core/consensus: logging leader index (#3334)

Added `core_consensus_decided_leader_index` gauge to reflect the leader index of QBFT decision round. Also, logging essential decision round data as a debug message.

category: feature
ticket: none

core/consensus/component.go

@@ -432,15 +432,31 @@ func (c *Component) runInstance(ctx context.Context, duty core.Duty) (err error)
 	}
 
 	// Instrument consensus instance.
-	var decided bool
+	var (
+		decided bool
+		nodes   = len(c.peers)
+	)
+
 	decideCallback := func(qcommit []qbft.Msg[core.Duty, [32]byte]) {
+		round := qcommit[0].Round()
 		decided = true
-		decidedRoundsGauge.WithLabelValues(duty.Type.String(), string(roundTimer.Type())).Set(float64(qcommit[0].Round()))
+		decidedRoundsGauge.WithLabelValues(duty.Type.String(), string(roundTimer.Type())).Set(float64(round))
 		inst.decidedAtCh <- time.Now()
+
+		leaderIndex := leader(duty, round, nodes)
+		leaderName := c.peers[leaderIndex].Name
+		log.Debug(ctx, "QBFT consensus decided",
+			z.Str("duty", duty.Type.String()),
+			z.U64("slot", duty.Slot),
+			z.I64("round", round),
+			z.I64("leader_index", leaderIndex),
+			z.Str("leader_name", leaderName))
+
+		decidedLeaderGauge.WithLabelValues(duty.Type.String()).Set(float64(leaderIndex))
 	}
 
 	// Create a new qbft definition for this instance.
-	def := newDefinition(len(c.peers), c.subscribers, roundTimer, decideCallback)
+	def := newDefinition(nodes, c.subscribers, roundTimer, decideCallback)
 
 	// Create a new transport that handles sending and receiving for this instance.
 	t := transport{
@@ -466,7 +482,7 @@ func (c *Component) runInstance(ctx context.Context, duty core.Duty) (err error)
 	}
 
 	// Run the algo, blocking until the context is cancelled.
-	err = qbft.Run[core.Duty, [32]byte](ctx, def, qt, duty, peerIdx, inst.hashCh)
+	err = qbft.Run(ctx, def, qt, duty, peerIdx, inst.hashCh)
 	if err != nil && !isContextErr(err) {
 		consensusError.Inc()
 		return err // Only return non-context errors.

core/consensus/metrics.go

@@ -9,12 +9,21 @@ import (
 )
 
 var (
+	// Using gauge since the value changes slowly, once per slot.
 	decidedRoundsGauge = promauto.NewGaugeVec(prometheus.GaugeOpts{
 		Namespace: "core",
 		Subsystem: "consensus",
 		Name:      "decided_rounds",
 		Help:      "Number of rounds it took to decide consensus instances by duty and timer type.",
-	}, []string{"duty", "timer"}) // Using gauge since the value changes slowly, once per slot.
+	}, []string{"duty", "timer"})
+
+	// Using gauge since the value changes slowly, once per slot.
+	decidedLeaderGauge = promauto.NewGaugeVec(prometheus.GaugeOpts{
+		Namespace: "core",
+		Subsystem: "consensus",
+		Name:      "decided_leader_index",
+		Help:      "Leader node index of the decision round by duty.",
+	}, []string{"duty"})
 
 	consensusDuration = promauto.NewHistogramVec(prometheus.HistogramOpts{
 		Namespace: "core",

docs/metrics.md

@@ -43,6 +43,7 @@ when storing metrics from multiple nodes or clusters in one Prometheus instance.
 | `core_bcast_recast_errors_total` | Counter | The total count of failed recasted registrations by source; `pregen` vs `downstream` | `source` |
 | `core_bcast_recast_registration_total` | Counter | The total number of unique validator registration stored in recaster per pubkey | `pubkey` |
 | `core_bcast_recast_total` | Counter | The total count of recasted registrations by source; `pregen` vs `downstream` | `source` |
+| `core_consensus_decided_leader_index` | Gauge | Leader node index of the decision round by duty. | `duty` |
 | `core_consensus_decided_rounds` | Gauge | Number of rounds it took to decide consensus instances by duty and timer type. | `duty, timer` |
 | `core_consensus_duration_seconds` | Histogram | Duration of a consensus instance in seconds by duty and timer type. | `duty, timer` |
 | `core_consensus_error_total` | Counter | Total count of consensus errors |  |