commitTime is used to derive next startTime. :)

consensus/consensus.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"math"
+	"math/rand"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -29,6 +30,10 @@ const (
 	roundDurationDelta     = 15 * time.Second   // Each successive round lasts 15 seconds longer.
 	roundDeadlineBare      = float64(1.0 / 3.0) // When the bare vote is due.
 	roundDeadlinePrecommit = float64(2.0 / 3.0) // When the precommit vote is due.
+
+	newBlockWaitDuration = roundDuration0 / 3 // The time to wait between commitTime and startTime of next consensus rounds.
+	voteRankCutoff       = 2                  // Higher ranks --> do not send votes.
+	unsolicitedVoteRate  = 0.01               // Probability of sending a high ranked vote.
 )
 
 //-----------------------------------------------------------------------------
@@ -45,10 +50,11 @@ func calcRoundStartTime(round uint16, startTime time.Time) time.Time {
 }
 
 // calcs the current round given startTime of round zero.
+// NOTE: round is zero if startTime is in the future.
 func calcRound(startTime time.Time) uint16 {
 	now := time.Now()
 	if now.Before(startTime) {
-		Panicf("Cannot calc round when startTime is in the future: %v", startTime)
+		return 0
 	}
 	// Start + D_0 * R + D_delta * (R^2 - R)/2 <= Now; find largest integer R.
 	// D_delta * R^2 + (2D_0 - D_delta) * R + 2(Start - Now) <= 0.
@@ -71,6 +77,7 @@ func calcRound(startTime time.Time) uint16 {
 }
 
 // convenience
+// NOTE: elapsedRatio can be negative if startTime is in the future.
 func calcRoundInfo(startTime time.Time) (round uint16, roundStartTime time.Time, roundDuration time.Duration,
 	roundElapsed time.Duration, elapsedRatio float64) {
 	round = calcRound(startTime)
@@ -346,7 +353,7 @@ func (cm *ConsensusManager) stageProposal(proposal *BlockPartSet) error {
 	cm.mtx.Unlock()
 
 	// Commit block onto the copied state.
-	err = stateCopy.CommitBlock(block, block.Header.Time) // NOTE: fake commit time.
+	err = stateCopy.CommitBlock(block)
 	if err != nil {
 		return err
 	}
@@ -409,7 +416,8 @@ func (cm *ConsensusManager) voteProposal(rs *RoundState) error {
 func (cm *ConsensusManager) precommitProposal(rs *RoundState) error {
 	// If we see a 2/3 majority for votes for a block, precommit.
 
-	if hash, ok := rs.RoundBareVotes.TwoThirdsMajority(); ok {
+	// TODO: maybe could use commitTime here and avg it with later commitTime?
+	if hash, _, ok := rs.RoundBareVotes.TwoThirdsMajority(); ok {
 		if len(hash) == 0 {
 			// 2/3 majority voted for nil.
 			return nil
@@ -442,18 +450,18 @@ func (cm *ConsensusManager) precommitProposal(rs *RoundState) error {
 }
 
 // Commit or unlock.
-// Call after RoundStepPrecommit, after round has expired.
-func (cm *ConsensusManager) commitOrUnlockProposal(rs *RoundState) error {
+// Call after RoundStepPrecommit, after round has completely expired.
+func (cm *ConsensusManager) commitOrUnlockProposal(rs *RoundState) (commitTime time.Time, err error) {
 	// If there exists a 2/3 majority of precommits.
 	// Validate the block and commit.
-	if hash, ok := rs.RoundPrecommits.TwoThirdsMajority(); ok {
+	if hash, commitTime, ok := rs.RoundPrecommits.TwoThirdsMajority(); ok {
 
 		// If the proposal is invalid or we don't have it,
 		// do not commit.
 		// TODO If we were just late to receive the block, when
 		// do we actually get it? Document it.
 		if cm.stageProposal(rs.Proposal) != nil {
-			return nil
+			return time.Time{}, nil
 		}
 		// TODO: Remove?
 		cm.cs.LockProposal(rs.Proposal)
@@ -465,16 +473,11 @@ func (cm *ConsensusManager) commitOrUnlockProposal(rs *RoundState) error {
 			Hash:   hash,
 		})
 		if err != nil {
-			return err
+			return time.Time{}, err
 		}
 		// Commit block.
-		// XXX use adjusted commit time.
-		// If we just use time.Now() we're not converging
-		// time differences between nodes, so nodes end up drifting
-		// in time.
-		commitTime := time.Now()
 		cm.commitProposal(rs.Proposal, commitTime)
-		return nil
+		return commitTime, nil
 	} else {
 		// Otherwise, if a 1/3 majority if a block that isn't our locked one exists, unlock.
 		locked := cm.cs.LockedProposal()
@@ -483,14 +486,13 @@ func (cm *ConsensusManager) commitOrUnlockProposal(rs *RoundState) error {
 				if hashOrNil == nil {
 					continue
 				}
-				hash := hashOrNil.([]byte)
-				if !bytes.Equal(hash, locked.Block().Hash()) {
+				if !bytes.Equal(hashOrNil, locked.Block().Hash()) {
 					// Unlock our lock.
 					cm.cs.LockProposal(nil)
 				}
 			}
 		}
-		return nil
+		return time.Time{}, nil
 	}
 }
 
@@ -511,6 +513,7 @@ func (cm *ConsensusManager) commitProposal(proposal *BlockPartSet, commitTime ti
 
 	// What was staged becomes committed.
 	cm.state = cm.stagedState
+	cm.state.Save(commitTime)
 	cm.cs.Update(cm.state)
 	cm.stagedProposal = nil
 	cm.stagedState = nil
@@ -650,7 +653,11 @@ func (cm *ConsensusManager) proposeAndVoteRoutine() {
 		_, _, roundDuration, _, elapsedRatio := calcRoundInfo(rs.StartTime)
 		switch rs.Step() {
 		case RoundStepStart:
-			// It's a new RoundState, immediately wake up and xn to RoundStepProposal.
+			// It's a new RoundState.
+			if elapsedRatio < 0 {
+				// startTime is in the future.
+				time.Sleep(time.Duration(-1.0*elapsedRatio) * roundDuration)
+			}
 			cm.doActionCh <- RoundAction{rs.Height, rs.Round, RoundStepProposal}
 		case RoundStepProposal:
 			// Wake up when it's time to vote.
@@ -722,14 +729,21 @@ func (cm *ConsensusManager) proposeAndVoteRoutine() {
 					log.Info("Error attempting to precommit for proposal: %v", err)
 				}
 			} else if step == RoundStepCommitOrUnlock && rs.Step() <= RoundStepPrecommits {
-				err := cm.commitOrUnlockProposal(rs)
+				commitTime, err := cm.commitOrUnlockProposal(rs)
 				if err != nil {
 					log.Info("Error attempting to commit or update for proposal: %v", err)
 				}
-				// Round is over. This is a special case.
-				// Prepare a new RoundState for the next state.
-				cm.cs.SetupRound(rs.Round + 1)
-				return // setAlarm() takes care of the rest.
+
+				if !commitTime.IsZero() {
+					// We already set up ConsensusState for the next height
+					// (it happens in the call to cm.commitProposal).
+					// XXX: call cm.cs.SetupHeight()
+				} else {
+					// Round is over. This is a special case.
+					// Prepare a new RoundState for the next state.
+					cm.cs.SetupRound(rs.Round + 1)
+					return // setAlarm() takes care of the rest.
+				}
 			} else {
 				return // Action is not relevant.
 			}
@@ -747,6 +761,7 @@ var (
 	ErrPeerStateInvalidStartTime = errors.New("Error peer state invalid startTime")
 )
 
+// TODO: voteRanks should purge bygone validators.
 type PeerState struct {
 	mtx                sync.Mutex
 	connected          bool
@@ -754,7 +769,7 @@ type PeerState struct {
 	height             uint32
 	startTime          time.Time // Derived from offset seconds.
 	blockPartsBitArray []byte
-	votesWanted        map[uint64]float32
+	voteRanks          map[uint64]uint8
 	cbHeight           uint32
 	cbRound            uint16
 	cbFunc             func()
@@ -762,10 +777,10 @@ type PeerState struct {
 
 func NewPeerState(peer *p2p.Peer) *PeerState {
 	return &PeerState{
-		connected:   true,
-		peer:        peer,
-		height:      0,
-		votesWanted: make(map[uint64]float32),
+		connected: true,
+		peer:      peer,
+		height:    0,
+		voteRanks: make(map[uint64]uint8),
 	}
 }
 
@@ -818,10 +833,15 @@ func (ps *PeerState) WantsVote(vote *Vote) bool {
 	if !ps.connected {
 		return false
 	}
-	// Only wants the vote if votesWanted says so
-	if ps.votesWanted[vote.SignerId] <= 0 {
-		// TODO: sometimes, send unsolicited votes to see if peer wants it.
-		return false
+	// Only wants the vote if voteRank is low.
+	if ps.voteRanks[vote.SignerId] > voteRankCutoff {
+		// Sometimes, send unsolicited votes to see if peer wants it.
+		if rand.Float32() < unsolicitedVoteRate {
+			// Continue on...
+		} else {
+			// Rank too high. Do not send vote.
+			return false
+		}
 	}
 	// Only wants the vote if peer's current height and round matches.
 	if ps.height == vote.Height {
@@ -890,7 +910,7 @@ func (ps *PeerState) ApplyKnownBlockPartsMessage(msg *KnownBlockPartsMessage) er
 func (ps *PeerState) ApplyVoteRankMessage(msg *VoteRankMessage) error {
 	ps.mtx.Lock()
 	defer ps.mtx.Unlock()
-	// XXX IMPLEMENT
+	ps.voteRanks[msg.ValidatorId] = msg.Rank
 	return nil
 }
 

consensus/state.go

@@ -22,6 +22,7 @@ type ConsensusState struct {
 	startTime      time.Time     // Start of round 0 for this height.
 	commits        *VoteSet      // Commits for this height.
 	roundState     *RoundState   // The RoundState object for the current round.
+	commitTime     time.Time     // Time at which a block was found to be committed by +2/3.
 }
 
 func NewConsensusState(state *State) *ConsensusState {
@@ -54,6 +55,7 @@ func (cs *ConsensusState) RoundState() *RoundState {
 	return cs.roundState
 }
 
+// Primarily gets called upon block commit by ConsensusManager.
 func (cs *ConsensusState) Update(state *State) {
 	cs.mtx.Lock()
 	defer cs.mtx.Unlock()
@@ -68,7 +70,7 @@ func (cs *ConsensusState) Update(state *State) {
 	cs.height = stateHeight
 	cs.validatorsR0 = state.Validators().Copy() // NOTE: immutable.
 	cs.lockedProposal = nil
-	cs.startTime = state.CommitTime() // XXX is this what we want?
+	cs.startTime = state.CommitTime().Add(newBlockWaitDuration) // NOTE: likely future time.
 	cs.commits = NewVoteSet(stateHeight, 0, VoteTypeCommit, cs.validatorsR0)
 
 	// Setup the roundState
@@ -77,7 +79,7 @@ func (cs *ConsensusState) Update(state *State) {
 
 }
 
-// If cs.roundSTate isn't at round, set up new roundState at round.
+// If cs.roundState isn't at round, set up new roundState at round.
 func (cs *ConsensusState) SetupRound(round uint16) {
 	cs.mtx.Lock()
 	defer cs.mtx.Unlock()

consensus/vote.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"io"
 	"sync"
+	"time"
 
 	. "github.com/tendermint/tendermint/binary"
 	. "github.com/tendermint/tendermint/blocks"
@@ -61,16 +62,19 @@ func (v *Vote) GetDocument() string {
 
 // VoteSet helps collect signatures from validators at each height+round
 // for a predefined vote type.
+// TODO: test majority calculations etc.
 type VoteSet struct {
-	mtx              sync.Mutex
-	height           uint32
-	round            uint16
-	type_            byte
-	validators       *ValidatorSet
-	votes            map[uint64]*Vote
-	votesByHash      map[string]uint64
-	totalVotes       uint64
-	totalVotingPower uint64
+	mtx                 sync.Mutex
+	height              uint32
+	round               uint16
+	type_               byte
+	validators          *ValidatorSet
+	votes               map[uint64]*Vote
+	votesByHash         map[string]uint64
+	totalVotes          uint64
+	totalVotingPower    uint64
+	oneThirdMajority    [][]byte
+	twoThirdsCommitTime time.Time
 }
 
 // Constructs a new VoteSet struct used to accumulate votes for each round.
@@ -126,49 +130,38 @@ func (vs *VoteSet) AddVote(vote *Vote) (bool, error) {
 		}
 	}
 	vs.votes[vote.SignerId] = vote
-	vs.votesByHash[string(vote.Hash)] += val.VotingPower
+	totalHashVotes := vs.votesByHash[string(vote.Hash)] + val.VotingPower
+	vs.votesByHash[string(vote.Hash)] = totalHashVotes
 	vs.totalVotes += val.VotingPower
+	// If we just nudged it up to one thirds majority, add it.
+	if totalHashVotes > vs.totalVotingPower/3 &&
+		(totalHashVotes-val.VotingPower) <= vs.totalVotingPower/3 {
+		vs.oneThirdMajority = append(vs.oneThirdMajority, vote.Hash)
+	} else if totalHashVotes > vs.totalVotingPower*2/3 &&
+		(totalHashVotes-val.VotingPower) <= vs.totalVotingPower*2/3 {
+		vs.twoThirdsCommitTime = time.Now()
+	}
 	return true, nil
 }
 
 // Returns either a blockhash (or nil) that received +2/3 majority.
 // If there exists no such majority, returns (nil, false).
-func (vs *VoteSet) TwoThirdsMajority() (hash []byte, ok bool) {
+func (vs *VoteSet) TwoThirdsMajority() (hash []byte, commitTime time.Time, ok bool) {
 	vs.mtx.Lock()
 	defer vs.mtx.Unlock()
-	twoThirdsMajority := (vs.totalVotingPower*2 + 2) / 3
-	if vs.totalVotes < twoThirdsMajority {
-		return nil, false
-	}
-	for hash, votes := range vs.votesByHash {
-		if votes >= twoThirdsMajority {
-			if hash == "" {
-				return nil, true
-			} else {
-				return []byte(hash), true
-			}
+	// There's only one or two in the array.
+	for _, hash := range vs.oneThirdMajority {
+		if vs.votesByHash[string(hash)] > vs.totalVotingPower*2/3 {
+			return hash, vs.twoThirdsCommitTime, true
 		}
 	}
-	return nil, false
+	return nil, time.Time{}, false
 }
 
 // Returns blockhashes (or nil) that received a +1/3 majority.
 // If there exists no such majority, returns nil.
-func (vs *VoteSet) OneThirdMajority() (hashes []interface{}) {
+func (vs *VoteSet) OneThirdMajority() (hashes [][]byte) {
 	vs.mtx.Lock()
 	defer vs.mtx.Unlock()
-	oneThirdMajority := (vs.totalVotingPower + 2) / 3
-	if vs.totalVotes < oneThirdMajority {
-		return nil
-	}
-	for hash, votes := range vs.votesByHash {
-		if votes >= oneThirdMajority {
-			if hash == "" {
-				hashes = append(hashes, nil)
-			} else {
-				hashes = append(hashes, []byte(hash))
-			}
-		}
-	}
-	return hashes
+	return vs.oneThirdMajority
 }

state/state.go

@@ -52,15 +52,19 @@ func LoadState(db db_.Db) *State {
 	return s
 }
 
-func (s *State) Save() {
+// Save this state into the db.
+// For convenience, the commitTime (required by ConsensusManager)
+// is saved here.
+func (s *State) Save(commitTime time.Time) {
 	s.mtx.Lock()
 	defer s.mtx.Unlock()
+	s.commitTime = commitTime
 	s.accounts.Save()
 	var buf bytes.Buffer
 	var n int64
 	var err error
 	WriteUInt32(&buf, s.height, &n, &err)
-	WriteTime(&buf, s.commitTime, &n, &err)
+	WriteTime(&buf, commitTime, &n, &err)
 	WriteByteSlice(&buf, s.accounts.Hash(), &n, &err)
 	for _, validator := range s.validators.Map() {
 		WriteBinary(&buf, validator, &n, &err)
@@ -91,7 +95,9 @@ func (s *State) CommitTx(tx *Tx) error {
 	return nil
 }
 
-func (s *State) CommitBlock(b *Block, commitTime time.Time) error {
+// This is called during staging.
+// The resulting state is cached until it is actually committed.
+func (s *State) CommitBlock(b *Block) error {
 	s.mtx.Lock()
 	defer s.mtx.Unlock()
 	// TODO commit the txs