// ElectRPC implements the Election.Elect rpc. func (this *Election) ElectRPC(reqHeader *msgpb.Header, request *thispb.ElectRequest) (status error) { if !this.InCommittee() { return errs.ErrInvalid } round := request.GetElectionRound() current := this.CurrentRound() if round != current+1 { this.Errorf("could not begin election round %d because current round "+ "is only at %d", round, current) return errs.ErrStale } uid := this.PaxosUIDFromElectionRound(round) paxos, errGet := this.GetPaxosInstance(uid) if errGet != nil { this.Errorf("could not find paxos instance for uid %s: %v", uid, errGet) return errGet } this.Infof("starting new election for round %d using paxos instance %s", round, uid) clientID := reqHeader.GetMessengerId() proposedValue := []byte(clientID) chosenValue, errPropose := paxos.Propose(proposedValue, msg.RequestTimeout(reqHeader)) if errPropose != nil { this.Errorf("could not propose %s as the leader for election round %d: %v", proposedValue, round, errPropose) return errPropose } winner := string(chosenValue) // Send the election result. response := thispb.ElectResponse{} response.ElectionRound = proto.Int64(round) response.ElectionWinner = proto.String(winner) message := thispb.ElectionMessage{} message.ElectResponse = &response if err := msg.SendResponseProto(this.msn, reqHeader, &message); err != nil { this.Errorf("could not send election response to %s: %v", clientID, err) return err } return nil }