Add sent block time metric (#5738)

beacon-chain/blockchain/metrics.go

@@ -1,13 +1,17 @@
 package blockchain
 
 import (
+	"time"
+
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/epoch/precompute"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	stateTrie "github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/shared/bytesutil"
 	"github.com/prysmaticlabs/prysm/shared/params"
+	"github.com/prysmaticlabs/prysm/shared/roughtime"
 )
 
 var (
@@ -83,6 +87,13 @@ var (
 		Name: "total_voted_target_balances",
 		Help: "The total amount of ether, in gwei, that is eligible for voting of previous epoch",
 	})
+	sentBlockPropagationHistogram = promauto.NewHistogram(
+		prometheus.HistogramOpts{
+			Name:    "block_sent_latency_milliseconds",
+			Help:    "Captures blocks broadcast time. Blocks sent in milliseconds distribution",
+			Buckets: []float64{1000, 2000, 3000, 4000, 5000, 6000},
+		},
+	)
 )
 
 // reportSlotMetrics reports slot related metrics.
@@ -183,3 +194,15 @@ func reportEpochMetrics(state *stateTrie.BeaconState) {
 		totalVotedTargetBalances.Set(float64(precompute.Balances.PrevEpochTargetAttested))
 	}
 }
+
+// This captures metrics for block sent time by subtracts slot start time.
+func captureSentTimeMetric(genesisTime uint64, currentSlot uint64) error {
+	startTime, err := helpers.SlotToTime(genesisTime, currentSlot)
+	if err != nil {
+		return err
+	}
+	diffMs := roughtime.Now().Sub(startTime) / time.Millisecond
+	sentBlockPropagationHistogram.Observe(float64(diffMs))
+
+	return nil
+}

beacon-chain/blockchain/receive_block.go

@@ -52,6 +52,11 @@ func (s *Service) ReceiveBlock(ctx context.Context, block *ethpb.SignedBeaconBlo
 		"blockRoot": hex.EncodeToString(root[:]),
 	}).Debug("Broadcasting block")
 
+	if err := captureSentTimeMetric(uint64(s.genesisTime.Unix()), block.Block.Slot); err != nil {
+		// If a node fails to capture metric, this shouldn't cause the block processing to fail.
+		log.Warnf("Could not capture block sent time metric: %v", err)
+	}
+
 	if err := s.ReceiveBlockNoPubsub(ctx, block); err != nil {
 		return err
 	}