wip trying something

CHANGELOG.md

@@ -24,6 +24,7 @@ The format is based on Keep a Changelog, and this project adheres to Semantic Ve
 - Added GetAggregatedAttestationV2 endpoint.
 - Added SubmitAttestationsV2 endpoint.
 - Validator REST mode Electra block support
+- Metric for the size of tracked validators cache
 
 ### Changed
 

beacon-chain/cache/tracked_validators.go

@@ -2,19 +2,28 @@ package cache
 
 import (
 	"sync"
+	"time"
 
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prysmaticlabs/prysm/v5/config/params"
 	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
 )
 
+var validatorInactivityThreshold = 5 // 5 epochs
+
 type TrackedValidator struct {
 	Active       bool
 	FeeRecipient primitives.ExecutionAddress
 	Index        primitives.ValidatorIndex
+	LastUpdated  time.Time
 }
 
 type TrackedValidatorsCache struct {
-	sync.Mutex
-	trackedValidators map[primitives.ValidatorIndex]TrackedValidator
+	sync.RWMutex
+	trackedValidators               map[primitives.ValidatorIndex]TrackedValidator
+	trackedValidatorsNum            uint64
+	trackedValidatorsNumLastUpdated uint64
+	trackedValidatorsMetric         prometheus.GaugeFunc
 }
 
 func NewTrackedValidatorsCache() *TrackedValidatorsCache {
@@ -24,8 +33,8 @@ func NewTrackedValidatorsCache() *TrackedValidatorsCache {
 }
 
 func (t *TrackedValidatorsCache) Validator(index primitives.ValidatorIndex) (TrackedValidator, bool) {
-	t.Lock()
-	defer t.Unlock()
+	t.RLock()
+	defer t.RUnlock()
 	val, ok := t.trackedValidators[index]
 	return val, ok
 }
@@ -34,6 +43,32 @@ func (t *TrackedValidatorsCache) Set(val TrackedValidator) {
 	t.Lock()
 	defer t.Unlock()
 	t.trackedValidators[val.Index] = val
+	t.updateTackedValidatorsNum()
+}
+
+func (t *TrackedValidatorsCache) updateTackedValidatorsNum() {
+	epochTime := uint64(params.BeaconConfig().SlotsPerEpoch) * params.BeaconConfig().SecondsPerSlot
+	if t.trackedValidatorsNumLastUpdated != 0 && t.trackedValidatorsNumLastUpdated+epochTime < uint64(time.Now().Unix()) {
+		// too early to update again
+		return
+	}
+	num := 0
+	for _, value := range t.trackedValidators {
+		if value.LastUpdated.Unix()+int64(validatorInactivityThreshold)*int64(epochTime) < time.Now().Unix() {
+			// validator expired
+			// TODO: should we prune?
+			continue
+		}
+		num++
+	}
+	t.trackedValidatorsNum = uint64(num)
+	t.trackedValidatorsNumLastUpdated = uint64(time.Now().Unix())
+}
+
+func (t *TrackedValidatorsCache) GetTrackedValidatorsNum() uint64 {
+	t.RLock()
+	defer t.RUnlock()
+	return t.trackedValidatorsNum
 }
 
 func (t *TrackedValidatorsCache) Prune() {
@@ -43,7 +78,32 @@ func (t *TrackedValidatorsCache) Prune() {
 }
 
 func (t *TrackedValidatorsCache) Validating() bool {
-	t.Lock()
-	defer t.Unlock()
+	t.RLock()
+	defer t.RUnlock()
 	return len(t.trackedValidators) > 0
 }
+
+func (t *TrackedValidatorsCache) Size() int {
+	t.RLock()
+	defer t.RUnlock()
+	return len(t.trackedValidators)
+}
+
+func (t *TrackedValidatorsCache) RegisterTrackedValidatorMetric() error {
+	t.Lock()
+	defer t.Unlock()
+	t.trackedValidatorsMetric = prometheus.NewGaugeFunc(
+		prometheus.GaugeOpts{
+			Name: "tracked_validator_count",
+			Help: "The total number of validators tracked by trackedValidatorsCache in the beacon node. This is updated at intervals via the push proposer settings API endpoint.",
+		},
+		func() float64 { return float64(t.GetTrackedValidatorsNum()) },
+	)
+	return prometheus.Register(t.trackedValidatorsMetric)
+}
+
+func (t *TrackedValidatorsCache) UnregisterTrackedValidatorMetric() {
+	t.RLock()
+	defer t.RUnlock()
+	prometheus.Unregister(t.trackedValidatorsMetric)
+}

beacon-chain/node/node.go

@@ -217,7 +217,9 @@ func New(cliCtx *cli.Context, cancel context.CancelFunc, opts ...Option) (*Beaco
 		return nil, err
 	}
 	beacon.collector = c
-
+	if err := beacon.trackedValidatorsCache.RegisterTrackedValidatorMetric(); err != nil {
+		return nil, errors.Wrap(err, "unable to register tracked validator metric")
+	}
 	// Do not store the finalized state as it has been provided to the respective services during
 	// their initialization.
 	beacon.finalizedStateAtStartUp = nil
@@ -457,6 +459,7 @@ func (b *BeaconNode) Close() {
 		log.WithError(err).Error("Failed to close database")
 	}
 	b.collector.unregister()
+	b.trackedValidatorsCache.UnregisterTrackedValidatorMetric()
 	b.cancel()
 	close(b.stop)
 }

beacon-chain/rpc/eth/validator/handlers.go

@@ -761,6 +761,7 @@ func (s *Server) PrepareBeaconProposer(w http.ResponseWriter, r *http.Request) {
 			Active:       true, // TODO: either check or add the field in the request
 			Index:        primitives.ValidatorIndex(validatorIndex),
 			FeeRecipient: feeRecipient,
+			LastUpdated:  time.Now().UTC(),
 		}
 		s.TrackedValidatorsCache.Set(val)
 		validatorIndices = append(validatorIndices, primitives.ValidatorIndex(validatorIndex))

beacon-chain/rpc/prysm/v1alpha1/validator/BUILD.bazel

@@ -33,6 +33,7 @@ go_library(
     importpath = "github.com/prysmaticlabs/prysm/v5/beacon-chain/rpc/prysm/v1alpha1/validator",
     visibility = ["//beacon-chain:__subpackages__"],
     deps = [
+        "//api:go_default_library",
         "//api/client/builder:go_default_library",
         "//async/event:go_default_library",
         "//beacon-chain/blockchain:go_default_library",