vendor: sync to latest core (#154)

* vendor: sync to latest core with BA3.0

* params: Update dmoment

19 files changed, 889 insertions, 343 deletions

diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/agreement-mgr.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/agreement-mgr.go
index e8cafbd68..e468e9c2e 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/agreement-mgr.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/agreement-mgr.go
@@ -22,6 +22,7 @@ import (
 	"errors"
 	"math"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/dexon-foundation/dexon-consensus/common"
@@ -41,7 +42,7 @@ func genValidLeader(
 		if block.Timestamp.After(time.Now()) {
 			return false, nil
 		}
-		if err := mgr.lattice.SanityCheck(block); err != nil {
+		if err := mgr.lattice.SanityCheck(block, true); err != nil {
 			if err == ErrRetrySanityCheckLater {
 				return false, nil
 			}
@@ -180,12 +181,23 @@ func (mgr *agreementMgr) appendConfig(
 			consensus:     mgr.con,
 			chainID:       i,
 			restartNotary: make(chan types.Position, 1),
+			roundValue:    &atomic.Value{},
 		}
+		recv.roundValue.Store(uint64(0))
 		agrModule := newAgreement(
 			mgr.con.ID,
 			recv,
 			newLeaderSelector(genValidLeader(mgr), mgr.logger),
-			mgr.signer)
+			mgr.signer,
+			mgr.logger)
+		// Hacky way to initialize first notarySet.
+		nodes, err := mgr.cache.GetNodeSet(round)
+		if err != nil {
+			return err
+		}
+		agrModule.notarySet = nodes.GetSubSet(
+			int(config.NotarySetSize),
+			types.NewNotarySetTarget(crs, i))
 		// Hacky way to make agreement module self contained.
 		recv.agreementModule = agrModule
 		mgr.baModules = append(mgr.baModules, agrModule)
@@ -266,7 +278,11 @@ func (mgr *agreementMgr) processAgreementResult(
 				return err
 			}
 		}
-		agreement.restart(nIDs, result.Position, crs)
+		leader, err := mgr.cache.GetLeaderNode(result.Position)
+		if err != nil {
+			return err
+		}
+		agreement.restart(nIDs, result.Position, leader, crs)
 	}
 	return nil
 }
@@ -332,14 +348,12 @@ func (mgr *agreementMgr) runBA(initRound uint64, chainID uint32) {
 			return
 		}
 		// Check if this node in notary set of this chain in this round.
-		nodeSet, err := mgr.cache.GetNodeSet(nextRound)
+		notarySet, err := mgr.cache.GetNotarySet(nextRound, chainID)
 		if err != nil {
 			panic(err)
 		}
 		setting.crs = config.crs
-		setting.notarySet = nodeSet.GetSubSet(
-			int(config.notarySetSize),
-			types.NewNotarySetTarget(config.crs, chainID))
+		setting.notarySet = notarySet
 		_, isNotary = setting.notarySet[mgr.ID]
 		if isNotary {
 			mgr.logger.Info("selected as notary set",
@@ -396,7 +410,7 @@ Loop:
 			<-setting.ticker.Tick()
 		}
 		// Run BA for this round.
-		recv.round = currentRound
+		recv.roundValue.Store(currentRound)
 		recv.changeNotaryTime = roundEndTime
 		recv.restartNotary <- types.Position{ChainID: math.MaxUint32}
 		if err := mgr.baRoutineForOneRound(&setting); err != nil {
@@ -435,12 +449,14 @@ Loop:
 				}
 			}
 			var nextHeight uint64
+			var nextTime time.Time
 			for {
-				nextHeight, err = mgr.lattice.NextHeight(recv.round, setting.chainID)
+				nextHeight, nextTime, err =
+					mgr.lattice.NextBlock(recv.round(), setting.chainID)
 				if err != nil {
 					mgr.logger.Debug("Error getting next height",
 						"error", err,
-						"round", recv.round,
+						"round", recv.round(),
 						"chainID", setting.chainID)
 					err = nil
 					nextHeight = oldPos.Height
@@ -456,12 +472,18 @@ Loop:
 				time.Sleep(100 * time.Millisecond)
 			}
 			nextPos := types.Position{
-				Round:   recv.round,
+				Round:   recv.round(),
 				ChainID: setting.chainID,
 				Height:  nextHeight,
 			}
 			oldPos = nextPos
-			agr.restart(setting.notarySet, nextPos, setting.crs)
+			leader, err := mgr.cache.GetLeaderNode(nextPos)
+			if err != nil {
+				return err
+			}
+			time.Sleep(nextTime.Sub(time.Now()))
+			setting.ticker.Restart()
+			agr.restart(setting.notarySet, nextPos, leader, setting.crs)
 		default:
 		}
 		if agr.pullVotes() {
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/agreement-state.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/agreement-state.go
index 77f293376..266e44294 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/agreement-state.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/agreement-state.go
@@ -35,7 +35,10 @@ type agreementStateType int
 
 // agreementStateType enum.
 const (
-	stateInitial agreementStateType = iota
+	stateFast agreementStateType = iota
+	stateFastVote
+	stateFastRollback
+	stateInitial
 	statePreCommit
 	stateCommit
 	stateForward
@@ -43,7 +46,7 @@ const (
 	stateSleep
 )
 
-var nullBlockHash = common.Hash{}
+var nullBlockHash common.Hash
 var skipBlockHash common.Hash
 
 func init() {
@@ -58,6 +61,63 @@ type agreementState interface {
 	clocks() int
 }
 
+//----- FastState -----
+type fastState struct {
+	a *agreementData
+}
+
+func newFastState(a *agreementData) *fastState {
+	return &fastState{a: a}
+}
+
+func (s *fastState) state() agreementStateType { return stateFast }
+func (s *fastState) clocks() int               { return 0 }
+func (s *fastState) nextState() (agreementState, error) {
+	if func() bool {
+		s.a.lock.Lock()
+		defer s.a.lock.Unlock()
+		return s.a.isLeader
+	}() {
+		hash := s.a.recv.ProposeBlock()
+		if hash != nullBlockHash {
+			s.a.lock.Lock()
+			defer s.a.lock.Unlock()
+			s.a.recv.ProposeVote(types.NewVote(types.VoteFast, hash, s.a.period))
+		}
+	}
+	return newFastVoteState(s.a), nil
+}
+
+//----- FastVoteState -----
+type fastVoteState struct {
+	a *agreementData
+}
+
+func newFastVoteState(a *agreementData) *fastVoteState {
+	return &fastVoteState{a: a}
+}
+
+func (s *fastVoteState) state() agreementStateType { return stateFastVote }
+func (s *fastVoteState) clocks() int               { return 2 }
+func (s *fastVoteState) nextState() (agreementState, error) {
+	return newFastRollbackState(s.a), nil
+}
+
+//----- FastRollbackState -----
+type fastRollbackState struct {
+	a *agreementData
+}
+
+func newFastRollbackState(a *agreementData) *fastRollbackState {
+	return &fastRollbackState{a: a}
+}
+
+func (s *fastRollbackState) state() agreementStateType { return stateFastRollback }
+func (s *fastRollbackState) clocks() int               { return 1 }
+func (s *fastRollbackState) nextState() (agreementState, error) {
+	return newInitialState(s.a), nil
+}
+
 //----- InitialState -----
 type initialState struct {
 	a *agreementData
@@ -70,10 +130,17 @@ func newInitialState(a *agreementData) *initialState {
 func (s *initialState) state() agreementStateType { return stateInitial }
 func (s *initialState) clocks() int               { return 0 }
 func (s *initialState) nextState() (agreementState, error) {
-	hash := s.a.recv.ProposeBlock()
-	s.a.lock.Lock()
-	defer s.a.lock.Unlock()
-	s.a.recv.ProposeVote(types.NewVote(types.VoteInit, hash, s.a.period))
+	if func() bool {
+		s.a.lock.Lock()
+		defer s.a.lock.Unlock()
+		return !s.a.isLeader
+	}() {
+		// Leader already proposed block in fastState.
+		hash := s.a.recv.ProposeBlock()
+		s.a.lock.Lock()
+		defer s.a.lock.Unlock()
+		s.a.recv.ProposeVote(types.NewVote(types.VoteInit, hash, s.a.period))
+	}
 	return newPreCommitState(s.a), nil
 }
 
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/agreement.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/agreement.go
index eead4628a..62bbe250f 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/agreement.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/agreement.go
@@ -31,6 +31,7 @@ import (
 
 // Errors for agreement module.
 var (
+	ErrInvalidVote            = fmt.Errorf("invalid vote")
 	ErrNotInNotarySet         = fmt.Errorf("not in notary set")
 	ErrIncorrectVoteSignature = fmt.Errorf("incorrect vote signature")
 )
@@ -73,6 +74,8 @@ type agreementReceiver interface {
 	// agreement module.
 	ConfirmBlock(common.Hash, map[types.NodeID]*types.Vote)
 	PullBlocks(common.Hashes)
+	ReportForkVote(v1, v2 *types.Vote)
+	ReportForkBlock(b1, b2 *types.Block)
 }
 
 type pendingBlock struct {
@@ -90,6 +93,7 @@ type agreementData struct {
 	recv agreementReceiver
 
 	ID           types.NodeID
+	isLeader     bool
 	leader       *leaderSelector
 	lockValue    common.Hash
 	lockRound    uint64
@@ -114,6 +118,7 @@ type agreement struct {
 	candidateBlock map[common.Hash]*types.Block
 	fastForward    chan uint64
 	signer         *utils.Signer
+	logger         common.Logger
 }
 
 // newAgreement creates a agreement instance.
@@ -121,7 +126,8 @@ func newAgreement(
 	ID types.NodeID,
 	recv agreementReceiver,
 	leader *leaderSelector,
-	signer *utils.Signer) *agreement {
+	signer *utils.Signer,
+	logger common.Logger) *agreement {
 	agreement := &agreement{
 		data: &agreementData{
 			recv:   recv,
@@ -132,6 +138,7 @@ func newAgreement(
 		candidateBlock: make(map[common.Hash]*types.Block),
 		fastForward:    make(chan uint64, 1),
 		signer:         signer,
+		logger:         logger,
 	}
 	agreement.stop()
 	return agreement
@@ -139,8 +146,8 @@ func newAgreement(
 
 // restart the agreement
 func (a *agreement) restart(
-	notarySet map[types.NodeID]struct{}, aID types.Position, crs common.Hash) {
-
+	notarySet map[types.NodeID]struct{}, aID types.Position, leader types.NodeID,
+	crs common.Hash) {
 	if !func() bool {
 		a.lock.Lock()
 		defer a.lock.Unlock()
@@ -162,12 +169,16 @@ func (a *agreement) restart(
 		a.data.leader.restart(crs)
 		a.data.lockValue = nullBlockHash
 		a.data.lockRound = 0
+		a.data.isLeader = a.data.ID == leader
 		a.fastForward = make(chan uint64, 1)
 		a.hasOutput = false
-		a.state = newInitialState(a.data)
+		a.state = newFastState(a.data)
 		a.notarySet = notarySet
 		a.candidateBlock = make(map[common.Hash]*types.Block)
-		a.aID.Store(aID)
+		a.aID.Store(struct {
+			pos    types.Position
+			leader types.NodeID
+		}{aID, leader})
 		return true
 	}() {
 		return
@@ -213,18 +224,24 @@ func (a *agreement) restart(
 	}()
 
 	for _, block := range replayBlock {
-		a.processBlock(block)
+		if err := a.processBlock(block); err != nil {
+			a.logger.Error("failed to process block when restarting agreement",
+				"block", block)
+		}
 	}
 
 	for _, vote := range replayVote {
-		a.processVote(vote)
+		if err := a.processVote(vote); err != nil {
+			a.logger.Error("failed to process vote when restarting agreement",
+				"vote", vote)
+		}
 	}
 }
 
 func (a *agreement) stop() {
 	a.restart(make(map[types.NodeID]struct{}), types.Position{
 		ChainID: math.MaxUint32,
-	}, common.Hash{})
+	}, types.NodeID{}, common.Hash{})
 }
 
 func isStop(aID types.Position) bool {
@@ -235,7 +252,12 @@ func isStop(aID types.Position) bool {
 func (a *agreement) clocks() int {
 	a.data.lock.RLock()
 	defer a.data.lock.RUnlock()
-	return a.state.clocks()
+	scale := int(a.data.period)
+	// 10 is a magic number derived from many years of experience.
+	if scale > 10 {
+		scale = 10
+	}
+	return a.state.clocks() * scale
 }
 
 // pullVotes returns if current agreement requires more votes to continue.
@@ -243,21 +265,31 @@ func (a *agreement) pullVotes() bool {
 	a.data.lock.RLock()
 	defer a.data.lock.RUnlock()
 	return a.state.state() == statePullVote ||
+		a.state.state() == stateFastRollback ||
 		(a.state.state() == statePreCommit && (a.data.period%3) == 0)
 }
 
 // agreementID returns the current agreementID.
 func (a *agreement) agreementID() types.Position {
-	return a.aID.Load().(types.Position)
+	return a.aID.Load().(struct {
+		pos    types.Position
+		leader types.NodeID
+	}).pos
+}
+
+// leader returns the current leader.
+func (a *agreement) leader() types.NodeID {
+	return a.aID.Load().(struct {
+		pos    types.Position
+		leader types.NodeID
+	}).leader
 }
 
 // nextState is called at the specific clock time.
 func (a *agreement) nextState() (err error) {
-	if func() bool {
-		a.lock.RLock()
-		defer a.lock.RUnlock()
-		return a.hasOutput
-	}() {
+	a.lock.Lock()
+	defer a.lock.Unlock()
+	if a.hasOutput {
 		a.state = newSleepState(a.data)
 		return
 	}
@@ -266,6 +298,9 @@ func (a *agreement) nextState() (err error) {
 }
 
 func (a *agreement) sanityCheck(vote *types.Vote) error {
+	if vote.Type >= types.MaxVoteType {
+		return ErrInvalidVote
+	}
 	if _, exist := a.notarySet[vote.ProposerID]; !exist {
 		return ErrNotInNotarySet
 	}
@@ -279,22 +314,21 @@ func (a *agreement) sanityCheck(vote *types.Vote) error {
 	return nil
 }
 
-func (a *agreement) checkForkVote(vote *types.Vote) error {
-	if err := func() error {
-		a.data.lock.RLock()
-		defer a.data.lock.RUnlock()
-		if votes, exist := a.data.votes[vote.Period]; exist {
-			if oldVote, exist := votes[vote.Type][vote.ProposerID]; exist {
-				if vote.BlockHash != oldVote.BlockHash {
-					return &ErrForkVote{vote.ProposerID, oldVote, vote}
-				}
+func (a *agreement) checkForkVote(vote *types.Vote) (
+	alreadyExist bool, err error) {
+	a.data.lock.RLock()
+	defer a.data.lock.RUnlock()
+	if votes, exist := a.data.votes[vote.Period]; exist {
+		if oldVote, exist := votes[vote.Type][vote.ProposerID]; exist {
+			alreadyExist = true
+			if vote.BlockHash != oldVote.BlockHash {
+				a.data.recv.ReportForkVote(oldVote, vote)
+				err = &ErrForkVote{vote.ProposerID, oldVote, vote}
+				return
 			}
 		}
-		return nil
-	}(); err != nil {
-		return err
 	}
-	return nil
+	return
 }
 
 // prepareVote prepares a vote.
@@ -314,6 +348,13 @@ func (a *agreement) processVote(vote *types.Vote) error {
 	aID := a.agreementID()
 	// Agreement module has stopped.
 	if isStop(aID) {
+		// Hacky way to not drop first votes for height 0.
+		if vote.Position.Height == uint64(0) {
+			a.pendingVote = append(a.pendingVote, pendingVote{
+				vote:         vote,
+				receivedTime: time.Now().UTC(),
+			})
+		}
 		return nil
 	}
 	if vote.Position != aID {
@@ -326,9 +367,13 @@ func (a *agreement) processVote(vote *types.Vote) error {
 		})
 		return nil
 	}
-	if err := a.checkForkVote(vote); err != nil {
+	exist, err := a.checkForkVote(vote)
+	if err != nil {
 		return err
 	}
+	if exist {
+		return nil
+	}
 
 	a.data.lock.Lock()
 	defer a.data.lock.Unlock()
@@ -336,12 +381,13 @@ func (a *agreement) processVote(vote *types.Vote) error {
 		a.data.votes[vote.Period] = newVoteListMap()
 	}
 	a.data.votes[vote.Period][vote.Type][vote.ProposerID] = vote
-	if !a.hasOutput && vote.Type == types.VoteCom {
+	if !a.hasOutput &&
+		(vote.Type == types.VoteCom || vote.Type == types.VoteFast) {
 		if hash, ok := a.data.countVoteNoLock(vote.Period, vote.Type); ok &&
 			hash != skipBlockHash {
 			a.hasOutput = true
 			a.data.recv.ConfirmBlock(hash,
-				a.data.votes[vote.Period][types.VoteCom])
+				a.data.votes[vote.Period][vote.Type])
 			return nil
 		}
 	} else if a.hasOutput {
@@ -443,6 +489,7 @@ func (a *agreement) processBlock(block *types.Block) error {
 	}
 	if b, exist := a.data.blocks[block.ProposerID]; exist {
 		if b.Hash != block.Hash {
+			a.data.recv.ReportForkBlock(b, block)
 			return &ErrFork{block.ProposerID, b.Hash, block.Hash}
 		}
 		return nil
@@ -452,6 +499,39 @@ func (a *agreement) processBlock(block *types.Block) error {
 	}
 	a.data.blocks[block.ProposerID] = block
 	a.addCandidateBlockNoLock(block)
+	if (a.state.state() == stateFast || a.state.state() == stateFastVote) &&
+		block.ProposerID == a.leader() {
+		go func() {
+			for func() bool {
+				a.lock.RLock()
+				defer a.lock.RUnlock()
+				if a.state.state() != stateFast && a.state.state() != stateFastVote {
+					return false
+				}
+				block, exist := a.data.blocks[a.leader()]
+				if !exist {
+					return true
+				}
+				a.data.lock.RLock()
+				defer a.data.lock.RUnlock()
+				ok, err := a.data.leader.validLeader(block)
+				if err != nil {
+					fmt.Println("Error checking validLeader for Fast BA",
+						"error", err, "block", block)
+					return false
+				}
+				if ok {
+					a.data.recv.ProposeVote(
+						types.NewVote(types.VoteFast, block.Hash, a.data.period))
+					return false
+				}
+				return true
+			}() {
+				// TODO(jimmy): retry interval should be related to configurations.
+				time.Sleep(250 * time.Millisecond)
+			}
+		}()
+	}
 	return nil
 }
 
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/consensus.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/consensus.go
index 0e5a1fbdb..0754e800f 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/consensus.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/consensus.go
@@ -22,6 +22,7 @@ import (
 	"encoding/hex"
 	"fmt"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/dexon-foundation/dexon-consensus/common"
@@ -69,11 +70,15 @@ type consensusBAReceiver struct {
 	agreementModule  *agreement
 	chainID          uint32
 	changeNotaryTime time.Time
-	round            uint64
+	roundValue       *atomic.Value
 	isNotary         bool
 	restartNotary    chan types.Position
 }
 
+func (recv *consensusBAReceiver) round() uint64 {
+	return recv.roundValue.Load().(uint64)
+}
+
 func (recv *consensusBAReceiver) ProposeVote(vote *types.Vote) {
 	if !recv.isNotary {
 		return
@@ -99,17 +104,20 @@ func (recv *consensusBAReceiver) ProposeBlock() common.Hash {
 	if !recv.isNotary {
 		return common.Hash{}
 	}
-	block := recv.consensus.proposeBlock(recv.chainID, recv.round)
+	block := recv.consensus.proposeBlock(recv.chainID, recv.round())
 	if block == nil {
 		recv.consensus.logger.Error("unable to propose block")
 		return nullBlockHash
 	}
-	if err := recv.consensus.preProcessBlock(block); err != nil {
-		recv.consensus.logger.Error("Failed to pre-process block", "error", err)
-		return common.Hash{}
-	}
-	recv.consensus.logger.Debug("Calling Network.BroadcastBlock", "block", block)
-	recv.consensus.network.BroadcastBlock(block)
+	go func() {
+		if err := recv.consensus.preProcessBlock(block); err != nil {
+			recv.consensus.logger.Error("Failed to pre-process block", "error", err)
+			return
+		}
+		recv.consensus.logger.Debug("Calling Network.BroadcastBlock",
+			"block", block)
+		recv.consensus.network.BroadcastBlock(block)
+	}()
 	return block.Hash
 }
 
@@ -122,7 +130,7 @@ func (recv *consensusBAReceiver) ConfirmBlock(
 		recv.consensus.logger.Info("Empty block is confirmed",
 			"position", &aID)
 		var err error
-		block, err = recv.consensus.proposeEmptyBlock(recv.round, recv.chainID)
+		block, err = recv.consensus.proposeEmptyBlock(recv.round(), recv.chainID)
 		if err != nil {
 			recv.consensus.logger.Error("Propose empty block failed", "error", err)
 			return
@@ -140,9 +148,19 @@ func (recv *consensusBAReceiver) ConfirmBlock(
 				defer recv.consensus.lock.Unlock()
 				recv.consensus.baConfirmedBlock[hash] = ch
 			}()
-			recv.consensus.network.PullBlocks(common.Hashes{hash})
 			go func() {
-				block = <-ch
+				hashes := common.Hashes{hash}
+			PullBlockLoop:
+				for {
+					recv.consensus.logger.Debug("Calling Network.PullBlock for BA block",
+						"hash", hash)
+					recv.consensus.network.PullBlocks(hashes)
+					select {
+					case block = <-ch:
+						break PullBlockLoop
+					case <-time.After(1 * time.Second):
+					}
+				}
 				recv.consensus.logger.Info("Receive unknown block",
 					"hash", hash.String()[:6],
 					"position", &block.Position,
@@ -242,7 +260,7 @@ CleanChannelLoop:
 	}
 	newPos := block.Position
 	if block.Timestamp.After(recv.changeNotaryTime) {
-		recv.round++
+		recv.roundValue.Store(recv.round() + 1)
 		newPos.Round++
 	}
 	recv.restartNotary <- newPos
@@ -256,6 +274,14 @@ func (recv *consensusBAReceiver) PullBlocks(hashes common.Hashes) {
 	recv.consensus.network.PullBlocks(hashes)
 }
 
+func (recv *consensusBAReceiver) ReportForkVote(v1, v2 *types.Vote) {
+	recv.consensus.gov.ReportForkVote(v1, v2)
+}
+
+func (recv *consensusBAReceiver) ReportForkBlock(b1, b2 *types.Block) {
+	recv.consensus.gov.ReportForkBlock(b1, b2)
+}
+
 // consensusDKGReceiver implements dkgReceiver.
 type consensusDKGReceiver struct {
 	ID           types.NodeID
@@ -388,6 +414,14 @@ type Consensus struct {
 	logger                     common.Logger
 	nonFinalizedBlockDelivered bool
 	resetRandomnessTicker      chan struct{}
+	resetDeliveryGuardTicker   chan struct{}
+	msgChan                    chan interface{}
+	waitGroup                  sync.WaitGroup
+
+	// Context of Dummy receiver during switching from syncer.
+	dummyCancel    context.CancelFunc
+	dummyFinished  <-chan struct{}
+	dummyMsgBuffer []interface{}
 }
 
 // NewConsensus construct an Consensus instance.
@@ -423,6 +457,9 @@ func NewConsensusForSimulation(
 // You need to provide the initial block for this newly created Consensus
 // instance to bootstrap with. A proper choice is the last finalized block you
 // delivered to syncer.
+//
+// NOTE: those confirmed blocks should be organized by chainID and sorted by
+//       their positions, in ascending order.
 func NewConsensusFromSyncer(
 	initBlock *types.Block,
 	initRoundBeginTime time.Time,
@@ -432,17 +469,43 @@ func NewConsensusFromSyncer(
 	networkModule Network,
 	prv crypto.PrivateKey,
 	latticeModule *Lattice,
-	blocks []*types.Block,
+	confirmedBlocks [][]*types.Block,
 	randomnessResults []*types.BlockRandomnessResult,
+	cachedMessages []interface{},
 	logger common.Logger) (*Consensus, error) {
 	// Setup Consensus instance.
 	con := newConsensusForRound(initBlock, initRoundBeginTime, app, gov, db,
 		networkModule, prv, logger, latticeModule, true)
-	// Dump all BA-confirmed blocks to the consensus instance.
-	for _, b := range blocks {
-		con.ccModule.registerBlock(b)
-		if err := con.processBlock(b); err != nil {
-			return nil, err
+	// Launch a dummy receiver before we start receiving from network module.
+	con.dummyMsgBuffer = cachedMessages
+	con.dummyCancel, con.dummyFinished = utils.LaunchDummyReceiver(
+		con.ctx, networkModule.ReceiveChan(), func(msg interface{}) {
+			con.dummyMsgBuffer = append(con.dummyMsgBuffer, msg)
+		})
+	// Dump all BA-confirmed blocks to the consensus instance, make sure these
+	// added blocks forming a DAG.
+	for {
+		updated := false
+		for idx, bs := range confirmedBlocks {
+			for bIdx, b := range bs {
+				// Only when its parent block is already added to lattice, we can
+				// then add this block. If not, our pulling mechanism would stop at
+				// the block we added, and lost its parent block forever.
+				if !latticeModule.Exist(b.ParentHash) {
+					logger.Debug("Skip discontinuous confirmed block",
+						"from", b,
+						"until", bs[len(bs)-1])
+					confirmedBlocks[idx] = bs[bIdx:]
+					break
+				}
+				con.ccModule.registerBlock(b)
+				if err := con.processBlock(b); err != nil {
+					return nil, err
+				}
+			}
+		}
+		if !updated {
+			break
 		}
 	}
 	// Dump all randomness result to the consensus instance.
@@ -504,22 +567,25 @@ func newConsensusForRound(
 	}
 	// Construct Consensus instance.
 	con := &Consensus{
-		ID:               ID,
-		ccModule:         newCompactionChain(gov),
-		lattice:          latticeModule,
-		app:              appModule,
-		debugApp:         debugApp,
-		gov:              gov,
-		db:               db,
-		network:          network,
-		baConfirmedBlock: make(map[common.Hash]chan<- *types.Block),
-		dkgReady:         sync.NewCond(&sync.Mutex{}),
-		cfgModule:        cfgModule,
-		dMoment:          initRoundBeginTime,
-		nodeSetCache:     nodeSetCache,
-		signer:           signer,
-		event:            common.NewEvent(),
-		logger:           logger,
+		ID:                       ID,
+		ccModule:                 newCompactionChain(gov),
+		lattice:                  latticeModule,
+		app:                      appModule,
+		debugApp:                 debugApp,
+		gov:                      gov,
+		db:                       db,
+		network:                  network,
+		baConfirmedBlock:         make(map[common.Hash]chan<- *types.Block),
+		dkgReady:                 sync.NewCond(&sync.Mutex{}),
+		cfgModule:                cfgModule,
+		dMoment:                  initRoundBeginTime,
+		nodeSetCache:             nodeSetCache,
+		signer:                   signer,
+		event:                    common.NewEvent(),
+		logger:                   logger,
+		resetRandomnessTicker:    make(chan struct{}),
+		resetDeliveryGuardTicker: make(chan struct{}),
+		msgChan:                  make(chan interface{}, 1024),
 	}
 	con.ctx, con.ctxCancel = context.WithCancel(context.Background())
 	con.baMgr = newAgreementMgr(con, initRound, initRoundBeginTime)
@@ -585,12 +651,40 @@ func (con *Consensus) Run() {
 	con.baMgr.run()
 	// Launch network handler.
 	con.logger.Debug("Calling Network.ReceiveChan")
-	go con.processMsg(con.network.ReceiveChan())
+	con.waitGroup.Add(1)
+	go con.deliverNetworkMsg()
+	con.waitGroup.Add(1)
+	go con.processMsg()
 	// Sleep until dMoment come.
 	time.Sleep(con.dMoment.Sub(time.Now().UTC()))
 	// Take some time to bootstrap.
 	time.Sleep(3 * time.Second)
+	con.waitGroup.Add(1)
 	go con.pullRandomness()
+	// Stop dummy receiver if launched.
+	if con.dummyCancel != nil {
+		con.logger.Trace("Stop dummy receiver")
+		con.dummyCancel()
+		<-con.dummyFinished
+		// Replay those cached messages.
+		con.logger.Trace("Dummy receiver stoped, start dumping cached messages",
+			"count", len(con.dummyMsgBuffer))
+		for _, msg := range con.dummyMsgBuffer {
+		loop:
+			for {
+				select {
+				case con.msgChan <- msg:
+					break loop
+				case <-time.After(50 * time.Millisecond):
+					con.logger.Debug(
+						"internal message channel is full when syncing")
+				}
+			}
+		}
+		con.logger.Trace("Finish dumping cached messages")
+	}
+	con.waitGroup.Add(1)
+	go con.deliveryGuard()
 	// Block until done.
 	select {
 	case <-con.ctx.Done():
@@ -785,18 +879,51 @@ func (con *Consensus) Stop() {
 	con.ctxCancel()
 	con.baMgr.stop()
 	con.event.Reset()
+	con.waitGroup.Wait()
 }
 
-func (con *Consensus) processMsg(msgChan <-chan interface{}) {
+func (con *Consensus) deliverNetworkMsg() {
+	defer con.waitGroup.Done()
+	recv := con.network.ReceiveChan()
+	for {
+		select {
+		case <-con.ctx.Done():
+			return
+		default:
+		}
+		select {
+		case msg := <-recv:
+		innerLoop:
+			for {
+				select {
+				case con.msgChan <- msg:
+					break innerLoop
+				case <-time.After(500 * time.Millisecond):
+					con.logger.Debug("internal message channel is full",
+						"pending", msg)
+				}
+			}
+		case <-con.ctx.Done():
+			return
+		}
+	}
+}
+
+func (con *Consensus) processMsg() {
+	defer con.waitGroup.Done()
 MessageLoop:
 	for {
+		select {
+		case <-con.ctx.Done():
+			return
+		default:
+		}
 		var msg interface{}
 		select {
-		case msg = <-msgChan:
+		case msg = <-con.msgChan:
 		case <-con.ctx.Done():
 			return
 		}
-
 		switch val := msg.(type) {
 		case *types.Block:
 			if ch, exist := func() (chan<- *types.Block, bool) {
@@ -805,7 +932,7 @@ MessageLoop:
 				ch, e := con.baConfirmedBlock[val.Hash]
 				return ch, e
 			}(); exist {
-				if err := con.lattice.SanityCheck(val); err != nil {
+				if err := con.lattice.SanityCheck(val, false); err != nil {
 					if err == ErrRetrySanityCheckLater {
 						err = nil
 					} else {
@@ -913,6 +1040,7 @@ func (con *Consensus) ProcessAgreementResult(
 	if err := VerifyAgreementResult(rand, con.nodeSetCache); err != nil {
 		return err
 	}
+	con.lattice.AddShallowBlock(rand.BlockHash, rand.Position)
 	// Syncing BA Module.
 	if err := con.baMgr.processAgreementResult(rand); err != nil {
 		return err
@@ -1007,10 +1135,16 @@ func (con *Consensus) preProcessBlock(b *types.Block) (err error) {
 }
 
 func (con *Consensus) pullRandomness() {
+	defer con.waitGroup.Done()
 	for {
 		select {
 		case <-con.ctx.Done():
 			return
+		default:
+		}
+		select {
+		case <-con.ctx.Done():
+			return
 		case <-con.resetRandomnessTicker:
 		case <-time.After(1500 * time.Millisecond):
 			// TODO(jimmy): pulling period should be related to lambdaBA.
@@ -1024,12 +1158,38 @@ func (con *Consensus) pullRandomness() {
 	}
 }
 
+func (con *Consensus) deliveryGuard() {
+	defer con.waitGroup.Done()
+	time.Sleep(con.dMoment.Sub(time.Now()))
+	// Node takes time to start.
+	time.Sleep(60 * time.Second)
+	for {
+		select {
+		case <-con.ctx.Done():
+			return
+		default:
+		}
+		select {
+		case <-con.ctx.Done():
+			return
+		case <-con.resetDeliveryGuardTicker:
+		case <-time.After(60 * time.Second):
+			con.logger.Error("no blocks delivered for too long", "ID", con.ID)
+			panic(fmt.Errorf("no blocks delivered for too long"))
+		}
+	}
+}
+
 // deliverBlock deliver a block to application layer.
 func (con *Consensus) deliverBlock(b *types.Block) {
 	select {
 	case con.resetRandomnessTicker <- struct{}{}:
 	default:
 	}
+	select {
+	case con.resetDeliveryGuardTicker <- struct{}{}:
+	default:
+	}
 	if err := con.db.UpdateBlock(*b); err != nil {
 		panic(err)
 	}
@@ -1086,9 +1246,7 @@ func (con *Consensus) deliverFinalizedBlocksWithoutLock() (err error) {
 	for _, b := range deliveredBlocks {
 		con.deliverBlock(b)
 	}
-	if err = con.lattice.PurgeBlocks(deliveredBlocks); err != nil {
-		return
-	}
+	err = con.lattice.PurgeBlocks(deliveredBlocks)
 	return
 }
 
@@ -1150,9 +1308,7 @@ func (con *Consensus) prepareBlock(b *types.Block,
 		err = ErrCRSNotReady
 		return
 	}
-	if err = con.signer.SignCRS(b, crs); err != nil {
-		return
-	}
+	err = con.signer.SignCRS(b, crs)
 	return
 }
 
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/db/level-db.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/db/level-db.go
index 75c30372f..1fe29fa10 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/db/level-db.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/db/level-db.go
@@ -72,11 +72,7 @@ func (lvl *LevelDBBackedDB) HasBlock(hash common.Hash) bool {
 }
 
 func (lvl *LevelDBBackedDB) internalHasBlock(key []byte) (bool, error) {
-	exists, err := lvl.db.Has(key, nil)
-	if err != nil {
-		return false, err
-	}
-	return exists, nil
+	return lvl.db.Has(key, nil)
 }
 
 // GetBlock implements the Reader.GetBlock method.
@@ -90,9 +86,6 @@ func (lvl *LevelDBBackedDB) GetBlock(
 		return
 	}
 	err = rlp.DecodeBytes(queried, &block)
-	if err != nil {
-		return
-	}
 	return
 }
 
@@ -113,9 +106,7 @@ func (lvl *LevelDBBackedDB) UpdateBlock(block types.Block) (err error) {
 		err = ErrBlockDoesNotExist
 		return
 	}
-	if err = lvl.db.Put(blockKey, marshaled, nil); err != nil {
-		return
-	}
+	err = lvl.db.Put(blockKey, marshaled, nil)
 	return
 }
 
@@ -134,9 +125,7 @@ func (lvl *LevelDBBackedDB) PutBlock(block types.Block) (err error) {
 		err = ErrBlockExists
 		return
 	}
-	if err = lvl.db.Put(blockKey, marshaled, nil); err != nil {
-		return
-	}
+	err = lvl.db.Put(blockKey, marshaled, nil)
 	return
 }
 
@@ -166,10 +155,7 @@ func (lvl *LevelDBBackedDB) PutCompactionChainTipInfo(
 	if info.Height+1 != height {
 		return ErrInvalidCompactionChainTipHeight
 	}
-	if err = lvl.db.Put(compactionChainTipInfoKey, marshaled, nil); err != nil {
-		return err
-	}
-	return nil
+	return lvl.db.Put(compactionChainTipInfoKey, marshaled, nil)
 }
 
 func (lvl *LevelDBBackedDB) internalGetCompactionChainTipInfo() (
@@ -181,9 +167,7 @@ func (lvl *LevelDBBackedDB) internalGetCompactionChainTipInfo() (
 		}
 		return
 	}
-	if err = rlp.DecodeBytes(queried, &info); err != nil {
-		return
-	}
+	err = rlp.DecodeBytes(queried, &info)
 	return
 }
 
@@ -201,11 +185,7 @@ func (lvl *LevelDBBackedDB) GetCompactionChainTipInfo() (
 
 // HasDKGPrivateKey check existence of DKG private key of one round.
 func (lvl *LevelDBBackedDB) HasDKGPrivateKey(round uint64) (bool, error) {
-	exists, err := lvl.db.Has(lvl.getDKGPrivateKeyKey(round), nil)
-	if err != nil {
-		return false, err
-	}
-	return exists, nil
+	return lvl.db.Has(lvl.getDKGPrivateKeyKey(round), nil)
 }
 
 // GetDKGPrivateKey get DKG private key of one round.
@@ -218,9 +198,7 @@ func (lvl *LevelDBBackedDB) GetDKGPrivateKey(round uint64) (
 		}
 		return
 	}
-	if err = rlp.DecodeBytes(queried, &prv); err != nil {
-		return
-	}
+	err = rlp.DecodeBytes(queried, &prv)
 	return
 }
 
@@ -239,11 +217,8 @@ func (lvl *LevelDBBackedDB) PutDKGPrivateKey(
 	if err != nil {
 		return err
 	}
-	if err := lvl.db.Put(
-		lvl.getDKGPrivateKeyKey(round), marshaled, nil); err != nil {
-		return err
-	}
-	return nil
+	return lvl.db.Put(
+		lvl.getDKGPrivateKeyKey(round), marshaled, nil)
 }
 
 func (lvl *LevelDBBackedDB) getBlockKey(hash common.Hash) (ret []byte) {
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/interfaces.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/interfaces.go
index aa87e38f7..a77ec9385 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/interfaces.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/interfaces.go
@@ -159,4 +159,7 @@ type Ticker interface {
 
 	// Stop the ticker.
 	Stop()
+
+	// Retart the ticker and clear all internal data.
+	Restart()
 }
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/lattice-data.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/lattice-data.go
index e55c0dbfc..cf81a1161 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/lattice-data.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/lattice-data.go
@@ -55,7 +55,7 @@ type ErrAckingBlockNotExists struct {
 }
 
 func (e ErrAckingBlockNotExists) Error() string {
-	return fmt.Sprintf("acking block %s not exists", e.hash)
+	return fmt.Sprintf("acking block %s not exists", e.hash.String()[:6])
 }
 
 // Errors for method usage
@@ -113,6 +113,8 @@ type latticeData struct {
 	blockByHash map[common.Hash]*types.Block
 	// This stores configuration for each round.
 	configs []*latticeDataConfig
+	// shallowBlocks stores the hash of blocks that their body is not receive yet.
+	shallowBlocks map[common.Hash]types.Position
 }
 
 // newLatticeData creates a new latticeData instance.
@@ -126,10 +128,11 @@ func newLatticeData(
 	genesisConfig.fromConfig(round, config)
 	genesisConfig.setRoundBeginTime(dMoment)
 	data = &latticeData{
-		db:          db,
-		chains:      make([]*chainStatus, genesisConfig.numChains),
-		blockByHash: make(map[common.Hash]*types.Block),
-		configs:     []*latticeDataConfig{genesisConfig},
+		db:            db,
+		chains:        make([]*chainStatus, genesisConfig.numChains),
+		blockByHash:   make(map[common.Hash]*types.Block),
+		configs:       []*latticeDataConfig{genesisConfig},
+		shallowBlocks: make(map[common.Hash]types.Position),
 	}
 	for i := range data.chains {
 		data.chains[i] = &chainStatus{
@@ -141,15 +144,35 @@ func newLatticeData(
 	return
 }
 
-func (data *latticeData) checkAckingRelations(b *types.Block) error {
+func (data *latticeData) addShallowBlock(hash common.Hash, pos types.Position) {
+	// We don't care other errors here. This `if` is to prevent being spammed by
+	// very old blocks.
+	if _, err := data.findBlock(hash); err != db.ErrBlockDoesNotExist {
+		return
+	}
+	data.shallowBlocks[hash] = pos
+}
+
+func (data *latticeData) checkAckingRelations(
+	b *types.Block, allowShallow bool) error {
 	acksByChainID := make(map[uint32]struct{}, len(data.chains))
 	for _, hash := range b.Acks {
 		bAck, err := data.findBlock(hash)
 		if err != nil {
 			if err == db.ErrBlockDoesNotExist {
-				return &ErrAckingBlockNotExists{hash}
+				err = &ErrAckingBlockNotExists{hash}
+				if allowShallow {
+					if pos, exist := data.shallowBlocks[hash]; exist {
+						bAck = &types.Block{
+							Position: pos,
+						}
+						err = nil
+					}
+				}
+			}
+			if err != nil {
+				return err
 			}
-			return err
 		}
 		// Check if it acks blocks from old rounds, the allowed round difference
 		// is 1.
@@ -172,7 +195,7 @@ func (data *latticeData) checkAckingRelations(b *types.Block) error {
 	return nil
 }
 
-func (data *latticeData) sanityCheck(b *types.Block) error {
+func (data *latticeData) sanityCheck(b *types.Block, allowShallow bool) error {
 	// TODO(mission): Check if its proposer is in validator set, lattice has no
 	// knowledge about node set.
 	config := data.getConfig(b.Position.Round)
@@ -196,7 +219,7 @@ func (data *latticeData) sanityCheck(b *types.Block) error {
 		if !config.isValidGenesisBlockTime(b) {
 			return ErrIncorrectBlockTime
 		}
-		return data.checkAckingRelations(b)
+		return data.checkAckingRelations(b, allowShallow)
 	}
 	// Check parent block if parent hash is specified.
 	if !b.ParentHash.Equal(common.Hash{}) {
@@ -257,10 +280,7 @@ func (data *latticeData) sanityCheck(b *types.Block) error {
 			return ErrNotAckParent
 		}
 	}
-	if err := data.checkAckingRelations(b); err != nil {
-		return err
-	}
-	return nil
+	return data.checkAckingRelations(b, allowShallow)
 }
 
 // addBlock processes blocks. It does sanity check, inserts block into lattice
@@ -504,19 +524,21 @@ func (data *latticeData) prepareEmptyBlock(b *types.Block) (err error) {
 }
 
 // TODO(mission): make more abstraction for this method.
-// nextHeight returns the next height of a chain.
-func (data *latticeData) nextHeight(
-	round uint64, chainID uint32) (uint64, error) {
+// nextBlock returns the next height and timestamp of a chain.
+func (data *latticeData) nextBlock(
+	round uint64, chainID uint32) (uint64, time.Time, error) {
 	chainTip := data.chains[chainID].tip
 	bindTip, err := data.isBindTip(
 		types.Position{Round: round, ChainID: chainID}, chainTip)
 	if err != nil {
-		return 0, err
+		return 0, time.Time{}, err
 	}
+	config := data.getConfig(round)
 	if bindTip {
-		return chainTip.Position.Height + 1, nil
+		return chainTip.Position.Height + 1,
+			chainTip.Timestamp.Add(config.minBlockTimeInterval), nil
 	}
-	return 0, nil
+	return 0, config.roundBeginTime, nil
 }
 
 // findBlock seeks blocks in memory or db.
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/lattice.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/lattice.go
index b30306aef..d531639b9 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/lattice.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/lattice.go
@@ -90,9 +90,7 @@ func (l *Lattice) PrepareBlock(
 	if b.Witness, err = l.app.PrepareWitness(b.Witness.Height); err != nil {
 		return
 	}
-	if err = l.signer.SignBlock(b); err != nil {
-		return
-	}
+	err = l.signer.SignBlock(b)
 	return
 }
 
@@ -103,17 +101,23 @@ func (l *Lattice) PrepareEmptyBlock(b *types.Block) (err error) {
 	if err = l.data.prepareEmptyBlock(b); err != nil {
 		return
 	}
-	if b.Hash, err = utils.HashBlock(b); err != nil {
-		return
-	}
+	b.Hash, err = utils.HashBlock(b)
 	return
 }
 
+// AddShallowBlock adds a hash of a block that is confirmed by other nodes but
+// the content is not arrived yet.
+func (l *Lattice) AddShallowBlock(hash common.Hash, pos types.Position) {
+	l.lock.Lock()
+	defer l.lock.Unlock()
+	l.data.addShallowBlock(hash, pos)
+}
+
 // SanityCheck checks the validity of a block.
 //
 // If any acking block of this block does not exist, Lattice caches this block
 // and retries when Lattice.ProcessBlock is called.
-func (l *Lattice) SanityCheck(b *types.Block) (err error) {
+func (l *Lattice) SanityCheck(b *types.Block, allowShallow bool) (err error) {
 	if b.IsEmpty() {
 		// Only need to verify block's hash.
 		var hash common.Hash
@@ -139,18 +143,13 @@ func (l *Lattice) SanityCheck(b *types.Block) (err error) {
 			return
 		}
 	}
-	if err = func() (err error) {
-		l.lock.RLock()
-		defer l.lock.RUnlock()
-		if err = l.data.sanityCheck(b); err != nil {
-			if _, ok := err.(*ErrAckingBlockNotExists); ok {
-				err = ErrRetrySanityCheckLater
-			}
-			return
+	l.lock.RLock()
+	defer l.lock.RUnlock()
+	if err = l.data.sanityCheck(b, allowShallow); err != nil {
+		if _, ok := err.(*ErrAckingBlockNotExists); ok {
+			err = ErrRetrySanityCheckLater
 		}
 		return
-	}(); err != nil {
-		return
 	}
 	return
 }
@@ -159,10 +158,8 @@ func (l *Lattice) SanityCheck(b *types.Block) (err error) {
 func (l *Lattice) Exist(hash common.Hash) bool {
 	l.lock.RLock()
 	defer l.lock.RUnlock()
-	if _, err := l.data.findBlock(hash); err != nil {
-		return false
-	}
-	return true
+	_, err := l.data.findBlock(hash)
+	return err == nil
 }
 
 // addBlockToLattice adds a block into lattice, and delivers blocks with the
@@ -189,7 +186,7 @@ func (l *Lattice) addBlockToLattice(
 			if tip = l.pool.tip(i); tip == nil {
 				continue
 			}
-			err = l.data.sanityCheck(tip)
+			err = l.data.sanityCheck(tip, false)
 			if err == nil {
 				var output []*types.Block
 				if output, err = l.data.addBlock(tip); err != nil {
@@ -199,6 +196,7 @@ func (l *Lattice) addBlockToLattice(
 						"block", tip, "error", err)
 					panic(err)
 				}
+				delete(l.data.shallowBlocks, tip.Hash)
 				hasOutput = true
 				outputBlocks = append(outputBlocks, output...)
 				l.pool.removeTip(i)
@@ -267,11 +265,11 @@ func (l *Lattice) ProcessBlock(
 		if len(toDelivered) == 0 {
 			break
 		}
-		hashes := make(common.Hashes, len(toDelivered))
-		for idx := range toDelivered {
-			hashes[idx] = toDelivered[idx].Hash
-		}
 		if l.debug != nil {
+			hashes := make(common.Hashes, len(toDelivered))
+			for idx := range toDelivered {
+				hashes[idx] = toDelivered[idx].Hash
+			}
 			l.debug.TotalOrderingDelivered(hashes, deliveredMode)
 		}
 		// Perform consensus timestamp module.
@@ -283,12 +281,13 @@ func (l *Lattice) ProcessBlock(
 	return
 }
 
-// NextHeight returns expected height of incoming block for specified chain and
-// given round.
-func (l *Lattice) NextHeight(round uint64, chainID uint32) (uint64, error) {
+// NextBlock returns expected height and timestamp of incoming block for
+// specified chain and given round.
+func (l *Lattice) NextBlock(round uint64, chainID uint32) (
+	uint64, time.Time, error) {
 	l.lock.RLock()
 	defer l.lock.RUnlock()
-	return l.data.nextHeight(round, chainID)
+	return l.data.nextBlock(round, chainID)
 }
 
 // PurgeBlocks purges blocks' cache in memory, this is called when the caller
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/leader-selector.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/leader-selector.go
index 94d28faeb..bcfa57fe6 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/leader-selector.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/leader-selector.go
@@ -150,10 +150,7 @@ func (l *leaderSelector) processBlock(block *types.Block) error {
 func (l *leaderSelector) potentialLeader(block *types.Block) (bool, *big.Int) {
 	dist := l.distance(block.CRSSignature)
 	cmp := l.minCRSBlock.Cmp(dist)
-	if cmp > 0 || (cmp == 0 && block.Hash.Less(l.minBlockHash)) {
-		return true, dist
-	}
-	return false, dist
+	return (cmp > 0 || (cmp == 0 && block.Hash.Less(l.minBlockHash))), dist
 }
 
 func (l *leaderSelector) updateLeader(block *types.Block, dist *big.Int) {
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/syncer/agreement.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/syncer/agreement.go
index 9b351eabc..acc4f1c6c 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/syncer/agreement.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/syncer/agreement.go
@@ -1,4 +1,4 @@
-// Copyright 2018 The dexon-consensus-core Authors
+// Copyright 2018 The dexon-consensus Authors
 // This file is part of the dexon-consensus-core library.
 //
 // The dexon-consensus-core library is free software: you can redistribute it
@@ -18,6 +18,9 @@
 package syncer
 
 import (
+	"context"
+	"time"
+
 	"github.com/dexon-foundation/dexon-consensus/common"
 	"github.com/dexon-foundation/dexon-consensus/core"
 	"github.com/dexon-foundation/dexon-consensus/core/types"
@@ -37,16 +40,14 @@ type agreement struct {
 	pendings         map[uint64]map[common.Hash]*types.AgreementResult
 	logger           common.Logger
 	confirmedBlocks  map[common.Hash]struct{}
+	ctx              context.Context
+	ctxCancel        context.CancelFunc
 }
 
 // newAgreement creates a new agreement instance.
-func newAgreement(
-	ch chan<- *types.Block,
-	pullChan chan<- common.Hash,
-	cache *utils.NodeSetCache,
-	logger common.Logger) *agreement {
-
-	return &agreement{
+func newAgreement(ch chan<- *types.Block, pullChan chan<- common.Hash,
+	cache *utils.NodeSetCache, logger common.Logger) *agreement {
+	a := &agreement{
 		cache:            cache,
 		inputChan:        make(chan interface{}, 1000),
 		outputChan:       ch,
@@ -58,11 +59,14 @@ func newAgreement(
 			map[uint64]map[common.Hash]*types.AgreementResult),
 		confirmedBlocks: make(map[common.Hash]struct{}),
 	}
+	a.ctx, a.ctxCancel = context.WithCancel(context.Background())
+	return a
 }
 
 // run starts the agreement, this does not start a new routine, go a new
 // routine explicitly in the caller.
 func (a *agreement) run() {
+	defer a.ctxCancel()
 	for {
 		select {
 		case val, ok := <-a.inputChan:
@@ -119,22 +123,35 @@ func (a *agreement) processAgreementResult(r *types.AgreementResult) {
 		return
 	}
 	if r.IsEmptyBlock {
-		// Empty block is also confirmed.
 		b := &types.Block{
 			Position: r.Position,
 		}
+		// Empty blocks should be confirmed directly, they won't be sent over
+		// the wire.
 		a.confirm(b)
-	} else {
-		needPull := true
-		if bs, exist := a.blocks[r.Position]; exist {
-			if b, exist := bs[r.BlockHash]; exist {
-				a.confirm(b)
-				needPull = false
-			}
+		return
+	}
+	if bs, exist := a.blocks[r.Position]; exist {
+		if b, exist := bs[r.BlockHash]; exist {
+			a.confirm(b)
+			return
 		}
-		if needPull {
-			a.agreementResults[r.BlockHash] = struct{}{}
-			a.pullChan <- r.BlockHash
+	}
+	a.agreementResults[r.BlockHash] = struct{}{}
+loop:
+	for {
+		select {
+		case a.pullChan <- r.BlockHash:
+			break loop
+		case <-a.ctx.Done():
+			a.logger.Error("pull request is not sent",
+				"position", &r.Position,
+				"hash", r.BlockHash.String()[:6])
+			return
+		case <-time.After(500 * time.Millisecond):
+			a.logger.Debug("pull request is unable to send",
+				"position", &r.Position,
+				"hash", r.BlockHash.String()[:6])
 		}
 	}
 }
@@ -168,7 +185,18 @@ func (a *agreement) confirm(b *types.Block) {
 	if _, exist := a.confirmedBlocks[b.Hash]; !exist {
 		delete(a.blocks, b.Position)
 		delete(a.agreementResults, b.Hash)
-		a.outputChan <- b
+	loop:
+		for {
+			select {
+			case a.outputChan <- b:
+				break loop
+			case <-a.ctx.Done():
+				a.logger.Error("confirmed block is not sent", "block", b)
+				return
+			case <-time.After(500 * time.Millisecond):
+				a.logger.Debug("agreement output channel is full", "block", b)
+			}
+		}
 		a.confirmedBlocks[b.Hash] = struct{}{}
 	}
 }
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/syncer/consensus.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/syncer/consensus.go
index 92f8fd8d0..75c106793 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/syncer/consensus.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/syncer/consensus.go
@@ -18,7 +18,6 @@
 package syncer
 
 import (
-	"bytes"
 	"context"
 	"fmt"
 	"sort"
@@ -40,7 +39,8 @@ var (
 	ErrNotSynced = fmt.Errorf("not synced yet")
 	// ErrGenesisBlockReached is reported when genesis block reached.
 	ErrGenesisBlockReached = fmt.Errorf("genesis block reached")
-	// ErrInvalidBlockOrder is reported when SyncBlocks receives unordered blocks.
+	// ErrInvalidBlockOrder is reported when SyncBlocks receives unordered
+	// blocks.
 	ErrInvalidBlockOrder = fmt.Errorf("invalid block order")
 	// ErrMismatchBlockHashSequence means the delivering sequence is not
 	// correct, compared to finalized blocks.
@@ -61,6 +61,7 @@ type Consensus struct {
 	prv          crypto.PrivateKey
 	network      core.Network
 	nodeSetCache *utils.NodeSetCache
+	tsigVerifier *core.TSigVerifierCache
 
 	lattice              *core.Lattice
 	validatedChains      map[uint32]struct{}
@@ -83,6 +84,9 @@ type Consensus struct {
 	ctxCancel          context.CancelFunc
 	syncedLastBlock    *types.Block
 	syncedConsensus    *core.Consensus
+	dummyCancel        context.CancelFunc
+	dummyFinished      <-chan struct{}
+	dummyMsgBuffer     []interface{}
 }
 
 // NewConsensus creates an instance for Consensus (syncer consensus).
@@ -102,6 +106,7 @@ func NewConsensus(
 		db:              db,
 		network:         network,
 		nodeSetCache:    utils.NewNodeSetCache(gov),
+		tsigVerifier:    core.NewTSigVerifierCache(gov, 7),
 		prv:             prv,
 		logger:          logger,
 		validatedChains: make(map[uint32]struct{}),
@@ -118,17 +123,15 @@ func NewConsensus(
 }
 
 func (con *Consensus) initConsensusObj(initBlock *types.Block) {
-	var cfg *types.Config
 	func() {
 		con.lock.Lock()
 		defer con.lock.Unlock()
 		con.latticeLastRound = initBlock.Position.Round
-		cfg = con.configs[con.latticeLastRound]
 		debugApp, _ := con.app.(core.Debug)
 		con.lattice = core.NewLattice(
 			con.roundBeginTimes[con.latticeLastRound],
 			con.latticeLastRound,
-			cfg,
+			con.configs[con.latticeLastRound],
 			utils.NewSigner(con.prv),
 			con.app,
 			debugApp,
@@ -136,37 +139,49 @@ func (con *Consensus) initConsensusObj(initBlock *types.Block) {
 			con.logger,
 		)
 	}()
-	con.startAgreement(cfg.NumChains)
+	con.startAgreement()
 	con.startNetwork()
 	con.startCRSMonitor()
 }
 
-func (con *Consensus) checkIfValidated() bool {
+func (con *Consensus) checkIfValidated() (validated bool) {
 	con.lock.RLock()
 	defer con.lock.RUnlock()
-	var numChains = con.configs[con.blocks[0][0].Position.Round].NumChains
-	var validatedChainCount uint32
+	var (
+		round               = con.blocks[0][0].Position.Round
+		numChains           = con.configs[round].NumChains
+		validatedChainCount uint32
+	)
 	// Make sure we validate some block in all chains.
 	for chainID := range con.validatedChains {
 		if chainID < numChains {
 			validatedChainCount++
 		}
 	}
-	if validatedChainCount == numChains {
-		return true
-	}
-	con.logger.Debug("not validated yet", "validated-chain", validatedChainCount)
-	return false
+	validated = validatedChainCount == numChains
+	con.logger.Debug("syncer chain-validation status",
+		"validated-chain", validatedChainCount,
+		"round", round,
+		"valid", validated)
+	return
 }
 
-func (con *Consensus) checkIfSynced(blocks []*types.Block) bool {
+func (con *Consensus) checkIfSynced(blocks []*types.Block) (synced bool) {
 	con.lock.RLock()
 	defer con.lock.RUnlock()
 	var (
-		numChains      = con.configs[con.blocks[0][0].Position.Round].NumChains
+		round          = con.blocks[0][0].Position.Round
+		numChains      = con.configs[round].NumChains
 		compactionTips = make([]*types.Block, numChains)
 		overlapCount   = uint32(0)
 	)
+	defer func() {
+		con.logger.Debug("syncer synced status",
+			"overlap-count", overlapCount,
+			"num-chain", numChains,
+			"last-block", blocks[len(blocks)-1],
+			"synced", synced)
+	}()
 	// Find tips (newset blocks) of each chain in compaction chain.
 	b := blocks[len(blocks)-1]
 	for tipCount := uint32(0); tipCount < numChains; {
@@ -178,7 +193,7 @@ func (con *Consensus) checkIfSynced(blocks []*types.Block) bool {
 			}
 		}
 		if (b.Finalization.ParentHash == common.Hash{}) {
-			return false
+			return
 		}
 		b1, err := con.db.GetBlock(b.Finalization.ParentHash)
 		if err != nil {
@@ -196,14 +211,8 @@ func (con *Consensus) checkIfSynced(blocks []*types.Block) bool {
 			}
 		}
 	}
-	if overlapCount == numChains {
-		return true
-	}
-	con.logger.Debug("not synced yet",
-		"overlap-count", overlapCount,
-		"num-chain", numChains,
-		"last-block", blocks[len(blocks)-1])
-	return false
+	synced = overlapCount == numChains
+	return
 }
 
 // ensureAgreementOverlapRound ensures the oldest blocks in each chain in
@@ -212,6 +221,10 @@ func (con *Consensus) checkIfSynced(blocks []*types.Block) bool {
 func (con *Consensus) ensureAgreementOverlapRound() bool {
 	con.lock.Lock()
 	defer con.lock.Unlock()
+	defer func() {
+		con.logger.Debug("ensureAgreementOverlapRound returned",
+			"round", con.agreementRoundCut)
+	}()
 	if con.agreementRoundCut > 0 {
 		return true
 	}
@@ -267,7 +280,6 @@ func (con *Consensus) ensureAgreementOverlapRound() bool {
 			"configs", len(con.configs))
 		if tipRoundMap[r] == con.configs[r].NumChains {
 			con.agreementRoundCut = r
-			con.logger.Info("agreement round cut found, round", r)
 			return true
 		}
 	}
@@ -278,12 +290,17 @@ func (con *Consensus) findLatticeSyncBlock(
 	blocks []*types.Block) (*types.Block, error) {
 	lastBlock := blocks[len(blocks)-1]
 	round := lastBlock.Position.Round
+	isConfigChanged := func(prev, cur *types.Config) bool {
+		return prev.K != cur.K ||
+			prev.NumChains != cur.NumChains ||
+			prev.PhiRatio != cur.PhiRatio
+	}
 	for {
 		// Find round r which r-1, r, r+1 are all in same total ordering config.
 		for {
-			sameAsPrevRound := round == 0 || !con.isConfigChanged(
+			sameAsPrevRound := round == 0 || !isConfigChanged(
 				con.configs[round-1], con.configs[round])
-			sameAsNextRound := !con.isConfigChanged(
+			sameAsNextRound := !isConfigChanged(
 				con.configs[round], con.configs[round+1])
 			if sameAsPrevRound && sameAsNextRound {
 				break
@@ -306,8 +323,9 @@ func (con *Consensus) findLatticeSyncBlock(
 			lastBlock = &b
 		}
 		// Find the deliver set by hash for two times. Blocks in a deliver set
-		// returned by total ordering is sorted by hash. If a block's parent hash
-		// is greater than its hash means there is a cut between deliver sets.
+		// returned by total ordering is sorted by hash. If a block's parent
+		// hash is greater than its hash means there is a cut between deliver
+		// sets.
 		var curBlock, prevBlock *types.Block
 		var deliverSetFirstBlock, deliverSetLastBlock *types.Block
 		curBlock = lastBlock
@@ -374,11 +392,13 @@ func (con *Consensus) processFinalizedBlock(block *types.Block) error {
 	if con.lattice == nil {
 		return nil
 	}
-	con.finalizedBlockHashes = append(con.finalizedBlockHashes, block.Hash)
 	delivered, err := con.lattice.ProcessFinalizedBlock(block)
 	if err != nil {
 		return err
 	}
+	con.lock.Lock()
+	defer con.lock.Unlock()
+	con.finalizedBlockHashes = append(con.finalizedBlockHashes, block.Hash)
 	for idx, b := range delivered {
 		if con.finalizedBlockHashes[idx] != b.Hash {
 			return ErrMismatchBlockHashSequence
@@ -393,18 +413,27 @@ func (con *Consensus) processFinalizedBlock(block *types.Block) error {
 // regards the blocks are the latest ones. Notice that latest can be true for
 // many times.
 // NOTICE: parameter "blocks" should be consecutive in compaction height.
+// NOTICE: this method is not expected to be called concurrently.
 func (con *Consensus) SyncBlocks(
-	blocks []*types.Block, latest bool) (bool, error) {
+	blocks []*types.Block, latest bool) (synced bool, err error) {
+	defer func() {
+		con.logger.Debug("SyncBlocks returned",
+			"synced", synced,
+			"error", err,
+			"last-block", con.syncedLastBlock)
+	}()
 	if con.syncedLastBlock != nil {
-		return true, ErrAlreadySynced
+		synced, err = true, ErrAlreadySynced
+		return
 	}
 	if len(blocks) == 0 {
-		return false, nil
+		return
 	}
 	// Check if blocks are consecutive.
 	for i := 1; i < len(blocks); i++ {
 		if blocks[i].Finalization.Height != blocks[i-1].Finalization.Height+1 {
-			return false, ErrInvalidBlockOrder
+			err = ErrInvalidBlockOrder
+			return
 		}
 	}
 	// Make sure the first block is the next block of current compaction chain
@@ -414,7 +443,8 @@ func (con *Consensus) SyncBlocks(
 		con.logger.Error("mismatched finalization height",
 			"now", blocks[0].Finalization.Height,
 			"expected", tipHeight+1)
-		return false, ErrInvalidSyncingFinalizationHeight
+		err = ErrInvalidSyncingFinalizationHeight
+		return
 	}
 	con.logger.Trace("syncBlocks",
 		"position", &blocks[0].Position,
@@ -425,30 +455,35 @@ func (con *Consensus) SyncBlocks(
 	con.setupConfigs(blocks)
 	for _, b := range blocks {
 		// TODO(haoping) remove this if lattice puts blocks into db.
-		if err := con.db.PutBlock(*b); err != nil {
+		if err = con.db.PutBlock(*b); err != nil {
 			// A block might be put into db when confirmed by BA, but not
 			// finalized yet.
 			if err == db.ErrBlockExists {
 				err = con.db.UpdateBlock(*b)
 			}
 			if err != nil {
-				return false, err
+				return
 			}
 		}
-		if err := con.db.PutCompactionChainTipInfo(
+		if err = con.db.PutCompactionChainTipInfo(
 			b.Hash, b.Finalization.Height); err != nil {
-			return false, err
+			return
 		}
-		if err := con.processFinalizedBlock(b); err != nil {
-			return false, err
+		if err = con.processFinalizedBlock(b); err != nil {
+			return
 		}
 	}
 	if latest && con.lattice == nil {
-		// New Lattice and find the deliver set of total ordering when "latest" is
-		// true for first time. Deliver set is found by block hashes.
-		syncBlock, err := con.findLatticeSyncBlock(blocks)
+		// New Lattice and find the deliver set of total ordering when "latest"
+		// is true for first time. Deliver set is found by block hashes.
+		var syncBlock *types.Block
+		syncBlock, err = con.findLatticeSyncBlock(blocks)
 		if err != nil {
-			return false, err
+			if err == ErrGenesisBlockReached {
+				con.logger.Debug("SyncBlocks skip error", "error", err)
+				err = nil
+			}
+			return
 		}
 		if syncBlock != nil {
 			con.logger.Debug("deliver set found", "block", syncBlock)
@@ -457,7 +492,8 @@ func (con *Consensus) SyncBlocks(
 			con.setupConfigs(blocks)
 			// Process blocks from syncBlock to blocks' last block.
 			b := blocks[len(blocks)-1]
-			blocksCount := b.Finalization.Height - syncBlock.Finalization.Height + 1
+			blocksCount :=
+				b.Finalization.Height - syncBlock.Finalization.Height + 1
 			blocksToProcess := make([]*types.Block, blocksCount)
 			for {
 				blocksToProcess[blocksCount-1] = b
@@ -465,15 +501,16 @@ func (con *Consensus) SyncBlocks(
 				if b.Hash == syncBlock.Hash {
 					break
 				}
-				b1, err := con.db.GetBlock(b.Finalization.ParentHash)
+				var b1 types.Block
+				b1, err = con.db.GetBlock(b.Finalization.ParentHash)
 				if err != nil {
-					return false, err
+					return
 				}
 				b = &b1
 			}
 			for _, b := range blocksToProcess {
-				if err := con.processFinalizedBlock(b); err != nil {
-					return false, err
+				if err = con.processFinalizedBlock(b); err != nil {
+					return
 				}
 			}
 		}
@@ -483,19 +520,25 @@ func (con *Consensus) SyncBlocks(
 		// overlapping of compaction chain and BA's oldest blocks means the
 		// syncing is done.
 		if con.checkIfValidated() && con.checkIfSynced(blocks) {
-			if err := con.Stop(); err != nil {
-				return false, err
+			if err = con.Stop(); err != nil {
+				return
 			}
+			con.dummyCancel, con.dummyFinished = utils.LaunchDummyReceiver(
+				context.Background(), con.network.ReceiveChan(),
+				func(msg interface{}) {
+					con.dummyMsgBuffer = append(con.dummyMsgBuffer, msg)
+				})
 			con.syncedLastBlock = blocks[len(blocks)-1]
-			con.logger.Info("syncer.Consensus synced",
-				"last-block", con.syncedLastBlock)
+			synced = true
 		}
 	}
-	return con.syncedLastBlock != nil, nil
+	return
 }
 
 // GetSyncedConsensus returns the core.Consensus instance after synced.
 func (con *Consensus) GetSyncedConsensus() (*core.Consensus, error) {
+	con.lock.Lock()
+	defer con.lock.Unlock()
 	if con.syncedConsensus != nil {
 		return con.syncedConsensus, nil
 	}
@@ -504,18 +547,16 @@ func (con *Consensus) GetSyncedConsensus() (*core.Consensus, error) {
 	}
 	// flush all blocks in con.blocks into core.Consensus, and build
 	// core.Consensus from syncer.
-	confirmedBlocks := []*types.Block{}
+	confirmedBlocks := make([][]*types.Block, len(con.blocks))
+	for i, bs := range con.blocks {
+		confirmedBlocks[i] = []*types.Block(bs)
+	}
 	randomnessResults := []*types.BlockRandomnessResult{}
-	func() {
-		con.lock.Lock()
-		defer con.lock.Unlock()
-		for _, bs := range con.blocks {
-			confirmedBlocks = append(confirmedBlocks, bs...)
-		}
-		for _, r := range con.randomnessResults {
-			randomnessResults = append(randomnessResults, r)
-		}
-	}()
+	for _, r := range con.randomnessResults {
+		randomnessResults = append(randomnessResults, r)
+	}
+	con.dummyCancel()
+	<-con.dummyFinished
 	var err error
 	con.syncedConsensus, err = core.NewConsensusFromSyncer(
 		con.syncedLastBlock,
@@ -528,6 +569,7 @@ func (con *Consensus) GetSyncedConsensus() (*core.Consensus, error) {
 		con.lattice,
 		confirmedBlocks,
 		randomnessResults,
+		con.dummyMsgBuffer,
 		con.logger)
 	return con.syncedConsensus, err
 }
@@ -535,13 +577,17 @@ func (con *Consensus) GetSyncedConsensus() (*core.Consensus, error) {
 // Stop the syncer.
 //
 // This method is mainly for caller to stop the syncer before synced, the syncer
-// would call this method automatically after synced.
+// would call this method automatically after being synced.
 func (con *Consensus) Stop() error {
+	con.logger.Trace("syncer is about to stop")
 	// Stop network and CRS routines, wait until they are all stoped.
 	con.ctxCancel()
+	con.logger.Trace("stop syncer modules")
 	con.moduleWaitGroup.Wait()
 	// Stop agreements.
+	con.logger.Trace("stop syncer agreement modules")
 	con.stopAgreement()
+	con.logger.Trace("syncer stopped")
 	return nil
 }
 
@@ -566,6 +612,10 @@ func (con *Consensus) setupConfigsUntilRound(round uint64) {
 	func() {
 		con.lock.Lock()
 		defer con.lock.Unlock()
+		con.logger.Debug("syncer setupConfigs",
+			"until-round", round,
+			"length", len(con.configs),
+			"lattice", con.latticeLastRound)
 		for r := uint64(len(con.configs)); r <= round; r++ {
 			cfg := utils.GetConfigWithPanic(con.gov, r, con.logger)
 			con.configs = append(con.configs, cfg)
@@ -589,6 +639,7 @@ func (con *Consensus) setupConfigsUntilRound(round uint64) {
 		}
 	}()
 	con.resizeByNumChains(curMaxNumChains)
+	con.logger.Trace("setupConfgis finished", "round", round)
 }
 
 // setupConfigs is called by SyncBlocks with blocks from compaction chain. In
@@ -601,9 +652,6 @@ func (con *Consensus) setupConfigs(blocks []*types.Block) {
 			maxRound = b.Position.Round
 		}
 	}
-	con.logger.Debug("syncer setupConfigs",
-		"max", maxRound,
-		"lattice", con.latticeLastRound)
 	// Get configs from governance.
 	//
 	// In fullnode, the notification of new round is yet another TX, which
@@ -623,7 +671,8 @@ func (con *Consensus) resizeByNumChains(numChains uint32) {
 			// Resize the pool of blocks.
 			con.blocks = append(con.blocks, types.ByPosition{})
 			// Resize agreement modules.
-			a := newAgreement(con.receiveChan, con.pullChan, con.nodeSetCache, con.logger)
+			a := newAgreement(
+				con.receiveChan, con.pullChan, con.nodeSetCache, con.logger)
 			con.agreements = append(con.agreements, a)
 			con.agreementWaitGroup.Add(1)
 			go func() {
@@ -635,7 +684,7 @@ func (con *Consensus) resizeByNumChains(numChains uint32) {
 }
 
 // startAgreement starts agreements for receiving votes and agreements.
-func (con *Consensus) startAgreement(numChains uint32) {
+func (con *Consensus) startAgreement() {
 	// Start a routine for listening receive channel and pull block channel.
 	go func() {
 		for {
@@ -648,8 +697,8 @@ func (con *Consensus) startAgreement(numChains uint32) {
 				func() {
 					con.lock.Lock()
 					defer con.lock.Unlock()
-					// If round is cut in agreements, do not add blocks with round less
-					// then cut round.
+					// If round is cut in agreements, do not add blocks with
+					// round less then cut round.
 					if b.Position.Round < con.agreementRoundCut {
 						return
 					}
@@ -667,6 +716,10 @@ func (con *Consensus) startAgreement(numChains uint32) {
 }
 
 func (con *Consensus) cacheRandomnessResult(r *types.BlockRandomnessResult) {
+	// There is no block randomness at round-0.
+	if r.Position.Round == 0 {
+		return
+	}
 	// We only have to cache randomness result after cutting round.
 	if r.Position.Round < func() uint64 {
 		con.lock.RLock()
@@ -675,23 +728,43 @@ func (con *Consensus) cacheRandomnessResult(r *types.BlockRandomnessResult) {
 	}() {
 		return
 	}
-	con.lock.Lock()
-	defer con.lock.Unlock()
-	if old, exists := con.randomnessResults[r.BlockHash]; exists {
-		if bytes.Compare(old.Randomness, r.Randomness) != 0 {
-			panic(fmt.Errorf("receive different randomness result: %s, %s",
-				r.BlockHash.String()[:6], &r.Position))
-		}
-		// We don't have to assign the map again.
+	if func() (exists bool) {
+		con.lock.RLock()
+		defer con.lock.RUnlock()
+		_, exists = con.randomnessResults[r.BlockHash]
+		return
+	}() {
+		return
+	}
+	v, ok, err := con.tsigVerifier.UpdateAndGet(r.Position.Round)
+	if err != nil {
+		con.logger.Error("Unable to get tsig verifier",
+			"hash", r.BlockHash.String()[:6],
+			"position", &r.Position,
+			"error", err)
+		return
+	}
+	if !ok {
+		con.logger.Error("Tsig is not ready", "position", &r.Position)
 		return
 	}
+	if !v.VerifySignature(r.BlockHash, crypto.Signature{
+		Type:      "bls",
+		Signature: r.Randomness}) {
+		con.logger.Info("Block randomness is not valid",
+			"position", &r.Position,
+			"hash", r.BlockHash.String()[:6])
+		return
+	}
+	con.lock.Lock()
+	defer con.lock.Unlock()
 	con.randomnessResults[r.BlockHash] = r
 }
 
 // startNetwork starts network for receiving blocks and agreement results.
 func (con *Consensus) startNetwork() {
+	con.moduleWaitGroup.Add(1)
 	go func() {
-		con.moduleWaitGroup.Add(1)
 		defer con.moduleWaitGroup.Done()
 	Loop:
 		for {
@@ -709,15 +782,22 @@ func (con *Consensus) startNetwork() {
 				default:
 					continue Loop
 				}
-				func() {
+				if func() bool {
 					con.lock.RLock()
 					defer con.lock.RUnlock()
 					if pos.ChainID >= uint32(len(con.agreements)) {
-						con.logger.Error("Unknown chainID message received (syncer)",
+						// This error might be easily encountered when the
+						// "latest" parameter of SyncBlocks is turned on too
+						// early.
+						con.logger.Error(
+							"Unknown chainID message received (syncer)",
 							"position", &pos)
+						return false
 					}
-				}()
-				con.agreements[pos.ChainID].inputChan <- val
+					return true
+				}() {
+					con.agreements[pos.ChainID].inputChan <- val
+				}
 			case <-con.ctx.Done():
 				return
 			}
@@ -732,19 +812,32 @@ func (con *Consensus) startCRSMonitor() {
 	// Notify all agreements for new CRS.
 	notifyNewCRS := func(round uint64) {
 		con.setupConfigsUntilRound(round)
-		con.lock.Lock()
-		defer con.lock.Unlock()
 		if round == lastNotifiedRound {
 			return
 		}
 		con.logger.Debug("CRS is ready", "round", round)
 		lastNotifiedRound = round
-		for _, a := range con.agreements {
-			a.inputChan <- round
+		con.lock.Lock()
+		defer con.lock.Unlock()
+		for idx, a := range con.agreements {
+		loop:
+			for {
+				select {
+				case <-con.ctx.Done():
+					break loop
+				case a.inputChan <- round:
+					break loop
+				case <-time.After(500 * time.Millisecond):
+					con.logger.Debug(
+						"agreement input channel is full when putting CRS",
+						"chainID", idx,
+						"round", round)
+				}
+			}
 		}
 	}
+	con.moduleWaitGroup.Add(1)
 	go func() {
-		con.moduleWaitGroup.Add(1)
 		defer con.moduleWaitGroup.Done()
 		for {
 			select {
@@ -781,9 +874,3 @@ func (con *Consensus) stopAgreement() {
 	close(con.receiveChan)
 	close(con.pullChan)
 }
-
-func (con *Consensus) isConfigChanged(prev, cur *types.Config) bool {
-	return prev.K != cur.K ||
-		prev.NumChains != cur.NumChains ||
-		prev.PhiRatio != cur.PhiRatio
-}
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/ticker.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/ticker.go
index f8d0c67d9..ffd5ab45d 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/ticker.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/ticker.go
@@ -36,12 +36,16 @@ const (
 // defaultTicker is a wrapper to implement ticker interface based on
 // time.Ticker.
 type defaultTicker struct {
-	ticker *time.Ticker
+	ticker   *time.Ticker
+	duration time.Duration
 }
 
 // newDefaultTicker constructs an defaultTicker instance by giving an interval.
 func newDefaultTicker(lambda time.Duration) *defaultTicker {
-	return &defaultTicker{ticker: time.NewTicker(lambda)}
+	return &defaultTicker{
+		ticker:   time.NewTicker(lambda),
+		duration: lambda,
+	}
 }
 
 // Tick implements Tick method of ticker interface.
@@ -54,6 +58,12 @@ func (t *defaultTicker) Stop() {
 	t.ticker.Stop()
 }
 
+// Restart implements Stop method of ticker interface.
+func (t *defaultTicker) Restart() {
+	t.ticker.Stop()
+	t.ticker = time.NewTicker(t.duration)
+}
+
 // newTicker is a helper to setup a ticker by giving an Governance. If
 // the governace object implements a ticker generator, a ticker from that
 // generator would be returned, else constructs a default one.
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/total-ordering.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/total-ordering.go
index de8dd0bb7..2e2158e7c 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/total-ordering.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/total-ordering.go
@@ -652,12 +652,14 @@ func (global *totalOrderingGlobalVector) addBlock(
 				return
 			}
 			// Add breakpoint.
-			global.breakpoints[chainID] = append(
-				global.breakpoints[chainID],
-				&totalOrderingBreakpoint{
-					roundID:    b.Position.Round,
-					lastHeight: tip.Position.Height,
-				})
+			if b.Position.Round > global.curRound {
+				global.breakpoints[chainID] = append(
+					global.breakpoints[chainID],
+					&totalOrderingBreakpoint{
+						roundID:    b.Position.Round,
+						lastHeight: tip.Position.Height,
+					})
+			}
 		} else {
 			if b.Position.Height != tip.Position.Height+1 {
 				err = ErrInvalidDAG
@@ -1052,7 +1054,6 @@ func (to *totalOrdering) generateDeliverSet() (
 	wg.Wait()
 	// Reset dirty chains.
 	to.dirtyChainIDs = to.dirtyChainIDs[:0]
-	// TODO(mission): ANS should be bounded by current numChains.
 	globalAnsLength := globalInfo.getAckingNodeSetLength(
 		globalInfo, cfg.k, cfg.numChains)
 CheckNextCandidateLoop:
@@ -1126,7 +1127,6 @@ CheckNextCandidateLoop:
 	checkANS := func() bool {
 		var chainAnsLength uint64
 		for p := range precedings {
-			// TODO(mission): ANS should be bound by current numChains.
 			chainAnsLength = to.candidates[p].getAckingNodeSetLength(
 				globalInfo, cfg.k, cfg.numChains)
 			if uint64(chainAnsLength) < uint64(cfg.numChains)-cfg.phi {
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/types/nodeset.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/types/nodeset.go
index da615e1f0..21a1e528e 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/types/nodeset.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/types/nodeset.go
@@ -41,6 +41,7 @@ type subSetTargetType byte
 const (
 	targetNotarySet subSetTargetType = iota
 	targetDKGSet
+	targetNodeLeader
 )
 
 type nodeRank struct {
@@ -72,6 +73,17 @@ func NewNodeSet() *NodeSet {
 	}
 }
 
+// NewNodeSetFromMap creates a new NodeSet from NodeID map.
+func NewNodeSetFromMap(nodes map[NodeID]struct{}) *NodeSet {
+	nIDs := make(map[NodeID]struct{}, len(nodes))
+	for nID := range nodes {
+		nIDs[nID] = struct{}{}
+	}
+	return &NodeSet{
+		IDs: nIDs,
+	}
+}
+
 // NewNotarySetTarget is the target for getting Notary Set.
 func NewNotarySetTarget(crs common.Hash, chainID uint32) *SubSetTarget {
 	binaryChainID := make([]byte, 4)
@@ -80,11 +92,23 @@ func NewNotarySetTarget(crs common.Hash, chainID uint32) *SubSetTarget {
 	return newTarget(targetNotarySet, crs[:], binaryChainID)
 }
 
-// NewDKGSetTarget  is the target for getting DKG Set.
+// NewDKGSetTarget is the target for getting DKG Set.
 func NewDKGSetTarget(crs common.Hash) *SubSetTarget {
 	return newTarget(targetDKGSet, crs[:])
 }
 
+// NewNodeLeaderTarget is the target for getting leader of fast BA.
+func NewNodeLeaderTarget(crs common.Hash, pos Position) *SubSetTarget {
+	binaryRoundID := make([]byte, 8)
+	binary.LittleEndian.PutUint64(binaryRoundID, pos.Round)
+	binaryChainID := make([]byte, 4)
+	binary.LittleEndian.PutUint32(binaryChainID, pos.ChainID)
+	binaryHeight := make([]byte, 8)
+	binary.LittleEndian.PutUint64(binaryHeight, pos.Height)
+	return newTarget(targetNodeLeader, crs[:],
+		binaryRoundID, binaryChainID, binaryHeight)
+}
+
 // Add a NodeID to the set.
 func (ns *NodeSet) Add(ID NodeID) {
 	ns.IDs[ID] = struct{}{}
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/types/vote.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/types/vote.go
index 7601542ae..97044f5aa 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/types/vote.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/types/vote.go
@@ -32,6 +32,7 @@ const (
 	VoteInit VoteType = iota
 	VotePreCom
 	VoteCom
+	VoteFast
 	// Do not add any type below MaxVoteType.
 	MaxVoteType
 )
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/utils.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/utils.go
index 0c2d15588..3b1069eb8 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/utils.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/utils.go
@@ -159,8 +159,10 @@ func VerifyAgreementResult(
 	if len(res.Votes) < len(notarySet)/3*2+1 {
 		return ErrNotEnoughVotes
 	}
-	if len(res.Votes) > len(notarySet) {
-		return ErrIncorrectVoteProposer
+	voted := make(map[types.NodeID]struct{}, len(notarySet))
+	voteType := res.Votes[0].Type
+	if voteType != types.VoteFast && voteType != types.VoteCom {
+		return ErrIncorrectVoteType
 	}
 	for _, vote := range res.Votes {
 		if res.IsEmptyBlock {
@@ -172,7 +174,7 @@ func VerifyAgreementResult(
 				return ErrIncorrectVoteBlockHash
 			}
 		}
-		if vote.Type != types.VoteCom {
+		if vote.Type != voteType {
 			return ErrIncorrectVoteType
 		}
 		if vote.Position != res.Position {
@@ -188,6 +190,10 @@ func VerifyAgreementResult(
 		if !ok {
 			return ErrIncorrectVoteSignature
 		}
+		voted[vote.ProposerID] = struct{}{}
+	}
+	if len(voted) < len(notarySet)/3*2+1 {
+		return ErrNotEnoughVotes
 	}
 	return nil
 }
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/utils/nodeset-cache.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/utils/nodeset-cache.go
index 6d4f7b0ba..8a07c9d2b 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/utils/nodeset-cache.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/utils/nodeset-cache.go
@@ -38,9 +38,11 @@ var (
 )
 
 type sets struct {
-	nodeSet   *types.NodeSet
-	notarySet []map[types.NodeID]struct{}
-	dkgSet    map[types.NodeID]struct{}
+	crs        common.Hash
+	nodeSet    *types.NodeSet
+	notarySet  []map[types.NodeID]struct{}
+	dkgSet     map[types.NodeID]struct{}
+	leaderNode []map[uint64]types.NodeID
 }
 
 // NodeSetCacheInterface interface specifies interface used by NodeSetCache.
@@ -146,6 +148,33 @@ func (cache *NodeSetCache) GetDKGSet(
 	return cache.cloneMap(IDs.dkgSet), nil
 }
 
+// GetLeaderNode returns the BA leader of the position.
+func (cache *NodeSetCache) GetLeaderNode(pos types.Position) (
+	types.NodeID, error) {
+	IDs, err := cache.getOrUpdate(pos.Round)
+	if err != nil {
+		return types.NodeID{}, err
+	}
+	if pos.ChainID >= uint32(len(IDs.leaderNode)) {
+		return types.NodeID{}, ErrInvalidChainID
+	}
+	cache.lock.Lock()
+	defer cache.lock.Unlock()
+	if _, exist := IDs.leaderNode[pos.ChainID][pos.Height]; !exist {
+		notarySet := types.NewNodeSetFromMap(IDs.notarySet[pos.ChainID])
+		leader :=
+			notarySet.GetSubSet(1, types.NewNodeLeaderTarget(IDs.crs, pos))
+		if len(leader) != 1 {
+			panic(errors.New("length of leader is not one"))
+		}
+		for nID := range leader {
+			IDs.leaderNode[pos.ChainID][pos.Height] = nID
+			break
+		}
+	}
+	return IDs.leaderNode[pos.ChainID][pos.Height], nil
+}
+
 func (cache *NodeSetCache) cloneMap(
 	nIDs map[types.NodeID]struct{}) map[types.NodeID]struct{} {
 	nIDsCopy := make(map[types.NodeID]struct{}, len(nIDs))
@@ -207,15 +236,21 @@ func (cache *NodeSetCache) update(
 		return
 	}
 	nIDs = &sets{
+		crs:       crs,
 		nodeSet:   nodeSet,
 		notarySet: make([]map[types.NodeID]struct{}, cfg.NumChains),
 		dkgSet: nodeSet.GetSubSet(
 			int(cfg.DKGSetSize), types.NewDKGSetTarget(crs)),
+		leaderNode: make([]map[uint64]types.NodeID, cfg.NumChains),
 	}
 	for i := range nIDs.notarySet {
 		nIDs.notarySet[i] = nodeSet.GetSubSet(
 			int(cfg.NotarySetSize), types.NewNotarySetTarget(crs, uint32(i)))
 	}
+	nodesPerChain := cfg.RoundInterval / cfg.MinBlockInterval
+	for i := range nIDs.leaderNode {
+		nIDs.leaderNode[i] = make(map[uint64]types.NodeID, nodesPerChain)
+	}
 
 	cache.rounds[round] = nIDs
 	// Purge older rounds.
diff --git a/vendor/github.com/dexon-foundation/dexon-consensus/core/utils/utils.go b/vendor/github.com/dexon-foundation/dexon-consensus/core/utils/utils.go
index 8c9f77a69..8486d2854 100644
--- a/vendor/github.com/dexon-foundation/dexon-consensus/core/utils/utils.go
+++ b/vendor/github.com/dexon-foundation/dexon-consensus/core/utils/utils.go
@@ -18,6 +18,7 @@
 package utils
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/dexon-foundation/dexon-consensus/common"
@@ -92,3 +93,36 @@ func VerifyDKGComplaint(
 	}
 	return ok, nil
 }
+
+// LaunchDummyReceiver launches a go routine to receive from the receive
+// channel of a network module. An context is required to stop the go routine
+// automatically. An optinal message handler could be provided.
+func LaunchDummyReceiver(
+	ctx context.Context, recv <-chan interface{}, handler func(interface{})) (
+	context.CancelFunc, <-chan struct{}) {
+	var (
+		dummyCtx, dummyCancel = context.WithCancel(ctx)
+		finishedChan          = make(chan struct{}, 1)
+	)
+	go func() {
+		defer func() {
+			finishedChan <- struct{}{}
+		}()
+	loop:
+		for {
+			select {
+			case <-dummyCtx.Done():
+				break loop
+			case v, ok := <-recv:
+				if !ok {
+					panic(fmt.Errorf(
+						"receive channel is closed before dummy receiver"))
+				}
+				if handler != nil {
+					handler(v)
+				}
+			}
+		}
+	}()
+	return dummyCancel, finishedChan
+}
diff --git a/vendor/vendor.json b/vendor/vendor.json
index f2da6e117..6d367a737 100644
--- a/vendor/vendor.json
+++ b/vendor/vendor.json
@@ -141,16 +141,16 @@
 		{
 			"checksumSHA1": "ZUuiRqS6PnoNIvBmLStVQiyhkOM=",
 			"path": "github.com/dexon-foundation/dexon-consensus/common",
-			"revision": "af8c182a07f9bf3a7a17c938c87f4eef489bb903",
-			"revisionTime": "2019-01-05T09:58:34Z",
+			"revision": "f4f572e4638309e523bbbde751547a9ea4d489bc",
+			"revisionTime": "2019-01-16T02:21:07Z",
 			"version": "master",
 			"versionExact": "master"
 		},
 		{
-			"checksumSHA1": "aqhVp5CBDq52ytHUH3HatpWhTDQ=",
+			"checksumSHA1": "TKAPWiezlt9t0oZca1Cq9S388lI=",
 			"path": "github.com/dexon-foundation/dexon-consensus/core",
-			"revision": "af8c182a07f9bf3a7a17c938c87f4eef489bb903",
-			"revisionTime": "2019-01-05T09:58:34Z",
+			"revision": "f4f572e4638309e523bbbde751547a9ea4d489bc",
+			"revisionTime": "2019-01-16T02:21:07Z",
 			"version": "master",
 			"versionExact": "master"
 		},
@@ -165,64 +165,64 @@
 		{
 			"checksumSHA1": "tQSbYCu5P00lUhKsx3IbBZCuSLY=",
 			"path": "github.com/dexon-foundation/dexon-consensus/core/crypto",
-			"revision": "af8c182a07f9bf3a7a17c938c87f4eef489bb903",
-			"revisionTime": "2019-01-05T09:58:34Z",
+			"revision": "f4f572e4638309e523bbbde751547a9ea4d489bc",
+			"revisionTime": "2019-01-16T02:21:07Z",
 			"version": "master",
 			"versionExact": "master"
 		},
 		{
 			"checksumSHA1": "W2P7pkuJ+26BpJg03K4Y0nB5obI=",
 			"path": "github.com/dexon-foundation/dexon-consensus/core/crypto/dkg",
-			"revision": "af8c182a07f9bf3a7a17c938c87f4eef489bb903",
-			"revisionTime": "2019-01-05T09:58:34Z",
+			"revision": "f4f572e4638309e523bbbde751547a9ea4d489bc",
+			"revisionTime": "2019-01-16T02:21:07Z",
 			"version": "master",
 			"versionExact": "master"
 		},
 		{
 			"checksumSHA1": "6Pf6caC8LTNCI7IflFmglKYnxYo=",
 			"path": "github.com/dexon-foundation/dexon-consensus/core/crypto/ecdsa",
-			"revision": "af8c182a07f9bf3a7a17c938c87f4eef489bb903",
-			"revisionTime": "2019-01-05T09:58:34Z",
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 			"version": "master",
 			"versionExact": "master"
 		},
 		{
-			"checksumSHA1": "PJXR1OuWwVVYrdJMK3skPr1/8ls=",
+			"checksumSHA1": "zpuCdMT8MGsy4pLgHKpg/Wd4izU=",
 			"path": "github.com/dexon-foundation/dexon-consensus/core/db",
-			"revision": "af8c182a07f9bf3a7a17c938c87f4eef489bb903",
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 			"version": "master",
 			"versionExact": "master"
 		},
 		{
-			"checksumSHA1": "h674l/hugVujbZUy/NSeDmio3/U=",
+			"checksumSHA1": "eq19vhMpc90UUJ7I91ti5P2CkQ0=",
 			"path": "github.com/dexon-foundation/dexon-consensus/core/syncer",
-			"revision": "af8c182a07f9bf3a7a17c938c87f4eef489bb903",
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 			"version": "master",
 			"versionExact": "master"
 		},
 		{
-			"checksumSHA1": "GRiBmU5T1LAoGHs5g1owGE1tNNo=",
+			"checksumSHA1": "zkrt3MOtqHPB3BmZtppZ9uesw3s=",
 			"path": "github.com/dexon-foundation/dexon-consensus/core/types",
-			"revision": "af8c182a07f9bf3a7a17c938c87f4eef489bb903",
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 			"version": "master",
 			"versionExact": "master"
 		},
 		{
 			"checksumSHA1": "rmv8uxwrqMhJAeA3RPvwYP8mFro=",
 			"path": "github.com/dexon-foundation/dexon-consensus/core/types/dkg",
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 			"version": "master",
 			"versionExact": "master"
 		},
 		{
-			"checksumSHA1": "NCAEGRVPfM0jCKdrBN2yvEXkeIo=",
+			"checksumSHA1": "FUHa68Hif8F8YHmx4h0sQIUNp40=",
 			"path": "github.com/dexon-foundation/dexon-consensus/core/utils",
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