op-node: Use RefMetrics and Event from op-service/metrics package (#7329)

* fix issue 6735

* delete NewEventLight

* deduplicate refmetrics, ensure only initialized metrics exist

---------
Co-authored-by: protolambda <proto@protolambda.com>

op-node/metrics/events.go

-package metrics
-
-import (
-	"fmt"
-	"time"
-
-	"github.com/ethereum-optimism/optimism/op-service/metrics"
-
-	"github.com/prometheus/client_golang/prometheus"
-)
-
-type EventMetrics struct {
-	Total    prometheus.Counter
-	LastTime prometheus.Gauge
-}
-
-func (e *EventMetrics) RecordEvent() {
-	e.Total.Inc()
-	e.LastTime.Set(float64(time.Now().Unix()))
-}
-
-func NewEventMetrics(factory metrics.Factory, ns string, name string, displayName string) *EventMetrics {
-	return &EventMetrics{
-		Total: factory.NewCounter(prometheus.CounterOpts{
-			Namespace: ns,
-			Name:      fmt.Sprintf("%s_total", name),
-			Help:      fmt.Sprintf("Count of %s events", displayName),
-		}),
-		LastTime: factory.NewGauge(prometheus.GaugeOpts{
-			Namespace: ns,
-			Name:      fmt.Sprintf("last_%s_unix", name),
-			Help:      fmt.Sprintf("Timestamp of last %s event", displayName),
-		}),
-	}
-}

op-service/metrics/event.go

@@ -16,8 +16,8 @@ func (e *Event) Record() {
 	e.LastTime.SetToCurrentTime()
 }
 
-func NewEvent(factory Factory, ns string, subsystem string, name string, displayName string) Event {
-	return Event{
+func NewEvent(factory Factory, ns string, subsystem string, name string, displayName string) *Event {
+	return &Event{
 		Total: factory.NewCounter(prometheus.CounterOpts{
 			Namespace: ns,
 			Name:      fmt.Sprintf("%s_total", name),

op-service/txmgr/metrics/tx_metrics.go

@@ -27,7 +27,7 @@ type TxMetrics struct {
 	currentNonce       prometheus.Gauge
 	pendingTxs         prometheus.Gauge
 	txPublishError     *prometheus.CounterVec
-	publishEvent       metrics.Event
+	publishEvent       *metrics.Event
 	confirmEvent       metrics.EventVec
 	rpcError           prometheus.Counter
 }