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// 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"
"sync"
"sync/atomic"
"github.com/dexon-foundation/dexon-consensus-core/common"
"github.com/dexon-foundation/dexon-consensus-core/core/types"
"github.com/dexon-foundation/dexon-consensus-core/crypto"
)
// Errors for agreement module.
var (
ErrNotValidator = fmt.Errorf("not a validaotr")
ErrIncorrectVoteSignature = fmt.Errorf("incorrect vote signature")
ErrForkVote = fmt.Errorf("fork vote")
)
// ErrFork for fork error in agreement.
type ErrFork struct {
vID types.ValidatorID
old, new common.Hash
}
func (e *ErrFork) Error() string {
return fmt.Sprintf("fork is found for %s, old %s, new %s",
e.vID.String(), e.old, e.new)
}
type blockProposerFn func() *types.Block
func newVoteListMap() []map[types.ValidatorID]*types.Vote {
listMap := make([]map[types.ValidatorID]*types.Vote, types.MaxVoteType)
for idx := range listMap {
listMap[idx] = make(map[types.ValidatorID]*types.Vote)
}
return listMap
}
// agreementReceiver is the interface receiving agreement event.
type agreementReceiver interface {
proposeVote(vote *types.Vote)
proposeBlock(common.Hash)
confirmBlock(common.Hash)
}
// position is the current round of the agreement.
type position struct {
ShardID uint64
ChainID uint64
Height uint64
}
// agreementData is the data for agreementState.
type agreementData struct {
recv agreementReceiver
ID types.ValidatorID
leader *leaderSelector
defaultBlock common.Hash
period uint64
requiredVote int
votes map[uint64][]map[types.ValidatorID]*types.Vote
votesLock sync.RWMutex
blocks map[types.ValidatorID]*types.Block
blockProposer blockProposerFn
}
// agreement is the agreement protocal describe in the Crypto Shuffle Algorithm.
type agreement struct {
state agreementState
data *agreementData
aID *atomic.Value
validators map[types.ValidatorID]struct{}
sigToPub SigToPubFn
hasOutput bool
}
// newAgreement creates a agreement instance.
func newAgreement(
ID types.ValidatorID,
recv agreementReceiver,
validators types.ValidatorIDs,
sigToPub SigToPubFn,
blockProposer blockProposerFn) *agreement {
agreement := &agreement{
data: &agreementData{
recv: recv,
ID: ID,
leader: newLeaderSelector(),
blockProposer: blockProposer,
},
aID: &atomic.Value{},
sigToPub: sigToPub,
}
agreement.restart(validators)
return agreement
}
// terminate the current running state.
func (a *agreement) terminate() {
if a.state != nil {
a.state.terminate()
}
}
// restart the agreement
func (a *agreement) restart(validators types.ValidatorIDs) {
a.data.votesLock.Lock()
defer a.data.votesLock.Unlock()
a.data.votes = make(map[uint64][]map[types.ValidatorID]*types.Vote)
a.data.votes[1] = newVoteListMap()
a.data.period = 1
a.data.blocks = make(map[types.ValidatorID]*types.Block)
a.data.requiredVote = len(validators)/3*2 + 1
a.hasOutput = false
a.state = newPrepareState(a.data)
a.validators = make(map[types.ValidatorID]struct{})
for _, v := range validators {
a.validators[v] = struct{}{}
}
}
// 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() position {
return a.aID.Load().(position)
}
// setAgreementID sets the current agreementID.
func (a *agreement) setAgreementID(ID position) {
a.aID.Store(ID)
}
// nextState is called at the spcifi 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 := a.validators[vote.ProposerID]; !exist {
return ErrNotValidator
}
ok, err := verifyVoteSignature(vote, a.sigToPub)
if err != nil {
return err
}
if !ok {
return ErrIncorrectVoteSignature
}
if _, exist := a.data.votes[vote.Period]; exist {
if oldVote, exist :=
a.data.votes[vote.Period][vote.Type][vote.ProposerID]; exist {
if vote.BlockHash != oldVote.BlockHash {
return ErrForkVote
}
}
}
return nil
}
// prepareVote prepares a vote.
func (a *agreement) prepareVote(vote *types.Vote, prv crypto.PrivateKey) (
err error) {
hash := hashVote(vote)
vote.Signature, err = prv.Sign(hash)
return
}
// processVote is the entry point for processing Vote.
func (a *agreement) processVote(vote *types.Vote) error {
vote = vote.Clone()
if err := a.sanityCheck(vote); err != nil {
return err
}
if func() bool {
a.data.votesLock.Lock()
defer a.data.votesLock.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.VoteConfirm {
if len(a.data.votes[vote.Period][types.VoteConfirm]) >=
a.data.requiredVote {
a.hasOutput = true
a.data.recv.confirmBlock(vote.BlockHash)
}
}
return true
}() {
return a.state.receiveVote()
}
return nil
}
// processBlock is the entry point for processing Block.
func (a *agreement) processBlock(block *types.Block) error {
if b, exist := a.data.blocks[block.ProposerID]; exist {
if b.Hash != block.Hash {
return &ErrFork{block.ProposerID, b.Hash, block.Hash}
}
return nil
}
a.data.blocks[block.ProposerID] = block
a.data.leader.processBlock(block)
return nil
}
func (a *agreementData) countVote(period uint64, voteType types.VoteType) (
blockHash common.Hash, ok bool) {
a.votesLock.RLock()
defer a.votesLock.RUnlock()
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
}
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