's additional documentation in walCheckpoint.go's header that should mention this:"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":354,"cache_read_input_tokens":51411,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":354},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUvLFkNKfKw6NkHWAr6L","type":"assistant","uuid":"a9abd90e-51b6-4eec-89e6-af433ab41b7c","timestamp":"2026-03-28T05:24:08.317Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"a9abd90e-51b6-4eec-89e6-af433ab41b7c","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01VsD1vT2qzVyHnSkTReDaxK","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01G8CkGR7JzaJTYvAX7NnzrN","name":"Read","input":{"file_path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","limit":55},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":354,"cache_read_input_tokens":51411,"output_tokens":121,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":354,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUvLFkNKfKw6NkHWAr6L","type":"assistant","uuid":"35d52783-099b-4005-9708-b5732ee3a614","timestamp":"2026-03-28T05:24:08.933Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"35d52783-099b-4005-9708-b5732ee3a614","isSidechain":false,"promptId":"d76a4a46-7268-4bc4-bb76-fc66c7547f28","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01G8CkGR7JzaJTYvAX7NnzrN","type":"tool_result","content":"1\t// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.\n2\t// All rights reserved. This file is part of cc-backend.\n3\t// Use of this source code is governed by a MIT-style\n4\t// license that can be found in the LICENSE file.\n5\t\n6\t// Package metricstore provides walCheckpoint.go: WAL-based checkpoint implementation.\n7\t//\n8\t// This replaces the Avro shadow tree with an append-only Write-Ahead Log (WAL)\n9\t// per host, eliminating the extra memory overhead of the AvroStore and providing\n10\t// truly continuous (per-write) crash safety.\n11\t//\n12\t// # Architecture\n13\t//\n14\t//\tMetric write (DecodeLine)\n15\t//\t │\n16\t//\t ├─► WriteToLevel() → main MemoryStore (unchanged)\n17\t//\t │\n18\t//\t └─► WALMessages channel\n19\t//\t │\n20\t//\t ▼\n21\t//\t WALStaging goroutine\n22\t//\t │\n23\t//\t ▼\n24\t//\t checkpoints/cluster/host/current.wal (append-only, binary)\n25\t//\n26\t//\tPeriodic checkpoint (Checkpointing goroutine):\n27\t//\t 1. Write <timestamp>.bin snapshot (column-oriented, from main tree)\n28\t//\t 2. Signal WALStaging to truncate current.wal per host\n29\t//\n30\t//\tOn restart (FromCheckpoint):\n31\t//\t 1. Load most recent <timestamp>.bin snapshot\n32\t//\t 2. Replay current.wal (overwrite-safe: buffer.write handles duplicate timestamps)\n33\t//\n34\t// # WAL Record Format\n35\t//\n36\t//\t[4B magic 0xCC1DA7A1][4B payload_len][payload][4B CRC32]\n37\t//\n38\t//\tpayload:\n39\t//\t [8B timestamp int64]\n40\t//\t [2B metric_name_len uint16][N metric name bytes]\n41\t//\t [1B selector_count uint8]\n42\t//\t per selector: [1B selector_len uint8][M selector bytes]\n43\t//\t [4B value float32 bits]\n44\t//\n45\t// # Binary Snapshot Format\n46\t//\n47\t//\t[4B magic 0xCC5B0001][8B from int64][8B to int64]\n48\t//\tLevel tree (recursive):\n49\t//\t [4B num_metrics uint32]\n50\t//\t per metric:\n51\t//\t [2B name_len uint16][N name bytes]\n52\t//\t [8B frequency int64][8B start int64]\n53\t//\t [4B num_values uint32][num_values × 4B float32]\n54\t//\t [4B num_children uint32]\n55\t//\t per child: [2B name_len uint16][N name bytes] + Level (recursive)"}]},"uuid":"dffdcaa0-66b7-4e76-b19b-0833d6e1816b","timestamp":"2026-03-28T05:24:08.948Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/walCheckpoint.go","content":"// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.\n// All rights reserved. This file is part of cc-backend.\n// Use of this source code is governed by a MIT-style\n// license that can be found in the LICENSE file.\n\n// Package metricstore provides walCheckpoint.go: WAL-based checkpoint implementation.\n//\n// This replaces the Avro shadow tree with an append-only Write-Ahead Log (WAL)\n// per host, eliminating the extra memory overhead of the AvroStore and providing\n// truly continuous (per-write) crash safety.\n//\n// # Architecture\n//\n//\tMetric write (DecodeLine)\n//\t │\n//\t ├─► WriteToLevel() → main MemoryStore (unchanged)\n//\t │\n//\t └─► WALMessages channel\n//\t │\n//\t ▼\n//\t WALStaging goroutine\n//\t │\n//\t ▼\n//\t checkpoints/cluster/host/current.wal (append-only, binary)\n//\n//\tPeriodic checkpoint (Checkpointing goroutine):\n//\t 1. Write <timestamp>.bin snapshot (column-oriented, from main tree)\n//\t 2. Signal WALStaging to truncate current.wal per host\n//\n//\tOn restart (FromCheckpoint):\n//\t 1. Load most recent <timestamp>.bin snapshot\n//\t 2. Replay current.wal (overwrite-safe: buffer.write handles duplicate timestamps)\n//\n// # WAL Record Format\n//\n//\t[4B magic 0xCC1DA7A1][4B payload_len][payload][4B CRC32]\n//\n//\tpayload:\n//\t [8B timestamp int64]\n//\t [2B metric_name_len uint16][N metric name bytes]\n//\t [1B selector_count uint8]\n//\t per selector: [1B selector_len uint8][M selector bytes]\n//\t [4B value float32 bits]\n//\n// # Binary Snapshot Format\n//\n//\t[4B magic 0xCC5B0001][8B from int64][8B to int64]\n//\tLevel tree (recursive):\n//\t [4B num_metrics uint32]\n//\t per metric:\n//\t [2B name_len uint16][N name bytes]\n//\t [8B frequency int64][8B start int64]\n//\t [4B num_values uint32][num_values × 4B float32]\n//\t [4B num_children uint32]\n//\t per child: [2B name_len uint16][N name bytes] + Level (recursive)","numLines":55,"startLine":1,"totalLines":979}},"sourceToolAssistantUUID":"35d52783-099b-4005-9708-b5732ee3a614","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"dffdcaa0-66b7-4e76-b19b-0833d6e1816b","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01Bd1wFnZBpg8pCsWmYJzhpY","type":"message","role":"assistant","content":[{"type":"text","text":"The header is about the internal architecture — no need to add config docs there. Let me also check the checkpoint.go header:"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":900,"cache_read_input_tokens":51765,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":900},"output_tokens":1,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUvLa3hdsDdH3rn9RGaA","type":"assistant","uuid":"4d49e921-28e6-40f1-a945-d35f02911fac","timestamp":"2026-03-28T05:24:13.309Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"4d49e921-28e6-40f1-a945-d35f02911fac","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_01Bd1wFnZBpg8pCsWmYJzhpY","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01WxnDVLpSPvE8kXmnZJco7X","name":"Read","input":{"file_path":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/checkpoint.go","limit":35},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":900,"cache_read_input_tokens":51765,"output_tokens":123,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":900,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUvLa3hdsDdH3rn9RGaA","type":"assistant","uuid":"7873a08d-bcf0-4a50-91aa-64e6b8d8faf8","timestamp":"2026-03-28T05:24:13.478Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"7873a08d-bcf0-4a50-91aa-64e6b8d8faf8","isSidechain":false,"promptId":"d76a4a46-7268-4bc4-bb76-fc66c7547f28","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01WxnDVLpSPvE8kXmnZJco7X","type":"tool_result","content":"1\t// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.\n2\t// All rights reserved. This file is part of cc-backend.\n3\t// Use of this source code is governed by a MIT-style\n4\t// license that can be found in the LICENSE file.\n5\t\n6\t// This file implements checkpoint persistence for the in-memory metric store.\n7\t//\n8\t// Checkpoints enable graceful restarts by periodically saving in-memory metric\n9\t// data to disk in JSON or binary format. The checkpoint system:\n10\t//\n11\t// Key Features:\n12\t// - Periodic background checkpointing via the Checkpointing() worker\n13\t// - Two format families: JSON (human-readable) and WAL+binary (compact, crash-safe)\n14\t// - Parallel checkpoint creation and loading using worker pools\n15\t// - Hierarchical file organization: checkpoint_dir/cluster/host/timestamp.{json|bin}\n16\t// - WAL file: checkpoint_dir/cluster/host/current.wal (append-only, per-entry)\n17\t// - Only saves unarchived data (archived data is already persisted elsewhere)\n18\t// - GC optimization during loading to prevent excessive heap growth\n19\t//\n20\t// Checkpoint Workflow:\n21\t// 1. Init() loads checkpoints within retention window at startup\n22\t// 2. Checkpointing() worker periodically saves new data\n23\t// 3. Shutdown() writes final checkpoint before exit\n24\t//\n25\t// File Organization:\n26\t//\n27\t//\tcheckpoints/\n28\t//\t cluster1/\n29\t//\t host001/\n30\t//\t 1234567890.json (JSON format: full subtree snapshot)\n31\t//\t 1234567890.bin (binary format: full subtree snapshot)\n32\t//\t current.wal (WAL format: append-only per-entry log)\n33\t//\t host002/\n34\t//\t ...\n35\tpackage metricstore"}]},"uuid":"37191f41-0f15-4009-87f7-4a7b451b7dd8","timestamp":"2026-03-28T05:24:13.492Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/pkg/metricstore/checkpoint.go","content":"// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.\n// All rights reserved. This file is part of cc-backend.\n// Use of this source code is governed by a MIT-style\n// license that can be found in the LICENSE file.\n\n// This file implements checkpoint persistence for the in-memory metric store.\n//\n// Checkpoints enable graceful restarts by periodically saving in-memory metric\n// data to disk in JSON or binary format. The checkpoint system:\n//\n// Key Features:\n// - Periodic background checkpointing via the Checkpointing() worker\n// - Two format families: JSON (human-readable) and WAL+binary (compact, crash-safe)\n// - Parallel checkpoint creation and loading using worker pools\n// - Hierarchical file organization: checkpoint_dir/cluster/host/timestamp.{json|bin}\n// - WAL file: checkpoint_dir/cluster/host/current.wal (append-only, per-entry)\n// - Only saves unarchived data (archived data is already persisted elsewhere)\n// - GC optimization during loading to prevent excessive heap growth\n//\n// Checkpoint Workflow:\n// 1. Init() loads checkpoints within retention window at startup\n// 2. Checkpointing() worker periodically saves new data\n// 3. Shutdown() writes final checkpoint before exit\n//\n// File Organization:\n//\n//\tcheckpoints/\n//\t cluster1/\n//\t host001/\n//\t 1234567890.json (JSON format: full subtree snapshot)\n//\t 1234567890.bin (binary format: full subtree snapshot)\n//\t current.wal (WAL format: append-only per-entry log)\n//\t host002/\n//\t ...\npackage metricstore","numLines":35,"startLine":1,"totalLines":671}},"sourceToolAssistantUUID":"7873a08d-bcf0-4a50-91aa-64e6b8d8faf8","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"37191f41-0f15-4009-87f7-4a7b451b7dd8","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_016drHZuJ1W2pAA4815Ck76V","type":"message","role":"assistant","content":[{"type":"text","text":"Now let me verify the build still passes after the schema change:"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":740,"cache_read_input_tokens":52665,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":740},"output_tokens":4,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZUvLuUkQGWJKgz28SKw1","type":"assistant","uuid":"ab6682e0-0b6e-418e-b3a1-0ced76c16262","timestamp":"2026-03-28T05:24:17.048Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"ab6682e0-0b6e-418e-b3a1-0ced76c16262","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_016drHZuJ1W2pAA4815Ck76V","type":"message","role":"assistant","content":[{"type":"tool_use","id":"toolu_01GhH244UwZnjZB5mhSTchaU","name":"Bash","input":{"command":"go build ./...","description":"Build after schema update"},"caller":{"type":"direct"}}],"stop_reason":"tool_use","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":740,"cache_read_input_tokens":52665,"output_tokens":107,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":740,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUvLuUkQGWJKgz28SKw1","type":"assistant","uuid":"8842fc38-6f4f-4466-ad83-6cbcfa1652eb","timestamp":"2026-03-28T05:24:17.506Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"8842fc38-6f4f-4466-ad83-6cbcfa1652eb","isSidechain":false,"promptId":"d76a4a46-7268-4bc4-bb76-fc66c7547f28","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01GhH244UwZnjZB5mhSTchaU","type":"tool_result","content":"(Bash completed with no output)","is_error":false}]},"uuid":"fbd8c003-b69e-42e1-b001-6c1913d01e15","timestamp":"2026-03-28T05:24:22.143Z","toolUseResult":{"stdout":"","stderr":"","interrupted":false,"isImage":false,"noOutputExpected":false},"sourceToolAssistantUUID":"8842fc38-6f4f-4466-ad83-6cbcfa1652eb","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"fbd8c003-b69e-42e1-b001-6c1913d01e15","isSidechain":false,"message":{"model":"claude-opus-4-6","id":"msg_011Axu7k4sxGqhjQ1RYVBtKH","type":"message","role":"assistant","content":[{"type":"text","text":"Updated:\n\n1. **`pkg/metricstore/configSchema.go`** — Added `max-wal-size` field to the `checkpoints` JSON schema with description, type `integer`, and `minimum: 0`.\n\nThe Go struct docs in `config.go` were already updated in the previous round. The example `configs/config.json` intentionally omits it since the default (0 = unlimited) is backward compatible — users only need to add it if they want to enable the limit."}],"stop_reason":"end_turn","stop_sequence":null,"usage":{"input_tokens":1,"cache_creation_input_tokens":106,"cache_read_input_tokens":53405,"output_tokens":115,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":106,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZUvMYR181fM2S4Td1xKy","type":"assistant","uuid":"b4e4cee6-51e7-4dd3-83b8-88885f28b7fd","timestamp":"2026-03-28T05:24:27.447Z","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"48e61be1-4e8f-43ae-8012-bce29c0f8228","isSidechain":false,"type":"system","subtype":"turn_duration","durationMs":84938,"messageCount":132,"timestamp":"2026-03-28T05:24:31.039Z","uuid":"fdd945a0-15fa-4589-ab13-61339448decc","isMeta":false,"userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
{"parentUuid":"fdd945a0-15fa-4589-ab13-61339448decc","isSidechain":false,"promptId":"6ffa0aca-dff0-4cd3-b556-96823f541c0c","type":"user","message":{"role":"user","content":"Also update the ReleaseNotes with the recent changes"},"uuid":"84c1fcb4-9e27-4db5-9ce3-b4a190055f32","timestamp":"2026-03-28T05:24:59.798Z","permissionMode":"acceptEdits","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"6b58db50-c38b-491e-89c6-1785c9f9fd5c","isSidechain":false,"promptId":"6ffa0aca-dff0-4cd3-b556-96823f541c0c","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01WF5UD8ZEeYQskYrvQ91Tzz","type":"tool_result","content":"1\t# `cc-backend` version 1.5.3\n2\t\n3\tSupports job archive version 3 and database version 11.\n4\t\n5\tThis is a bugfix release of `cc-backend`, the API backend and frontend\n6\timplementation of ClusterCockpit.\n7\tFor release specific notes visit the [ClusterCockpit Documentation](https://clusterockpit.org/docs/release/).\n8\tIf you are upgrading from v1.5.1 no database migration is required.\n9\tIf you are upgrading from v1.5.0 you need to do another DB migration. This\n10\tshould not take long. For optimal database performance after the migration it is\n11\trecommended to apply the new `optimize-db` flag, which runs the sqlite `ANALYZE`\n12\tand `VACUUM` commands. Depending on your database size (more then 40GB) the\n13\t`VACUUM` may take up to 2h. You can also run the `ANALYZE` command manually.\n14\tWhile we are confident that the memory issue with the metricstore cleanup move\n15\tpolicy is fixed, it is still recommended to use delete policy for cleanup.\n16\tThis is also the default.\n17\t\n18\t## Changes in 1.5.3\n19\t\n20\t### Bug fixes\n21\t\n22\t- **Doubleranged filter fixes**: Range filters now correctly handle zero as a\n23\t boundary value. Improved validation and UI text for \"more than equal\" and\n24\t \"less than equal\" range selections.\n25\t- **Lineprotocol body parsing interrupted**: Switched from `ReadTimeout` to\n26\t `ReadHeaderTimeout` so that long-running metric submissions are no longer\n27\t cut off mid-stream.\n28\t- **Checkpoint archiving continues on error**: A single cluster's archiving\n29\t failure no longer aborts the entire cleanup operation. Errors are collected\n30\t and reported per cluster.\n31\t- **Parquet row group overflow**: Added periodic flush during checkpoint\n32\t archiving to prevent exceeding the parquet-go 32k column-write limit.\n33\t- **Removed metrics excluded from subcluster config**: Metrics removed from a\n34\t subcluster are no longer returned by `GetMetricConfigSubCluster`.\n35\t\n36\t### MetricStore performance\n37\t\n38\t- **WAL writer throughput**: Decoupled WAL file flushing from message processing\n39\t using a periodic 5-second batch flush (up to 4096 messages per cycle),\n40\t significantly increasing metric ingestion throughput.\n41\t- **Improved shutdown time**: HTTP shutdown timeout reduced; metricstore and\n42\t archiver now shut down concurrently. Overall shutdown deadline raised to\n43\t 60 seconds.\n44\t\n45\t### New features\n46\t\n47\t- **Manual checkpoint cleanup flag**: New `-cleanup-checkpoints` CLI flag\n48\t triggers checkpoint cleanup without starting the server, useful for\n49\t maintenance windows or automated cleanup scripts.\n50\t- **Explicit node state queries in node view**: Node health and scheduler state\n51\t are now fetched independently from metric data for fresher status information.\n52\t\n53\t### Logging improvements\n54\t\n55\t- **Reduced tagger log noise**: Missing metrics and expression evaluation errors\n56\t in the job classification tagger are now logged at debug level instead of\n57\t error level.\n58\t\n59\t## Changes in 1.5.2\n60\t"}]},"uuid":"f50b84bc-2e9a-4b9b-81da-3d2d9aa8f414","timestamp":"2026-03-28T05:25:03.913Z","toolUseResult":{"type":"text","file":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/ReleaseNotes.md","content":"# `cc-backend` version 1.5.3\n\nSupports job archive version 3 and database version 11.\n\nThis is a bugfix release of `cc-backend`, the API backend and frontend\nimplementation of ClusterCockpit.\nFor release specific notes visit the [ClusterCockpit Documentation](https://clusterockpit.org/docs/release/).\nIf you are upgrading from v1.5.1 no database migration is required.\nIf you are upgrading from v1.5.0 you need to do another DB migration. This\nshould not take long. For optimal database performance after the migration it is\nrecommended to apply the new `optimize-db` flag, which runs the sqlite `ANALYZE`\nand `VACUUM` commands. Depending on your database size (more then 40GB) the\n`VACUUM` may take up to 2h. You can also run the `ANALYZE` command manually.\nWhile we are confident that the memory issue with the metricstore cleanup move\npolicy is fixed, it is still recommended to use delete policy for cleanup.\nThis is also the default.\n\n## Changes in 1.5.3\n\n### Bug fixes\n\n- **Doubleranged filter fixes**: Range filters now correctly handle zero as a\n boundary value. Improved validation and UI text for \"more than equal\" and\n \"less than equal\" range selections.\n- **Lineprotocol body parsing interrupted**: Switched from `ReadTimeout` to\n `ReadHeaderTimeout` so that long-running metric submissions are no longer\n cut off mid-stream.\n- **Checkpoint archiving continues on error**: A single cluster's archiving\n failure no longer aborts the entire cleanup operation. Errors are collected\n and reported per cluster.\n- **Parquet row group overflow**: Added periodic flush during checkpoint\n archiving to prevent exceeding the parquet-go 32k column-write limit.\n- **Removed metrics excluded from subcluster config**: Metrics removed from a\n subcluster are no longer returned by `GetMetricConfigSubCluster`.\n\n### MetricStore performance\n\n- **WAL writer throughput**: Decoupled WAL file flushing from message processing\n using a periodic 5-second batch flush (up to 4096 messages per cycle),\n significantly increasing metric ingestion throughput.\n- **Improved shutdown time**: HTTP shutdown timeout reduced; metricstore and\n archiver now shut down concurrently. Overall shutdown deadline raised to\n 60 seconds.\n\n### New features\n\n- **Manual checkpoint cleanup flag**: New `-cleanup-checkpoints` CLI flag\n triggers checkpoint cleanup without starting the server, useful for\n maintenance windows or automated cleanup scripts.\n- **Explicit node state queries in node view**: Node health and scheduler state\n are now fetched independently from metric data for fresher status information.\n\n### Logging improvements\n\n- **Reduced tagger log noise**: Missing metrics and expression evaluation errors\n in the job classification tagger are now logged at debug level instead of\n error level.\n\n## Changes in 1.5.2\n","numLines":60,"startLine":1,"totalLines":455}},"sourceToolAssistantUUID":"6b58db50-c38b-491e-89c6-1785c9f9fd5c","userType":"external","entrypoint":"cli","cwd":"/Users/jan/prg/ClusterCockpit/cc-backend","sessionId":"039c7932-07b5-4d72-987c-d7fa070361c1","version":"2.1.86","gitBranch":"hotfix","slug":"atomic-giggling-gizmo"}
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{"parentUuid":"c5c21539-1438-409b-a8ba-2e0133bc0eb4","isSidechain":false,"promptId":"6ffa0aca-dff0-4cd3-b556-96823f541c0c","type":"user","message":{"role":"user","content":[{"tool_use_id":"toolu_01Windy46BF4qf8MyEwjTfSK","type":"tool_result","content":"The file /Users/jan/prg/ClusterCockpit/cc-backend/ReleaseNotes.md has been updated successfully."}]},"uuid":"dcfb917a-6cd6-4d9d-ad39-5bfbbb5802e5","timestamp":"2026-03-28T05:25:12.012Z","toolUseResult":{"filePath":"/Users/jan/prg/ClusterCockpit/cc-backend/ReleaseNotes.md","oldString":"## Changes in 1.5.3\n\n### Bug fixes","newString":"## Changes in 1.5.3\n\n### Bug fixes\n\n- **WAL not rotated on partial checkpoint failure**: When binary checkpointing\n failed for some hosts, WAL files for successfully checkpointed hosts were not\n rotated and the checkpoint timestamp was not advanced. Partial successes now\n correctly advance the checkpoint and rotate WAL files for completed hosts.\n- **Unbounded WAL file growth**: If binary checkpointing consistently failed for\n a host, its `current.wal` file grew without limit until disk exhaustion. A new\n `max-wal-size` configuration option (in the `checkpoints` block) allows setting\n a per-host WAL size cap in bytes. When exceeded, the WAL is force-rotated.\n Defaults to 0 (unlimited) for backward compatibility.","originalFile":"# `cc-backend` version 1.5.3\n\nSupports job archive version 3 and database version 11.\n\nThis is a bugfix release of `cc-backend`, the API backend and frontend\nimplementation of ClusterCockpit.\nFor release specific notes visit the [ClusterCockpit Documentation](https://clusterockpit.org/docs/release/).\nIf you are upgrading from v1.5.1 no database migration is required.\nIf you are upgrading from v1.5.0 you need to do another DB migration. This\nshould not take long. For optimal database performance after the migration it is\nrecommended to apply the new `optimize-db` flag, which runs the sqlite `ANALYZE`\nand `VACUUM` commands. Depending on your database size (more then 40GB) the\n`VACUUM` may take up to 2h. You can also run the `ANALYZE` command manually.\nWhile we are confident that the memory issue with the metricstore cleanup move\npolicy is fixed, it is still recommended to use delete policy for cleanup.\nThis is also the default.\n\n## Changes in 1.5.3\n\n### Bug fixes\n\n- **Doubleranged filter fixes**: Range filters now correctly handle zero as a\n boundary value. Improved validation and UI text for \"more than equal\" and\n \"less than equal\" range selections.\n- **Lineprotocol body parsing interrupted**: Switched from `ReadTimeout` to\n `ReadHeaderTimeout` so that long-running metric submissions are no longer\n cut off mid-stream.\n- **Checkpoint archiving continues on error**: A single cluster's archiving\n failure no longer aborts the entire cleanup operation. Errors are collected\n and reported per cluster.\n- **Parquet row group overflow**: Added periodic flush during checkpoint\n archiving to prevent exceeding the parquet-go 32k column-write limit.\n- **Removed metrics excluded from subcluster config**: Metrics removed from a\n subcluster are no longer returned by `GetMetricConfigSubCluster`.\n\n### MetricStore performance\n\n- **WAL writer throughput**: Decoupled WAL file flushing from message processing\n using a periodic 5-second batch flush (up to 4096 messages per cycle),\n significantly increasing metric ingestion throughput.\n- **Improved shutdown time**: HTTP shutdown timeout reduced; metricstore and\n archiver now shut down concurrently. Overall shutdown deadline raised to\n 60 seconds.\n\n### New features\n\n- **Manual checkpoint cleanup flag**: New `-cleanup-checkpoints` CLI flag\n triggers checkpoint cleanup without starting the server, useful for\n maintenance windows or automated cleanup scripts.\n- **Explicit node state queries in node view**: Node health and scheduler state\n are now fetched independently from metric data for fresher status information.\n\n### Logging improvements\n\n- **Reduced tagger log noise**: Missing metrics and expression evaluation errors\n in the job classification tagger are now logged at debug level instead of\n error level.\n\n## Changes in 1.5.2\n\n### Bug fixes\n\n- **Memory spike in parquet writer**: Fixed memory spikes when using the\n metricstore move (archive) policy with the parquet writer. The writer now\n processes data in a streaming fashion to avoid accumulating large allocations.\n- **Top list query fixes**: Fixed top list queries in analysis and dashboard\n views.\n- **Exclude down nodes from HealthCheck**: Down nodes are now excluded from\n health checks in both the REST and NATS handlers.\n- **Node state priority order**: Node state determination now enforces a\n priority order. Exception: idle+down results in idle.\n- **Blocking ReceiveNats call**: Fixed a blocking NATS receive call in the\n metricstore.\n\n### Database performance\n\n- **Reduced insert pressure**: Bulk insert operations (node state updates, user\n and job cache syncs) now use explicit transactions and deferred inserts,\n significantly reducing write contention on the SQLite database.\n- **SyncJobs wrapped in transaction**: `SyncJobs` now runs inside a transaction\n for better consistency and reduced lock contention.\n- **Configurable busy timeout**: New `busy-timeout` configuration option for the\n SQLite connection. This allows tuning how long the driver waits for a locked\n database before returning an error, which improves resilience under concurrent\n write load.\n- **Increased default SQLite timeout**: The default SQLite connection timeout\n has been raised to reduce spurious timeout errors under load.\n- **Optimized stats queries**: Improved sortby handling in stats queries, fixed\n cache key passing, and simplified a stats query condition that caused an\n expensive unnecessary subquery.\n\n### MetricStore performance\n\n- **Sharded WAL consumer**: The WAL consumer is now sharded for significantly\n higher write throughput.\n- **NATS contention fix**: Fixed contention in the metricstore NATS ingestion\n path.\n\n### NATS API\n\n- **Nodestate health checks in NATS API**: The NATS node state handler now\n performs the same metric health checks as the REST API handler, including\n per-subcluster health checks and `MonitoringStateFailed` fallback for nodes\n without health data.\n\n### Logging improvements\n\n- **Better error context**: Several repository functions now include the calling\n function name in error messages for easier diagnosis.\n- **Reduced log noise**: `ErrNoRows` (no results found) is no longer logged as\n an error in `scanRow`; common \"no rows\" paths are now silent.\n- **Debug-level missing metrics**: Warning about missing metrics in the metric\n store has been downgraded to debug level to reduce log noise in normal\n operation.\n- **Checkpoint archiving log**: Added an informational log message when the\n metricstore checkpoint archiving process runs.\n- **Auth failure context**: Auth failure log messages now include more context\n information.\n\n### Behavior changes\n\n- **DB-based metricHealth**: Replaced heuristic-based metric health with\n DB-based metric health for the node view, providing more accurate health\n status information.\n- **Removed minRunningFor filter remnants**: Cleaned up remaining `minRunningFor`\n references from the GraphQL schema and query builder.\n\n### Frontend\n\n- **Streamlined statsSeries**: Unified stats series calculation and rendering\n across plot components.\n- **Clarified plot titles**: Improved titles in dashboard and health views.\n- **Bumped frontend dependencies**: Updated frontend dependencies to latest\n versions.\n\n### Dependencies\n\n- **cc-lib upgraded**: Updated to latest cc-lib version.\n\n## Known issues\n\n- The new dynamic memory management is not bullet proof yet across restarts.\n Buffers that are kept outside the retention period may be lost across a\n restart. We will fix that in a subsequent patch release.\n- To use the new log viewer (which is only working when starting cc-backend with\n systemd) in the admin interface the user under which the cc-backend process is\n running has to be allowed to execute the journalctl command.\n- The user configuration keys for the ui have changed. Therefore old user\n configuration persisted in the database is not used anymore. It is recommended\n to configure the metrics shown in the ui-config section and remove all records\n in the table after the update.\n- Currently energy footprint metrics of type energy are ignored for calculating\n total energy.\n- With energy footprint metrics of type power the unit is ignored and it is\n assumed the metric has the unit Watt.\n\n## Changes in 1.5.1\n\n### Database\n\n- **New migration (version 11)**: Optimized database index count and added covering indexes for stats queries for significantly improved query performance\n- **Migration 9 fix**: Removed redundant indices from migration 9 that are superseded by migration 11\n- **Optional DB optimization flag**: Added `-optimize-db` CLI flag to run `ANALYZE` on demand; removed automatic ANALYZE on startup\n- **Selective stats queries**: Stats queries are now selective, reducing unnecessary computation\n- **User list paging**: Added paging support to the user list for better scalability\n- **SQLite configuration hardening**: Sanitized SQLite configuration with new configurable options; fixes large heap allocations in the SQLite driver\n- **Query cancellation**: Long-running database queries can now be cancelled\n- **Resource leak fix**: Added missing `defer Close()` calls for all query result sets\n\n### Bug fixes\n\n- **Segfault when taggers misconfigured**: Fixed crash when `enable-job-taggers` is set but tagger rule directories are missing\n- **GroupBy stats query complexity**: Reduced complexity for `groupBy` statistics queries\n- **Ranged filter conditions**: Fixed GT and LT conditions in ranged filters\n- **Energy filter preset**: Reduced energy filter preset to a more practical default\n- **JSON validity check**: Fixed wrong field being checked for JSON validity\n- **Tagger float rounding**: Fixed rounding of floats in tagger messages\n- **Node view null safety**: Added null-safe checks in node view to prevent runtime errors\n- **Public dashboard null safety**: Added null-safe checks in the public dashboard to prevent runtime errors\n\n### Frontend\n\n- **Bumped patch versions**: Updated frontend dependencies to latest patch versions\n\n### Documentation\n\n- **New DB config options**: Added new database configuration options to README\n\n---\n\n_The sections below document all features and changes introduced in the 1.5.0 major release, which 1.5.1 is based on._\n\n## Breaking changes\n\n### Configuration changes\n\n- **JSON attribute naming**: All JSON configuration attributes now use `kebab-case`\n style consistently (e.g., `api-allowed-ips` instead of `apiAllowedIPs`).\n Update your `config.json` accordingly.\n- **Removed `disable-archive` option**: This obsolete configuration option has been removed.\n- **Removed `clusters` config section**: The separate clusters configuration section\n has been removed. Cluster information is now derived from the job archive.\n- **`apiAllowedIPs` is now optional**: If not specified, defaults to not\n restricted.\n\n### Architecture changes\n\n- **Web framework replaced**: Migrated from `gorilla/mux` to `chi` as the HTTP\n router. This should be transparent to users but affects how middleware and\n routes are composed. A proper 404 handler is now in place.\n- **MetricStore moved**: The `metricstore` package has been moved from `internal/`\n to `pkg/` as it is now part of the public API.\n- **MySQL/MariaDB support removed**: Only SQLite is now supported as the database backend.\n- **Archive to Cleanup renaming**: Archive-related functions have been refactored\n and renamed to \"Cleanup\" for clarity.\n- **`minRunningFor` filter removed**: This undocumented filter has been removed\n from the API and frontend.\n\n### Dependency changes\n\n- **cc-lib v2.8.0**: Switched to cc-lib version 2 with updated APIs\n- **cclib NATS client**: Now using the cclib NATS client implementation\n- Removed obsolete `util.Float` usage from cclib\n\n## Major new features\n\n### NATS API Integration\n\n- **Real-time job events**: Subscribe to job start/stop events via NATS\n- **Node state updates**: Receive real-time node state changes via NATS\n- **Configurable subjects**: NATS API subjects are now configurable via `api-subjects`\n- **Deadlock fixes**: Improved NATS client stability and graceful shutdown\n\n### Public Dashboard\n\n- **Public-facing interface**: New public dashboard route for external users\n- **DoubleMetricPlot component**: New visualization component for comparing metrics\n- **Improved layout**: Reviewed and optimized dashboard layouts for better readability\n\n### Enhanced Node Management\n\n- **Node state tracking**: New node table in database with timestamp tracking\n- **Node state filtering**: Filter jobs by node state in systems view\n- **Node list enhancements**: Improved paging, filtering, and continuous scroll support\n- **Nodestate retention and archiving**: Node state data is now subject to configurable\n retention policies and can be archived to Parquet format for long-term storage\n- **Faulty node metric tracking**: Faulty node state metric lists are persisted to the database\n\n### Health Monitoring\n\n- **Health status dashboard**: New dedicated \"Health\" tab in the status details view\n showing per-node metric health across the cluster\n- **CCMS health check**: Support for querying health status of external\n cc-metric-store (CCMS) instances via the API\n- **GraphQL health endpoints**: New GraphQL queries and resolvers for health data\n- **Cluster/subcluster filter**: Filter health status view by cluster or subcluster\n\n### Log Viewer\n\n- **Web-based log viewer**: New log viewer page in the admin interface for inspecting\n backend log output directly from the browser without shell access\n- **Accessible from header**: Quick access link from the navigation header\n\n### MetricStore Improvements\n\n- **Memory tracking worker**: New worker for CCMS memory usage tracking\n- **Dynamic retention**: Support for job specific dynamic retention times\n- **Improved compression**: Transparent compression for job archive imports\n- **Parallel processing**: Parallelized Iter function in all archive backends\n\n### Job Tagging System\n\n- **Job tagger option**: Enable automatic job tagging via configuration flag\n- **Application detection**: Automatic detection of applications (MATLAB, GROMACS, etc.)\n- **Job classification**: Automatic detection of pathological jobs\n- **omit-tagged**: Option to exclude tagged jobs from retention/cleanup operations (`none`, `all`, or `user`)\n- **Admin UI trigger**: Taggers can be run on-demand from the admin web interface\n without restarting the backend\n\n### Archive Backends\n\n- **Parquet archive format**: New Parquet file format for job archiving, providing\n columnar storage with efficient compression for analytical workloads\n- **S3 backend**: Full support for S3-compatible object storage\n- **SQLite backend**: Full support for SQLite backend using blobs\n- **Performance improvements**: Fixed performance bugs in archive backends\n- **Better error handling**: Improved error messages and fallback handling\n- **Zstd compression**: Parquet writers use zstd compression for better\n compression ratios compared to the previous snappy default\n- **Optimized sort order**: Job and nodestate Parquet files are sorted by\n cluster, subcluster, and start time for efficient range queries\n\n### Unified Archive Retention and Format Conversion\n\n- **Uniform retention policy**: Job archive retention now supports both JSON and\n Parquet as target formats under a single, consistent policy configuration\n- **Archive manager tool**: The `tools/archive-manager` utility now supports\n format conversion between JSON and Parquet job archives\n- **Parquet reader**: Full Parquet archive reader implementation for reading back\n archived job data\n\n## New features and improvements\n\n### Frontend\n\n- **Loading indicators**: Added loading indicators to status detail and job lists\n- **Job info layout**: Reviewed and improved job info row layout\n- **Metric selection**: Enhanced metric selection with drag-and-drop fixes\n- **Filter presets**: Move list filter preset to URL for easy sharing\n- **Job comparison**: Improved job comparison views and plots\n- **Subcluster reactivity**: Job list now reacts to subcluster filter changes\n- **Short jobs quick selection**: New \"Short jobs\" quick-filter button in job lists\n replaces the removed undocumented `minRunningFor` filter\n- **Row plot cursor sync**: Cursor position is now synchronized across all metric\n plots in a job list row for easier cross-metric comparison\n- **Disabled metrics handling**: Improved handling and display of disabled metrics\n across job view, node view, and list rows\n- **\"Not configured\" info cards**: Informational cards shown when optional features\n are not yet configured\n- **Frontend dependencies**: Bumped frontend dependencies to latest versions\n- **Svelte 5 compatibility**: Fixed Svelte state warnings and compatibility issues\n\n### Backend\n\n- **Progress bars**: Import function now shows progress during long operations\n- **Better logging**: Improved logging with appropriate log levels throughout\n- **Graceful shutdown**: Fixed shutdown timeout bugs and hanging issues\n- **Configuration defaults**: Sensible defaults for most configuration options\n- **Documentation**: Extensive documentation improvements across packages\n- **Server flag in systemd unit**: Example systemd unit now includes the `-server` flag\n\n### Security\n\n- **LDAP security hardening**: Improved input validation, connection handling, and\n error reporting in the LDAP authenticator\n- **OIDC security hardening**: Stricter token validation and improved error handling\n in the OIDC authenticator\n- **Auth schema extensions**: Additional schema fields for improved auth configuration\n\n### API improvements\n\n- **Role-based metric visibility**: Metrics can now have role-based access control\n- **Job exclusivity filter**: New filter for exclusive vs. shared jobs\n- **Improved error messages**: Better error messages and documentation in REST API\n- **GraphQL enhancements**: Improved GraphQL queries and resolvers\n- **Stop job lookup order**: Reversed lookup order in stop job requests for\n more reliable job matching (cluster+jobId first, then jobId alone)\n\n### Performance\n\n- **Database indices**: Optimized SQLite indices for better query performance\n- **Job cache**: Introduced caching table for faster job inserts\n- **Parallel imports**: Archive imports now run in parallel where possible\n- **External tool integration**: Optimized use of external tools (fd) for better performance\n- **Node repository queries**: Reviewed and optimized node repository SQL queries\n- **Buffer pool**: Resized and pooled internal buffers for better memory reuse\n\n### Developer experience\n\n- **AI agent guidelines**: Added documentation for AI coding agents (AGENTS.md, CLAUDE.md)\n- **Example API payloads**: Added example JSON API payloads for testing\n- **Unit tests**: Added more unit tests for NATS API, node repository, and other components\n- **Test improvements**: Better test coverage; test DB is now copied before unit tests\n to avoid state pollution between test runs\n- **Parquet writer tests**: Comprehensive tests for Parquet archive writing and conversion\n\n## Bug fixes\n\n- Fixed nodelist paging issues\n- Fixed metric select drag and drop functionality\n- Fixed render race conditions in nodeList\n- Fixed tag count grouping including type\n- Fixed wrong metricstore schema (missing comma)\n- Fixed configuration issues causing shutdown hangs\n- Fixed deadlock when NATS is not configured\n- Fixed archive backend performance bugs\n- Fixed continuous scroll buildup on refresh\n- Improved footprint calculation logic\n- Fixed polar plot data query decoupling\n- Fixed missing resolution parameter handling\n- Fixed node table initialization fallback\n- Fixed reactivity key placement in nodeList\n- Fixed nodeList resolver data handling and increased nodestate filter cutoff\n- Fixed job always being transferred to main job table before archiving\n- Fixed AppTagger error handling and logging\n- Fixed log endpoint formatting and correctness\n- Fixed automatic refresh in metric status tab\n- Fixed NULL value handling in `health_state` and `health_metrics` columns\n- Fixed bugs related to `job_cache` IDs being used in the main job table\n- Fixed SyncJobs bug causing start job hooks to be called with wrong (cache) IDs\n- Fixed 404 handler route for sub-routers\n\n## Configuration changes\n\n### New configuration options\n\n```json\n{\n \"main\": {\n \"enable-job-taggers\": true,\n \"resampling\": {\n \"minimum-points\": 600,\n \"trigger\": 180,\n \"resolutions\": [240, 60]\n },\n \"api-subjects\": {\n \"subject-job-event\": \"cc.job.event\",\n \"subject-node-state\": \"cc.node.state\"\n }\n },\n \"nats\": {\n \"address\": \"nats://0.0.0.0:4222\",\n \"username\": \"root\",\n \"password\": \"root\"\n },\n \"cron\": {\n \"commit-job-worker\": \"1m\",\n \"duration-worker\": \"5m\",\n \"footprint-worker\": \"10m\"\n },\n \"metric-store\": {\n \"cleanup\": {\n \"mode\": \"archive\",\n \"interval\": \"48h\",\n \"directory\": \"./var/archive\"\n }\n },\n \"archive\": {\n \"retention\": {\n \"policy\": \"delete\",\n \"age\": \"6months\",\n \"target-format\": \"parquet\"\n }\n },\n \"nodestate\": {\n \"retention\": {\n \"policy\": \"archive\",\n \"age\": \"30d\",\n \"archive-path\": \"./var/nodestate-archive\"\n }\n }\n}\n```\n\n## Migration notes\n\n- Review and update your `config.json` to use kebab-case attribute names\n- If using NATS, configure the new `nats` and `api-subjects` sections\n- If using S3 archive backend, configure the new `archive` section options\n- Test the new public dashboard at `/public` route\n- Review cron worker configuration if you need different frequencies\n- If using the archive retention feature, configure the `target-format` option\n to choose between `json` (default) and `parquet` output formats\n- Consider enabling nodestate retention if you track node states over 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Partial successes now","+ correctly advance the checkpoint and rotate WAL files for completed hosts.","+- **Unbounded WAL file growth**: If binary checkpointing consistently failed for","+ a host, its `current.wal` file grew without limit until disk exhaustion. A new","+ `max-wal-size` configuration option (in the `checkpoints` block) allows setting","+ a per-host WAL size cap in bytes. When exceeded, the WAL is force-rotated.","+ Defaults to 0 (unlimited) for backward compatibility.","+"," - **Doubleranged filter fixes**: Range filters now correctly handle zero as a"," boundary value. 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