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|
// Copyright 2018 The dexon-consensus Authors
// This file is part of the dexon-consensus library.
//
// The dexon-consensus library is free software: you can redistribute it
// and/or modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation, either version 3 of the License,
// or (at your option) any later version.
//
// The dexon-consensus library is distributed in the hope that it will be
// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
// General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the dexon-consensus library. If not, see
// <http://www.gnu.org/licenses/>.
package core
import (
"fmt"
"math"
"sync"
"sync/atomic"
"time"
"github.com/dexon-foundation/dexon-consensus/common"
"github.com/dexon-foundation/dexon-consensus/core/types"
"github.com/dexon-foundation/dexon-consensus/core/utils"
)
// closedchan is a reusable closed channel.
var closedchan = make(chan struct{})
func init() {
close(closedchan)
}
// Errors for agreement module.
var (
ErrInvalidVote = fmt.Errorf("invalid vote")
ErrNotInNotarySet = fmt.Errorf("not in notary set")
ErrIncorrectVoteSignature = fmt.Errorf("incorrect vote signature")
ErrIncorrectVotePartialSignature = fmt.Errorf("incorrect vote psig")
ErrMismatchBlockPosition = fmt.Errorf("mismatch block position")
)
// ErrFork for fork error in agreement.
type ErrFork struct {
nID types.NodeID
old, new common.Hash
}
func (e *ErrFork) Error() string {
return fmt.Sprintf("fork is found for %s, old %s, new %s",
e.nID.String(), e.old, e.new)
}
// ErrForkVote for fork vote error in agreement.
type ErrForkVote struct {
nID types.NodeID
old, new *types.Vote
}
func (e *ErrForkVote) Error() string {
return fmt.Sprintf("fork vote is found for %s, old %s, new %s",
e.nID.String(), e.old, e.new)
}
func newVoteListMap() []map[types.NodeID]*types.Vote {
listMap := make([]map[types.NodeID]*types.Vote, types.MaxVoteType)
for idx := range listMap {
listMap[idx] = make(map[types.NodeID]*types.Vote)
}
return listMap
}
// agreementReceiver is the interface receiving agreement event.
type agreementReceiver interface {
ProposeVote(vote *types.Vote)
ProposeBlock() common.Hash
// ConfirmBlock is called with lock hold. User can safely use all data within
// agreement module.
ConfirmBlock(common.Hash, map[types.NodeID]*types.Vote)
PullBlocks(common.Hashes)
ReportForkVote(v1, v2 *types.Vote)
ReportForkBlock(b1, b2 *types.Block)
VerifyPartialSignature(vote *types.Vote) bool
}
type pendingBlock struct {
block *types.Block
receivedTime time.Time
}
type pendingVote struct {
vote *types.Vote
receivedTime time.Time
}
// agreementData is the data for agreementState.
type agreementData struct {
recv agreementReceiver
ID types.NodeID
isLeader bool
leader *leaderSelector
lockValue common.Hash
lockIter uint64
period uint64
requiredVote int
votes map[uint64][]map[types.NodeID]*types.Vote
lock sync.RWMutex
blocks map[types.NodeID]*types.Block
blocksLock sync.Mutex
}
// agreement is the agreement protocal describe in the Crypto Shuffle Algorithm.
type agreement struct {
state agreementState
data *agreementData
aID *atomic.Value
doneChan chan struct{}
notarySet map[types.NodeID]struct{}
hasVoteFast bool
hasOutput bool
lock sync.RWMutex
pendingBlock []pendingBlock
pendingVote []pendingVote
pendingAgreementResult map[types.Position]*types.AgreementResult
candidateBlock map[common.Hash]*types.Block
fastForward chan uint64
signer *utils.Signer
logger common.Logger
}
// newAgreement creates a agreement instance.
func newAgreement(
ID types.NodeID,
recv agreementReceiver,
leader *leaderSelector,
signer *utils.Signer,
logger common.Logger) *agreement {
agreement := &agreement{
data: &agreementData{
recv: recv,
ID: ID,
leader: leader,
},
aID: &atomic.Value{},
pendingAgreementResult: make(map[types.Position]*types.AgreementResult),
candidateBlock: make(map[common.Hash]*types.Block),
fastForward: make(chan uint64, 1),
signer: signer,
logger: logger,
}
agreement.stop()
return agreement
}
// restart the agreement
func (a *agreement) restart(
notarySet map[types.NodeID]struct{}, aID types.Position, leader types.NodeID,
crs common.Hash) {
if !func() bool {
a.lock.Lock()
defer a.lock.Unlock()
if !isStop(aID) {
oldAID := a.agreementID()
if !isStop(oldAID) && !aID.Newer(oldAID) {
return false
}
}
a.logger.Debug("Restarting BA",
"notarySet", notarySet, "position", aID, "leader", leader)
a.data.lock.Lock()
defer a.data.lock.Unlock()
a.data.blocksLock.Lock()
defer a.data.blocksLock.Unlock()
a.data.votes = make(map[uint64][]map[types.NodeID]*types.Vote)
a.data.votes[1] = newVoteListMap()
a.data.period = 2
a.data.blocks = make(map[types.NodeID]*types.Block)
a.data.requiredVote = len(notarySet)*2/3 + 1
a.data.leader.restart(crs)
a.data.lockValue = types.SkipBlockHash
a.data.lockIter = 0
a.data.isLeader = a.data.ID == leader
if a.doneChan != nil {
close(a.doneChan)
}
a.doneChan = make(chan struct{})
a.fastForward = make(chan uint64, 1)
a.hasVoteFast = false
a.hasOutput = false
a.state = newFastState(a.data)
a.notarySet = notarySet
a.candidateBlock = make(map[common.Hash]*types.Block)
a.aID.Store(struct {
pos types.Position
leader types.NodeID
}{aID, leader})
return true
}() {
return
}
if isStop(aID) {
return
}
var result *types.AgreementResult
func() {
a.lock.Lock()
defer a.lock.Unlock()
newPendingAgreementResult := make(
map[types.Position]*types.AgreementResult)
for pos, agr := range a.pendingAgreementResult {
if pos.Newer(aID) {
newPendingAgreementResult[pos] = agr
} else if pos == aID {
result = agr
}
}
a.pendingAgreementResult = newPendingAgreementResult
}()
expireTime := time.Now().Add(-10 * time.Second)
replayBlock := make([]*types.Block, 0)
func() {
a.lock.Lock()
defer a.lock.Unlock()
newPendingBlock := make([]pendingBlock, 0)
for _, pending := range a.pendingBlock {
if aID.Newer(pending.block.Position) {
continue
} else if pending.block.Position == aID {
if result == nil ||
result.Position.Round < DKGDelayRound ||
result.BlockHash == pending.block.Hash {
replayBlock = append(replayBlock, pending.block)
}
} else if pending.receivedTime.After(expireTime) {
newPendingBlock = append(newPendingBlock, pending)
}
}
a.pendingBlock = newPendingBlock
}()
replayVote := make([]*types.Vote, 0)
func() {
a.lock.Lock()
defer a.lock.Unlock()
newPendingVote := make([]pendingVote, 0)
for _, pending := range a.pendingVote {
if aID.Newer(pending.vote.Position) {
continue
} else if pending.vote.Position == aID {
if result == nil || result.Position.Round < DKGDelayRound {
replayVote = append(replayVote, pending.vote)
}
} else if pending.receivedTime.After(expireTime) {
newPendingVote = append(newPendingVote, pending)
}
}
a.pendingVote = newPendingVote
}()
for _, block := range replayBlock {
if err := a.processBlock(block); err != nil {
a.logger.Error("Failed to process block when restarting agreement",
"block", block)
}
}
if result != nil {
if err := a.processAgreementResult(result); err != nil {
a.logger.Error("Failed to process agreement result when retarting",
"result", result)
}
}
for _, vote := range replayVote {
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{
Height: math.MaxUint64,
}, types.NodeID{}, common.Hash{})
}
func isStop(aID types.Position) bool {
return aID.Height == math.MaxUint64
}
// clocks returns how many time this state is required.
func (a *agreement) clocks() int {
a.data.lock.RLock()
defer a.data.lock.RUnlock()
scale := int(a.data.period) - 1
if a.state.state() == stateForward {
scale = 1
}
if scale < 1 {
// just in case.
scale = 1
}
// 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.
func (a *agreement) pullVotes() bool {
a.data.lock.RLock()
defer a.data.lock.RUnlock()
return a.state.state() == statePullVote ||
a.state.state() == stateInitial ||
(a.state.state() == statePreCommit && (a.data.period%3) == 0)
}
// agreementID returns the current agreementID.
func (a *agreement) agreementID() 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) {
a.lock.Lock()
defer a.lock.Unlock()
if a.hasOutput {
a.state = newSleepState(a.data)
return
}
a.state, err = a.state.nextState()
return
}
func (a *agreement) sanityCheck(vote *types.Vote) error {
if vote.Type >= types.MaxVoteType {
return ErrInvalidVote
}
if _, exist := a.notarySet[vote.ProposerID]; !exist {
return ErrNotInNotarySet
}
ok, err := utils.VerifyVoteSignature(vote)
if err != nil {
return err
}
if !ok {
return ErrIncorrectVoteSignature
}
if !a.data.recv.VerifyPartialSignature(vote) {
return ErrIncorrectVotePartialSignature
}
return nil
}
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
}
// prepareVote prepares a vote.
func (a *agreement) prepareVote(vote *types.Vote) (err error) {
vote.Position = a.agreementID()
err = a.signer.SignVote(vote)
return
}
func (a *agreement) updateFilter(filter *utils.VoteFilter) {
a.lock.RLock()
defer a.lock.RUnlock()
a.data.lock.RLock()
defer a.data.lock.RUnlock()
filter.Confirm = a.hasOutput
filter.LockIter = a.data.lockIter
filter.Period = a.data.period
filter.Height = a.agreementID().Height
}
// processVote is the entry point for processing Vote.
func (a *agreement) processVote(vote *types.Vote) error {
a.lock.Lock()
defer a.lock.Unlock()
if err := a.sanityCheck(vote); err != nil {
return err
}
aID := a.agreementID()
// Agreement module has stopped.
if isStop(aID) {
// Hacky way to not drop first votes for genesis height.
if vote.Position.Height == types.GenesisHeight {
a.pendingVote = append(a.pendingVote, pendingVote{
vote: vote,
receivedTime: time.Now().UTC(),
})
}
return nil
}
if vote.Position != aID {
if aID.Newer(vote.Position) {
return nil
}
a.pendingVote = append(a.pendingVote, pendingVote{
vote: vote,
receivedTime: time.Now().UTC(),
})
return nil
}
exist, err := a.checkForkVote(vote)
if err != nil {
return err
}
if exist {
return nil
}
a.data.lock.Lock()
defer a.data.lock.Unlock()
if _, exist := a.data.votes[vote.Period]; !exist {
a.data.votes[vote.Period] = newVoteListMap()
}
if _, exist := a.data.votes[vote.Period][vote.Type][vote.ProposerID]; exist {
return nil
}
a.data.votes[vote.Period][vote.Type][vote.ProposerID] = vote
if !a.hasOutput &&
(vote.Type == types.VoteCom ||
vote.Type == types.VoteFast ||
vote.Type == types.VoteFastCom) {
if hash, ok := a.data.countVoteNoLock(vote.Period, vote.Type); ok &&
hash != types.SkipBlockHash {
if vote.Type == types.VoteFast {
if !a.hasVoteFast {
if a.state.state() == stateFast ||
a.state.state() == stateFastVote {
a.data.recv.ProposeVote(
types.NewVote(types.VoteFastCom, hash, vote.Period))
a.hasVoteFast = true
}
if a.data.lockIter == 0 {
a.data.lockValue = hash
a.data.lockIter = 1
}
}
} else {
a.hasOutput = true
a.data.recv.ConfirmBlock(hash,
a.data.votes[vote.Period][vote.Type])
if a.doneChan != nil {
close(a.doneChan)
a.doneChan = nil
}
}
return nil
}
} else if a.hasOutput {
return nil
}
// Check if the agreement requires fast-forwarding.
if len(a.fastForward) > 0 {
return nil
}
if vote.Type == types.VotePreCom {
if vote.Period < a.data.lockIter {
// This PreCom is useless for us.
return nil
}
if hash, ok := a.data.countVoteNoLock(vote.Period, vote.Type); ok &&
hash != types.SkipBlockHash {
// Condition 1.
if vote.Period > a.data.lockIter {
a.data.lockValue = hash
a.data.lockIter = vote.Period
}
// Condition 2.
if vote.Period > a.data.period {
a.fastForward <- vote.Period
if a.doneChan != nil {
close(a.doneChan)
a.doneChan = nil
}
return nil
}
}
}
// Condition 3.
if vote.Type == types.VoteCom && vote.Period >= a.data.period &&
len(a.data.votes[vote.Period][types.VoteCom]) >= a.data.requiredVote {
hashes := common.Hashes{}
addPullBlocks := func(voteType types.VoteType) {
for _, vote := range a.data.votes[vote.Period][voteType] {
if vote.BlockHash == types.NullBlockHash ||
vote.BlockHash == types.SkipBlockHash {
continue
}
if _, found := a.findCandidateBlockNoLock(vote.BlockHash); !found {
hashes = append(hashes, vote.BlockHash)
}
}
}
addPullBlocks(types.VotePreCom)
addPullBlocks(types.VoteCom)
if len(hashes) > 0 {
a.data.recv.PullBlocks(hashes)
}
a.fastForward <- vote.Period + 1
if a.doneChan != nil {
close(a.doneChan)
a.doneChan = nil
}
return nil
}
return nil
}
func (a *agreement) processFinalizedBlock(block *types.Block) {
a.lock.Lock()
defer a.lock.Unlock()
if a.hasOutput {
return
}
aID := a.agreementID()
if aID.Older(block.Position) {
return
}
a.addCandidateBlockNoLock(block)
a.hasOutput = true
a.data.lock.Lock()
defer a.data.lock.Unlock()
a.data.recv.ConfirmBlock(block.Hash, nil)
if a.doneChan != nil {
close(a.doneChan)
a.doneChan = nil
}
}
func (a *agreement) processAgreementResult(result *types.AgreementResult) error {
a.lock.Lock()
defer a.lock.Unlock()
aID := a.agreementID()
if result.Position.Older(aID) {
return nil
} else if result.Position.Newer(aID) {
a.pendingAgreementResult[result.Position] = result
return nil
}
if a.hasOutput {
return nil
}
a.data.lock.Lock()
defer a.data.lock.Unlock()
if _, exist := a.findCandidateBlockNoLock(result.BlockHash); !exist {
a.data.recv.PullBlocks(common.Hashes{result.BlockHash})
}
a.hasOutput = true
a.data.recv.ConfirmBlock(result.BlockHash, nil)
if a.doneChan != nil {
close(a.doneChan)
a.doneChan = nil
}
return nil
}
func (a *agreement) done() <-chan struct{} {
a.lock.Lock()
defer a.lock.Unlock()
select {
case period := <-a.fastForward:
a.data.lock.Lock()
defer a.data.lock.Unlock()
if period <= a.data.period {
break
}
a.data.setPeriod(period)
a.state = newPreCommitState(a.data)
a.doneChan = make(chan struct{})
return closedchan
default:
}
if a.doneChan == nil {
return closedchan
}
return a.doneChan
}
func (a *agreement) confirmed() bool {
a.lock.RLock()
defer a.lock.RUnlock()
return a.confirmedNoLock()
}
func (a *agreement) confirmedNoLock() bool {
return a.hasOutput
}
// processBlock is the entry point for processing Block.
func (a *agreement) processBlock(block *types.Block) error {
a.lock.Lock()
defer a.lock.Unlock()
a.data.blocksLock.Lock()
defer a.data.blocksLock.Unlock()
aID := a.agreementID()
if block.Position != aID {
// Agreement module has stopped.
if !isStop(aID) {
if aID.Newer(block.Position) {
return nil
}
}
a.pendingBlock = append(a.pendingBlock, pendingBlock{
block: block,
receivedTime: time.Now().UTC(),
})
return nil
} else if a.confirmedNoLock() {
return nil
}
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
}
if err := a.data.leader.processBlock(block); err != nil {
return err
}
a.data.blocks[block.ProposerID] = block
a.addCandidateBlockNoLock(block)
if block.ProposerID != a.data.ID &&
(a.state.state() == stateFast || a.state.state() == stateFastVote) &&
block.ProposerID == a.leader() {
go func() {
for func() bool {
if aID != a.agreementID() {
return false
}
a.lock.RLock()
defer a.lock.RUnlock()
if a.state.state() != stateFast && a.state.state() != stateFastVote {
return false
}
a.data.lock.RLock()
defer a.data.lock.RUnlock()
a.data.blocksLock.Lock()
defer a.data.blocksLock.Unlock()
block, exist := a.data.blocks[a.leader()]
if !exist {
return true
}
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
}
func (a *agreement) addCandidateBlock(block *types.Block) {
a.lock.Lock()
defer a.lock.Unlock()
a.addCandidateBlockNoLock(block)
}
func (a *agreement) addCandidateBlockNoLock(block *types.Block) {
a.candidateBlock[block.Hash] = block
}
func (a *agreement) findCandidateBlockNoLock(
hash common.Hash) (*types.Block, bool) {
b, e := a.candidateBlock[hash]
return b, e
}
// find a block in both candidate blocks and pending blocks in leader-selector.
// A block might be confirmed by others while we can't verify its validity.
func (a *agreement) findBlockNoLock(hash common.Hash) (*types.Block, bool) {
b, e := a.findCandidateBlockNoLock(hash)
if !e {
b, e = a.data.leader.findPendingBlock(hash)
}
return b, e
}
func (a *agreementData) countVote(period uint64, voteType types.VoteType) (
blockHash common.Hash, ok bool) {
a.lock.RLock()
defer a.lock.RUnlock()
return a.countVoteNoLock(period, voteType)
}
func (a *agreementData) countVoteNoLock(
period uint64, voteType types.VoteType) (blockHash common.Hash, ok bool) {
votes, exist := a.votes[period]
if !exist {
return
}
candidate := make(map[common.Hash]int)
for _, vote := range votes[voteType] {
if _, exist := candidate[vote.BlockHash]; !exist {
candidate[vote.BlockHash] = 0
}
candidate[vote.BlockHash]++
}
for candidateHash, votes := range candidate {
if votes >= a.requiredVote {
blockHash = candidateHash
ok = true
return
}
}
return
}
func (a *agreementData) setPeriod(period uint64) {
for i := a.period + 1; i <= period; i++ {
if _, exist := a.votes[i]; !exist {
a.votes[i] = newVoteListMap()
}
}
a.period = period
}
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