Add parquet file job archiving target

pkg/archive/parquet/writer.go

@@ -0,0 +1,113 @@
+// 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 parquet
+
+import (
+	"bytes"
+	"fmt"
+	"time"
+
+	cclog "github.com/ClusterCockpit/cc-lib/v2/ccLogger"
+	pq "github.com/parquet-go/parquet-go"
+)
+
+// ParquetWriter batches ParquetJobRows and flushes them to a target
+// when the estimated size exceeds maxSizeBytes.
+type ParquetWriter struct {
+	target       ParquetTarget
+	maxSizeBytes int64
+	rows         []ParquetJobRow
+	currentSize  int64
+	fileCounter  int
+	datePrefix   string
+}
+
+// NewParquetWriter creates a new writer that flushes batches to the given target.
+// maxSizeMB sets the approximate maximum size per parquet file in megabytes.
+func NewParquetWriter(target ParquetTarget, maxSizeMB int) *ParquetWriter {
+	return &ParquetWriter{
+		target:       target,
+		maxSizeBytes: int64(maxSizeMB) * 1024 * 1024,
+		datePrefix:   time.Now().Format("2006-01-02"),
+	}
+}
+
+// AddJob adds a row to the current batch. If the estimated batch size
+// exceeds the configured maximum, the batch is flushed to the target first.
+func (pw *ParquetWriter) AddJob(row ParquetJobRow) error {
+	rowSize := estimateRowSize(&row)
+
+	if pw.currentSize+rowSize > pw.maxSizeBytes && len(pw.rows) > 0 {
+		if err := pw.Flush(); err != nil {
+			return err
+		}
+	}
+
+	pw.rows = append(pw.rows, row)
+	pw.currentSize += rowSize
+	return nil
+}
+
+// Flush writes the current batch to a parquet file on the target.
+func (pw *ParquetWriter) Flush() error {
+	if len(pw.rows) == 0 {
+		return nil
+	}
+
+	pw.fileCounter++
+	fileName := fmt.Sprintf("cc-archive-%s-%03d.parquet", pw.datePrefix, pw.fileCounter)
+
+	data, err := writeParquetBytes(pw.rows)
+	if err != nil {
+		return fmt.Errorf("write parquet buffer: %w", err)
+	}
+
+	if err := pw.target.WriteFile(fileName, data); err != nil {
+		return fmt.Errorf("write parquet file %q: %w", fileName, err)
+	}
+
+	cclog.Infof("Parquet retention: wrote %s (%d jobs, %d bytes)", fileName, len(pw.rows), len(data))
+	pw.rows = pw.rows[:0]
+	pw.currentSize = 0
+	return nil
+}
+
+// Close flushes any remaining rows and finalizes the writer.
+func (pw *ParquetWriter) Close() error {
+	return pw.Flush()
+}
+
+func writeParquetBytes(rows []ParquetJobRow) ([]byte, error) {
+	var buf bytes.Buffer
+
+	writer := pq.NewGenericWriter[ParquetJobRow](&buf,
+		pq.Compression(&pq.Snappy),
+	)
+
+	if _, err := writer.Write(rows); err != nil {
+		return nil, err
+	}
+	if err := writer.Close(); err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+func estimateRowSize(row *ParquetJobRow) int64 {
+	// Fixed fields: ~100 bytes for numeric fields + strings estimate
+	size := int64(200)
+	size += int64(len(row.Cluster) + len(row.SubCluster) + len(row.Partition) +
+		len(row.Project) + len(row.User) + len(row.State))
+	size += int64(len(row.ResourcesJSON))
+	size += int64(len(row.StatisticsJSON))
+	size += int64(len(row.TagsJSON))
+	size += int64(len(row.MetaDataJSON))
+	size += int64(len(row.FootprintJSON))
+	size += int64(len(row.EnergyFootJSON))
+	size += int64(len(row.MetricDataGz))
+	return size
+}