tendermint/consensus/state.go

package consensus

import (
	"bytes"
	"errors"
	"fmt"
	"path/filepath"
	"reflect"
	"runtime/debug"
	"sync"
	"time"

	fail "github.com/ebuchman/fail-test"

	wire "github.com/tendermint/go-wire"
	cmn "github.com/tendermint/tmlibs/common"
	"github.com/tendermint/tmlibs/log"

	cfg "github.com/tendermint/tendermint/config"
	cstypes "github.com/tendermint/tendermint/consensus/types"
	"github.com/tendermint/tendermint/proxy"
	sm "github.com/tendermint/tendermint/state"
	"github.com/tendermint/tendermint/types"
)

//-----------------------------------------------------------------------------
// Config

const (
	proposalHeartbeatIntervalSeconds = 2
)

//-----------------------------------------------------------------------------
// Errors

var (
	ErrInvalidProposalSignature = errors.New("Error invalid proposal signature")
	ErrInvalidProposalPOLRound  = errors.New("Error invalid proposal POL round")
	ErrAddingVote               = errors.New("Error adding vote")
	ErrVoteHeightMismatch       = errors.New("Error vote height mismatch")
)

//-----------------------------------------------------------------------------

var (
	msgQueueSize = 1000
)

// msgs from the reactor which may update the state
type msgInfo struct {
	Msg     ConsensusMessage `json:"msg"`
	PeerKey string           `json:"peer_key"`
}

// internally generated messages which may update the state
type timeoutInfo struct {
	Duration time.Duration         `json:"duration"`
	Height   int                   `json:"height"`
	Round    int                   `json:"round"`
	Step     cstypes.RoundStepType `json:"step"`
}

func (ti *timeoutInfo) String() string {
	return fmt.Sprintf("%v ; %d/%d %v", ti.Duration, ti.Height, ti.Round, ti.Step)
}

// ConsensusState handles execution of the consensus algorithm.
// It processes votes and proposals, and upon reaching agreement,
// commits blocks to the chain and executes them against the application.
// The internal state machine receives input from peers, the internal validator, and from a timer.
type ConsensusState struct {
	cmn.BaseService

	// config details
	config        *cfg.ConsensusConfig
	privValidator types.PrivValidator // for signing votes

	// services for creating and executing blocks
	proxyAppConn proxy.AppConnConsensus
	blockStore   types.BlockStore
	mempool      types.Mempool

	// internal state
	mtx sync.Mutex
	cstypes.RoundState
	state *sm.State // State until height-1.

	// state changes may be triggered by msgs from peers,
	// msgs from ourself, or by timeouts
	peerMsgQueue     chan msgInfo
	internalMsgQueue chan msgInfo
	timeoutTicker    TimeoutTicker

	// we use PubSub to trigger msg broadcasts in the reactor,
	// and to notify external subscribers, eg. through a websocket
	evsw types.EventSwitch

	// a Write-Ahead Log ensures we can recover from any kind of crash
	// and helps us avoid signing conflicting votes
	wal          *WAL
	replayMode   bool // so we don't log signing errors during replay
	doWALCatchup bool // determines if we even try to do the catchup

	// for tests where we want to limit the number of transitions the state makes
	nSteps int

	// some functions can be overwritten for testing
	decideProposal func(height, round int)
	doPrevote      func(height, round int)
	setProposal    func(proposal *types.Proposal) error

	// closed when we finish shutting down
	done chan struct{}
}

// NewConsensusState returns a new ConsensusState.
func NewConsensusState(config *cfg.ConsensusConfig, state *sm.State, proxyAppConn proxy.AppConnConsensus, blockStore types.BlockStore, mempool types.Mempool) *ConsensusState {
	cs := &ConsensusState{
		config:           config,
		proxyAppConn:     proxyAppConn,
		blockStore:       blockStore,
		mempool:          mempool,
		peerMsgQueue:     make(chan msgInfo, msgQueueSize),
		internalMsgQueue: make(chan msgInfo, msgQueueSize),
		timeoutTicker:    NewTimeoutTicker(),
		done:             make(chan struct{}),
		doWALCatchup:     true,
	}
	// set function defaults (may be overwritten before calling Start)
	cs.decideProposal = cs.defaultDecideProposal
	cs.doPrevote = cs.defaultDoPrevote
	cs.setProposal = cs.defaultSetProposal

	cs.updateToState(state)
	// Don't call scheduleRound0 yet.
	// We do that upon Start().
	cs.reconstructLastCommit(state)
	cs.BaseService = *cmn.NewBaseService(nil, "ConsensusState", cs)
	return cs
}

//----------------------------------------
// Public interface

// SetLogger implements Service.
func (cs *ConsensusState) SetLogger(l log.Logger) {
	cs.BaseService.Logger = l
	cs.timeoutTicker.SetLogger(l)
}

// SetEventSwitch implements events.Eventable
func (cs *ConsensusState) SetEventSwitch(evsw types.EventSwitch) {
	cs.evsw = evsw
}

// String returns a string.
func (cs *ConsensusState) String() string {
	// better not to access shared variables
	return cmn.Fmt("ConsensusState") //(H:%v R:%v S:%v", cs.Height, cs.Round, cs.Step)
}

// GetState returns a copy of the chain state.
func (cs *ConsensusState) GetState() *sm.State {
	cs.mtx.Lock()
	defer cs.mtx.Unlock()
	return cs.state.Copy()
}

// GetRoundState returns a copy of the internal consensus state.
func (cs *ConsensusState) GetRoundState() *cstypes.RoundState {
	cs.mtx.Lock()
	defer cs.mtx.Unlock()
	return cs.getRoundState()
}

func (cs *ConsensusState) getRoundState() *cstypes.RoundState {
	rs := cs.RoundState // copy
	return &rs
}

// GetValidators returns a copy of the current validators.
func (cs *ConsensusState) GetValidators() (int, []*types.Validator) {
	cs.mtx.Lock()
	defer cs.mtx.Unlock()
	return cs.state.LastBlockHeight, cs.state.Validators.Copy().Validators
}

// SetPrivValidator sets the private validator account for signing votes.
func (cs *ConsensusState) SetPrivValidator(priv types.PrivValidator) {
	cs.mtx.Lock()
	defer cs.mtx.Unlock()
	cs.privValidator = priv
}

// SetTimeoutTicker sets the local timer. It may be useful to overwrite for testing.
func (cs *ConsensusState) SetTimeoutTicker(timeoutTicker TimeoutTicker) {
	cs.mtx.Lock()
	defer cs.mtx.Unlock()
	cs.timeoutTicker = timeoutTicker
}

// LoadCommit loads the commit for a given height.
func (cs *ConsensusState) LoadCommit(height int) *types.Commit {
	cs.mtx.Lock()
	defer cs.mtx.Unlock()
	if height == cs.blockStore.Height() {
		return cs.blockStore.LoadSeenCommit(height)
	}
	return cs.blockStore.LoadBlockCommit(height)
}

// OnStart implements cmn.Service.
// It loads the latest state via the WAL, and starts the timeout and receive routines.
func (cs *ConsensusState) OnStart() error {

	walFile := cs.config.WalFile()
	if err := cs.OpenWAL(walFile); err != nil {
		cs.Logger.Error("Error loading ConsensusState wal", "err", err.Error())
		return err
	}

	// we need the timeoutRoutine for replay so
	//  we don't block on the tick chan.
	// NOTE: we will get a build up of garbage go routines
	//  firing on the tockChan until the receiveRoutine is started
	//  to deal with them (by that point, at most one will be valid)
	cs.timeoutTicker.Start()

	// we may have lost some votes if the process crashed
	// reload from consensus log to catchup
	if cs.doWALCatchup {
		if err := cs.catchupReplay(cs.Height); err != nil {
			cs.Logger.Error("Error on catchup replay. Proceeding to start ConsensusState anyway", "err", err.Error())
			// NOTE: if we ever do return an error here,
			// make sure to stop the timeoutTicker
		}
	}

	// now start the receiveRoutine
	go cs.receiveRoutine(0)

	// schedule the first round!
	// use GetRoundState so we don't race the receiveRoutine for access
	cs.scheduleRound0(cs.GetRoundState())

	return nil
}

// timeoutRoutine: receive requests for timeouts on tickChan and fire timeouts on tockChan
// receiveRoutine: serializes processing of proposoals, block parts, votes; coordinates state transitions
func (cs *ConsensusState) startRoutines(maxSteps int) {
	cs.timeoutTicker.Start()
	go cs.receiveRoutine(maxSteps)
}

// OnStop implements cmn.Service. It stops all routines and waits for the WAL to finish.
func (cs *ConsensusState) OnStop() {
	cs.BaseService.OnStop()

	cs.timeoutTicker.Stop()

	// Make BaseService.Wait() wait until cs.wal.Wait()
	if cs.wal != nil && cs.IsRunning() {
		cs.wal.Wait()
	}
}

// Wait waits for the the main routine to return.
// NOTE: be sure to Stop() the event switch and drain
// any event channels or this may deadlock
func (cs *ConsensusState) Wait() {
	<-cs.done
}

// OpenWAL opens a file to log all consensus messages and timeouts for deterministic accountability
func (cs *ConsensusState) OpenWAL(walFile string) (err error) {
	err = cmn.EnsureDir(filepath.Dir(walFile), 0700)
	if err != nil {
		cs.Logger.Error("Error ensuring ConsensusState wal dir", "err", err.Error())
		return err
	}

	cs.mtx.Lock()
	defer cs.mtx.Unlock()
	wal, err := NewWAL(walFile, cs.config.WalLight)
	if err != nil {
		return err
	}
	wal.SetLogger(cs.Logger.With("wal", walFile))
	if _, err := wal.Start(); err != nil {
		return err
	}
	cs.wal = wal
	return nil
}

//------------------------------------------------------------
// Public interface for passing messages into the consensus state, possibly causing a state transition.
// If peerKey == "", the msg is considered internal.
// Messages are added to the appropriate queue (peer or internal).
// If the queue is full, the function may block.
// TODO: should these return anything or let callers just use events?

// AddVote inputs a vote.
func (cs *ConsensusState) AddVote(vote *types.Vote, peerKey string) (added bool, err error) {
	if peerKey == "" {
		cs.internalMsgQueue <- msgInfo{&VoteMessage{vote}, ""}
	} else {
		cs.peerMsgQueue <- msgInfo{&VoteMessage{vote}, peerKey}
	}

	// TODO: wait for event?!
	return false, nil
}

// SetProposal inputs a proposal.
func (cs *ConsensusState) SetProposal(proposal *types.Proposal, peerKey string) error {

	if peerKey == "" {
		cs.internalMsgQueue <- msgInfo{&ProposalMessage{proposal}, ""}
	} else {
		cs.peerMsgQueue <- msgInfo{&ProposalMessage{proposal}, peerKey}
	}

	// TODO: wait for event?!
	return nil
}

// AddProposalBlockPart inputs a part of the proposal block.
func (cs *ConsensusState) AddProposalBlockPart(height, round int, part *types.Part, peerKey string) error {

	if peerKey == "" {
		cs.internalMsgQueue <- msgInfo{&BlockPartMessage{height, round, part}, ""}
	} else {
		cs.peerMsgQueue <- msgInfo{&BlockPartMessage{height, round, part}, peerKey}
	}

	// TODO: wait for event?!
	return nil
}

// SetProposalAndBlock inputs the proposal and all block parts.
func (cs *ConsensusState) SetProposalAndBlock(proposal *types.Proposal, block *types.Block, parts *types.PartSet, peerKey string) error {
	cs.SetProposal(proposal, peerKey)
	for i := 0; i < parts.Total(); i++ {
		part := parts.GetPart(i)
		cs.AddProposalBlockPart(proposal.Height, proposal.Round, part, peerKey)
	}
	return nil // TODO errors
}

//------------------------------------------------------------
// internal functions for managing the state

func (cs *ConsensusState) updateHeight(height int) {
	cs.Height = height
}

func (cs *ConsensusState) updateRoundStep(round int, step cstypes.RoundStepType) {
	cs.Round = round
	cs.Step = step
}

// enterNewRound(height, 0) at cs.StartTime.
func (cs *ConsensusState) scheduleRound0(rs *cstypes.RoundState) {
	//cs.Logger.Info("scheduleRound0", "now", time.Now(), "startTime", cs.StartTime)
	sleepDuration := rs.StartTime.Sub(time.Now())
	cs.scheduleTimeout(sleepDuration, rs.Height, 0, cstypes.RoundStepNewHeight)
}

// Attempt to schedule a timeout (by sending timeoutInfo on the tickChan)
func (cs *ConsensusState) scheduleTimeout(duration time.Duration, height, round int, step cstypes.RoundStepType) {
	cs.timeoutTicker.ScheduleTimeout(timeoutInfo{duration, height, round, step})
}

// send a msg into the receiveRoutine regarding our own proposal, block part, or vote
func (cs *ConsensusState) sendInternalMessage(mi msgInfo) {
	select {
	case cs.internalMsgQueue <- mi:
	default:
		// NOTE: using the go-routine means our votes can
		// be processed out of order.
		// TODO: use CList here for strict determinism and
		// attempt push to internalMsgQueue in receiveRoutine
		cs.Logger.Info("Internal msg queue is full. Using a go-routine")
		go func() { cs.internalMsgQueue <- mi }()
	}
}

// Reconstruct LastCommit from SeenCommit, which we saved along with the block,
// (which happens even before saving the state)
func (cs *ConsensusState) reconstructLastCommit(state *sm.State) {
	if state.LastBlockHeight == 0 {
		return
	}
	seenCommit := cs.blockStore.LoadSeenCommit(state.LastBlockHeight)
	lastPrecommits := types.NewVoteSet(state.ChainID, state.LastBlockHeight, seenCommit.Round(), types.VoteTypePrecommit, state.LastValidators)
	for _, precommit := range seenCommit.Precommits {
		if precommit == nil {
			continue
		}
		added, err := lastPrecommits.AddVote(precommit)
		if !added || err != nil {
			cmn.PanicCrisis(cmn.Fmt("Failed to reconstruct LastCommit: %v", err))
		}
	}
	if !lastPrecommits.HasTwoThirdsMajority() {
		cmn.PanicSanity("Failed to reconstruct LastCommit: Does not have +2/3 maj")
	}
	cs.LastCommit = lastPrecommits
}

// Updates ConsensusState and increments height to match that of state.
// The round becomes 0 and cs.Step becomes cstypes.RoundStepNewHeight.
func (cs *ConsensusState) updateToState(state *sm.State) {
	if cs.CommitRound > -1 && 0 < cs.Height && cs.Height != state.LastBlockHeight {
		cmn.PanicSanity(cmn.Fmt("updateToState() expected state height of %v but found %v",
			cs.Height, state.LastBlockHeight))
	}
	if cs.state != nil && cs.state.LastBlockHeight+1 != cs.Height {
		// This might happen when someone else is mutating cs.state.
		// Someone forgot to pass in state.Copy() somewhere?!
		cmn.PanicSanity(cmn.Fmt("Inconsistent cs.state.LastBlockHeight+1 %v vs cs.Height %v",
			cs.state.LastBlockHeight+1, cs.Height))
	}

	// If state isn't further out than cs.state, just ignore.
	// This happens when SwitchToConsensus() is called in the reactor.
	// We don't want to reset e.g. the Votes.
	if cs.state != nil && (state.LastBlockHeight <= cs.state.LastBlockHeight) {
		cs.Logger.Info("Ignoring updateToState()", "newHeight", state.LastBlockHeight+1, "oldHeight", cs.state.LastBlockHeight+1)
		return
	}

	// Reset fields based on state.
	validators := state.Validators
	lastPrecommits := (*types.VoteSet)(nil)
	if cs.CommitRound > -1 && cs.Votes != nil {
		if !cs.Votes.Precommits(cs.CommitRound).HasTwoThirdsMajority() {
			cmn.PanicSanity("updateToState(state) called but last Precommit round didn't have +2/3")
		}
		lastPrecommits = cs.Votes.Precommits(cs.CommitRound)
	}

	// Next desired block height
	height := state.LastBlockHeight + 1

	// RoundState fields
	cs.updateHeight(height)
	cs.updateRoundStep(0, cstypes.RoundStepNewHeight)
	if cs.CommitTime.IsZero() {
		// "Now" makes it easier to sync up dev nodes.
		// We add timeoutCommit to allow transactions
		// to be gathered for the first block.
		// And alternative solution that relies on clocks:
		//  cs.StartTime = state.LastBlockTime.Add(timeoutCommit)
		cs.StartTime = cs.config.Commit(time.Now())
	} else {
		cs.StartTime = cs.config.Commit(cs.CommitTime)
	}
	cs.Validators = validators
	cs.Proposal = nil
	cs.ProposalBlock = nil
	cs.ProposalBlockParts = nil
	cs.LockedRound = 0
	cs.LockedBlock = nil
	cs.LockedBlockParts = nil
	cs.Votes = cstypes.NewHeightVoteSet(state.ChainID, height, validators)
	cs.CommitRound = -1
	cs.LastCommit = lastPrecommits
	cs.LastValidators = state.LastValidators

	cs.state = state

	// Finally, broadcast RoundState
	cs.newStep()
}

func (cs *ConsensusState) newStep() {
	rs := cs.RoundStateEvent()
	cs.wal.Save(rs)
	cs.nSteps += 1
	// newStep is called by updateToStep in NewConsensusState before the evsw is set!
	if cs.evsw != nil {
		types.FireEventNewRoundStep(cs.evsw, rs)
	}
}

//-----------------------------------------
// the main go routines

// receiveRoutine handles messages which may cause state transitions.
// it's argument (n) is the number of messages to process before exiting - use 0 to run forever
// It keeps the RoundState and is the only thing that updates it.
// Updates (state transitions) happen on timeouts, complete proposals, and 2/3 majorities.
// ConsensusState must be locked before any internal state is updated.
func (cs *ConsensusState) receiveRoutine(maxSteps int) {
	defer func() {
		if r := recover(); r != nil {
			cs.Logger.Error("CONSENSUS FAILURE!!!", "err", r, "stack", string(debug.Stack()))
		}
	}()

	for {
		if maxSteps > 0 {
			if cs.nSteps >= maxSteps {
				cs.Logger.Info("reached max steps. exiting receive routine")
				cs.nSteps = 0
				return
			}
		}
		rs := cs.RoundState
		var mi msgInfo

		select {
		case height := <-cs.mempool.TxsAvailable():
			cs.handleTxsAvailable(height)
		case mi = <-cs.peerMsgQueue:
			cs.wal.Save(mi)
			// handles proposals, block parts, votes
			// may generate internal events (votes, complete proposals, 2/3 majorities)
			cs.handleMsg(mi)
		case mi = <-cs.internalMsgQueue:
			cs.wal.Save(mi)
			// handles proposals, block parts, votes
			cs.handleMsg(mi)
		case ti := <-cs.timeoutTicker.Chan(): // tockChan:
			cs.wal.Save(ti)
			// if the timeout is relevant to the rs
			// go to the next step
			cs.handleTimeout(ti, rs)
		case <-cs.Quit:

			// NOTE: the internalMsgQueue may have signed messages from our
			// priv_val that haven't hit the WAL, but its ok because
			// priv_val tracks LastSig

			// close wal now that we're done writing to it
			if cs.wal != nil {
				cs.wal.Stop()
			}

			close(cs.done)
			return
		}
	}
}

// state transitions on complete-proposal, 2/3-any, 2/3-one
func (cs *ConsensusState) handleMsg(mi msgInfo) {
	cs.mtx.Lock()
	defer cs.mtx.Unlock()

	var err error
	msg, peerKey := mi.Msg, mi.PeerKey
	switch msg := msg.(type) {
	case *ProposalMessage:
		// will not cause transition.
		// once proposal is set, we can receive block parts
		err = cs.setProposal(msg.Proposal)
	case *BlockPartMessage:
		// if the proposal is complete, we'll enterPrevote or tryFinalizeCommit
		_, err = cs.addProposalBlockPart(msg.Height, msg.Part, peerKey != "")
		if err != nil && msg.Round != cs.Round {
			err = nil
		}
	case *VoteMessage:
		// attempt to add the vote and dupeout the validator if its a duplicate signature
		// if the vote gives us a 2/3-any or 2/3-one, we transition
		err := cs.tryAddVote(msg.Vote, peerKey)
		if err == ErrAddingVote {
			// TODO: punish peer
		}

		// NOTE: the vote is broadcast to peers by the reactor listening
		// for vote events

		// TODO: If rs.Height == vote.Height && rs.Round < vote.Round,
		// the peer is sending us CatchupCommit precommits.
		// We could make note of this and help filter in broadcastHasVoteMessage().
	default:
		cs.Logger.Error("Unknown msg type", reflect.TypeOf(msg))
	}
	if err != nil {
		cs.Logger.Error("Error with msg", "type", reflect.TypeOf(msg), "peer", peerKey, "err", err, "msg", msg)
	}
}

func (cs *ConsensusState) handleTimeout(ti timeoutInfo, rs cstypes.RoundState) {
	cs.Logger.Debug("Received tock", "timeout", ti.Duration, "height", ti.Height, "round", ti.Round, "step", ti.Step)

	// timeouts must be for current height, round, step
	if ti.Height != rs.Height || ti.Round < rs.Round || (ti.Round == rs.Round && ti.Step < rs.Step) {
		cs.Logger.Debug("Ignoring tock because we're ahead", "height", rs.Height, "round", rs.Round, "step", rs.Step)
		return
	}

	// the timeout will now cause a state transition
	cs.mtx.Lock()
	defer cs.mtx.Unlock()

	switch ti.Step {
	case cstypes.RoundStepNewHeight:
		// NewRound event fired from enterNewRound.
		// XXX: should we fire timeout here (for timeout commit)?
		cs.enterNewRound(ti.Height, 0)
	case cstypes.RoundStepNewRound:
		cs.enterPropose(ti.Height, 0)
	case cstypes.RoundStepPropose:
		types.FireEventTimeoutPropose(cs.evsw, cs.RoundStateEvent())
		cs.enterPrevote(ti.Height, ti.Round)
	case cstypes.RoundStepPrevoteWait:
		types.FireEventTimeoutWait(cs.evsw, cs.RoundStateEvent())
		cs.enterPrecommit(ti.Height, ti.Round)
	case cstypes.RoundStepPrecommitWait:
		types.FireEventTimeoutWait(cs.evsw, cs.RoundStateEvent())
		cs.enterNewRound(ti.Height, ti.Round+1)
	default:
		panic(cmn.Fmt("Invalid timeout step: %v", ti.Step))
	}

}

func (cs *ConsensusState) handleTxsAvailable(height int) {
	cs.mtx.Lock()
	defer cs.mtx.Unlock()
	// we only need to do this for round 0
	cs.enterPropose(height, 0)
}

//-----------------------------------------------------------------------------
// State functions
// Used internally by handleTimeout and handleMsg to make state transitions

// Enter: `timeoutNewHeight` by startTime (commitTime+timeoutCommit),
// 	or, if SkipTimeout==true, after receiving all precommits from (height,round-1)
// Enter: `timeoutPrecommits` after any +2/3 precommits from (height,round-1)
// Enter: +2/3 precommits for nil at (height,round-1)
// Enter: +2/3 prevotes any or +2/3 precommits for block or any from (height, round)
// NOTE: cs.StartTime was already set for height.
func (cs *ConsensusState) enterNewRound(height int, round int) {
	if cs.Height != height || round < cs.Round || (cs.Round == round && cs.Step != cstypes.RoundStepNewHeight) {
		cs.Logger.Debug(cmn.Fmt("enterNewRound(%v/%v): Invalid args. Current step: %v/%v/%v", height, round, cs.Height, cs.Round, cs.Step))
		return
	}

	if now := time.Now(); cs.StartTime.After(now) {
		cs.Logger.Info("Need to set a buffer and log message here for sanity.", "startTime", cs.StartTime, "now", now)
	}

	cs.Logger.Info(cmn.Fmt("enterNewRound(%v/%v). Current: %v/%v/%v", height, round, cs.Height, cs.Round, cs.Step))

	// Increment validators if necessary
	validators := cs.Validators
	if cs.Round < round {
		validators = validators.Copy()
		validators.IncrementAccum(round - cs.Round)
	}

	// Setup new round
	// we don't fire newStep for this step,
	// but we fire an event, so update the round step first
	cs.updateRoundStep(round, cstypes.RoundStepNewRound)
	cs.Validators = validators
	if round == 0 {
		// We've already reset these upon new height,
		// and meanwhile we might have received a proposal
		// for round 0.
	} else {
		cs.Proposal = nil
		cs.ProposalBlock = nil
		cs.ProposalBlockParts = nil
	}
	cs.Votes.SetRound(round + 1) // also track next round (round+1) to allow round-skipping

	types.FireEventNewRound(cs.evsw, cs.RoundStateEvent())

	// Wait for txs to be available in the mempool
	// before we enterPropose in round 0. If the last block changed the app hash,
	// we may need an empty "proof" block, and enterPropose immediately.
	waitForTxs := cs.config.WaitForTxs() && round == 0 && !cs.needProofBlock(height)
	if waitForTxs {
		if cs.config.CreateEmptyBlocksInterval > 0 {
			cs.scheduleTimeout(cs.config.EmptyBlocksInterval(), height, round, cstypes.RoundStepNewRound)
		}
		go cs.proposalHeartbeat(height, round)
	} else {
		cs.enterPropose(height, round)
	}
}

// needProofBlock returns true on the first height (so the genesis app hash is signed right away)
// and where the last block (height-1) caused the app hash to change
func (cs *ConsensusState) needProofBlock(height int) bool {
	if height == 1 {
		return true
	}

	lastBlockMeta := cs.blockStore.LoadBlockMeta(height - 1)
	if !bytes.Equal(cs.state.AppHash, lastBlockMeta.Header.AppHash) {
		return true
	}
	return false
}

func (cs *ConsensusState) proposalHeartbeat(height, round int) {
	counter := 0
	addr := cs.privValidator.GetAddress()
	valIndex, v := cs.Validators.GetByAddress(addr)
	if v == nil {
		// not a validator
		valIndex = -1
	}
	chainID := cs.state.ChainID
	for {
		rs := cs.GetRoundState()
		// if we've already moved on, no need to send more heartbeats
		if rs.Step > cstypes.RoundStepNewRound || rs.Round > round || rs.Height > height {
			return
		}
		heartbeat := &types.Heartbeat{
			Height:           rs.Height,
			Round:            rs.Round,
			Sequence:         counter,
			ValidatorAddress: addr,
			ValidatorIndex:   valIndex,
		}
		cs.privValidator.SignHeartbeat(chainID, heartbeat)
		heartbeatEvent := types.EventDataProposalHeartbeat{heartbeat}
		types.FireEventProposalHeartbeat(cs.evsw, heartbeatEvent)
		counter += 1
		time.Sleep(proposalHeartbeatIntervalSeconds * time.Second)
	}
}

// Enter (CreateEmptyBlocks): from enterNewRound(height,round)
// Enter (CreateEmptyBlocks, CreateEmptyBlocksInterval > 0 ): after enterNewRound(height,round), after timeout of CreateEmptyBlocksInterval
// Enter (!CreateEmptyBlocks) : after enterNewRound(height,round), once txs are in the mempool
func (cs *ConsensusState) enterPropose(height int, round int) {
	if cs.Height != height || round < cs.Round || (cs.Round == round && cstypes.RoundStepPropose <= cs.Step) {
		cs.Logger.Debug(cmn.Fmt("enterPropose(%v/%v): Invalid args. Current step: %v/%v/%v", height, round, cs.Height, cs.Round, cs.Step))
		return
	}
	cs.Logger.Info(cmn.Fmt("enterPropose(%v/%v). Current: %v/%v/%v", height, round, cs.Height, cs.Round, cs.Step))

	defer func() {
		// Done enterPropose:
		cs.updateRoundStep(round, cstypes.RoundStepPropose)
		cs.newStep()

		// If we have the whole proposal + POL, then goto Prevote now.
		// else, we'll enterPrevote when the rest of the proposal is received (in AddProposalBlockPart),
		// or else after timeoutPropose
		if cs.isProposalComplete() {
			cs.enterPrevote(height, cs.Round)
		}
	}()

	// If we don't get the proposal and all block parts quick enough, enterPrevote
	cs.scheduleTimeout(cs.config.Propose(round), height, round, cstypes.RoundStepPropose)

	// Nothing more to do if we're not a validator
	if cs.privValidator == nil {
		cs.Logger.Debug("This node is not a validator")
		return
	}

	if !cs.isProposer() {
		cs.Logger.Info("enterPropose: Not our turn to propose", "proposer", cs.Validators.GetProposer().Address, "privValidator", cs.privValidator)
		if cs.Validators.HasAddress(cs.privValidator.GetAddress()) {
			cs.Logger.Debug("This node is a validator")
		} else {
			cs.Logger.Debug("This node is not a validator")
		}
	} else {
		cs.Logger.Info("enterPropose: Our turn to propose", "proposer", cs.Validators.GetProposer().Address, "privValidator", cs.privValidator)
		cs.Logger.Debug("This node is a validator")
		cs.decideProposal(height, round)
	}
}

func (cs *ConsensusState) isProposer() bool {
	return bytes.Equal(cs.Validators.GetProposer().Address, cs.privValidator.GetAddress())
}

func (cs *ConsensusState) defaultDecideProposal(height, round int) {
	var block *types.Block
	var blockParts *types.PartSet

	// Decide on block
	if cs.LockedBlock != nil {
		// If we're locked onto a block, just choose that.
		block, blockParts = cs.LockedBlock, cs.LockedBlockParts
	} else {
		// Create a new proposal block from state/txs from the mempool.
		block, blockParts = cs.createProposalBlock()
		if block == nil { // on error
			return
		}
	}

	// Make proposal
	polRound, polBlockID := cs.Votes.POLInfo()
	proposal := types.NewProposal(height, round, blockParts.Header(), polRound, polBlockID)
	if err := cs.privValidator.SignProposal(cs.state.ChainID, proposal); err == nil {
		// Set fields
		/*  fields set by setProposal and addBlockPart
		cs.Proposal = proposal
		cs.ProposalBlock = block
		cs.ProposalBlockParts = blockParts
		*/

		// send proposal and block parts on internal msg queue
		cs.sendInternalMessage(msgInfo{&ProposalMessage{proposal}, ""})
		for i := 0; i < blockParts.Total(); i++ {
			part := blockParts.GetPart(i)
			cs.sendInternalMessage(msgInfo{&BlockPartMessage{cs.Height, cs.Round, part}, ""})
		}
		cs.Logger.Info("Signed proposal", "height", height, "round", round, "proposal", proposal)
		cs.Logger.Debug(cmn.Fmt("Signed proposal block: %v", block))
	} else {
		if !cs.replayMode {
			cs.Logger.Error("enterPropose: Error signing proposal", "height", height, "round", round, "err", err)
		}
	}
}

// Returns true if the proposal block is complete &&
// (if POLRound was proposed, we have +2/3 prevotes from there).
func (cs *ConsensusState) isProposalComplete() bool {
	if cs.Proposal == nil || cs.ProposalBlock == nil {
		return false
	}
	// we have the proposal. if there's a POLRound,
	// make sure we have the prevotes from it too
	if cs.Proposal.POLRound < 0 {
		return true
	} else {
		// if this is false the proposer is lying or we haven't received the POL yet
		return cs.Votes.Prevotes(cs.Proposal.POLRound).HasTwoThirdsMajority()
	}
}

// Create the next block to propose and return it.
// Returns nil block upon error.
// NOTE: keep it side-effect free for clarity.
func (cs *ConsensusState) createProposalBlock() (block *types.Block, blockParts *types.PartSet) {
	var commit *types.Commit
	if cs.Height == 1 {
		// We're creating a proposal for the first block.
		// The commit is empty, but not nil.
		commit = &types.Commit{}
	} else if cs.LastCommit.HasTwoThirdsMajority() {
		// Make the commit from LastCommit
		commit = cs.LastCommit.MakeCommit()
	} else {
		// This shouldn't happen.
		cs.Logger.Error("enterPropose: Cannot propose anything: No commit for the previous block.")
		return
	}

	// Mempool validated transactions
	txs := cs.mempool.Reap(cs.config.MaxBlockSizeTxs)
	return types.MakeBlock(cs.Height, cs.state.ChainID, txs, commit,
		cs.state.LastBlockID, cs.state.Validators.Hash(),
		cs.state.AppHash, cs.state.Params.BlockPartSizeBytes)
}

// Enter: `timeoutPropose` after entering Propose.
// Enter: proposal block and POL is ready.
// Enter: any +2/3 prevotes for future round.
// Prevote for LockedBlock if we're locked, or ProposalBlock if valid.
// Otherwise vote nil.
func (cs *ConsensusState) enterPrevote(height int, round int) {
	if cs.Height != height || round < cs.Round || (cs.Round == round && cstypes.RoundStepPrevote <= cs.Step) {
		cs.Logger.Debug(cmn.Fmt("enterPrevote(%v/%v): Invalid args. Current step: %v/%v/%v", height, round, cs.Height, cs.Round, cs.Step))
		return
	}

	defer func() {
		// Done enterPrevote:
		cs.updateRoundStep(round, cstypes.RoundStepPrevote)
		cs.newStep()
	}()

	// fire event for how we got here
	if cs.isProposalComplete() {
		types.FireEventCompleteProposal(cs.evsw, cs.RoundStateEvent())
	} else {
		// we received +2/3 prevotes for a future round
		// TODO: catchup event?
	}

	cs.Logger.Info(cmn.Fmt("enterPrevote(%v/%v). Current: %v/%v/%v", height, round, cs.Height, cs.Round, cs.Step))

	// Sign and broadcast vote as necessary
	cs.doPrevote(height, round)

	// Once `addVote` hits any +2/3 prevotes, we will go to PrevoteWait
	// (so we have more time to try and collect +2/3 prevotes for a single block)
}

func (cs *ConsensusState) defaultDoPrevote(height int, round int) {
	logger := cs.Logger.With("height", height, "round", round)
	// If a block is locked, prevote that.
	if cs.LockedBlock != nil {
		logger.Info("enterPrevote: Block was locked")
		cs.signAddVote(types.VoteTypePrevote, cs.LockedBlock.Hash(), cs.LockedBlockParts.Header())
		return
	}

	// If ProposalBlock is nil, prevote nil.
	if cs.ProposalBlock == nil {
		logger.Info("enterPrevote: ProposalBlock is nil")
		cs.signAddVote(types.VoteTypePrevote, nil, types.PartSetHeader{})
		return
	}

	// Validate proposal block
	err := cs.state.ValidateBlock(cs.ProposalBlock)
	if err != nil {
		// ProposalBlock is invalid, prevote nil.
		logger.Error("enterPrevote: ProposalBlock is invalid", "err", err)
		cs.signAddVote(types.VoteTypePrevote, nil, types.PartSetHeader{})
		return
	}

	// Prevote cs.ProposalBlock
	// NOTE: the proposal signature is validated when it is received,
	// and the proposal block parts are validated as they are received (against the merkle hash in the proposal)
	logger.Info("enterPrevote: ProposalBlock is valid")
	cs.signAddVote(types.VoteTypePrevote, cs.ProposalBlock.Hash(), cs.ProposalBlockParts.Header())
}

// Enter: any +2/3 prevotes at next round.
func (cs *ConsensusState) enterPrevoteWait(height int, round int) {
	if cs.Height != height || round < cs.Round || (cs.Round == round && cstypes.RoundStepPrevoteWait <= cs.Step) {
		cs.Logger.Debug(cmn.Fmt("enterPrevoteWait(%v/%v): Invalid args. Current step: %v/%v/%v", height, round, cs.Height, cs.Round, cs.Step))
		return
	}
	if !cs.Votes.Prevotes(round).HasTwoThirdsAny() {
		cmn.PanicSanity(cmn.Fmt("enterPrevoteWait(%v/%v), but Prevotes does not have any +2/3 votes", height, round))
	}
	cs.Logger.Info(cmn.Fmt("enterPrevoteWait(%v/%v). Current: %v/%v/%v", height, round, cs.Height, cs.Round, cs.Step))

	defer func() {
		// Done enterPrevoteWait:
		cs.updateRoundStep(round, cstypes.RoundStepPrevoteWait)
		cs.newStep()
	}()

	// Wait for some more prevotes; enterPrecommit
	cs.scheduleTimeout(cs.config.Prevote(round), height, round, cstypes.RoundStepPrevoteWait)
}

// Enter: `timeoutPrevote` after any +2/3 prevotes.
// Enter: +2/3 precomits for block or nil.
// Enter: any +2/3 precommits for next round.
// Lock & precommit the ProposalBlock if we have enough prevotes for it (a POL in this round)
// else, unlock an existing lock and precommit nil if +2/3 of prevotes were nil,
// else, precommit nil otherwise.
func (cs *ConsensusState) enterPrecommit(height int, round int) {
	if cs.Height != height || round < cs.Round || (cs.Round == round && cstypes.RoundStepPrecommit <= cs.Step) {
		cs.Logger.Debug(cmn.Fmt("enterPrecommit(%v/%v): Invalid args. Current step: %v/%v/%v", height, round, cs.Height, cs.Round, cs.Step))
		return
	}

	cs.Logger.Info(cmn.Fmt("enterPrecommit(%v/%v). Current: %v/%v/%v", height, round, cs.Height, cs.Round, cs.Step))

	defer func() {
		// Done enterPrecommit:
		cs.updateRoundStep(round, cstypes.RoundStepPrecommit)
		cs.newStep()
	}()

	blockID, ok := cs.Votes.Prevotes(round).TwoThirdsMajority()

	// If we don't have a polka, we must precommit nil
	if !ok {
		if cs.LockedBlock != nil {
			cs.Logger.Info("enterPrecommit: No +2/3 prevotes during enterPrecommit while we're locked. Precommitting nil")
		} else {
			cs.Logger.Info("enterPrecommit: No +2/3 prevotes during enterPrecommit. Precommitting nil.")
		}
		cs.signAddVote(types.VoteTypePrecommit, nil, types.PartSetHeader{})
		return
	}

	// At this point +2/3 prevoted for a particular block or nil
	types.FireEventPolka(cs.evsw, cs.RoundStateEvent())

	// the latest POLRound should be this round
	polRound, _ := cs.Votes.POLInfo()
	if polRound < round {
		cmn.PanicSanity(cmn.Fmt("This POLRound should be %v but got %", round, polRound))
	}

	// +2/3 prevoted nil. Unlock and precommit nil.
	if len(blockID.Hash) == 0 {
		if cs.LockedBlock == nil {
			cs.Logger.Info("enterPrecommit: +2/3 prevoted for nil.")
		} else {
			cs.Logger.Info("enterPrecommit: +2/3 prevoted for nil. Unlocking")
			cs.LockedRound = 0
			cs.LockedBlock = nil
			cs.LockedBlockParts = nil
			types.FireEventUnlock(cs.evsw, cs.RoundStateEvent())
		}
		cs.signAddVote(types.VoteTypePrecommit, nil, types.PartSetHeader{})
		return
	}

	// At this point, +2/3 prevoted for a particular block.

	// If we're already locked on that block, precommit it, and update the LockedRound
	if cs.LockedBlock.HashesTo(blockID.Hash) {
		cs.Logger.Info("enterPrecommit: +2/3 prevoted locked block. Relocking")
		cs.LockedRound = round
		types.FireEventRelock(cs.evsw, cs.RoundStateEvent())
		cs.signAddVote(types.VoteTypePrecommit, blockID.Hash, blockID.PartsHeader)
		return
	}

	// If +2/3 prevoted for proposal block, stage and precommit it
	if cs.ProposalBlock.HashesTo(blockID.Hash) {
		cs.Logger.Info("enterPrecommit: +2/3 prevoted proposal block. Locking", "hash", blockID.Hash)
		// Validate the block.
		if err := cs.state.ValidateBlock(cs.ProposalBlock); err != nil {
			cmn.PanicConsensus(cmn.Fmt("enterPrecommit: +2/3 prevoted for an invalid block: %v", err))
		}
		cs.LockedRound = round
		cs.LockedBlock = cs.ProposalBlock
		cs.LockedBlockParts = cs.ProposalBlockParts
		types.FireEventLock(cs.evsw, cs.RoundStateEvent())
		cs.signAddVote(types.VoteTypePrecommit, blockID.Hash, blockID.PartsHeader)
		return
	}

	// There was a polka in this round for a block we don't have.
	// Fetch that block, unlock, and precommit nil.
	// The +2/3 prevotes for this round is the POL for our unlock.
	// TODO: In the future save the POL prevotes for justification.
	cs.LockedRound = 0
	cs.LockedBlock = nil
	cs.LockedBlockParts = nil
	if !cs.ProposalBlockParts.HasHeader(blockID.PartsHeader) {
		cs.ProposalBlock = nil
		cs.ProposalBlockParts = types.NewPartSetFromHeader(blockID.PartsHeader)
	}
	types.FireEventUnlock(cs.evsw, cs.RoundStateEvent())
	cs.signAddVote(types.VoteTypePrecommit, nil, types.PartSetHeader{})
}

// Enter: any +2/3 precommits for next round.
func (cs *ConsensusState) enterPrecommitWait(height int, round int) {
	if cs.Height != height || round < cs.Round || (cs.Round == round && cstypes.RoundStepPrecommitWait <= cs.Step) {
		cs.Logger.Debug(cmn.Fmt("enterPrecommitWait(%v/%v): Invalid args. Current step: %v/%v/%v", height, round, cs.Height, cs.Round, cs.Step))
		return
	}
	if !cs.Votes.Precommits(round).HasTwoThirdsAny() {
		cmn.PanicSanity(cmn.Fmt("enterPrecommitWait(%v/%v), but Precommits does not have any +2/3 votes", height, round))
	}
	cs.Logger.Info(cmn.Fmt("enterPrecommitWait(%v/%v). Current: %v/%v/%v", height, round, cs.Height, cs.Round, cs.Step))

	defer func() {
		// Done enterPrecommitWait:
		cs.updateRoundStep(round, cstypes.RoundStepPrecommitWait)
		cs.newStep()
	}()

	// Wait for some more precommits; enterNewRound
	cs.scheduleTimeout(cs.config.Precommit(round), height, round, cstypes.RoundStepPrecommitWait)

}

// Enter: +2/3 precommits for block
func (cs *ConsensusState) enterCommit(height int, commitRound int) {
	if cs.Height != height || cstypes.RoundStepCommit <= cs.Step {
		cs.Logger.Debug(cmn.Fmt("enterCommit(%v/%v): Invalid args. Current step: %v/%v/%v", height, commitRound, cs.Height, cs.Round, cs.Step))
		return
	}
	cs.Logger.Info(cmn.Fmt("enterCommit(%v/%v). Current: %v/%v/%v", height, commitRound, cs.Height, cs.Round, cs.Step))

	defer func() {
		// Done enterCommit:
		// keep cs.Round the same, commitRound points to the right Precommits set.
		cs.updateRoundStep(cs.Round, cstypes.RoundStepCommit)
		cs.CommitRound = commitRound
		cs.CommitTime = time.Now()
		cs.newStep()

		// Maybe finalize immediately.
		cs.tryFinalizeCommit(height)
	}()

	blockID, ok := cs.Votes.Precommits(commitRound).TwoThirdsMajority()
	if !ok {
		cmn.PanicSanity("RunActionCommit() expects +2/3 precommits")
	}

	// The Locked* fields no longer matter.
	// Move them over to ProposalBlock if they match the commit hash,
	// otherwise they'll be cleared in updateToState.
	if cs.LockedBlock.HashesTo(blockID.Hash) {
		cs.ProposalBlock = cs.LockedBlock
		cs.ProposalBlockParts = cs.LockedBlockParts
	}

	// If we don't have the block being committed, set up to get it.
	if !cs.ProposalBlock.HashesTo(blockID.Hash) {
		if !cs.ProposalBlockParts.HasHeader(blockID.PartsHeader) {
			// We're getting the wrong block.
			// Set up ProposalBlockParts and keep waiting.
			cs.ProposalBlock = nil
			cs.ProposalBlockParts = types.NewPartSetFromHeader(blockID.PartsHeader)
		} else {
			// We just need to keep waiting.
		}
	}
}

// If we have the block AND +2/3 commits for it, finalize.
func (cs *ConsensusState) tryFinalizeCommit(height int) {
	if cs.Height != height {
		cmn.PanicSanity(cmn.Fmt("tryFinalizeCommit() cs.Height: %v vs height: %v", cs.Height, height))
	}

	blockID, ok := cs.Votes.Precommits(cs.CommitRound).TwoThirdsMajority()
	if !ok || len(blockID.Hash) == 0 {
		cs.Logger.Error("Attempt to finalize failed. There was no +2/3 majority, or +2/3 was for <nil>.", "height", height)
		return
	}
	if !cs.ProposalBlock.HashesTo(blockID.Hash) {
		// TODO: this happens every time if we're not a validator (ugly logs)
		// TODO: ^^ wait, why does it matter that we're a validator?
		cs.Logger.Info("Attempt to finalize failed. We don't have the commit block.", "height", height, "proposal-block", cs.ProposalBlock.Hash(), "commit-block", blockID.Hash)
		return
	}

	//	go
	cs.finalizeCommit(height)
}

// Increment height and goto cstypes.RoundStepNewHeight
func (cs *ConsensusState) finalizeCommit(height int) {
	if cs.Height != height || cs.Step != cstypes.RoundStepCommit {
		cs.Logger.Debug(cmn.Fmt("finalizeCommit(%v): Invalid args. Current step: %v/%v/%v", height, cs.Height, cs.Round, cs.Step))
		return
	}

	blockID, ok := cs.Votes.Precommits(cs.CommitRound).TwoThirdsMajority()
	block, blockParts := cs.ProposalBlock, cs.ProposalBlockParts

	if !ok {
		cmn.PanicSanity(cmn.Fmt("Cannot finalizeCommit, commit does not have two thirds majority"))
	}
	if !blockParts.HasHeader(blockID.PartsHeader) {
		cmn.PanicSanity(cmn.Fmt("Expected ProposalBlockParts header to be commit header"))
	}
	if !block.HashesTo(blockID.Hash) {
		cmn.PanicSanity(cmn.Fmt("Cannot finalizeCommit, ProposalBlock does not hash to commit hash"))
	}
	if err := cs.state.ValidateBlock(block); err != nil {
		cmn.PanicConsensus(cmn.Fmt("+2/3 committed an invalid block: %v", err))
	}

	cs.Logger.Info(cmn.Fmt("Finalizing commit of block with %d txs", block.NumTxs),
		"height", block.Height, "hash", block.Hash(), "root", block.AppHash)
	cs.Logger.Info(cmn.Fmt("%v", block))

	fail.Fail() // XXX

	// Save to blockStore.
	if cs.blockStore.Height() < block.Height {
		// NOTE: the seenCommit is local justification to commit this block,
		// but may differ from the LastCommit included in the next block
		precommits := cs.Votes.Precommits(cs.CommitRound)
		seenCommit := precommits.MakeCommit()
		cs.blockStore.SaveBlock(block, blockParts, seenCommit)
	} else {
		// Happens during replay if we already saved the block but didn't commit
		cs.Logger.Info("Calling finalizeCommit on already stored block", "height", block.Height)
	}

	fail.Fail() // XXX

	// Finish writing to the WAL for this height.
	// NOTE: If we fail before writing this, we'll never write it,
	// and just recover by running ApplyBlock in the Handshake.
	// If we moved it before persisting the block, we'd have to allow
	// WAL replay for blocks with an #ENDHEIGHT
	// As is, ConsensusState should not be started again
	// until we successfully call ApplyBlock (ie. here or in Handshake after restart)
	if cs.wal != nil {
		cs.wal.Save(EndHeightMessage{uint64(height)})
	}

	fail.Fail() // XXX

	// Create a copy of the state for staging
	// and an event cache for txs
	stateCopy := cs.state.Copy()
	eventCache := types.NewEventCache(cs.evsw)

	// Execute and commit the block, update and save the state, and update the mempool.
	// All calls to the proxyAppConn come here.
	// NOTE: the block.AppHash wont reflect these txs until the next block
	err := stateCopy.ApplyBlock(eventCache, cs.proxyAppConn, block, blockParts.Header(), cs.mempool)
	if err != nil {
		cs.Logger.Error("Error on ApplyBlock. Did the application crash? Please restart tendermint", "err", err)
		err := cmn.Kill()
		if err != nil {
			cs.Logger.Error("Failed to kill this process - please do so manually", "err", err)
		}
		return
	}

	fail.Fail() // XXX

	// Fire event for new block.
	// NOTE: If we fail before firing, these events will never fire
	//
	// TODO: Either
	//	* Fire before persisting state, in ApplyBlock
	//	* Fire on start up if we haven't written any new WAL msgs
	//   Both options mean we may fire more than once. Is that fine ?
	types.FireEventNewBlock(cs.evsw, types.EventDataNewBlock{block})
	types.FireEventNewBlockHeader(cs.evsw, types.EventDataNewBlockHeader{block.Header})
	eventCache.Flush()

	fail.Fail() // XXX

	// NewHeightStep!
	cs.updateToState(stateCopy)

	fail.Fail() // XXX

	// cs.StartTime is already set.
	// Schedule Round0 to start soon.
	cs.scheduleRound0(&cs.RoundState)

	// By here,
	// * cs.Height has been increment to height+1
	// * cs.Step is now cstypes.RoundStepNewHeight
	// * cs.StartTime is set to when we will start round0.
}

//-----------------------------------------------------------------------------

func (cs *ConsensusState) defaultSetProposal(proposal *types.Proposal) error {
	// Already have one
	// TODO: possibly catch double proposals
	if cs.Proposal != nil {
		return nil
	}

	// Does not apply
	if proposal.Height != cs.Height || proposal.Round != cs.Round {
		return nil
	}

	// We don't care about the proposal if we're already in cstypes.RoundStepCommit.
	if cstypes.RoundStepCommit <= cs.Step {
		return nil
	}

	// Verify POLRound, which must be -1 or between 0 and proposal.Round exclusive.
	if proposal.POLRound != -1 &&
		(proposal.POLRound < 0 || proposal.Round <= proposal.POLRound) {
		return ErrInvalidProposalPOLRound
	}

	// Verify signature
	if !cs.Validators.GetProposer().PubKey.VerifyBytes(types.SignBytes(cs.state.ChainID, proposal), proposal.Signature) {
		return ErrInvalidProposalSignature
	}

	cs.Proposal = proposal
	cs.ProposalBlockParts = types.NewPartSetFromHeader(proposal.BlockPartsHeader)
	return nil
}

// NOTE: block is not necessarily valid.
// Asynchronously triggers either enterPrevote (before we timeout of propose) or tryFinalizeCommit, once we have the full block.
func (cs *ConsensusState) addProposalBlockPart(height int, part *types.Part, verify bool) (added bool, err error) {
	// Blocks might be reused, so round mismatch is OK
	if cs.Height != height {
		return false, nil
	}

	// We're not expecting a block part.
	if cs.ProposalBlockParts == nil {
		return false, nil // TODO: bad peer? Return error?
	}

	added, err = cs.ProposalBlockParts.AddPart(part, verify)
	if err != nil {
		return added, err
	}
	if added && cs.ProposalBlockParts.IsComplete() {
		// Added and completed!
		var n int
		var err error
		cs.ProposalBlock = wire.ReadBinary(&types.Block{}, cs.ProposalBlockParts.GetReader(),
			cs.state.Params.BlockSizeParams.MaxBytes, &n, &err).(*types.Block)
		// NOTE: it's possible to receive complete proposal blocks for future rounds without having the proposal
		cs.Logger.Info("Received complete proposal block", "height", cs.ProposalBlock.Height, "hash", cs.ProposalBlock.Hash())
		if cs.Step == cstypes.RoundStepPropose && cs.isProposalComplete() {
			// Move onto the next step
			cs.enterPrevote(height, cs.Round)
		} else if cs.Step == cstypes.RoundStepCommit {
			// If we're waiting on the proposal block...
			cs.tryFinalizeCommit(height)
		}
		return true, err
	}
	return added, nil
}

// Attempt to add the vote. if its a duplicate signature, dupeout the validator
func (cs *ConsensusState) tryAddVote(vote *types.Vote, peerKey string) error {
	_, err := cs.addVote(vote, peerKey)
	if err != nil {
		// If the vote height is off, we'll just ignore it,
		// But if it's a conflicting sig, broadcast evidence tx for slashing.
		// If it's otherwise invalid, punish peer.
		if err == ErrVoteHeightMismatch {
			return err
		} else if _, ok := err.(*types.ErrVoteConflictingVotes); ok {
			if bytes.Equal(vote.ValidatorAddress, cs.privValidator.GetAddress()) {
				cs.Logger.Error("Found conflicting vote from ourselves. Did you unsafe_reset a validator?", "height", vote.Height, "round", vote.Round, "type", vote.Type)
				return err
			}
			cs.Logger.Error("Found conflicting vote. Publish evidence (TODO)", "height", vote.Height, "round", vote.Round, "type", vote.Type, "valAddr", vote.ValidatorAddress, "valIndex", vote.ValidatorIndex)

			// TODO: track evidence for inclusion in a block

			return err
		} else {
			// Probably an invalid signature. Bad peer.
			cs.Logger.Error("Error attempting to add vote", "err", err)
			return ErrAddingVote
		}
	}
	return nil
}

//-----------------------------------------------------------------------------

func (cs *ConsensusState) addVote(vote *types.Vote, peerKey string) (added bool, err error) {
	cs.Logger.Debug("addVote", "voteHeight", vote.Height, "voteType", vote.Type, "valIndex", vote.ValidatorIndex, "csHeight", cs.Height)

	// A precommit for the previous height?
	// These come in while we wait timeoutCommit
	if vote.Height+1 == cs.Height {
		if !(cs.Step == cstypes.RoundStepNewHeight && vote.Type == types.VoteTypePrecommit) {
			// TODO: give the reason ..
			// fmt.Errorf("tryAddVote: Wrong height, not a LastCommit straggler commit.")
			return added, ErrVoteHeightMismatch
		}
		added, err = cs.LastCommit.AddVote(vote)
		if added {
			cs.Logger.Info(cmn.Fmt("Added to lastPrecommits: %v", cs.LastCommit.StringShort()))
			types.FireEventVote(cs.evsw, types.EventDataVote{vote})

			// if we can skip timeoutCommit and have all the votes now,
			if cs.config.SkipTimeoutCommit && cs.LastCommit.HasAll() {
				// go straight to new round (skip timeout commit)
				// cs.scheduleTimeout(time.Duration(0), cs.Height, 0, cstypes.RoundStepNewHeight)
				cs.enterNewRound(cs.Height, 0)
			}
		}

		return
	}

	// A prevote/precommit for this height?
	if vote.Height == cs.Height {
		height := cs.Height
		added, err = cs.Votes.AddVote(vote, peerKey)
		if added {
			types.FireEventVote(cs.evsw, types.EventDataVote{vote})

			switch vote.Type {
			case types.VoteTypePrevote:
				prevotes := cs.Votes.Prevotes(vote.Round)
				cs.Logger.Info("Added to prevote", "vote", vote, "prevotes", prevotes.StringShort())
				// First, unlock if prevotes is a valid POL.
				// >> lockRound < POLRound <= unlockOrChangeLockRound (see spec)
				// NOTE: If (lockRound < POLRound) but !(POLRound <= unlockOrChangeLockRound),
				// we'll still enterNewRound(H,vote.R) and enterPrecommit(H,vote.R) to process it
				// there.
				if (cs.LockedBlock != nil) && (cs.LockedRound < vote.Round) && (vote.Round <= cs.Round) {
					blockID, ok := prevotes.TwoThirdsMajority()
					if ok && !cs.LockedBlock.HashesTo(blockID.Hash) {
						cs.Logger.Info("Unlocking because of POL.", "lockedRound", cs.LockedRound, "POLRound", vote.Round)
						cs.LockedRound = 0
						cs.LockedBlock = nil
						cs.LockedBlockParts = nil
						types.FireEventUnlock(cs.evsw, cs.RoundStateEvent())
					}
				}
				if cs.Round <= vote.Round && prevotes.HasTwoThirdsAny() {
					// Round-skip over to PrevoteWait or goto Precommit.
					cs.enterNewRound(height, vote.Round) // if the vote is ahead of us
					if prevotes.HasTwoThirdsMajority() {
						cs.enterPrecommit(height, vote.Round)
					} else {
						cs.enterPrevote(height, vote.Round) // if the vote is ahead of us
						cs.enterPrevoteWait(height, vote.Round)
					}
				} else if cs.Proposal != nil && 0 <= cs.Proposal.POLRound && cs.Proposal.POLRound == vote.Round {
					// If the proposal is now complete, enter prevote of cs.Round.
					if cs.isProposalComplete() {
						cs.enterPrevote(height, cs.Round)
					}
				}
			case types.VoteTypePrecommit:
				precommits := cs.Votes.Precommits(vote.Round)
				cs.Logger.Info("Added to precommit", "vote", vote, "precommits", precommits.StringShort())
				blockID, ok := precommits.TwoThirdsMajority()
				if ok {
					if len(blockID.Hash) == 0 {
						cs.enterNewRound(height, vote.Round+1)
					} else {
						cs.enterNewRound(height, vote.Round)
						cs.enterPrecommit(height, vote.Round)
						cs.enterCommit(height, vote.Round)

						if cs.config.SkipTimeoutCommit && precommits.HasAll() {
							// if we have all the votes now,
							// go straight to new round (skip timeout commit)
							// cs.scheduleTimeout(time.Duration(0), cs.Height, 0, cstypes.RoundStepNewHeight)
							cs.enterNewRound(cs.Height, 0)
						}

					}
				} else if cs.Round <= vote.Round && precommits.HasTwoThirdsAny() {
					cs.enterNewRound(height, vote.Round)
					cs.enterPrecommit(height, vote.Round)
					cs.enterPrecommitWait(height, vote.Round)
				}
			default:
				cmn.PanicSanity(cmn.Fmt("Unexpected vote type %X", vote.Type)) // Should not happen.
			}
		}
		// Either duplicate, or error upon cs.Votes.AddByIndex()
		return
	} else {
		err = ErrVoteHeightMismatch
	}

	// Height mismatch, bad peer?
	cs.Logger.Info("Vote ignored and not added", "voteHeight", vote.Height, "csHeight", cs.Height, "err", err)
	return
}

func (cs *ConsensusState) signVote(type_ byte, hash []byte, header types.PartSetHeader) (*types.Vote, error) {
	addr := cs.privValidator.GetAddress()
	valIndex, _ := cs.Validators.GetByAddress(addr)
	vote := &types.Vote{
		ValidatorAddress: addr,
		ValidatorIndex:   valIndex,
		Height:           cs.Height,
		Round:            cs.Round,
		Type:             type_,
		BlockID:          types.BlockID{hash, header},
	}
	err := cs.privValidator.SignVote(cs.state.ChainID, vote)
	return vote, err
}

// sign the vote and publish on internalMsgQueue
func (cs *ConsensusState) signAddVote(type_ byte, hash []byte, header types.PartSetHeader) *types.Vote {
	// if we don't have a key or we're not in the validator set, do nothing
	if cs.privValidator == nil || !cs.Validators.HasAddress(cs.privValidator.GetAddress()) {
		return nil
	}
	vote, err := cs.signVote(type_, hash, header)
	if err == nil {
		cs.sendInternalMessage(msgInfo{&VoteMessage{vote}, ""})
		cs.Logger.Info("Signed and pushed vote", "height", cs.Height, "round", cs.Round, "vote", vote, "err", err)
		return vote
	} else {
		//if !cs.replayMode {
		cs.Logger.Error("Error signing vote", "height", cs.Height, "round", cs.Round, "vote", vote, "err", err)
		//}
		return nil
	}
}

//---------------------------------------------------------

func CompareHRS(h1, r1 int, s1 cstypes.RoundStepType, h2, r2 int, s2 cstypes.RoundStepType) int {
	if h1 < h2 {
		return -1
	} else if h1 > h2 {
		return 1
	}
	if r1 < r2 {
		return -1
	} else if r1 > r2 {
		return 1
	}
	if s1 < s2 {
		return -1
	} else if s1 > s2 {
		return 1
	}
	return 0
}