metrics.go

// Package metrics provides a set of metrics for the op-node.
package metrics

import (
	"context"
	"encoding/binary"
	"errors"
	"fmt"
	"net"
	"strconv"
	"time"

	ophttp "github.com/ethereum-optimism/optimism/op-node/http"
	"github.com/ethereum-optimism/optimism/op-service/metrics"

	pb "github.com/libp2p/go-libp2p-pubsub/pb"
	libp2pmetrics "github.com/libp2p/go-libp2p/core/metrics"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/collectors"
	"github.com/prometheus/client_golang/prometheus/promhttp"

	"github.com/ethereum/go-ethereum"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/rpc"

	"github.com/ethereum-optimism/optimism/op-node/eth"
)

const (
	Namespace = "op_node"

	RPCServerSubsystem = "rpc_server"
	RPCClientSubsystem = "rpc_client"

	BatchMethod = "<batch>"
)

type Metricer interface {
	RecordInfo(version string)
	RecordUp()
	RecordRPCServerRequest(method string) func()
	RecordRPCClientRequest(method string) func(err error)
	RecordRPCClientResponse(method string, err error)
	SetDerivationIdle(status bool)
	RecordPipelineReset()
	RecordSequencingError()
	RecordPublishingError()
	RecordDerivationError()
	RecordReceivedUnsafePayload(payload *eth.ExecutionPayload)
	recordRef(layer string, name string, num uint64, timestamp uint64, h common.Hash)
	RecordL1Ref(name string, ref eth.L1BlockRef)
	RecordL2Ref(name string, ref eth.L2BlockRef)
	RecordUnsafePayloadsBuffer(length uint64, memSize uint64, next eth.BlockID)
	CountSequencedTxs(count int)
	RecordL1ReorgDepth(d uint64)
	RecordSequencerInconsistentL1Origin(from eth.BlockID, to eth.BlockID)
	RecordSequencerReset()
	RecordGossipEvent(evType int32)
	IncPeerCount()
	DecPeerCount()
	IncStreamCount()
	DecStreamCount()
	RecordBandwidth(ctx context.Context, bwc *libp2pmetrics.BandwidthCounter)
	RecordSequencerBuildingDiffTime(duration time.Duration)
	RecordSequencerSealingTime(duration time.Duration)
	Document() []metrics.DocumentedMetric
	RecordChannelInputBytes(num int)
	// P2P Metrics
	SetPeerScores(scores map[string]float64)
	ClientPayloadByNumberEvent(num uint64, resultCode byte, duration time.Duration)
	ServerPayloadByNumberEvent(num uint64, resultCode byte, duration time.Duration)
	PayloadsQuarantineSize(n int)
	RecordPeerUnban()
	RecordIPUnban()
	RecordDial(allow bool)
	RecordAccept(allow bool)
}

// Metrics tracks all the metrics for the op-node.
type Metrics struct {
	Info *prometheus.GaugeVec
	Up   prometheus.Gauge

	RPCServerRequestsTotal          *prometheus.CounterVec
	RPCServerRequestDurationSeconds *prometheus.HistogramVec
	RPCClientRequestsTotal          *prometheus.CounterVec
	RPCClientRequestDurationSeconds *prometheus.HistogramVec
	RPCClientResponsesTotal         *prometheus.CounterVec

	L1SourceCache *CacheMetrics
	L2SourceCache *CacheMetrics

	DerivationIdle prometheus.Gauge

	PipelineResets   *EventMetrics
	UnsafePayloads   *EventMetrics
	DerivationErrors *EventMetrics
	SequencingErrors *EventMetrics
	PublishingErrors *EventMetrics

	P2PReqDurationSeconds *prometheus.HistogramVec
	P2PReqTotal           *prometheus.CounterVec
	P2PPayloadByNumber    *prometheus.GaugeVec

	PayloadsQuarantineTotal prometheus.Gauge

	SequencerInconsistentL1Origin *EventMetrics
	SequencerResets               *EventMetrics

	L1RequestDurationSeconds *prometheus.HistogramVec

	SequencerBuildingDiffDurationSeconds prometheus.Histogram
	SequencerBuildingDiffTotal           prometheus.Counter

	SequencerSealingDurationSeconds prometheus.Histogram
	SequencerSealingTotal           prometheus.Counter

	UnsafePayloadsBufferLen     prometheus.Gauge
	UnsafePayloadsBufferMemSize prometheus.Gauge

	RefsNumber  *prometheus.GaugeVec
	RefsTime    *prometheus.GaugeVec
	RefsHash    *prometheus.GaugeVec
	RefsSeqNr   *prometheus.GaugeVec
	RefsLatency *prometheus.GaugeVec
	// hash of the last seen block per name, so we don't reduce/increase latency on updates of the same data,
	// and only count the first occurrence
	LatencySeen map[string]common.Hash

	L1ReorgDepth prometheus.Histogram

	TransactionsSequencedTotal prometheus.Counter

	// P2P Metrics
	PeerCount         prometheus.Gauge
	StreamCount       prometheus.Gauge
	PeerScores        *prometheus.GaugeVec
	GossipEventsTotal *prometheus.CounterVec
	BandwidthTotal    *prometheus.GaugeVec
	PeerUnbans        prometheus.Counter
	IPUnbans          prometheus.Counter
	Dials             *prometheus.CounterVec
	Accepts           *prometheus.CounterVec

	ChannelInputBytes prometheus.Counter

	registry *prometheus.Registry
	factory  metrics.Factory
}

var _ Metricer = (*Metrics)(nil)

// NewMetrics creates a new [Metrics] instance with the given process name.
func NewMetrics(procName string) *Metrics {
	if procName == "" {
		procName = "default"
	}
	ns := Namespace + "_" + procName

	registry := prometheus.NewRegistry()
	registry.MustRegister(collectors.NewProcessCollector(collectors.ProcessCollectorOpts{}))
	registry.MustRegister(collectors.NewGoCollector())
	factory := metrics.With(registry)
	return &Metrics{
		Info: factory.NewGaugeVec(prometheus.GaugeOpts{
			Namespace: ns,
			Name:      "info",
			Help:      "Pseudo-metric tracking version and config info",
		}, []string{
			"version",
		}),
		Up: factory.NewGauge(prometheus.GaugeOpts{
			Namespace: ns,
			Name:      "up",
			Help:      "1 if the op node has finished starting up",
		}),

		RPCServerRequestsTotal: factory.NewCounterVec(prometheus.CounterOpts{
			Namespace: ns,
			Subsystem: RPCServerSubsystem,
			Name:      "requests_total",
			Help:      "Total requests to the RPC server",
		}, []string{
			"method",
		}),
		RPCServerRequestDurationSeconds: factory.NewHistogramVec(prometheus.HistogramOpts{
			Namespace: ns,
			Subsystem: RPCServerSubsystem,
			Name:      "request_duration_seconds",
			Buckets:   []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10},
			Help:      "Histogram of RPC server request durations",
		}, []string{
			"method",
		}),
		RPCClientRequestsTotal: factory.NewCounterVec(prometheus.CounterOpts{
			Namespace: ns,
			Subsystem: RPCClientSubsystem,
			Name:      "requests_total",
			Help:      "Total RPC requests initiated by the opnode's RPC client",
		}, []string{
			"method",
		}),
		RPCClientRequestDurationSeconds: factory.NewHistogramVec(prometheus.HistogramOpts{
			Namespace: ns,
			Subsystem: RPCClientSubsystem,
			Name:      "request_duration_seconds",
			Buckets:   []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10},
			Help:      "Histogram of RPC client request durations",
		}, []string{
			"method",
		}),
		RPCClientResponsesTotal: factory.NewCounterVec(prometheus.CounterOpts{
			Namespace: ns,
			Subsystem: RPCClientSubsystem,
			Name:      "responses_total",
			Help:      "Total RPC request responses received by the opnode's RPC client",
		}, []string{
			"method",
			"error",
		}),

		L1SourceCache: NewCacheMetrics(factory, ns, "l1_source_cache", "L1 Source cache"),
		L2SourceCache: NewCacheMetrics(factory, ns, "l2_source_cache", "L2 Source cache"),

		DerivationIdle: factory.NewGauge(prometheus.GaugeOpts{
			Namespace: ns,
			Name:      "derivation_idle",
			Help:      "1 if the derivation pipeline is idle",
		}),

		PipelineResets:   NewEventMetrics(factory, ns, "pipeline_resets", "derivation pipeline resets"),
		UnsafePayloads:   NewEventMetrics(factory, ns, "unsafe_payloads", "unsafe payloads"),
		DerivationErrors: NewEventMetrics(factory, ns, "derivation_errors", "derivation errors"),
		SequencingErrors: NewEventMetrics(factory, ns, "sequencing_errors", "sequencing errors"),
		PublishingErrors: NewEventMetrics(factory, ns, "publishing_errors", "p2p publishing errors"),

		SequencerInconsistentL1Origin: NewEventMetrics(factory, ns, "sequencer_inconsistent_l1_origin", "events when the sequencer selects an inconsistent L1 origin"),
		SequencerResets:               NewEventMetrics(factory, ns, "sequencer_resets", "sequencer resets"),

		UnsafePayloadsBufferLen: factory.NewGauge(prometheus.GaugeOpts{
			Namespace: ns,
			Name:      "unsafe_payloads_buffer_len",
			Help:      "Number of buffered L2 unsafe payloads",
		}),
		UnsafePayloadsBufferMemSize: factory.NewGauge(prometheus.GaugeOpts{
			Namespace: ns,
			Name:      "unsafe_payloads_buffer_mem_size",
			Help:      "Total estimated memory size of buffered L2 unsafe payloads",
		}),

		RefsNumber: factory.NewGaugeVec(prometheus.GaugeOpts{
			Namespace: ns,
			Name:      "refs_number",
			Help:      "Gauge representing the different L1/L2 reference block numbers",
		}, []string{
			"layer",
			"type",
		}),
		RefsTime: factory.NewGaugeVec(prometheus.GaugeOpts{
			Namespace: ns,
			Name:      "refs_time",
			Help:      "Gauge representing the different L1/L2 reference block timestamps",
		}, []string{
			"layer",
			"type",
		}),
		RefsHash: factory.NewGaugeVec(prometheus.GaugeOpts{
			Namespace: ns,
			Name:      "refs_hash",
			Help:      "Gauge representing the different L1/L2 reference block hashes truncated to float values",
		}, []string{
			"layer",
			"type",
		}),
		RefsSeqNr: factory.NewGaugeVec(prometheus.GaugeOpts{
			Namespace: ns,
			Name:      "refs_seqnr",
			Help:      "Gauge representing the different L2 reference sequence numbers",
		}, []string{
			"type",
		}),
		RefsLatency: factory.NewGaugeVec(prometheus.GaugeOpts{
			Namespace: ns,
			Name:      "refs_latency",
			Help:      "Gauge representing the different L1/L2 reference block timestamps minus current time, in seconds",
		}, []string{
			"layer",
			"type",
		}),
		LatencySeen: make(map[string]common.Hash),

		L1ReorgDepth: factory.NewHistogram(prometheus.HistogramOpts{
			Namespace: ns,
			Name:      "l1_reorg_depth",
			Buckets:   []float64{0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5, 10.5, 20.5, 50.5, 100.5},
			Help:      "Histogram of L1 Reorg Depths",
		}),

		TransactionsSequencedTotal: factory.NewGauge(prometheus.GaugeOpts{
			Namespace: ns,
			Name:      "transactions_sequenced_total",
			Help:      "Count of total transactions sequenced",
		}),

		PeerCount: factory.NewGauge(prometheus.GaugeOpts{
			Namespace: ns,
			Subsystem: "p2p",
			Name:      "peer_count",
			Help:      "Count of currently connected p2p peers",
		}),
		// Notice: We cannot use peer ids as [Labels] in the GaugeVec
		// since peer ids would open a service attack vector.
		// Each peer id would be a separate metric, flooding prometheus.
		//
		// [Labels]: https://prometheus.io/docs/practices/naming/#labels
		PeerScores: factory.NewGaugeVec(prometheus.GaugeOpts{
			Namespace: ns,
			Subsystem: "p2p",
			Name:      "peer_scores",
			Help:      "Count of peer scores grouped by score",
		}, []string{
			"band",
		}),
		StreamCount: factory.NewGauge(prometheus.GaugeOpts{
			Namespace: ns,
			Subsystem: "p2p",
			Name:      "stream_count",
			Help:      "Count of currently connected p2p streams",
		}),
		GossipEventsTotal: factory.NewCounterVec(prometheus.CounterOpts{
			Namespace: ns,
			Subsystem: "p2p",
			Name:      "gossip_events_total",
			Help:      "Count of gossip events by type",
		}, []string{
			"type",
		}),
		BandwidthTotal: factory.NewGaugeVec(prometheus.GaugeOpts{
			Namespace: ns,
			Subsystem: "p2p",
			Name:      "bandwidth_bytes_total",
			Help:      "P2P bandwidth by direction",
		}, []string{
			"direction",
		}),
		PeerUnbans: factory.NewCounter(prometheus.CounterOpts{
			Namespace: ns,
			Subsystem: "p2p",
			Name:      "peer_unbans",
			Help:      "Count of peer unbans",
		}),
		IPUnbans: factory.NewCounter(prometheus.CounterOpts{
			Namespace: ns,
			Subsystem: "p2p",
			Name:      "ip_unbans",
			Help:      "Count of IP unbans",
		}),
		Dials: factory.NewCounterVec(prometheus.CounterOpts{
			Namespace: ns,
			Subsystem: "p2p",
			Name:      "dials",
			Help:      "Count of outgoing dial attempts, with label to filter to allowed attempts",
		}, []string{"allow"}),
		Accepts: factory.NewCounterVec(prometheus.CounterOpts{
			Namespace: ns,
			Subsystem: "p2p",
			Name:      "accepts",
			Help:      "Count of incoming dial attempts to accept, with label to filter to allowed attempts",
		}, []string{"allow"}),

		ChannelInputBytes: factory.NewCounter(prometheus.CounterOpts{
			Namespace: ns,
			Name:      "channel_input_bytes",
			Help:      "Number of compressed bytes added to the channel",
		}),

		P2PReqDurationSeconds: factory.NewHistogramVec(prometheus.HistogramOpts{
			Namespace: ns,
			Subsystem: "p2p",
			Name:      "req_duration_seconds",
			Buckets:   []float64{},
			Help:      "Duration of P2P requests",
		}, []string{
			"p2p_role", // "client" or "server"
			"p2p_method",
			"result_code",
		}),

		P2PReqTotal: factory.NewCounterVec(prometheus.CounterOpts{
			Namespace: ns,
			Subsystem: "p2p",
			Name:      "req_total",
			Help:      "Number of P2P requests",
		}, []string{
			"p2p_role", // "client" or "server"
			"p2p_method",
			"result_code",
		}),

		P2PPayloadByNumber: factory.NewGaugeVec(prometheus.GaugeOpts{
			Namespace: ns,
			Subsystem: "p2p",
			Name:      "payload_by_number",
			Help:      "Payload by number requests",
		}, []string{
			"p2p_role", // "client" or "server"
		}),
		PayloadsQuarantineTotal: factory.NewGauge(prometheus.GaugeOpts{
			Namespace: ns,
			Subsystem: "p2p",
			Name:      "payloads_quarantine_total",
			Help:      "number of unverified execution payloads buffered in quarantine",
		}),

		L1RequestDurationSeconds: factory.NewHistogramVec(prometheus.HistogramOpts{
			Namespace: ns,
			Name:      "l1_request_seconds",
			Buckets: []float64{
				.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10},
			Help: "Histogram of L1 request time",
		}, []string{"request"}),

		SequencerBuildingDiffDurationSeconds: factory.NewHistogram(prometheus.HistogramOpts{
			Namespace: ns,
			Name:      "sequencer_building_diff_seconds",
			Buckets: []float64{
				-10, -5, -2.5, -1, -.5, -.25, -.1, -0.05, -0.025, -0.01, -0.005,
				.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10},
			Help: "Histogram of Sequencer building time, minus block time",
		}),
		SequencerBuildingDiffTotal: factory.NewCounter(prometheus.CounterOpts{
			Namespace: ns,
			Name:      "sequencer_building_diff_total",
			Help:      "Number of sequencer block building jobs",
		}),
		SequencerSealingDurationSeconds: factory.NewHistogram(prometheus.HistogramOpts{
			Namespace: ns,
			Name:      "sequencer_sealing_seconds",
			Buckets:   []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10},
			Help:      "Histogram of Sequencer block sealing time",
		}),
		SequencerSealingTotal: factory.NewCounter(prometheus.CounterOpts{
			Namespace: ns,
			Name:      "sequencer_sealing_total",
			Help:      "Number of sequencer block sealing jobs",
		}),

		registry: registry,
		factory:  factory,
	}
}

// SetPeerScores updates the peer score [prometheus.GaugeVec].
// This takes a map of labels to scores.
func (m *Metrics) SetPeerScores(scores map[string]float64) {
	for label, score := range scores {
		m.PeerScores.WithLabelValues(label).Set(score)
	}
}

// RecordInfo sets a pseudo-metric that contains versioning and
// config info for the opnode.
func (m *Metrics) RecordInfo(version string) {
	m.Info.WithLabelValues(version).Set(1)
}

// RecordUp sets the up metric to 1.
func (m *Metrics) RecordUp() {
	prometheus.MustRegister()
	m.Up.Set(1)
}

// RecordRPCServerRequest is a helper method to record an incoming RPC
// call to the opnode's RPC server. It bumps the requests metric,
// and tracks how long it takes to serve a response.
func (m *Metrics) RecordRPCServerRequest(method string) func() {
	m.RPCServerRequestsTotal.WithLabelValues(method).Inc()
	timer := prometheus.NewTimer(m.RPCServerRequestDurationSeconds.WithLabelValues(method))
	return func() {
		timer.ObserveDuration()
	}
}

// RecordRPCClientRequest is a helper method to record an RPC client
// request. It bumps the requests metric, tracks the response
// duration, and records the response's error code.
func (m *Metrics) RecordRPCClientRequest(method string) func(err error) {
	m.RPCClientRequestsTotal.WithLabelValues(method).Inc()
	timer := prometheus.NewTimer(m.RPCClientRequestDurationSeconds.WithLabelValues(method))
	return func(err error) {
		m.RecordRPCClientResponse(method, err)
		timer.ObserveDuration()
	}
}

// RecordRPCClientResponse records an RPC response. It will
// convert the passed-in error into something metrics friendly.
// Nil errors get converted into <nil>, RPC errors are converted
// into rpc_<error code>, HTTP errors are converted into
// http_<status code>, and everything else is converted into
// <unknown>.
func (m *Metrics) RecordRPCClientResponse(method string, err error) {
	var errStr string
	var rpcErr rpc.Error
	var httpErr rpc.HTTPError
	if err == nil {
		errStr = "<nil>"
	} else if errors.As(err, &rpcErr) {
		errStr = fmt.Sprintf("rpc_%d", rpcErr.ErrorCode())
	} else if errors.As(err, &httpErr) {
		errStr = fmt.Sprintf("http_%d", httpErr.StatusCode)
	} else if errors.Is(err, ethereum.NotFound) {
		errStr = "<not found>"
	} else {
		errStr = "<unknown>"
	}
	m.RPCClientResponsesTotal.WithLabelValues(method, errStr).Inc()
}

func (m *Metrics) SetDerivationIdle(status bool) {
	var val float64
	if status {
		val = 1
	}
	m.DerivationIdle.Set(val)
}

func (m *Metrics) RecordPipelineReset() {
	m.PipelineResets.RecordEvent()
}

func (m *Metrics) RecordSequencingError() {
	m.SequencingErrors.RecordEvent()
}

func (m *Metrics) RecordPublishingError() {
	m.PublishingErrors.RecordEvent()
}

func (m *Metrics) RecordDerivationError() {
	m.DerivationErrors.RecordEvent()
}

func (m *Metrics) RecordReceivedUnsafePayload(payload *eth.ExecutionPayload) {
	m.UnsafePayloads.RecordEvent()
	m.recordRef("l2", "received_payload", uint64(payload.BlockNumber), uint64(payload.Timestamp), payload.BlockHash)
}

func (m *Metrics) recordRef(layer string, name string, num uint64, timestamp uint64, h common.Hash) {
	m.RefsNumber.WithLabelValues(layer, name).Set(float64(num))
	if timestamp != 0 {
		m.RefsTime.WithLabelValues(layer, name).Set(float64(timestamp))
		// only meter the latency when we first see this hash for the given label name
		if m.LatencySeen[name] != h {
			m.LatencySeen[name] = h
			m.RefsLatency.WithLabelValues(layer, name).Set(float64(timestamp) - (float64(time.Now().UnixNano()) / 1e9))
		}
	}
	// we map the first 8 bytes to a float64, so we can graph changes of the hash to find divergences visually.
	// We don't do math.Float64frombits, just a regular conversion, to keep the value within a manageable range.
	m.RefsHash.WithLabelValues(layer, name).Set(float64(binary.LittleEndian.Uint64(h[:])))
}

func (m *Metrics) RecordL1Ref(name string, ref eth.L1BlockRef) {
	m.recordRef("l1", name, ref.Number, ref.Time, ref.Hash)
}

func (m *Metrics) RecordL2Ref(name string, ref eth.L2BlockRef) {
	m.recordRef("l2", name, ref.Number, ref.Time, ref.Hash)
	m.recordRef("l1_origin", name, ref.L1Origin.Number, 0, ref.L1Origin.Hash)
	m.RefsSeqNr.WithLabelValues(name).Set(float64(ref.SequenceNumber))
}

func (m *Metrics) RecordUnsafePayloadsBuffer(length uint64, memSize uint64, next eth.BlockID) {
	m.recordRef("l2", "l2_buffer_unsafe", next.Number, 0, next.Hash)
	m.UnsafePayloadsBufferLen.Set(float64(length))
	m.UnsafePayloadsBufferMemSize.Set(float64(memSize))
}

func (m *Metrics) CountSequencedTxs(count int) {
	m.TransactionsSequencedTotal.Add(float64(count))
}

func (m *Metrics) RecordL1ReorgDepth(d uint64) {
	m.L1ReorgDepth.Observe(float64(d))
}

func (m *Metrics) RecordSequencerInconsistentL1Origin(from eth.BlockID, to eth.BlockID) {
	m.SequencerInconsistentL1Origin.RecordEvent()
	m.recordRef("l1_origin", "inconsistent_from", from.Number, 0, from.Hash)
	m.recordRef("l1_origin", "inconsistent_to", to.Number, 0, to.Hash)
}

func (m *Metrics) RecordSequencerReset() {
	m.SequencerResets.RecordEvent()
}

func (m *Metrics) RecordGossipEvent(evType int32) {
	m.GossipEventsTotal.WithLabelValues(pb.TraceEvent_Type_name[evType]).Inc()
}

func (m *Metrics) IncPeerCount() {
	m.PeerCount.Inc()
}

func (m *Metrics) DecPeerCount() {
	m.PeerCount.Dec()
}

func (m *Metrics) IncStreamCount() {
	m.StreamCount.Inc()
}

func (m *Metrics) DecStreamCount() {
	m.StreamCount.Dec()
}

func (m *Metrics) RecordBandwidth(ctx context.Context, bwc *libp2pmetrics.BandwidthCounter) {
	tick := time.NewTicker(10 * time.Second)
	defer tick.Stop()

	for {
		select {
		case <-tick.C:
			bwTotals := bwc.GetBandwidthTotals()
			m.BandwidthTotal.WithLabelValues("in").Set(float64(bwTotals.TotalIn))
			m.BandwidthTotal.WithLabelValues("out").Set(float64(bwTotals.TotalOut))
		case <-ctx.Done():
			return
		}
	}
}

// RecordL1RequestTime tracks the amount of time the derivation pipeline spent waiting for L1 data requests.
func (m *Metrics) RecordL1RequestTime(method string, duration time.Duration) {
	m.L1RequestDurationSeconds.WithLabelValues(method).Observe(float64(duration) / float64(time.Second))
}

// RecordSequencerBuildingDiffTime tracks the amount of time the sequencer was allowed between
// start to finish, incl. sealing, minus the block time.
// Ideally this is 0, realistically the sequencer scheduler may be busy with other jobs like syncing sometimes.
func (m *Metrics) RecordSequencerBuildingDiffTime(duration time.Duration) {
	m.SequencerBuildingDiffTotal.Inc()
	m.SequencerBuildingDiffDurationSeconds.Observe(float64(duration) / float64(time.Second))
}

// RecordSequencerSealingTime tracks the amount of time the sequencer took to finish sealing the block.
// Ideally this is 0, realistically it may take some time.
func (m *Metrics) RecordSequencerSealingTime(duration time.Duration) {
	m.SequencerSealingTotal.Inc()
	m.SequencerSealingDurationSeconds.Observe(float64(duration) / float64(time.Second))
}

// Serve starts the metrics server on the given hostname and port.
// The server will be closed when the passed-in context is cancelled.
func (m *Metrics) Serve(ctx context.Context, hostname string, port int) error {
	addr := net.JoinHostPort(hostname, strconv.Itoa(port))
	server := ophttp.NewHttpServer(promhttp.InstrumentMetricHandler(
		m.registry, promhttp.HandlerFor(m.registry, promhttp.HandlerOpts{}),
	))
	server.Addr = addr
	go func() {
		<-ctx.Done()
		server.Close()
	}()
	return server.ListenAndServe()
}

func (m *Metrics) Document() []metrics.DocumentedMetric {
	return m.factory.Document()
}

func (m *Metrics) ClientPayloadByNumberEvent(num uint64, resultCode byte, duration time.Duration) {
	if resultCode > 4 { // summarize all high codes to reduce metrics overhead
		resultCode = 5
	}
	code := strconv.FormatUint(uint64(resultCode), 10)
	m.P2PReqTotal.WithLabelValues("client", "payload_by_number", code).Inc()
	m.P2PReqDurationSeconds.WithLabelValues("client", "payload_by_number", code).Observe(float64(duration) / float64(time.Second))
	m.P2PPayloadByNumber.WithLabelValues("client").Set(float64(num))
}

func (m *Metrics) ServerPayloadByNumberEvent(num uint64, resultCode byte, duration time.Duration) {
	code := strconv.FormatUint(uint64(resultCode), 10)
	m.P2PReqTotal.WithLabelValues("server", "payload_by_number", code).Inc()
	m.P2PReqDurationSeconds.WithLabelValues("server", "payload_by_number", code).Observe(float64(duration) / float64(time.Second))
	m.P2PPayloadByNumber.WithLabelValues("server").Set(float64(num))
}

func (m *Metrics) PayloadsQuarantineSize(n int) {
	m.PayloadsQuarantineTotal.Set(float64(n))
}

func (m *Metrics) RecordChannelInputBytes(inputCompressedBytes int) {
	m.ChannelInputBytes.Add(float64(inputCompressedBytes))
}

func (m *Metrics) RecordPeerUnban() {
	m.PeerUnbans.Inc()
}

func (m *Metrics) RecordIPUnban() {
	m.IPUnbans.Inc()
}

func (m *Metrics) RecordDial(allow bool) {
	if allow {
		m.Dials.WithLabelValues("true").Inc()
	} else {
		m.Dials.WithLabelValues("false").Inc()
	}
}

func (m *Metrics) RecordAccept(allow bool) {
	if allow {
		m.Accepts.WithLabelValues("true").Inc()
	} else {
		m.Accepts.WithLabelValues("false").Inc()
	}
}

type noopMetricer struct{}

var NoopMetrics Metricer = new(noopMetricer)

func (n *noopMetricer) RecordInfo(version string) {
}

func (n *noopMetricer) RecordUp() {
}

func (n *noopMetricer) RecordRPCServerRequest(method string) func() {
	return func() {}
}

func (n *noopMetricer) RecordRPCClientRequest(method string) func(err error) {
	return func(err error) {}
}

func (n *noopMetricer) RecordRPCClientResponse(method string, err error) {
}

func (n *noopMetricer) SetDerivationIdle(status bool) {
}

func (n *noopMetricer) RecordPipelineReset() {
}

func (n *noopMetricer) RecordSequencingError() {
}

func (n *noopMetricer) RecordPublishingError() {
}

func (n *noopMetricer) RecordDerivationError() {
}

func (n *noopMetricer) RecordReceivedUnsafePayload(payload *eth.ExecutionPayload) {
}

func (n *noopMetricer) recordRef(layer string, name string, num uint64, timestamp uint64, h common.Hash) {
}

func (n *noopMetricer) RecordL1Ref(name string, ref eth.L1BlockRef) {
}

func (n *noopMetricer) RecordL2Ref(name string, ref eth.L2BlockRef) {
}

func (n *noopMetricer) RecordUnsafePayloadsBuffer(length uint64, memSize uint64, next eth.BlockID) {
}

func (n *noopMetricer) CountSequencedTxs(count int) {
}

func (n *noopMetricer) RecordL1ReorgDepth(d uint64) {
}

func (n *noopMetricer) RecordSequencerInconsistentL1Origin(from eth.BlockID, to eth.BlockID) {
}

func (n *noopMetricer) RecordSequencerReset() {
}

func (n *noopMetricer) RecordGossipEvent(evType int32) {
}

func (n *noopMetricer) SetPeerScores(scores map[string]float64) {
}

func (n *noopMetricer) IncPeerCount() {
}

func (n *noopMetricer) DecPeerCount() {
}

func (n *noopMetricer) IncStreamCount() {
}

func (n *noopMetricer) DecStreamCount() {
}

func (n *noopMetricer) RecordBandwidth(ctx context.Context, bwc *libp2pmetrics.BandwidthCounter) {
}

func (n *noopMetricer) RecordSequencerBuildingDiffTime(duration time.Duration) {
}

func (n *noopMetricer) RecordSequencerSealingTime(duration time.Duration) {
}

func (n *noopMetricer) Document() []metrics.DocumentedMetric {
	return nil
}

func (n *noopMetricer) ClientPayloadByNumberEvent(num uint64, resultCode byte, duration time.Duration) {
}

func (n *noopMetricer) ServerPayloadByNumberEvent(num uint64, resultCode byte, duration time.Duration) {
}

func (n *noopMetricer) PayloadsQuarantineSize(int) {
}

func (n *noopMetricer) RecordChannelInputBytes(int) {
}

func (n *noopMetricer) RecordPeerUnban() {
}

func (n *noopMetricer) RecordIPUnban() {
}

func (n *noopMetricer) RecordDial(allow bool) {
}

func (n *noopMetricer) RecordAccept(allow bool) {
}