Cache: sync committee index position (#9317)

* Add sync committee index cache

* Update BUILD.bazel

Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>

beacon-chain/cache/BUILD.bazel

@@ -10,6 +10,7 @@ go_library(
         "committees.go",
         "common.go",
         "doc.go",
+        "error.go",
         "proposer_indices_type.go",
         "skip_slot_cache.go",
         "subnet_ids.go",
@@ -17,10 +18,12 @@ go_library(
         "//fuzz:fuzzing_enabled": [
             "committee_disabled.go",
             "proposer_indices_disabled.go",
+            "sync_committee_disabled.go",
         ],
         "//conditions:default": [
             "committee.go",
             "proposer_indices.go",
+            "sync_committee.go",
         ],
     }),
     importpath = "github.com/prysmaticlabs/prysm/beacon-chain/cache",
@@ -32,6 +35,7 @@ go_library(
     deps = [
         "//beacon-chain/state:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",
+        "//shared/bytesutil:go_default_library",
         "//shared/copyutil:go_default_library",
         "//shared/hashutil:go_default_library",
         "//shared/params:go_default_library",
@@ -58,6 +62,7 @@ go_test(
         "proposer_indices_test.go",
         "skip_slot_cache_test.go",
         "subnet_ids_test.go",
+        "sync_committee_test.go",
     ],
     embed = [":go_default_library"],
     deps = [
@@ -66,6 +71,7 @@ go_test(
         "//proto/prysm/v1alpha1:go_default_library",
         "//shared/bytesutil:go_default_library",
         "//shared/params:go_default_library",
+        "//shared/testutil:go_default_library",
         "//shared/testutil/assert:go_default_library",
         "//shared/testutil/require:go_default_library",
         "@com_github_google_gofuzz//:go_default_library",

beacon-chain/cache/error.go

@@ -0,0 +1,9 @@
+package cache
+
+import "errors"
+
+// Sync committee cache related errors
+
+// ErrNonExistingSyncCommitteeKey when sync committee key (root) does not exist in cache.
+var ErrNonExistingSyncCommitteeKey = errors.New("does not exist sync committee key")
+var errNotSyncCommitteeIndexPosition = errors.New("not syncCommitteeIndexPosition struct")

beacon-chain/cache/sync_committee.go

@@ -0,0 +1,187 @@
+// +build !libfuzzer
+
+package cache
+
+import (
+	"sync"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/shared/bytesutil"
+	"k8s.io/client-go/tools/cache"
+)
+
+var (
+	maxSyncCommitteeSize = uint64(3) // Allows 3 forks to happen around `EPOCHS_PER_SYNC_COMMITTEE_PERIOD` boundary.
+
+	// SyncCommitteeCacheMiss tracks the number of committee requests that aren't present in the cache.
+	SyncCommitteeCacheMiss = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "sync_committee_index_cache_miss_total",
+		Help: "The number of committee requests that aren't present in the sync committee index cache.",
+	})
+	// SyncCommitteeCacheHit tracks the number of committee requests that are in the cache.
+	SyncCommitteeCacheHit = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "sync_committee_index_cache_hit_total",
+		Help: "The number of committee requests that are present in the sync committee index cache.",
+	})
+)
+
+// SyncCommitteeCache utilizes a FIFO cache to sufficiently cache validator position within sync committee.
+// It is thread safe with concurrent read write.
+type SyncCommitteeCache struct {
+	cache *cache.FIFO
+	lock  sync.RWMutex
+}
+
+// Index position of all validators in sync committee where `currentSyncCommitteeRoot` is the
+// key and `vIndexToPositionMap` is value. Inside `vIndexToPositionMap`, validator positions
+// are cached where key is the validator index and the value is the `positionInCommittee` struct.
+type syncCommitteeIndexPosition struct {
+	currentSyncCommitteeRoot [32]byte
+	vIndexToPositionMap      map[types.ValidatorIndex]*positionInCommittee
+}
+
+// Index position of individual validator of current period and next period sync committee.
+type positionInCommittee struct {
+	currentPeriod []types.CommitteeIndex
+	nextPeriod    []types.CommitteeIndex
+}
+
+// NewSyncCommittee initializes and returns a new SyncCommitteeCache.
+func NewSyncCommittee() *SyncCommitteeCache {
+	return &SyncCommitteeCache{
+		cache: cache.NewFIFO(keyFn),
+	}
+}
+
+// CurrentPeriodIndexPosition returns current period index position of a validator index with respect with
+// sync committee. If the input validator index has no assignment, an empty list will be returned.
+// If the input root does not exist in cache, `ErrNonExistingSyncCommitteeKey` is returned.
+// Manual checking of state for index position in state is recommended when `ErrNonExistingSyncCommitteeKey` is returned.
+func (s *SyncCommitteeCache) CurrentPeriodIndexPosition(root [32]byte, valIdx types.ValidatorIndex) ([]types.CommitteeIndex, error) {
+	s.lock.RLock()
+	defer s.lock.RUnlock()
+
+	pos, err := s.idxPositionInCommittee(root, valIdx)
+	if err != nil {
+		return nil, err
+	}
+	if pos == nil {
+		return []types.CommitteeIndex{}, nil
+	}
+
+	return pos.currentPeriod, nil
+}
+
+// NextPeriodIndexPosition returns next period index position of a validator index in respect with sync committee.
+// If the input validator index has no assignment, an empty list will be returned.
+// If the input root does not exist in cache, `ErrNonExistingSyncCommitteeKey` is returned.
+// Manual checking of state for index position in state is recommended when `ErrNonExistingSyncCommitteeKey` is returned.
+func (s *SyncCommitteeCache) NextPeriodIndexPosition(root [32]byte, valIdx types.ValidatorIndex) ([]types.CommitteeIndex, error) {
+	s.lock.RLock()
+	defer s.lock.RUnlock()
+
+	pos, err := s.idxPositionInCommittee(root, valIdx)
+	if err != nil {
+		return nil, err
+	}
+	if pos == nil {
+		return []types.CommitteeIndex{}, nil
+	}
+	return pos.nextPeriod, nil
+}
+
+// Helper function for `CurrentPeriodIndexPosition` and `NextPeriodIndexPosition` to return a mapping
+// of validator index to its index(s) position in the sync committee.
+func (s *SyncCommitteeCache) idxPositionInCommittee(
+	root [32]byte, valIdx types.ValidatorIndex,
+) (*positionInCommittee, error) {
+	obj, exists, err := s.cache.GetByKey(key(root))
+	if err != nil {
+		return nil, err
+	}
+	if !exists {
+		SyncCommitteeCacheMiss.Inc()
+		return nil, ErrNonExistingSyncCommitteeKey
+	}
+	item, ok := obj.(*syncCommitteeIndexPosition)
+	if !ok {
+		return nil, errNotSyncCommitteeIndexPosition
+	}
+	idxInCommittee, ok := item.vIndexToPositionMap[valIdx]
+	if !ok {
+		SyncCommitteeCacheMiss.Inc()
+		return nil, nil
+	}
+	SyncCommitteeCacheHit.Inc()
+	return idxInCommittee, nil
+}
+
+// UpdatePositionsInCommittee updates caching of validators position in sync committee in respect to
+// current epoch and next epoch. This should be called when `current_sync_committee` and `next_sync_committee`
+// change and that happens every `EPOCHS_PER_SYNC_COMMITTEE_PERIOD`.
+func (s *SyncCommitteeCache) UpdatePositionsInCommittee(syncCommitteeBoundaryRoot [32]byte, st state.BeaconStateAltair) error {
+	csc, err := st.CurrentSyncCommittee()
+	if err != nil {
+		return err
+	}
+	positionsMap := make(map[types.ValidatorIndex]*positionInCommittee)
+	for i, pubkey := range csc.Pubkeys {
+		p := bytesutil.ToBytes48(pubkey)
+		validatorIndex, ok := st.ValidatorIndexByPubkey(p)
+		if !ok {
+			continue
+		}
+		if _, ok := positionsMap[validatorIndex]; !ok {
+			m := &positionInCommittee{currentPeriod: []types.CommitteeIndex{types.CommitteeIndex(i)}, nextPeriod: []types.CommitteeIndex{}}
+			positionsMap[validatorIndex] = m
+		} else {
+			positionsMap[validatorIndex].currentPeriod = append(positionsMap[validatorIndex].currentPeriod, types.CommitteeIndex(i))
+		}
+	}
+
+	nsc, err := st.NextSyncCommittee()
+	if err != nil {
+		return err
+	}
+	for i, pubkey := range nsc.Pubkeys {
+		p := bytesutil.ToBytes48(pubkey)
+		validatorIndex, ok := st.ValidatorIndexByPubkey(p)
+		if !ok {
+			continue
+		}
+		if _, ok := positionsMap[validatorIndex]; !ok {
+			m := &positionInCommittee{nextPeriod: []types.CommitteeIndex{types.CommitteeIndex(i)}, currentPeriod: []types.CommitteeIndex{}}
+			positionsMap[validatorIndex] = m
+		} else {
+			positionsMap[validatorIndex].nextPeriod = append(positionsMap[validatorIndex].nextPeriod, types.CommitteeIndex(i))
+		}
+	}
+
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	if err := s.cache.Add(&syncCommitteeIndexPosition{
+		currentSyncCommitteeRoot: syncCommitteeBoundaryRoot,
+		vIndexToPositionMap:      positionsMap,
+	}); err != nil {
+		return err
+	}
+	trim(s.cache, maxSyncCommitteeSize)
+
+	return nil
+}
+
+// Given the `syncCommitteeIndexPosition` object, this returns the key of the object.
+// The key is the `currentSyncCommitteeRoot` within the field.
+// Error gets returned if input does not comply with `currentSyncCommitteeRoot` object.
+func keyFn(obj interface{}) (string, error) {
+	info, ok := obj.(*syncCommitteeIndexPosition)
+	if !ok {
+		return "", errNotSyncCommitteeIndexPosition
+	}
+
+	return string(info.currentSyncCommitteeRoot[:]), nil
+}

beacon-chain/cache/sync_committee_disabled.go

@@ -0,0 +1,32 @@
+// +build libfuzzer
+
+package cache
+
+import (
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+)
+
+// FakeSyncCommitteeCache is a fake `SyncCommitteeCache` to satisfy fuzzing.
+type FakeSyncCommitteeCache struct {
+}
+
+// NewSyncCommittee initializes and returns a new SyncCommitteeCache.
+func NewSyncCommittee() *FakeSyncCommitteeCache {
+	return &FakeSyncCommitteeCache{}
+}
+
+// CurrentEpochIndexPosition -- fake.
+func (s *FakeSyncCommitteeCache) CurrentPeriodIndexPosition(root [32]byte, valIdx types.ValidatorIndex) ([]types.CommitteeIndex, error) {
+	return nil, nil
+}
+
+// NextEpochIndexPosition -- fake.
+func (s *FakeSyncCommitteeCache) NextPeriodIndexPosition(root [32]byte, valIdx types.ValidatorIndex) ([]types.CommitteeIndex, error) {
+	return nil, nil
+}
+
+// UpdatePositionsInCommittee -- fake.
+func (s *FakeSyncCommitteeCache) UpdatePositionsInCommittee(syncCommitteeBoundaryRoot [32]byte, state state.BeaconStateAltair) error {
+	return nil
+}

beacon-chain/cache/sync_committee_test.go

@@ -0,0 +1,222 @@
+package cache_test
+
+import (
+	"testing"
+
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/shared/bytesutil"
+	"github.com/prysmaticlabs/prysm/shared/params"
+	"github.com/prysmaticlabs/prysm/shared/testutil"
+	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+)
+
+func TestSyncCommitteeCache_CanUpdateAndRetrieve(t *testing.T) {
+	numValidators := 101
+	deterministicState, _ := testutil.DeterministicGenesisStateAltair(t, uint64(numValidators))
+	pubKeys := make([][]byte, deterministicState.NumValidators())
+	for i, val := range deterministicState.Validators() {
+		pubKeys[i] = val.PublicKey
+	}
+	tests := []struct {
+		name                 string
+		currentSyncCommittee *ethpb.SyncCommittee
+		nextSyncCommittee    *ethpb.SyncCommittee
+		currentSyncMap       map[types.ValidatorIndex][]types.CommitteeIndex
+		nextSyncMap          map[types.ValidatorIndex][]types.CommitteeIndex
+	}{
+		{
+			name: "only current epoch",
+			currentSyncCommittee: convertToCommittee([][]byte{
+				pubKeys[1], pubKeys[2], pubKeys[3], pubKeys[2], pubKeys[2],
+			}),
+			nextSyncCommittee: convertToCommittee([][]byte{}),
+			currentSyncMap: map[types.ValidatorIndex][]types.CommitteeIndex{
+				1: {0},
+				2: {1, 3, 4},
+				3: {2},
+			},
+			nextSyncMap: map[types.ValidatorIndex][]types.CommitteeIndex{
+				1: {},
+				2: {},
+				3: {},
+			},
+		},
+		{
+			name:                 "only next epoch",
+			currentSyncCommittee: convertToCommittee([][]byte{}),
+			nextSyncCommittee: convertToCommittee([][]byte{
+				pubKeys[1], pubKeys[2], pubKeys[3], pubKeys[2], pubKeys[2],
+			}),
+			currentSyncMap: map[types.ValidatorIndex][]types.CommitteeIndex{
+				1: {},
+				2: {},
+				3: {},
+			},
+			nextSyncMap: map[types.ValidatorIndex][]types.CommitteeIndex{
+				1: {0},
+				2: {1, 3, 4},
+				3: {2},
+			},
+		},
+		{
+			name: "some current epoch and some next epoch",
+			currentSyncCommittee: convertToCommittee([][]byte{
+				pubKeys[1],
+				pubKeys[2],
+				pubKeys[3],
+				pubKeys[2],
+				pubKeys[2],
+			}),
+			nextSyncCommittee: convertToCommittee([][]byte{
+				pubKeys[7],
+				pubKeys[6],
+				pubKeys[5],
+				pubKeys[4],
+				pubKeys[7],
+			}),
+			currentSyncMap: map[types.ValidatorIndex][]types.CommitteeIndex{
+				1: {0},
+				2: {1, 3, 4},
+				3: {2},
+			},
+			nextSyncMap: map[types.ValidatorIndex][]types.CommitteeIndex{
+				7: {0, 4},
+				6: {1},
+				5: {2},
+				4: {3},
+			},
+		},
+		{
+			name: "some current epoch and some next epoch duplicated across",
+			currentSyncCommittee: convertToCommittee([][]byte{
+				pubKeys[1],
+				pubKeys[2],
+				pubKeys[3],
+				pubKeys[2],
+				pubKeys[2],
+			}),
+			nextSyncCommittee: convertToCommittee([][]byte{
+				pubKeys[2],
+				pubKeys[1],
+				pubKeys[3],
+				pubKeys[2],
+				pubKeys[1],
+			}),
+			currentSyncMap: map[types.ValidatorIndex][]types.CommitteeIndex{
+				1: {0},
+				2: {1, 3, 4},
+				3: {2},
+			},
+			nextSyncMap: map[types.ValidatorIndex][]types.CommitteeIndex{
+				1: {1, 4},
+				2: {0, 3},
+				3: {2},
+			},
+		},
+		{
+			name: "all duplicated",
+			currentSyncCommittee: convertToCommittee([][]byte{
+				pubKeys[100],
+				pubKeys[100],
+				pubKeys[100],
+				pubKeys[100],
+			}),
+			nextSyncCommittee: convertToCommittee([][]byte{
+				pubKeys[100],
+				pubKeys[100],
+				pubKeys[100],
+				pubKeys[100],
+			}),
+			currentSyncMap: map[types.ValidatorIndex][]types.CommitteeIndex{
+				100: {0, 1, 2, 3},
+			},
+			nextSyncMap: map[types.ValidatorIndex][]types.CommitteeIndex{
+				100: {0, 1, 2, 3},
+			},
+		},
+		{
+			name: "unknown keys",
+			currentSyncCommittee: convertToCommittee([][]byte{
+				pubKeys[100],
+				pubKeys[100],
+				pubKeys[100],
+				pubKeys[100],
+			}),
+			nextSyncCommittee: convertToCommittee([][]byte{
+				pubKeys[100],
+				pubKeys[100],
+				pubKeys[100],
+				pubKeys[100],
+			}),
+			currentSyncMap: map[types.ValidatorIndex][]types.CommitteeIndex{
+				1: {},
+			},
+			nextSyncMap: map[types.ValidatorIndex][]types.CommitteeIndex{
+				1: {},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			s, _ := testutil.DeterministicGenesisStateAltair(t, uint64(numValidators))
+			require.NoError(t, s.SetCurrentSyncCommittee(tt.currentSyncCommittee))
+			require.NoError(t, s.SetNextSyncCommittee(tt.nextSyncCommittee))
+			cache := cache.NewSyncCommittee()
+			r := [32]byte{'a'}
+			require.NoError(t, cache.UpdatePositionsInCommittee(r, s))
+			for key, indices := range tt.currentSyncMap {
+				pos, err := cache.CurrentPeriodIndexPosition(r, key)
+				require.NoError(t, err)
+				require.DeepEqual(t, indices, pos)
+			}
+			for key, indices := range tt.nextSyncMap {
+				pos, err := cache.NextPeriodIndexPosition(r, key)
+				require.NoError(t, err)
+				require.DeepEqual(t, indices, pos)
+			}
+		})
+	}
+}
+
+func TestSyncCommitteeCache_RootDoesNotExist(t *testing.T) {
+	c := cache.NewSyncCommittee()
+	_, err := c.CurrentPeriodIndexPosition([32]byte{}, 0)
+	require.Equal(t, cache.ErrNonExistingSyncCommitteeKey, err)
+}
+
+func TestSyncCommitteeCache_CanRotate(t *testing.T) {
+	c := cache.NewSyncCommittee()
+	s, _ := testutil.DeterministicGenesisStateAltair(t, 64)
+	require.NoError(t, s.SetCurrentSyncCommittee(convertToCommittee([][]byte{{1}})))
+	require.NoError(t, c.UpdatePositionsInCommittee([32]byte{'a'}, s))
+	require.NoError(t, s.SetCurrentSyncCommittee(convertToCommittee([][]byte{{2}})))
+	require.NoError(t, c.UpdatePositionsInCommittee([32]byte{'b'}, s))
+	require.NoError(t, s.SetCurrentSyncCommittee(convertToCommittee([][]byte{{3}})))
+	require.NoError(t, c.UpdatePositionsInCommittee([32]byte{'c'}, s))
+	require.NoError(t, s.SetCurrentSyncCommittee(convertToCommittee([][]byte{{4}})))
+	require.NoError(t, c.UpdatePositionsInCommittee([32]byte{'d'}, s))
+
+	_, err := c.CurrentPeriodIndexPosition([32]byte{'a'}, 0)
+	require.Equal(t, cache.ErrNonExistingSyncCommitteeKey, err)
+
+	_, err = c.CurrentPeriodIndexPosition([32]byte{'c'}, 0)
+	require.NoError(t, err)
+}
+
+func convertToCommittee(inputKeys [][]byte) *ethpb.SyncCommittee {
+	var pubKeys [][]byte
+	for i := uint64(0); i < params.BeaconConfig().SyncCommitteeSize; i++ {
+		if i < uint64(len(inputKeys)) {
+			pubKeys = append(pubKeys, bytesutil.PadTo(inputKeys[i], params.BeaconConfig().BLSPubkeyLength))
+		} else {
+			pubKeys = append(pubKeys, bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength))
+		}
+	}
+
+	return &ethpb.SyncCommittee{
+		Pubkeys:         pubKeys,
+		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
+	}
+}