Refactor memorystore

Fix issues
Add unit test
Add documentation

internal/memorystore/archive.go

@@ -75,10 +75,10 @@ func ArchiveCheckpoints(checkpointsDir, archiveDir string, from int64, deleteIns
 
 	var wg sync.WaitGroup
 	n, errs := int32(0), int32(0)
-	work := make(chan workItem, NumWorkers)
+	work := make(chan workItem, Keys.NumWorkers)
 
-	wg.Add(NumWorkers)
+	wg.Add(Keys.NumWorkers)
-	for worker := 0; worker < NumWorkers; worker++ {
+	for worker := 0; worker < Keys.NumWorkers; worker++ {
 		go func() {
 			defer wg.Done()
 			for workItem := range work {
@@ -116,7 +116,7 @@ func ArchiveCheckpoints(checkpointsDir, archiveDir string, from int64, deleteIns
 	}
 
 	if errs > 0 {
-		return int(n), fmt.Errorf("%d errors happend while archiving (%d successes)", errs, n)
+		return int(n), fmt.Errorf("%d errors happened while archiving (%d successes)", errs, n)
 	}
 	return int(n), nil
 }
@@ -147,11 +147,11 @@ func archiveCheckpoints(dir string, archiveDir string, from int64, deleteInstead
 	}
 
 	filename := filepath.Join(archiveDir, fmt.Sprintf("%d.zip", from))
-	f, err := os.OpenFile(filename, os.O_CREATE|os.O_WRONLY, 0o644)
+	f, err := os.OpenFile(filename, os.O_CREATE|os.O_WRONLY, CheckpointFilePerms)
 	if err != nil && os.IsNotExist(err) {
-		err = os.MkdirAll(archiveDir, 0o755)
+		err = os.MkdirAll(archiveDir, CheckpointDirPerms)
 		if err == nil {
-			f, err = os.OpenFile(filename, os.O_CREATE|os.O_WRONLY, 0o644)
+			f, err = os.OpenFile(filename, os.O_CREATE|os.O_WRONLY, CheckpointFilePerms)
 		}
 	}
 	if err != nil {

internal/memorystore/buffer.go

@@ -105,46 +105,6 @@ func (b *buffer) firstWrite() int64 {
 
 func (b *buffer) close() {}
 
-/*
-func (b *buffer) close() {
-	if b.closed {
-		return
-	}
-
-	b.closed = true
-	n, sum, min, max := 0, 0., math.MaxFloat64, -math.MaxFloat64
-	for _, x := range b.data {
-		if x.IsNaN() {
-			continue
-		}
-
-		n += 1
-		f := float64(x)
-		sum += f
-		min = math.Min(min, f)
-		max = math.Max(max, f)
-	}
-
-	b.statisticts.samples = n
-	if n > 0 {
-		b.statisticts.avg = Float(sum / float64(n))
-		b.statisticts.min = Float(min)
-		b.statisticts.max = Float(max)
-	} else {
-		b.statisticts.avg = NaN
-		b.statisticts.min = NaN
-		b.statisticts.max = NaN
-	}
-}
-*/
-
-// func interpolate(idx int, data []Float) Float {
-// 	if idx == 0 || idx+1 == len(data) {
-// 		return NaN
-// 	}
-// 	return (data[idx-1] + data[idx+1]) / 2.0
-// }
-
 // Return all known values from `from` to `to`. Gaps of information are represented as NaN.
 // Simple linear interpolation is done between the two neighboring cells if possible.
 // If values at the start or end are missing, instead of NaN values, the second and thrid

internal/memorystore/checkpoint.go

@@ -28,6 +28,17 @@ import (
 	"github.com/linkedin/goavro/v2"
 )
 
+// File operation constants
+const (
+	// CheckpointFilePerms defines default permissions for checkpoint files
+	CheckpointFilePerms = 0o644
+	// CheckpointDirPerms defines default permissions for checkpoint directories
+	CheckpointDirPerms = 0o755
+	// GCTriggerInterval determines how often GC is forced during checkpoint loading
+	// GC is triggered every GCTriggerInterval*NumWorkers loaded hosts
+	GCTriggerInterval = 100
+)
+
 // Whenever changed, update MarshalJSON as well!
 type CheckpointMetrics struct {
 	Data      []schema.Float `json:"data"`
@@ -171,9 +182,9 @@ func (m *MemoryStore) ToCheckpoint(dir string, from, to int64) (int, error) {
 	n, errs := int32(0), int32(0)
 
 	var wg sync.WaitGroup
-	wg.Add(NumWorkers)
+	wg.Add(Keys.NumWorkers)
-	work := make(chan workItem, NumWorkers*2)
+	work := make(chan workItem, Keys.NumWorkers*2)
-	for worker := 0; worker < NumWorkers; worker++ {
+	for worker := 0; worker < Keys.NumWorkers; worker++ {
 		go func() {
 			defer wg.Done()
 
@@ -205,7 +216,7 @@ func (m *MemoryStore) ToCheckpoint(dir string, from, to int64) (int, error) {
 	wg.Wait()
 
 	if errs > 0 {
-		return int(n), fmt.Errorf("[METRICSTORE]> %d errors happend while creating checkpoints (%d successes)", errs, n)
+		return int(n), fmt.Errorf("[METRICSTORE]> %d errors happened while creating checkpoints (%d successes)", errs, n)
 	}
 	return int(n), nil
 }
@@ -285,11 +296,11 @@ func (l *Level) toCheckpoint(dir string, from, to int64, m *MemoryStore) error {
 	}
 
 	filepath := path.Join(dir, fmt.Sprintf("%d.json", from))
-	f, err := os.OpenFile(filepath, os.O_CREATE|os.O_WRONLY, 0o644)
+	f, err := os.OpenFile(filepath, os.O_CREATE|os.O_WRONLY, CheckpointFilePerms)
 	if err != nil && os.IsNotExist(err) {
-		err = os.MkdirAll(dir, 0o755)
+		err = os.MkdirAll(dir, CheckpointDirPerms)
 		if err == nil {
-			f, err = os.OpenFile(filepath, os.O_CREATE|os.O_WRONLY, 0o644)
+			f, err = os.OpenFile(filepath, os.O_CREATE|os.O_WRONLY, CheckpointFilePerms)
 		}
 	}
 	if err != nil {
@@ -307,11 +318,11 @@ func (l *Level) toCheckpoint(dir string, from, to int64, m *MemoryStore) error {
 
 func (m *MemoryStore) FromCheckpoint(dir string, from int64, extension string) (int, error) {
 	var wg sync.WaitGroup
-	work := make(chan [2]string, NumWorkers)
+	work := make(chan [2]string, Keys.NumWorkers)
 	n, errs := int32(0), int32(0)
 
-	wg.Add(NumWorkers)
+	wg.Add(Keys.NumWorkers)
-	for worker := 0; worker < NumWorkers; worker++ {
+	for worker := 0; worker < Keys.NumWorkers; worker++ {
 		go func() {
 			defer wg.Done()
 			for host := range work {
@@ -347,7 +358,7 @@ func (m *MemoryStore) FromCheckpoint(dir string, from int64, extension string) (
 			}
 
 			i++
-			if i%NumWorkers == 0 && i > 100 {
+			if i%Keys.NumWorkers == 0 && i > GCTriggerInterval {
 				// Forcing garbage collection runs here regulary during the loading of checkpoints
 				// will decrease the total heap size after loading everything back to memory is done.
 				// While loading data, the heap will grow fast, so the GC target size will double
@@ -368,7 +379,7 @@ done:
 	}
 
 	if errs > 0 {
-		return int(n), fmt.Errorf("[METRICSTORE]> %d errors happend while creating checkpoints (%d successes)", errs, n)
+		return int(n), fmt.Errorf("[METRICSTORE]> %d errors happened while creating checkpoints (%d successes)", errs, n)
 	}
 	return int(n), nil
 }
@@ -379,7 +390,7 @@ done:
 func (m *MemoryStore) FromCheckpointFiles(dir string, from int64) (int, error) {
 	if _, err := os.Stat(dir); os.IsNotExist(err) {
 		// The directory does not exist, so create it using os.MkdirAll()
-		err := os.MkdirAll(dir, 0o755) // 0755 sets the permissions for the directory
+		err := os.MkdirAll(dir, CheckpointDirPerms) // CheckpointDirPerms sets the permissions for the directory
 		if err != nil {
 			cclog.Fatalf("[METRICSTORE]> Error creating directory: %#v\n", err)
 		}
@@ -464,7 +475,7 @@ func (l *Level) loadAvroFile(m *MemoryStore, f *os.File, from int64) error {
 	// Create a new OCF reader from the buffered reader
 	ocfReader, err := goavro.NewOCFReader(br)
 	if err != nil {
-		panic(err)
+		return fmt.Errorf("[METRICSTORE]> error creating OCF reader: %w", err)
 	}
 
 	metricsData := make(map[string]schema.FloatArray)
@@ -477,7 +488,7 @@ func (l *Level) loadAvroFile(m *MemoryStore, f *os.File, from int64) error {
 
 		record, ok := datum.(map[string]any)
 		if !ok {
-			panic("[METRICSTORE]> failed to assert datum as map[string]interface{}")
+			return fmt.Errorf("[METRICSTORE]> failed to assert datum as map[string]interface{}")
 		}
 
 		for key, value := range record {
@@ -559,7 +570,7 @@ func (l *Level) createBuffer(m *MemoryStore, metricName string, floatArray schem
 		l.metrics[minfo.offset] = b
 	} else {
 		if prev.start > b.start {
-			return errors.New("wooops")
+			return fmt.Errorf("[METRICSTORE]> buffer start time %d is before previous buffer start %d", b.start, prev.start)
 		}
 
 		b.prev = prev
@@ -623,7 +634,7 @@ func (l *Level) loadFile(cf *CheckpointFile, m *MemoryStore) error {
 			l.metrics[minfo.offset] = b
 		} else {
 			if prev.start > b.start {
-				return errors.New("wooops")
+				return fmt.Errorf("[METRICSTORE]> buffer start time %d is before previous buffer start %d", b.start, prev.start)
 			}
 
 			b.prev = prev
@@ -700,13 +711,17 @@ func (l *Level) fromCheckpoint(m *MemoryStore, dir string, from int64, extension
 	loader := loaders[extension]
 
 	for _, filename := range files {
-		f, err := os.Open(path.Join(dir, filename))
+		// Use a closure to ensure file is closed immediately after use
-		if err != nil {
+		err := func() error {
-			return filesLoaded, err
+			f, err := os.Open(path.Join(dir, filename))
-		}
+			if err != nil {
-		defer f.Close()
+				return err
+			}
+			defer f.Close()
 
-		if err = loader(m, f, from); err != nil {
+			return loader(m, f, from)
+		}()
+		if err != nil {
 			return filesLoaded, err
 		}
 

internal/memorystore/config.go

@@ -12,6 +12,9 @@ import (
 var InternalCCMSFlag bool = false
 
 type MetricStoreConfig struct {
+	// Number of concurrent workers for checkpoint and archive operations.
+	// If not set or 0, defaults to min(runtime.NumCPU()/2+1, 10)
+	NumWorkers int `json:"num-workers"`
 	Checkpoints struct {
 		FileFormat string `json:"file-format"`
 		Interval   string `json:"interval"`
@@ -62,7 +65,7 @@ const (
 	AvgAggregation
 )
 
-func AssignAggregationStratergy(str string) (AggregationStrategy, error) {
+func AssignAggregationStrategy(str string) (AggregationStrategy, error) {
 	switch str {
 	case "":
 		return NoAggregation, nil

internal/memorystore/level.go

@@ -39,7 +39,7 @@ func (l *Level) findLevelOrCreate(selector []string, nMetrics int) *Level {
 		// Children map needs to be created...
 		l.lock.RUnlock()
 	} else {
-		child, ok := l.children[selector[0]]
+		child, ok = l.children[selector[0]]
 		l.lock.RUnlock()
 		if ok {
 			return child.findLevelOrCreate(selector[1:], nMetrics)

internal/memorystore/memorystore.go

@@ -3,6 +3,20 @@
 // Use of this source code is governed by a MIT-style
 // license that can be found in the LICENSE file.
 
+// Package memorystore provides an efficient in-memory time-series metric storage system
+// with support for hierarchical data organization, checkpointing, and archiving.
+//
+// The package organizes metrics in a tree structure (cluster → host → component) and
+// provides concurrent read/write access to metric data with configurable aggregation strategies.
+// Background goroutines handle periodic checkpointing (JSON or Avro format), archiving old data,
+// and enforcing retention policies.
+//
+// Key features:
+//   - In-memory metric storage with configurable retention
+//   - Hierarchical data organization (selectors)
+//   - Concurrent checkpoint/archive workers
+//   - Support for sum and average aggregation
+//   - NATS integration for metric ingestion
 package memorystore
 
 import (
@@ -10,18 +24,14 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
-	"os"
-	"os/signal"
 	"runtime"
 	"sync"
-	"syscall"
 	"time"
 
 	"github.com/ClusterCockpit/cc-backend/internal/config"
 	"github.com/ClusterCockpit/cc-backend/pkg/archive"
 	cclog "github.com/ClusterCockpit/cc-lib/ccLogger"
 	"github.com/ClusterCockpit/cc-lib/resampler"
-	"github.com/ClusterCockpit/cc-lib/runtimeEnv"
 	"github.com/ClusterCockpit/cc-lib/schema"
 	"github.com/ClusterCockpit/cc-lib/util"
 )
@@ -29,14 +39,12 @@ import (
 var (
 	singleton  sync.Once
 	msInstance *MemoryStore
+	// shutdownFunc stores the context cancellation function created in Init
+	// and is called during Shutdown to cancel all background goroutines
+	shutdownFunc context.CancelFunc
 )
 
-var NumWorkers int = 4
 
-func init() {
-	maxWorkers := 10
-	NumWorkers = min(runtime.NumCPU()/2+1, maxWorkers)
-}
 
 type Metric struct {
 	Name         string
@@ -61,30 +69,34 @@ func Init(rawConfig json.RawMessage, wg *sync.WaitGroup) {
 		}
 	}
 
+	// Set NumWorkers from config or use default
+	if Keys.NumWorkers <= 0 {
+		maxWorkers := 10
+		Keys.NumWorkers = min(runtime.NumCPU()/2+1, maxWorkers)
+	}
+	cclog.Debugf("[METRICSTORE]> Using %d workers for checkpoint/archive operations\n", Keys.NumWorkers)
+
+	// Helper function to add metric configuration
+	addMetricConfig := func(mc schema.MetricConfig) {
+		agg, err := AssignAggregationStrategy(mc.Aggregation)
+		if err != nil {
+			cclog.Warnf("Could not find aggregation strategy for metric config '%s': %s", mc.Name, err.Error())
+		}
+
+		AddMetric(mc.Name, MetricConfig{
+			Frequency:   int64(mc.Timestep),
+			Aggregation: agg,
+		})
+	}
+
 	for _, c := range archive.Clusters {
 		for _, mc := range c.MetricConfig {
-			agg, err := AssignAggregationStratergy(mc.Aggregation)
+			addMetricConfig(*mc)
-			if err != nil {
-				cclog.Warnf("Could not find aggregation stratergy for metric config '%s': %s", mc.Name, err.Error())
-			}
-
-			AddMetric(mc.Name, MetricConfig{
-				Frequency:   int64(mc.Timestep),
-				Aggregation: agg,
-			})
 		}
 
 		for _, sc := range c.SubClusters {
 			for _, mc := range sc.MetricConfig {
-				agg, err := AssignAggregationStratergy(mc.Aggregation)
+				addMetricConfig(mc)
-				if err != nil {
-					cclog.Warnf("Could not find aggregation stratergy for metric config '%s': %s", mc.Name, err.Error())
-				}
-
-				AddMetric(mc.Name, MetricConfig{
-					Frequency:   int64(mc.Timestep),
-					Aggregation: agg,
-				})
 			}
 		}
 	}
@@ -126,15 +138,11 @@ func Init(rawConfig json.RawMessage, wg *sync.WaitGroup) {
 	Archiving(wg, ctx)
 	DataStaging(wg, ctx)
 
-	wg.Add(1)
+	// Note: Signal handling has been removed from this function.
-	sigs := make(chan os.Signal, 1)
+	// The caller is responsible for handling shutdown signals and calling
-	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
+	// the shutdown() function when appropriate.
-	go func() {
+	// Store the shutdown function for later use by Shutdown()
-		defer wg.Done()
+	shutdownFunc = shutdown
-		<-sigs
-		runtimeEnv.SystemdNotifiy(false, "[METRICSTORE]> Shutting down ...")
-		shutdown()
-	}()
 
 	if Keys.Nats != nil {
 		for _, natsConf := range Keys.Nats {
@@ -190,6 +198,11 @@ func GetMemoryStore() *MemoryStore {
 }
 
 func Shutdown() {
+	// Cancel the context to signal all background goroutines to stop
+	if shutdownFunc != nil {
+		shutdownFunc()
+	}
+
 	cclog.Infof("[METRICSTORE]> Writing to '%s'...\n", Keys.Checkpoints.RootDir)
 	var files int
 	var err error
@@ -207,70 +220,8 @@ func Shutdown() {
 		cclog.Errorf("[METRICSTORE]> Writing checkpoint failed: %s\n", err.Error())
 	}
 	cclog.Infof("[METRICSTORE]> Done! (%d files written)\n", files)
-
-	// ms.PrintHeirarchy()
 }
 
-// func (m *MemoryStore) PrintHeirarchy() {
-// 	m.root.lock.Lock()
-// 	defer m.root.lock.Unlock()
-
-// 	fmt.Printf("Root : \n")
-
-// 	for lvl1, sel1 := range m.root.children {
-// 		fmt.Printf("\t%s\n", lvl1)
-// 		for lvl2, sel2 := range sel1.children {
-// 			fmt.Printf("\t\t%s\n", lvl2)
-// 			if lvl1 == "fritz" && lvl2 == "f0201" {
-
-// 				for name, met := range m.Metrics {
-// 					mt := sel2.metrics[met.Offset]
-
-// 					fmt.Printf("\t\t\t\t%s\n", name)
-// 					fmt.Printf("\t\t\t\t")
-
-// 					for mt != nil {
-// 						// if name == "cpu_load" {
-// 						fmt.Printf("%d(%d) -> %#v", mt.start, len(mt.data), mt.data)
-// 						// }
-// 						mt = mt.prev
-// 					}
-// 					fmt.Printf("\n")
-
-// 				}
-// 			}
-// 			for lvl3, sel3 := range sel2.children {
-// 				if lvl1 == "fritz" && lvl2 == "f0201" && lvl3 == "hwthread70" {
-
-// 					fmt.Printf("\t\t\t\t\t%s\n", lvl3)
-
-// 					for name, met := range m.Metrics {
-// 						mt := sel3.metrics[met.Offset]
-
-// 						fmt.Printf("\t\t\t\t\t\t%s\n", name)
-
-// 						fmt.Printf("\t\t\t\t\t\t")
-
-// 						for mt != nil {
-// 							// if name == "clock" {
-// 							fmt.Printf("%d(%d) -> %#v", mt.start, len(mt.data), mt.data)
-
-// 							mt = mt.prev
-// 						}
-// 						fmt.Printf("\n")
-
-// 					}
-
-// 					// for i, _ := range sel3.metrics {
-// 					// 	fmt.Printf("\t\t\t\t\t%s\n", getName(configmetrics, i))
-// 					// }
-// 				}
-// 			}
-// 		}
-// 	}
-
-// }
-
 func getName(m *MemoryStore, i int) string {
 	for key, val := range m.Metrics {
 		if val.offset == i {

internal/memorystore/memorystore_test.go

@@ -0,0 +1,156 @@
+// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.
+// All rights reserved. This file is part of cc-backend.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package memorystore
+
+import (
+	"testing"
+
+	"github.com/ClusterCockpit/cc-lib/schema"
+)
+
+func TestAssignAggregationStrategy(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected AggregationStrategy
+		wantErr  bool
+	}{
+		{"empty string", "", NoAggregation, false},
+		{"sum", "sum", SumAggregation, false},
+		{"avg", "avg", AvgAggregation, false},
+		{"invalid", "invalid", NoAggregation, true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, err := AssignAggregationStrategy(tt.input)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("AssignAggregationStrategy(%q) error = %v, wantErr %v", tt.input, err, tt.wantErr)
+				return
+			}
+			if result != tt.expected {
+				t.Errorf("AssignAggregationStrategy(%q) = %v, want %v", tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestAddMetric(t *testing.T) {
+	// Reset Metrics before test
+	Metrics = make(map[string]MetricConfig)
+
+	err := AddMetric("test_metric", MetricConfig{
+		Frequency:   60,
+		Aggregation: SumAggregation,
+	})
+	if err != nil {
+		t.Errorf("AddMetric() error = %v", err)
+	}
+
+	if _, ok := Metrics["test_metric"]; !ok {
+		t.Error("AddMetric() did not add metric to Metrics map")
+	}
+
+	// Test updating with higher frequency
+	err = AddMetric("test_metric", MetricConfig{
+		Frequency:   120,
+		Aggregation: SumAggregation,
+	})
+	if err != nil {
+		t.Errorf("AddMetric() error = %v", err)
+	}
+
+	if Metrics["test_metric"].Frequency != 120 {
+		t.Errorf("AddMetric() frequency = %d, want 120", Metrics["test_metric"].Frequency)
+	}
+
+	// Test updating with lower frequency (should not update)
+	err = AddMetric("test_metric", MetricConfig{
+		Frequency:   30,
+		Aggregation: SumAggregation,
+	})
+	if err != nil {
+		t.Errorf("AddMetric() error = %v", err)
+	}
+
+	if Metrics["test_metric"].Frequency != 120 {
+		t.Errorf("AddMetric() frequency = %d, want 120 (should not downgrade)", Metrics["test_metric"].Frequency)
+	}
+}
+
+func TestGetMetricFrequency(t *testing.T) {
+	// Reset Metrics before test
+	Metrics = map[string]MetricConfig{
+		"test_metric": {
+			Frequency:   60,
+			Aggregation: SumAggregation,
+		},
+	}
+
+	freq, err := GetMetricFrequency("test_metric")
+	if err != nil {
+		t.Errorf("GetMetricFrequency() error = %v", err)
+	}
+	if freq != 60 {
+		t.Errorf("GetMetricFrequency() = %d, want 60", freq)
+	}
+
+	_, err = GetMetricFrequency("nonexistent")
+	if err == nil {
+		t.Error("GetMetricFrequency() expected error for nonexistent metric")
+	}
+}
+
+func TestBufferWrite(t *testing.T) {
+	b := newBuffer(100, 10)
+
+	// Test writing value
+	nb, err := b.write(100, schema.Float(42.0))
+	if err != nil {
+		t.Errorf("buffer.write() error = %v", err)
+	}
+	if nb != b {
+		t.Error("buffer.write() created new buffer unexpectedly")
+	}
+	if len(b.data) != 1 {
+		t.Errorf("buffer.write() len(data) = %d, want 1", len(b.data))
+	}
+	if b.data[0] != schema.Float(42.0) {
+		t.Errorf("buffer.write() data[0] = %v, want 42.0", b.data[0])
+	}
+
+	// Test writing value from past (should error)
+	_, err = b.write(50, schema.Float(10.0))
+	if err == nil {
+		t.Error("buffer.write() expected error for past timestamp")
+	}
+}
+
+func TestBufferRead(t *testing.T) {
+	b := newBuffer(100, 10)
+	
+	// Write some test data
+	b.write(100, schema.Float(1.0))
+	b.write(110, schema.Float(2.0))
+	b.write(120, schema.Float(3.0))
+
+	// Read data
+	data := make([]schema.Float, 3)
+	result, from, to, err := b.read(100, 130, data)
+	if err != nil {
+		t.Errorf("buffer.read() error = %v", err)
+	}
+	// Buffer read should return from as firstWrite (start + freq/2)
+	if from != 100 {
+		t.Errorf("buffer.read() from = %d, want 100", from)
+	}
+	if to != 130 {
+		t.Errorf("buffer.read() to = %d, want 130", to)
+	}
+	if len(result) != 3 {
+		t.Errorf("buffer.read() len(result) = %d, want 3", len(result))
+	}
+}