feat: add metrics for pebbledb read/writes

ethdb/pebble/pebble.go

@@ -87,6 +87,11 @@ type Database struct {
 	liveIterGauge          *metrics.Gauge   // Gauge for tracking the number of live database iterators
 	levelsGauge            []*metrics.Gauge // Gauge for tracking the number of tables in levels
 
+	// Read and Write Amplification metrics
+	readAmpGauge       *metrics.GaugeFloat64   // Gauge for tracking read amplification
+	levelWriteAmpGauge []*metrics.GaugeFloat64 // Gauge for tracking write amplification per level
+	totalWriteAmpGauge *metrics.GaugeFloat64   // Gauge for tracking total write amplification
+
 	quitLock sync.RWMutex    // Mutex protecting the quit channel and the closed flag
 	quitChan chan chan error // Quit channel to stop the metrics collection before closing the database
 	closed   bool            // keep track of whether we're Closed
@@ -164,6 +169,26 @@ func (d *Database) onWriteStallEnd() {
 	d.writeDelayStartTime = time.Time{}
 }
 
+// Track SST file operations
+func (d *Database) onTableCreated(info pebble.TableCreateInfo) {
+	metrics.GetOrRegisterMeter(d.namespace+"file/sst/created", nil).Mark(1)
+	d.log.Debug("SST file created", "reason", info.Reason, "fileNum", info.FileNum)
+}
+
+func (d *Database) onTableDeleted(info pebble.TableDeleteInfo) {
+	metrics.GetOrRegisterMeter(d.namespace+"file/sst/deleted", nil).Mark(1)
+}
+
+// Track WAL (.log) file operations
+func (d *Database) onWALCreated(info pebble.WALCreateInfo) {
+	metrics.GetOrRegisterMeter(d.namespace+"file/wal/created", nil).Mark(1)
+	d.log.Debug("WAL file created", "fileNum", info.FileNum, "recycled", info.RecycledFileNum)
+}
+
+func (d *Database) onWALDeleted(info pebble.WALDeleteInfo) {
+	metrics.GetOrRegisterMeter(d.namespace+"file/wal/deleted", nil).Mark(1)
+}
+
 // panicLogger is just a noop logger to disable Pebble's internal logger.
 //
 // TODO(karalabe): Remove when Pebble sets this as the default.
@@ -277,6 +302,10 @@ func New(file string, cache int, handles int, namespace string, readonly bool) (
 			CompactionEnd:   db.onCompactionEnd,
 			WriteStallBegin: db.onWriteStallBegin,
 			WriteStallEnd:   db.onWriteStallEnd,
+			TableCreated:    db.onTableCreated,
+			TableDeleted:    db.onTableDeleted,
+			WALCreated:      db.onWALCreated,
+			WALDeleted:      db.onWALDeleted,
 		},
 		Logger: panicLogger{}, // TODO(karalabe): Delete when this is upstreamed in Pebble
 
@@ -338,6 +367,10 @@ func New(file string, cache int, handles int, namespace string, readonly bool) (
 	db.liveCompSizeGauge = metrics.GetOrRegisterGauge(namespace+"compact/live/size", nil)
 	db.liveIterGauge = metrics.GetOrRegisterGauge(namespace+"iter/count", nil)
 
+	// Register read and write amplification metrics
+	db.readAmpGauge = metrics.GetOrRegisterGaugeFloat64(namespace+"readamp", nil)
+	db.totalWriteAmpGauge = metrics.GetOrRegisterGaugeFloat64(namespace+"writeamp/total", nil)
+
 	// Start up the metrics gathering and return
 	go db.meter(metricsGatheringInterval, namespace)
 	return db, nil
@@ -616,14 +649,29 @@ func (d *Database) meter(refresh time.Duration, namespace string) {
 		d.filterHitGauge.Update(stats.Filter.Hits)
 		d.filterMissGauge.Update(stats.Filter.Misses)
 
+		// Update read amplification metric
+		// ReadAmp returns the current read amplification of the database
+		d.readAmpGauge.Update(float64(stats.ReadAmp()))
+
+		// Calculate and update write amplification metrics per level
 		for i, level := range stats.Levels {
 			// Append metrics for additional layers
 			if i >= len(d.levelsGauge) {
 				d.levelsGauge = append(d.levelsGauge, metrics.GetOrRegisterGauge(namespace+fmt.Sprintf("tables/level%v", i), nil))
+				d.levelWriteAmpGauge = append(d.levelWriteAmpGauge, metrics.GetOrRegisterGaugeFloat64(namespace+fmt.Sprintf("writeamp/level%v", i), nil))
 			}
 			d.levelsGauge[i].Update(level.NumFiles)
+
+			// Update write amplification for this level (as float)
+			writeAmp := level.WriteAmp()
+			d.levelWriteAmpGauge[i].Update(writeAmp)
 		}
 
+		// Calculate total write amplification (as float)
+		totalMetrics := stats.Total()
+		totalWriteAmp := totalMetrics.WriteAmp()
+		d.totalWriteAmpGauge.Update(totalWriteAmp)
+
 		// Sleep a bit, then repeat the stats collection
 		select {
 		case errc = <-d.quitChan: