go
func (cm *ConsensusModule) persistToStorage() {
	var termData bytes.Buffer
	if err := gob.NewEncoder(&termData).Encode(cm.currentTerm); err != nil {
		log.Fatal(err)
	}
	cm.storage.Set("currentTerm", termData.Bytes())

	var votedData bytes.Buffer
	if err := gob.NewEncoder(&votedData).Encode(cm.votedFor); err != nil {
		log.Fatal(err)
	}
	cm.storage.Set("votedFor", votedData.Bytes())

	var logData bytes.Buffer
	if err := gob.NewEncoder(&logData).Encode(cm.log); err != nil {
		log.Fatal(err)
	}
	cm.storage.Set("log", logData.Bytes())
}


// Submit submits a new command to the CM. This function doesn't block; clients
// read the commit channel passed in the constructor to be notified of new
// committed entries. It returns true iff this CM is the leader - in which case
// the command is accepted. If false is returned, the client will have to find
// a different CM to submit this command to.
func (cm *ConsensusModule) Submit(command interface{}) bool {
	cm.mu.Lock()
	cm.dlog("Submit received by %v: %v", cm.state, command)
	if cm.state == Leader {
		cm.log = append(cm.log, LogEntry{Command: command, Term: cm.currentTerm})
		cm.persistToStorage()
		cm.dlog("... log=%v", cm.log)
		cm.mu.Unlock()
		cm.triggerAEChan <- struct{}{}
		return true
	}

	cm.mu.Unlock()
	return false
}


// RequestVote RPC.
func (cm *ConsensusModule) RequestVote(args RequestVoteArgs, reply *RequestVoteReply) error {
	cm.mu.Lock()
	defer cm.mu.Unlock()
	if cm.state == Dead {
		return nil
	}
	lastLogIndex, lastLogTerm := cm.lastLogIndexAndTerm()
	cm.dlog("RequestVote: %+v [currentTerm=%d, votedFor=%d, log index/term=(%d, %d)]", args, cm.currentTerm, cm.votedFor, lastLogIndex, lastLogTerm)

	if args.Term > cm.currentTerm {
		cm.dlog("... term out of date in RequestVote")
		cm.becomeFollower(args.Term)
	}

	if cm.currentTerm == args.Term &&
		(cm.votedFor == -1 || cm.votedFor == args.CandidateId) &&
		(args.LastLogTerm > lastLogTerm ||
			(args.LastLogTerm == lastLogTerm && args.LastLogIndex >= lastLogIndex)) {
		reply.VoteGranted = true
		cm.votedFor = args.CandidateId
		cm.electionResetEvent = time.Now()
	} else {
		reply.VoteGranted = false
	}
	reply.Term = cm.currentTerm
	cm.persistToStorage()
	cm.dlog("... RequestVote reply: %+v", reply)
	return nil
}

func (cm *ConsensusModule) AppendEntries(args AppendEntriesArgs, reply *AppendEntriesReply) error {