// 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 }