func (this *Paxos) doUpdateConfig(change *thispb.Configuration) error {
if !this.wal.IsRecovering() {
record := thispb.WALRecord{}
record.ConfigChange = change
_, errQueue := wal.QueueChangeProto(this.wal, this.uid, &record)
if errQueue != nil {
this.Errorf("could not append config change wal record: %v", errQueue)
return errQueue
}
}
this.doRestoreConfig(change)
return nil
}
func (this *Paxos) doUpdateLearner(change *thispb.LearnerChange) error {
if this.chosenValue != nil {
return nil
}
if !this.wal.IsRecovering() {
walRecord := thispb.WALRecord{}
walRecord.LearnerChange = change
_, errQueue := wal.QueueChangeProto(this.wal, this.uid, &walRecord)
if errQueue != nil {
this.Errorf("could not write learner change record: %v", errQueue)
return errQueue
}
}
if change.ChosenValue != nil {
this.chosenValue = change.GetChosenValue()
this.Infof("consensus result learned from proposer is %s",
this.chosenValue)
if this.watch != nil {
this.watch.ConsensusUpdate(this.uid, -1, this.chosenValue)
}
return nil
}
acceptor := change.GetVotedAcceptor()
for index := range change.VotedBallotList {
ballot := change.VotedBallotList[index]
value := change.VotedValueList[index]
this.ballotValueMap[ballot] = value
acceptorSet, found := this.ballotAcceptorsMap[ballot]
if !found {
acceptorSet = make(map[string]struct{})
this.ballotAcceptorsMap[ballot] = acceptorSet
}
acceptorSet[acceptor] = struct{}{}
if len(acceptorSet) >= this.MajoritySize() {
this.chosenValue = value
this.Infof("consensus result learned through votes is %s", value)
if this.watch != nil {
this.watch.ConsensusUpdate(this.uid, -1, this.chosenValue)
}
}
}
return nil
}
// RecoverCheckpoint recovers state from a checkpoint record.
func (this *Paxos) RecoverCheckpoint(uid string, data []byte) error {
if uid != this.uid {
this.Errorf("checkpoint record doesn't belong to this instance")
return errs.ErrInvalid
}
walRecord := thispb.WALRecord{}
if err := proto.Unmarshal(data, &walRecord); err != nil {
this.Errorf("could not parse checkpoint wal record: %v", err)
return err
}
if walRecord.Checkpoint == nil {
this.Errorf("checkpoint record has no data")
return errs.ErrInvalid
}
checkpoint := walRecord.GetCheckpoint()
config := checkpoint.GetConfiguration()
this.doRestoreConfig(config)
if this.IsProposer() {
if checkpoint.ProposerState == nil {
this.Errorf("checkpoint record has no proposer state")
return errs.ErrInvalid
}
this.doRestoreProposer(checkpoint.GetProposerState())
}
if this.IsAcceptor() {
if checkpoint.AcceptorState == nil {
this.Errorf("checkpoint record has no acceptor state")
return errs.ErrInvalid
}
this.doRestoreAcceptor(checkpoint.GetAcceptorState())
}
if this.IsLearner() {
if checkpoint.LearnerState == nil {
this.Errorf("checkpoint record has no learner state")
}
this.doRestoreLearner(checkpoint.GetLearnerState())
}
return nil
}
func (this *Paxos) doUpdateProposer(change *thispb.ProposerChange) error {
if !this.wal.IsRecovering() {
walRecord := thispb.WALRecord{}
walRecord.ProposerChange = change
_, errSync := wal.SyncChangeProto(this.wal, this.uid, &walRecord)
if errSync != nil {
this.Errorf("could not write proposer change record: %v", errSync)
return errSync
}
}
if change.ProposalBallot != nil {
ballot := change.GetProposalBallot()
if this.proposalBallot < ballot {
this.proposalBallot = ballot
}
}
return nil
}
// TakeCheckpoint saves current state into the wal as a checkpoint record.
func (this *Paxos) TakeCheckpoint() error {
lock := this.ctlr.ReadLockAll()
defer lock.Unlock()
if !this.IsConfigured() {
this.Errorf("classic paxos instance is not yet configured")
return errs.ErrInvalid
}
checkpoint := thispb.Checkpoint{}
config := thispb.Configuration{}
this.doSaveConfiguration(&config)
checkpoint.Configuration = &config
if this.IsProposer() {
state := thispb.ProposerState{}
this.doSaveProposer(&state)
checkpoint.ProposerState = &state
}
if this.IsAcceptor() {
state := thispb.AcceptorState{}
this.doSaveAcceptor(&state)
checkpoint.AcceptorState = &state
}
if this.IsLearner() {
state := thispb.LearnerState{}
this.doSaveLearner(&state)
checkpoint.LearnerState = &state
}
walRecord := thispb.WALRecord{}
walRecord.Checkpoint = &checkpoint
errAppend := wal.AppendCheckpointProto(this.wal, this.uid, &walRecord)
if errAppend != nil {
this.Errorf("could not append checkpoint record: %v", errAppend)
return errAppend
}
return nil
}
func (this *Paxos) doUpdateAcceptor(change *thispb.AcceptorChange) error {
if !this.wal.IsRecovering() {
walRecord := thispb.WALRecord{}
walRecord.AcceptorChange = change
_, errSync := wal.SyncChangeProto(this.wal, this.uid, &walRecord)
if errSync != nil {
this.Errorf("could not write acceptor change record: %v", errSync)
return errSync
}
}
if change.PromisedBallot != nil {
this.promisedBallot = change.GetPromisedBallot()
}
if change.VotedBallot != nil {
ballot := change.GetVotedBallot()
value := change.GetVotedValue()
this.votedBallot = ballot
this.votedValue = value
this.votedValueMap[ballot] = value
}
if change.AckedLearner != nil {
learner := change.GetAckedLearner()
if change.GetAckedChosenValue() {
this.doneLearnerSet[learner] = struct{}{}
} else {
for _, ballot := range change.GetAckedBallotList() {
learnerSet, found := this.learnerAckMap[ballot]
if !found {
learnerSet = make(map[string]struct{})
this.learnerAckMap[ballot] = learnerSet
}
learnerSet[learner] = struct{}{}
}
}
}
return nil
}
// RecoverChange recovers an update from a change record.
func (this *Paxos) RecoverChange(lsn wal.LSN, uid string, data []byte) error {
if lsn == nil {
// We reached end of wal recovery, figure out the current state and resume
// any inflight operations.
_ = this.Refresh()
return nil
}
if uid != this.uid {
this.Errorf("change record doesn't belong to this instance")
return errs.ErrInvalid
}
walRecord := thispb.WALRecord{}
if err := proto.Unmarshal(data, &walRecord); err != nil {
this.Errorf("could not parse change record: %v", err)
return err
}
switch {
case walRecord.ConfigChange != nil:
return this.doUpdateConfig(walRecord.GetConfigChange())
case walRecord.ProposerChange != nil:
return this.doUpdateProposer(walRecord.GetProposerChange())
case walRecord.AcceptorChange != nil:
return this.doUpdateAcceptor(walRecord.GetAcceptorChange())
case walRecord.LearnerChange != nil:
return this.doUpdateLearner(walRecord.GetLearnerChange())
default:
this.Errorf("invalid/corrupt wal change record: %s", walRecord)
return errs.ErrCorrupt
}
return nil
}