op-batcher: Add Channel Output Bytes Counter

op-batcher/metrics/metrics.go

@@ -58,14 +58,17 @@ type Metrics struct {
 	PendingBlocksCount prometheus.GaugeVec
 	BlocksAddedCount   prometheus.Gauge
 
-	ChannelInputBytes   prometheus.GaugeVec
-	ChannelReadyBytes   prometheus.Gauge
-	ChannelOutputBytes  prometheus.Gauge
-	ChannelClosedReason prometheus.Gauge
-	ChannelNumFrames    prometheus.Gauge
-	ChannelComprRatio   prometheus.Histogram
+	ChannelInputBytes       prometheus.GaugeVec
+	ChannelReadyBytes       prometheus.Gauge
+	ChannelOutputBytes      prometheus.Gauge
+	ChannelClosedReason     prometheus.Gauge
+	ChannelNumFrames        prometheus.Gauge
+	ChannelComprRatio       prometheus.Histogram
+	ChannelOutputBytesTotal prometheus.Counter
 
 	BatcherTxEvs opmetrics.EventVec
+
+	lastChannelOutputBytes int
 }
 
 var _ Metricer = (*Metrics)(nil)
@@ -144,6 +147,11 @@ func NewMetrics(procName string) *Metrics {
 			Help:      "Compression ratios of closed channel.",
 			Buckets:   append([]float64{0.1, 0.2}, prometheus.LinearBuckets(0.3, 0.05, 14)...),
 		}),
+		ChannelOutputBytesTotal: factory.NewCounter(prometheus.CounterOpts{
+			Namespace: ns,
+			Name:      "output_bytes_total",
+			Help:      "Total number of compressed output bytes from a channel.",
+		}),
 
 		BatcherTxEvs: opmetrics.NewEventVec(factory, ns, "batcher_tx", "BatcherTx", []string{"stage"}),
 	}
@@ -220,6 +228,10 @@ func (m *Metrics) RecordChannelClosed(id derive.ChannelID, numPendingBlocks int,
 	m.ChannelInputBytes.WithLabelValues(StageClosed).Set(float64(inputBytes))
 	m.ChannelOutputBytes.Set(float64(outputComprBytes))
 
+	outputBytesDelta := outputComprBytes - m.lastChannelOutputBytes
+	m.lastChannelOutputBytes = outputComprBytes
+	m.ChannelOutputBytesTotal.Add(float64(outputBytesDelta))
+
 	var comprRatio float64
 	if inputBytes > 0 {
 		comprRatio = float64(outputComprBytes) / float64(inputBytes)