// 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() }