tweak: Add stream tracer timer.

eth/filters/metrics.go

@@ -145,6 +145,16 @@ var (
 			Help:      "Number of dropped txs sent",
 		},
 	)
+
+	metricsTraceTxTimer = prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Subsystem: streamSubsystem,
+			Name:      "trace_tx_duration",
+			Help:      "Trace tx duration in seconds",
+			Buckets:   []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10},
+		},
+		[]string{},
+	)
 )
 
 func init() {
@@ -173,4 +183,6 @@ func init() {
 	register(metricsDroppedTxsEnd)
 	register(metricsDroppedTxsReceived)
 	register(metricsDroppedTxsSent)
+
+	register(metricsTraceTxTimer)
 }

eth/filters/trace_api.go

@@ -7,6 +7,8 @@ import (
 	"fmt"
 	"math/big"
 
+	"github.com/prometheus/client_golang/prometheus"
+
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/consensus/misc/eip1559"
@@ -273,7 +275,11 @@ func traceTx(message *core.Message, txCtx *tracers.Context, vmctx vm.BlockContex
 	if _, err = core.ApplyMessage(vmenv, message, new(core.GasPool).AddGas(message.GasLimit)); err != nil {
 		return nil, fmt.Errorf("tracing failed: %w", err)
 	}
-	return tracer.GetTrace()
+
+	timer := prometheus.NewTimer(metricsTraceTxTimer.With(nil))
+	trace, err := tracer.GetTrace()
+	timer.ObserveDuration()
+	return trace, err
 }
 
 // traceBlock traces all transactions in a block.