Golang classic.PaxosMessage类代码示例

// Phase1RPC handles ClassicPaxos.Phase1 rpc.
func (this *Paxos) Phase1RPC(header *msgpb.Header,
	request *thispb.Phase1Request) (status error) {

	if !this.IsAcceptor() {
		this.Errorf("this paxos instance is not an acceptor; rejecting %s", header)
		return errs.ErrInvalid
	}

	lock, errLock := this.ctlr.TimedLock(msg.RequestTimeout(header),
		"acceptor")
	if errLock != nil {
		return errLock
	}
	defer lock.Unlock()

	clientID := header.GetMessengerId()
	respond := func() error {
		response := thispb.Phase1Response{}
		response.PromisedBallot = proto.Int64(this.promisedBallot)
		if this.votedBallot >= 0 {
			response.VotedBallot = proto.Int64(this.votedBallot)
			response.VotedValue = this.votedValue
		}
		message := thispb.PaxosMessage{}
		message.Phase1Response = &response
		errSend := msg.SendResponseProto(this.msn, header, &message)
		if errSend != nil {
			this.Errorf("could not send phase1 response to %s: %v", clientID,
				errSend)
			return errSend
		}
		return nil
	}

	ballot := request.GetBallotNumber()
	if ballot < this.promisedBallot {
		this.Warningf("phase1 request from %s is ignored due to stale ballot %d",
			clientID, ballot)
		return respond()
	}

	if ballot == this.promisedBallot {
		this.Warningf("duplicate phase1 request from client %s with an already "+
			"promised ballot number %d", clientID, ballot)
		return respond()
	}

	// Save the promise into the wal.
	change := thispb.AcceptorChange{}
	change.PromisedBallot = proto.Int64(ballot)
	if err := this.doUpdateAcceptor(&change); err != nil {
		this.Errorf("could not update acceptor state: %v", err)
		return err
	}

	this.Infof("this acceptor has now promised higher ballot %d from %s", ballot,
		clientID)
	return respond()
}

// LearnRPC handles ClassicPaxos.Learn rpc.
func (this *Paxos) LearnRPC(header *msgpb.Header,
	request *thispb.LearnRequest) (status error) {

	if !this.IsLearner() {
		this.Errorf("this paxos instance is not a learner; rejecting %s", header)
		return errs.ErrInvalid
	}

	lock, errLock := this.ctlr.TimedLock(msg.RequestTimeout(header), "learner")
	if errLock != nil {
		return errLock
	}
	defer lock.Unlock()

	acceptor := header.GetMessengerId()
	if this.chosenValue == nil {
		change := thispb.LearnerChange{}
		change.VotedBallotList = request.VotedBallotList
		change.VotedValueList = request.VotedValueList
		change.VotedAcceptor = proto.String(acceptor)
		if err := this.doUpdateLearner(&change); err != nil {
			this.Errorf("could not update learner state: %v", err)
			return err
		}
	}

	response := thispb.LearnResponse{}
	if this.chosenValue != nil {
		response.KnowsChosenValue = proto.Bool(true)
	}
	message := thispb.PaxosMessage{}
	message.LearnResponse = &response
	errSend := msg.SendResponseProto(this.msn, header, &message)
	if errSend != nil {
		this.Errorf("could not respond to learn request from %s: %v", acceptor,
			errSend)
		return errSend
	}
	return nil
}

// Propose proposes given value for a consensus.
//
// value: The value to propose for consensus.
//
// timeout: Maximum time duration for the propose operation.
//
// Returns the chosen value on success.
func (this *Paxos) Propose(value []byte, timeout time.Duration) (
	[]byte, error) {

	// If local instance is not a proposer, find a random proposer.
	proposer := this.msn.UID()
	if !this.IsProposer() {
		proposer = this.proposerList[rand.Intn(len(this.proposerList))]
		this.Infof("using %s as the proposer", proposer)
	}

	// Send the propose request.
	request := thispb.ProposeRequest{}
	request.ProposedValue = value
	message := thispb.PaxosMessage{}
	message.ProposeRequest = &request
	reqHeader := this.msn.NewRequest(this.namespace, this.uid,
		"ClassicPaxos.Propose", timeout)
	errSend := msg.SendProto(this.msn, proposer, reqHeader, &message)
	if errSend != nil {
		this.Errorf("could not send propose request to %s: %v", proposer, errSend)
		return nil, errSend
	}

	// Wait for the response.
	_, errRecv := msg.ReceiveProto(this.msn, reqHeader, &message)
	if errRecv != nil {
		this.Errorf("could not receive propose response from %s: %v", proposer,
			errRecv)
		return nil, errRecv
	}

	if message.ProposeResponse == nil {
		this.Errorf("propose response from %s is empty", proposer)
		return nil, errs.ErrCorrupt
	}

	response := message.GetProposeResponse()
	return response.GetChosenValue(), nil
}

// NotifyAllLearners sends the current vote to all learners.
func (this *Paxos) NotifyAllLearners() (status error) {
	if !this.IsConfigured() || !this.IsAcceptor() {
		return nil
	}

	defer func() {
		if status != nil && !errs.IsClosed(status) {
			now := time.Now()
			next := now.Add(this.opts.LearnRetryInterval)
			_ = this.alarm.ScheduleAt(this.uid, next, this.NotifyAllLearners)
		}
	}()

	rlock := this.ctlr.ReadLock("acceptor", "config")
	// Stop notifications when all learners know the consensus value.
	if len(this.doneLearnerSet) == len(this.learnerList) {
		rlock.Unlock()
		return nil
	}
	// Make a copy of what we need: learners and the vote map.
	numLearners := len(this.learnerList)
	learnerList := append([]string{}, this.learnerList...)
	votedValueMap := make(map[int64][]byte)
	for ballot, value := range this.votedValueMap {
		if ackMap := this.learnerAckMap[ballot]; len(ackMap) < numLearners {
			votedValueMap[ballot] = value
		}
	}
	rlock.Unlock()

	request := thispb.LearnRequest{}
	for ballot, value := range votedValueMap {
		request.VotedBallotList = append(request.VotedBallotList, ballot)
		request.VotedValueList = append(request.VotedValueList, value)
	}
	message := thispb.PaxosMessage{}
	message.LearnRequest = &request

	// Send notification to all learners.
	reqHeader := this.msn.NewRequest(this.namespace, this.uid,
		"ClassicPaxos.Learn", this.opts.LearnTimeout)
	defer this.msn.CloseMessage(reqHeader)

	count, errSend := msg.SendAllProto(this.msn, learnerList, reqHeader,
		&message)
	if errSend != nil {
		this.Errorf("could not send learn request to all learners: %v", errSend)
		return errSend
	}

	// Wait for responses from all learners.
	for ii := 0; ii < count; ii++ {
		message := thispb.PaxosMessage{}
		resHeader, errRecv := msg.ReceiveProto(this.msn, reqHeader, &message)
		if errRecv != nil {
			this.Warningf("could not receive learner responses: %v", errRecv)
			break
		}

		learner := resHeader.GetMessengerId()
		if message.LearnResponse == nil {
			continue
		}
		response := message.GetLearnResponse()

		// Save the learner acknowledgment to the wal.
		change := thispb.AcceptorChange{}
		change.AckedLearner = proto.String(learner)
		if response.GetKnowsChosenValue() {
			change.AckedChosenValue = proto.Bool(true)
		} else {
			for ballot := range votedValueMap {
				change.AckedBallotList = append(change.AckedBallotList, ballot)
			}
		}
		if err := this.UpdateAcceptor(&change); err != nil {
			this.Errorf("could not update acceptor state: %v", err)
			return err
		}
	}
	return nil
}

// Phase2RPC handles ClassicPaxos.Phase2 rpc.
func (this *Paxos) Phase2RPC(header *msgpb.Header,
	request *thispb.Phase2Request) (status error) {

	if !this.IsAcceptor() {
		this.Errorf("this paxos instance is not an acceptor; rejecting %s", header)
		return errs.ErrInvalid
	}

	lock, errLock := this.ctlr.TimedLock(msg.RequestTimeout(header), "acceptor")
	if errLock != nil {
		return errLock
	}
	defer lock.Unlock()

	clientID := header.GetMessengerId()
	respond := func() error {
		response := thispb.Phase2Response{}
		response.PromisedBallot = proto.Int64(this.promisedBallot)
		if this.votedBallot >= 0 {
			response.VotedBallot = proto.Int64(this.votedBallot)
			response.VotedValue = this.votedValue
		}
		message := thispb.PaxosMessage{}
		message.Phase2Response = &response
		errSend := msg.SendResponseProto(this.msn, header, &message)
		if errSend != nil {
			this.Errorf("could not send phase2 response to %s: %v", clientID,
				errSend)
			return errSend
		}
		return nil
	}

	ballot := request.GetBallotNumber()
	if ballot < this.promisedBallot {
		this.Warningf("phase2 request from %s is ignored due to stale ballot %d",
			clientID, ballot)
		return respond()
	}

	if ballot > this.promisedBallot {
		this.Errorf("phase2 request from client %s without acquiring a prior "+
			"promise", clientID)
		return respond()
	}
	value := request.GetProposedValue()

	// Save the phase2 vote into the wal.
	change := thispb.AcceptorChange{}
	change.VotedBallot = proto.Int64(ballot)
	change.VotedValue = value
	if err := this.doUpdateAcceptor(&change); err != nil {
		this.Errorf("could not update acceptor state: %v", err)
		return err
	}

	this.Infof("this acceptor has voted for %d in ballot %s", ballot, value)
	if err := respond(); err != nil {
		return err
	}

	// Schedule a notification to all learners.
	_ = this.alarm.ScheduleAt(this.uid, time.Now(), this.NotifyAllLearners)
	return nil
}

// ProposeRPC handles ClassicPaxos.Propose rpc.
func (this *Paxos) ProposeRPC(header *msgpb.Header,
	request *thispb.ProposeRequest) (status error) {

	if !this.IsProposer() {
		this.Errorf("this paxos instance is not a proposer; rejecting %s", header)
		return errs.ErrInvalid
	}

	// OPTIMIZATION If this object is also a learner and already knows the
	// consensus result, we don't need to perform expensive proposal.
	if this.IsLearner() {
		lock := this.ctlr.ReadLock("learner")
		defer lock.Unlock()

		if this.chosenValue != nil {
			response := thispb.ProposeResponse{}
			response.ChosenValue = this.chosenValue
			message := thispb.PaxosMessage{}
			message.ProposeResponse = &response
			errSend := msg.SendResponseProto(this.msn, header, &message)
			if errSend != nil {
				this.Errorf("could not send known chosen value as the propose "+
					"response: %v", errSend)
				return errSend
			}
			return nil
		}
		lock.Unlock()
	}

	var chosen []byte
	proposal := request.GetProposedValue()
	for ii := 0; chosen == nil && msg.RequestTimeout(header) > 0; ii++ {
		if ii > 0 {
			time.Sleep(this.opts.ProposeRetryInterval)
		}

		// Get the next proposal ballot number.
		ballot, errNext := this.GetNextProposalBallot(msg.RequestTimeout(header))
		if errNext != nil {
			this.Errorf("could not select higher ballot: %v", errNext)
			return errNext
		}
		this.Infof("using ballot number %d for the proposal", ballot)

		lock := this.ctlr.ReadLock("config")
		phase1AcceptorList := this.getPhase1AcceptorList(ballot)
		lock.Unlock()

		// Collect phase1 promises from majority number of acceptors.
		votedValue, acceptorList, errPhase1 := this.doPhase1(header, ballot,
			phase1AcceptorList)
		if errPhase1 != nil {
			this.Warningf("could not complete paxos phase1: %v", errPhase1)
			continue
		}

		// If a value was already voted, it may have been chosen, so propose it
		// instead.
		value := proposal
		if votedValue != nil {
			value = votedValue
		}

		// Collect phase2 votes from majority number of acceptors.
		errPhase2 := this.doPhase2(header, ballot, value, acceptorList)
		if errPhase2 != nil {
			this.Warningf("could not complete paxos phase2: %v", errPhase2)
			continue
		}

		// A value is chosen, break out of the loop.
		chosen = value
		break
	}

	if chosen == nil {
		this.Errorf("could not propose value %s", proposal)
		return errs.ErrRetry
	}

	// If local node is a learner, update him with the consensus result directly.
	defer func() {
		if this.IsLearner() {
			lock, errLock := this.ctlr.Lock("learner")
			if errLock != nil {
				return
			}
			defer lock.Unlock()

			change := thispb.LearnerChange{}
			change.ChosenValue = chosen
			if err := this.doUpdateLearner(&change); err != nil {
				this.Warningf("could not update local learner with the consensus "+
					"result (ignored): %v", err)
			}
		}
	}()

//.........这里部分代码省略.........

// doPhase2 performs classic paxos phase2 steps.
func (this *Paxos) doPhase2(ctxHeader *msgpb.Header, ballot int64,
	value []byte, acceptorList []string) error {

	phase2request := thispb.Phase2Request{}
	phase2request.BallotNumber = proto.Int64(ballot)
	phase2request.ProposedValue = value
	message := thispb.PaxosMessage{}
	message.Phase2Request = &phase2request

	header := msg.NewNestedRequest(this.msn, ctxHeader, this.namespace, this.uid,
		"ClassicPaxos.Phase2")
	defer this.msn.CloseMessage(header)

	count, errSend := msg.SendAllProto(this.msn, acceptorList, header, &message)
	if errSend != nil && count < this.MajoritySize() {
		this.Errorf("could not send phase2 request to majority acceptors: %v",
			errSend)
		return errSend
	}
	this.Infof("send phase2 request %s to acceptors: %v", header, acceptorList)

	responseMap := make(map[string]*thispb.Phase2Response)
	for ii := 0; ii < count && len(responseMap) < this.MajoritySize(); ii++ {
		message := thispb.PaxosMessage{}
		resHeader, errRecv := msg.ReceiveProto(this.msn, header, &message)
		if errRecv != nil {
			break
		}

		acceptor := resHeader.GetMessengerId()
		if _, ok := responseMap[acceptor]; ok {
			this.Warningf("duplicate phase2 response from %s (ignored)", acceptor)
			continue
		}

		if message.Phase2Response == nil {
			this.Warningf("phase2 response data is empty from %s (ignored)",
				acceptor)
			continue
		}
		response := message.GetPhase2Response()
		promisedBallot := response.GetPromisedBallot()

		if promisedBallot < ballot {
			this.Errorf("as per phase2 response, acceptor %s seems to have rolled "+
				"back on his phase1 promise to ballot %d", acceptor, ballot)
			continue
		}

		if promisedBallot > ballot {
			this.Warningf("acceptor %s has moved on to higher ballot %d", acceptor,
				promisedBallot)
			break
		}

		responseMap[acceptor] = response
	}

	if len(responseMap) < this.MajoritySize() {
		this.Warningf("could not get majority phase2 votes %v for value [%s] "+
			"ballot %d", responseMap, value, ballot)
		return errs.ErrRetry
	}

	this.Infof("value [%s] is chosen by phase2 responses %v", value, responseMap)
	return nil
}

// doPhase1 performs classic paxos phase1 steps.
func (this *Paxos) doPhase1(ctxHeader *msgpb.Header, ballot int64,
	phase1AcceptorList []string) ([]byte, []string, error) {

	phase1request := thispb.Phase1Request{}
	phase1request.BallotNumber = proto.Int64(ballot)
	message := thispb.PaxosMessage{}
	message.Phase1Request = &phase1request

	reqHeader := msg.NewNestedRequest(this.msn, ctxHeader, this.namespace,
		this.uid, "ClassicPaxos.Phase1")
	defer this.msn.CloseMessage(reqHeader)

	count, errSend := msg.SendAllProto(this.msn, phase1AcceptorList, reqHeader,
		&message)
	if errSend != nil && count < this.MajoritySize() {
		this.Errorf("could not send phase1 request to majority nodes: %v", errSend)
		return nil, nil, errSend
	}
	this.Infof("sent phase1 request %s to acceptors %v", reqHeader,
		phase1AcceptorList)

	var acceptorList []string
	maxVotedBallot := int64(-1)
	var maxVotedValue []byte
	responseMap := make(map[string]*thispb.Phase1Response)

	for ii := 0; ii < count && len(responseMap) < this.MajoritySize(); ii++ {
		message := thispb.PaxosMessage{}
		resHeader, errRecv := msg.ReceiveProto(this.msn, reqHeader, &message)
		if errRecv != nil {
			this.Warningf("could not receive more phase1 responses for %s: %v",
				reqHeader, errRecv)
			break
		}

		acceptor := resHeader.GetMessengerId()
		if _, ok := responseMap[acceptor]; ok {
			this.Warningf("duplicate phase1 response from %s (ignored)", acceptor)
			continue
		}

		if message.Phase1Response == nil {
			this.Warningf("phase1 response data is empty from %s (ignored)",
				acceptor)
			continue
		}

		response := message.GetPhase1Response()
		if response.PromisedBallot == nil {
			this.Warningf("phase1 response from %s has no promise ballot", acceptor)
			continue
		}

		promisedBallot := response.GetPromisedBallot()
		if promisedBallot > ballot {
			this.Warningf("acceptor %s has moved on to ballot %d", acceptor,
				promisedBallot)
			break
		}

		if promisedBallot < ballot {
			this.Errorf("acceptor %s did not promise this ballot %d", acceptor,
				ballot)
			continue
		}

		// We received a promise from this acceptor.
		acceptorList = append(acceptorList, acceptor)
		responseMap[acceptor] = response

		// If there was a voted value already, we need to pick the max voted value.
		if response.VotedBallot != nil {
			votedBallot := response.GetVotedBallot()
			if votedBallot > maxVotedBallot {
				maxVotedBallot = votedBallot
				maxVotedValue = response.GetVotedValue()
			}
		}
	}

	if len(responseMap) < this.MajoritySize() {
		this.Warningf("could not get majority phase1 votes %v for ballot %d",
			responseMap, ballot)
		return nil, nil, errs.ErrRetry
	}

	if maxVotedValue == nil {
		this.Infof("no prior value was chosen as per phase1 responses %v",
			responseMap)
	} else {
		this.Infof("value [%s] could have been chosen as per phase1 responses %v",
			maxVotedValue, responseMap)
	}

	return maxVotedValue, acceptorList, nil
}