Periodically PullGossip only from connected validators (#2399)

Author: StephenButtolph

chains/manager.go

@@ -859,13 +859,14 @@ func (m *manager) createAvalancheChain(
 	// Create engine, bootstrapper and state-syncer in this order,
 	// to make sure start callbacks are duly initialized
 	snowmanEngineConfig := smeng.Config{
-		Ctx:           ctx,
-		AllGetsServer: snowGetHandler,
-		VM:            vmWrappingProposerVM,
-		Sender:        snowmanMessageSender,
-		Validators:    vdrs,
-		Params:        consensusParams,
-		Consensus:     snowmanConsensus,
+		Ctx:                 ctx,
+		AllGetsServer:       snowGetHandler,
+		VM:                  vmWrappingProposerVM,
+		Sender:              snowmanMessageSender,
+		Validators:          vdrs,
+		ConnectedValidators: connectedValidators,
+		Params:              consensusParams,
+		Consensus:           snowmanConsensus,
 	}
 	snowmanEngine, err := smeng.New(snowmanEngineConfig)
 	if err != nil {
@@ -1201,14 +1202,15 @@ func (m *manager) createSnowmanChain(
 	// Create engine, bootstrapper and state-syncer in this order,
 	// to make sure start callbacks are duly initialized
 	engineConfig := smeng.Config{
-		Ctx:           ctx,
-		AllGetsServer: snowGetHandler,
-		VM:            vm,
-		Sender:        messageSender,
-		Validators:    vdrs,
-		Params:        consensusParams,
-		Consensus:     consensus,
-		PartialSync:   m.PartialSyncPrimaryNetwork && ctx.ChainID == constants.PlatformChainID,
+		Ctx:                 ctx,
+		AllGetsServer:       snowGetHandler,
+		VM:                  vm,
+		Sender:              messageSender,
+		Validators:          vdrs,
+		ConnectedValidators: connectedValidators,
+		Params:              consensusParams,
+		Consensus:           consensus,
+		PartialSync:         m.PartialSyncPrimaryNetwork && ctx.ChainID == constants.PlatformChainID,
 	}
 	engine, err := smeng.New(engineConfig)
 	if err != nil {

node/overridden_manager.go

@@ -68,10 +68,6 @@ func (o *overriddenManager) Sample(_ ids.ID, size int) ([]ids.NodeID, error) {
 	return o.manager.Sample(o.subnetID, size)
 }
 
-func (o *overriddenManager) UniformSample(_ ids.ID, size int) ([]ids.NodeID, error) {
-	return o.manager.UniformSample(o.subnetID, size)
-}
-
 func (o *overriddenManager) GetMap(ids.ID) map[ids.NodeID]*validators.GetValidatorOutput {
 	return o.manager.GetMap(o.subnetID)
 }

snow/engine/common/tracker/peers.go

@@ -33,6 +33,9 @@ type Peers interface {
 	ConnectedPercent() float64
 	// TotalWeight returns the total validator weight
 	TotalWeight() uint64
+	// SampleValidator returns a randomly selected connected validator. If there
+	// are no currently connected validators then it will return false.
+	SampleValidator() (ids.NodeID, bool)
 	// PreferredPeers returns the currently connected validators. If there are
 	// no currently connected validators then it will return the currently
 	// connected peers.
@@ -108,6 +111,13 @@ func (p *lockedPeers) TotalWeight() uint64 {
 	return p.peers.TotalWeight()
 }
 
+func (p *lockedPeers) SampleValidator() (ids.NodeID, bool) {
+	p.lock.RLock()
+	defer p.lock.RUnlock()
+
+	return p.peers.SampleValidator()
+}
+
 func (p *lockedPeers) PreferredPeers() set.Set[ids.NodeID] {
 	p.lock.RLock()
 	defer p.lock.RUnlock()
@@ -263,6 +273,10 @@ func (p *peerData) TotalWeight() uint64 {
 	return p.totalWeight
 }
 
+func (p *peerData) SampleValidator() (ids.NodeID, bool) {
+	return p.connectedValidators.Peek()
+}
+
 func (p *peerData) PreferredPeers() set.Set[ids.NodeID] {
 	if p.connectedValidators.Len() == 0 {
 		connectedPeers := set.NewSet[ids.NodeID](p.connectedPeers.Len())

snow/engine/snowman/config.go

@@ -8,6 +8,7 @@ import (
 	"github.com/ava-labs/avalanchego/snow/consensus/snowball"
 	"github.com/ava-labs/avalanchego/snow/consensus/snowman"
 	"github.com/ava-labs/avalanchego/snow/engine/common"
+	"github.com/ava-labs/avalanchego/snow/engine/common/tracker"
 	"github.com/ava-labs/avalanchego/snow/engine/snowman/block"
 	"github.com/ava-labs/avalanchego/snow/validators"
 )
@@ -16,11 +17,12 @@ import (
 type Config struct {
 	common.AllGetsServer
 
-	Ctx         *snow.ConsensusContext
-	VM          block.ChainVM
-	Sender      common.Sender
-	Validators  validators.Manager
-	Params      snowball.Parameters
-	Consensus   snowman.Consensus
-	PartialSync bool
+	Ctx                 *snow.ConsensusContext
+	VM                  block.ChainVM
+	Sender              common.Sender
+	Validators          validators.Manager
+	ConnectedValidators tracker.Peers
+	Params              snowball.Parameters
+	Consensus           snowman.Consensus
+	PartialSync         bool
 }

snow/engine/snowman/config_test.go

@@ -8,16 +8,18 @@ import (
 	"github.com/ava-labs/avalanchego/snow/consensus/snowball"
 	"github.com/ava-labs/avalanchego/snow/consensus/snowman"
 	"github.com/ava-labs/avalanchego/snow/engine/common"
+	"github.com/ava-labs/avalanchego/snow/engine/common/tracker"
 	"github.com/ava-labs/avalanchego/snow/engine/snowman/block"
 	"github.com/ava-labs/avalanchego/snow/validators"
 )
 
 func DefaultConfig() Config {
 	return Config{
-		Ctx:        snow.DefaultConsensusContextTest(),
-		VM:         &block.TestVM{},
-		Sender:     &common.SenderTest{},
-		Validators: validators.NewManager(),
+		Ctx:                 snow.DefaultConsensusContextTest(),
+		VM:                  &block.TestVM{},
+		Sender:              &common.SenderTest{},
+		Validators:          validators.NewManager(),
+		ConnectedValidators: tracker.NewPeers(),
 		Params: snowball.Parameters{
 			K:                     1,
 			AlphaPreference:       1,

snow/engine/snowman/transitive.go

@@ -169,11 +169,10 @@ func (t *Transitive) Gossip(ctx context.Context) error {
 
 		// Uniform sampling is used here to reduce bandwidth requirements of
 		// nodes with a large amount of stake weight.
-		vdrIDs, err := t.Validators.UniformSample(t.Ctx.SubnetID, 1)
-		if err != nil {
+		vdrID, ok := t.ConnectedValidators.SampleValidator()
+		if !ok {
 			t.Ctx.Log.Error("skipping block gossip",
-				zap.String("reason", "no validators"),
-				zap.Error(err),
+				zap.String("reason", "no connected validators"),
 			)
 			return nil
 		}
@@ -190,9 +189,13 @@ func (t *Transitive) Gossip(ctx context.Context) error {
 		}
 
 		t.requestID++
-		vdrSet := set.Of(vdrIDs...)
-		preferredID := t.Consensus.Preference()
-		t.Sender.SendPullQuery(ctx, vdrSet, t.requestID, preferredID, nextHeightToAccept)
+		t.Sender.SendPullQuery(
+			ctx,
+			set.Of(vdrID),
+			t.requestID,
+			t.Consensus.Preference(),
+			nextHeightToAccept,
+		)
 	} else {
 		t.Ctx.Log.Debug("skipping block gossip",
 			zap.String("reason", "blocks currently processing"),

snow/engine/snowman/transitive_test.go

@@ -22,6 +22,7 @@ import (
 	"github.com/ava-labs/avalanchego/snow/validators"
 	"github.com/ava-labs/avalanchego/utils/constants"
 	"github.com/ava-labs/avalanchego/utils/set"
+	"github.com/ava-labs/avalanchego/version"
 )
 
 var (
@@ -41,6 +42,9 @@ func setup(t *testing.T, engCfg Config) (ids.NodeID, validators.Manager, *common
 
 	vdr := ids.GenerateTestNodeID()
 	require.NoError(vals.AddStaker(engCfg.Ctx.SubnetID, vdr, nil, ids.Empty, 1))
+	require.NoError(engCfg.ConnectedValidators.Connected(context.Background(), vdr, version.CurrentApp))
+
+	vals.RegisterCallbackListener(engCfg.Ctx.SubnetID, engCfg.ConnectedValidators)
 
 	sender := &common.SenderTest{T: t}
 	engCfg.Sender = sender

snow/validators/manager.go

@@ -85,10 +85,6 @@ type Manager interface {
 	// If sampling the requested size isn't possible, an error will be returned.
 	Sample(subnetID ids.ID, size int) ([]ids.NodeID, error)
 
-	// UniformSample returns a collection of validatorIDs in the subnet.
-	// If sampling the requested size isn't possible, an error will be returned.
-	UniformSample(subnetID ids.ID, size int) ([]ids.NodeID, error)
-
 	// Map of the validators in this subnet
 	GetMap(subnetID ids.ID) map[ids.NodeID]*GetValidatorOutput
 
@@ -257,21 +253,6 @@ func (m *manager) Sample(subnetID ids.ID, size int) ([]ids.NodeID, error) {
 	return set.Sample(size)
 }
 
-func (m *manager) UniformSample(subnetID ids.ID, size int) ([]ids.NodeID, error) {
-	if size == 0 {
-		return nil, nil
-	}
-
-	m.lock.RLock()
-	set, exists := m.subnetToVdrs[subnetID]
-	m.lock.RUnlock()
-	if !exists {
-		return nil, ErrMissingValidators
-	}
-
-	return set.UniformSample(size)
-}
-
 func (m *manager) GetMap(subnetID ids.ID) map[ids.NodeID]*GetValidatorOutput {
 	m.lock.RLock()
 	set, exists := m.subnetToVdrs[subnetID]

snow/validators/set.go

@@ -243,13 +243,6 @@ func (s *vdrSet) Sample(size int) ([]ids.NodeID, error) {
 	return s.sample(size)
 }
 
-func (s *vdrSet) UniformSample(size int) ([]ids.NodeID, error) {
-	s.lock.RLock()
-	defer s.lock.RUnlock()
-
-	return s.uniformSample(size)
-}
-
 func (s *vdrSet) sample(size int) ([]ids.NodeID, error) {
 	if !s.samplerInitialized {
 		if err := s.sampler.Initialize(s.weights); err != nil {
@@ -270,22 +263,6 @@ func (s *vdrSet) sample(size int) ([]ids.NodeID, error) {
 	return list, nil
 }
 
-func (s *vdrSet) uniformSample(size int) ([]ids.NodeID, error) {
-	uniform := sampler.NewUniform()
-	uniform.Initialize(uint64(len(s.vdrSlice)))
-
-	indices, err := uniform.Sample(size)
-	if err != nil {
-		return nil, err
-	}
-
-	list := make([]ids.NodeID, size)
-	for i, index := range indices {
-		list[i] = s.vdrSlice[index].NodeID
-	}
-	return list, nil
-}
-
 func (s *vdrSet) TotalWeight() (uint64, error) {
 	s.lock.RLock()
 	defer s.lock.RUnlock()

utils/set/set.go

@@ -184,7 +184,7 @@ func (s Set[_]) MarshalJSON() ([]byte, error) {
 	return jsonBuf.Bytes(), errs.Err
 }
 
-// Returns an element. If the set is empty, returns false
+// Returns a random element. If the set is empty, returns false
 func (s *Set[T]) Peek() (T, bool) {
 	for elt := range *s {
 		return elt, true