chore(core): remove block time metric and track last time subscriptio…

…n was stuck

core/listener.go

@@ -163,7 +163,6 @@ func (cl *Listener) listen(ctx context.Context, sub <-chan types.EventDataSigned
 				return errors.New("underlying subscription was closed")
 			}
 
-			cl.metrics.observeBlockTime(ctx)
 			log.Debugw("listener: new block from core", "height", b.Header.Height)
 
 			err := cl.handleNewSignedBlock(ctx, b)

core/metrics.go

@@ -11,9 +11,6 @@ import (
 var meter = otel.Meter("core")
 
 type metrics struct {
-	blockTime     time.Time
-	blockTimeInst metric.Float64Histogram
-
 	lastTimeSubscriptionStuck     time.Time
 	lastTimeSubscriptionStuckInst metric.Int64Observable
 	lastTimeSubscriptionStuckReg  metric.Registration
@@ -25,14 +22,6 @@ func newMetrics() (*metrics, error) {
 	m := new(metrics)
 
 	var err error
-	m.blockTimeInst, err = meter.Float64Histogram(
-		"core_listener_block_time",
-		metric.WithDescription("time between blocks coming through core listener block subscription"),
-	)
-	if err != nil {
-		return nil, err
-	}
-
 	m.subscriptionStuckInst, err = meter.Int64Counter(
 		"core_listener_subscription_stuck_count",
 		metric.WithDescription("number of times core listener block subscription has been stuck/retried"),
@@ -64,21 +53,10 @@ func (m *metrics) observe(ctx context.Context, observeFn func(context.Context))
 	observeFn(ctx)
 }
 
-func (m *metrics) observeBlockTime(ctx context.Context) {
-	m.observe(ctx, func(ctx context.Context) {
-		now := time.Now()
-
-		if !m.blockTime.IsZero() {
-			m.blockTimeInst.Record(ctx, now.Sub(m.blockTime).Seconds())
-		}
-
-		m.blockTime = now
-	})
-}
-
 func (m *metrics) subscriptionStuck(ctx context.Context) {
 	m.observe(ctx, func(ctx context.Context) {
 		m.subscriptionStuckInst.Add(ctx, 1)
+		m.lastTimeSubscriptionStuck = time.Now()
 	})
 }