// Copyright 2018 The dexon-consensus-core Authors
// This file is part of the dexon-consensus-core library.
//
// The dexon-consensus-core 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-core 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-core library. If not, see
// <http://www.gnu.org/licenses/>.
package core
import (
"fmt"
"math"
"sync"
"sync/atomic"
"time"
"github.com/dexon-foundation/dexon-consensus-core/common"
"github.com/dexon-foundation/dexon-consensus-core/core/types"
)
// Errors for agreement module.
var (
ErrNotInNotarySet = fmt.Errorf("not in notary set")
ErrIncorrectVoteSignature = fmt.Errorf("incorrect vote signature")
)
// 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(common.Hash, map[types.NodeID]*types.Vote)
}
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
leader *leaderSelector
lockValue common.Hash
lockRound 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
notarySet map[types.NodeID]struct{}
hasOutput bool
lock sync.RWMutex
pendingBlock []pendingBlock
pendingVote []pendingVote
candidateBlock map[common.Hash]*types.Block
fastForward chan uint64
authModule *Authenticator
}
// newAgreement creates a agreement instance.
func newAgreement(
ID types.NodeID,
recv agreementReceiver,
notarySet map[types.NodeID]struct{},
leader *leaderSelector,
authModule *Authenticator) *agreement {
agreement := &agreement{
data: &agreementData{
recv: recv,
ID: ID,
leader: leader,
},
aID: &atomic.Value{},
candidateBlock: make(map[common.Hash]*types.Block),
fastForward: make(chan uint64, 1),
authModule: authModule,
}
agreement.stop()
return agreement
}
// restart the agreement
func (a *agreement) restart(
notarySet map[types.NodeID]struct{}, aID types.Position) {
func() {
a.lock.Lock()
defer a.lock.Unlock()
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 = 1
a.data.blocks = make(map[types.NodeID]*types.Block)
a.data.requiredVote = len(notarySet)/3*2 + 1
a.data.leader.restart()
a.data.lockValue = nullBlockHash
a.data.lockRound = 1
a.fastForward = make(chan uint64, 1)
a.hasOutput = false
a.state = newInitialState(a.data)
a.notarySet = notarySet
a.candidateBlock = make(map[common.Hash]*types.Block)
a.aID.Store(aID)
}()
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 pending.block.Position == aID {
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 pending.vote.Position == aID {
replayVote = append(replayVote, pending.vote)
} else if pending.receivedTime.After(expireTime) {
newPendingVote = append(newPendingVote, pending)
}
}
a.pendingVote = newPendingVote
}()
for _, block := range replayBlock {
a.processBlock(block)
}
for _, vote := range replayVote {
a.processVote(vote)
}
}
func (a *agreement) stop() {
a.restart(make(map[types.NodeID]struct{}), types.Position{
ChainID: math.MaxUint32,
})
}
// clocks returns how many time this state is required.
func (a *agreement) clocks() int {
return a.state.clocks()
}
// agreementID returns the current agreementID.
func (a *agreement) agreementID() types.Position {
return a.aID.Load().(types.Position)
}
// nextState is called at the specific clock time.
func (a *agreement) nextState() (err error) {
a.state, err = a.state.nextState()
return
}
func (a *agreement) sanityCheck(vote *types.Vote) error {
if exist := func() bool {
a.lock.RLock()
defer a.lock.RUnlock()
_, exist := a.notarySet[vote.ProposerID]
return exist
}(); !exist {
return ErrNotInNotarySet
}
ok, err := verifyVoteSignature(vote)
if err != nil {
return err
}
if !ok {
return ErrIncorrectVoteSignature
}
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}
}
}
}
return nil
}(); err != nil {
return err
}
return nil
}
// prepareVote prepares a vote.
func (a *agreement) prepareVote(vote *types.Vote) (err error) {
vote.Position = a.agreementID()
err = a.authModule.SignVote(vote)
return
}
// processVote is the entry point for processing Vote.
func (a *agreement) processVote(vote *types.Vote) error {
if err := a.sanityCheck(vote); err != nil {
return err
}
if vote.Position != a.agreementID() {
a.lock.Lock()
defer a.lock.Unlock()
a.pendingVote = append(a.pendingVote, pendingVote{
vote: vote,
receivedTime: time.Now().UTC(),
})
return nil
}
if err := a.checkForkVote(vote); err != nil {
return err
}
a.data.lock.Lock()
defer a.data.lock.Unlock()
if _, exist := a.data.votes[vote.Period]; !exist {
a.data.votes[vote.Period] = newVoteListMap()
}
a.data.votes[vote.Period][vote.Type][vote.ProposerID] = vote
if !a.hasOutput && vote.Type == types.VoteCom {
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])
return nil
}
} else if a.hasOutput {
return nil
}
// Check if the agreement requires fast-forwarding.
if vote.Type == types.VotePreCom {
if hash, ok := a.data.countVoteNoLock(vote.Period, vote.Type); ok &&
hash != skipBlockHash {
// Condition 1.
if a.data.period >= vote.Period && vote.Period > a.data.lockRound &&
vote.BlockHash != a.data.lockValue {
a.data.lockValue = hash
a.data.lockRound = vote.Period
a.fastForward <- a.data.period + 1
return nil
}
// Condition 2.
if vote.Period > a.data.period {
a.data.lockValue = hash
a.data.lockRound = vote.Period
a.fastForward <- vote.Period
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 {
a.fastForward <- vote.Period + 1
return nil
}
return nil
}
func (a *agreement) done() <-chan struct{} {
ch := make(chan struct{}, 1)
if a.hasOutput {
ch <- struct{}{}
} else {
select {
case period := <-a.fastForward:
if period <= a.data.period {
break
}
a.data.setPeriod(period)
a.state = newPreCommitState(a.data)
ch <- struct{}{}
default:
}
}
return ch
}
// processBlock is the entry point for processing Block.
func (a *agreement) processBlock(block *types.Block) error {
a.data.blocksLock.Lock()
defer a.data.blocksLock.Unlock()
if block.Position != a.agreementID() {
a.pendingBlock = append(a.pendingBlock, pendingBlock{
block: block,
receivedTime: time.Now().UTC(),
})
return nil
}
if b, exist := a.data.blocks[block.ProposerID]; exist {
if b.Hash != block.Hash {
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.addCandidateBlock(block)
return nil
}
func (a *agreement) addCandidateBlock(block *types.Block) {
a.lock.Lock()
defer a.lock.Unlock()
a.candidateBlock[block.Hash] = block
}
func (a *agreement) findCandidateBlock(hash common.Hash) (*types.Block, bool) {
a.lock.RLock()
defer a.lock.RUnlock()
b, e := a.candidateBlock[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
}
