private int ProcessRequestVote(Protocol p)
{
lock (this)
{
var r = p as RequestVote;
if (LogSequence.TrySetTerm(r.Argument.Term))
{
// new term found.
ConvertStateTo(RaftState.Follower);
}
// else continue process
r.Result.Term = LogSequence.Term;
// RequestVote RPC
// Receiver implementation:
// 1.Reply false if term < currentTerm(§5.1)
// 2.If votedFor is null or candidateId, and candidate’s log is at
// least as up - to - date as receiver’s log, grant vote(§5.2, §5.4)
r.Result.VoteGranted = (r.Argument.Term >= LogSequence.Term) &&
LogSequence.CanVoteFor(r.Argument.CandidateId) &&
IsLastLogUpToDate(r.Argument.LastLogTerm, r.Argument.LastLogIndex);
if (r.Result.VoteGranted)
{
LogSequence.SetVoteFor(r.Argument.CandidateId);
}
logger.Debug("{0}: VoteFor={1} Rpc={2}", Name, LogSequence.VoteFor, r);
r.SendResultCode(0);
return(Procedure.Success);
}
}
private void SendRequestVote(SchedulerTask ThisTask)
{
lock (this)
{
VoteSuccess.Clear(); // 每次选举开始清除。
LeaderId = string.Empty;
LogSequence.SetVoteFor(Name); // Vote Self First.
LogSequence.TrySetTerm(LogSequence.Term + 1);
WaitMajorityVoteTimoutTask?.Cancel();
WaitMajorityVoteTimoutTask = null;
var arg = new RequestVoteArgument();
arg.Term = LogSequence.Term;
arg.CandidateId = Name;
var log = LogSequence.LastRaftLog();
arg.LastLogIndex = log.Index;
arg.LastLogTerm = log.Term;
Server.Config.ForEachConnector(
(c) =>
{
if (false == c.IsHandshakeDone)
{
return;
}
var rpc = new RequestVote()
{
Argument = arg
};
rpc.Send(c.Socket, (p) => ProcessRequestVoteResult(rpc, c));
logger.Debug("{0}: SendRequestVote {1}", Name, rpc);
});
// 定时，如果超时选举还未完成，再次发起选举。
WaitMajorityVoteTimoutTask = Scheduler.Instance.Schedule(
(ThisTask) =>
{
lock (this)
{
StartRequestVoteDelayTask = null;
ConvertStateTo(RaftState.Candidate);
}
},
RaftConfig.AppendEntriesTimeout + 1000);
}
}
private void ConvertStateFromFollwerTo(RaftState newState)
{
switch (newState)
{
case RaftState.Follower:
logger.Info($"RaftState {Name}: Follower->Follower");
return;
case RaftState.Candidate:
logger.Info($"RaftState {Name}: Follower->Candidate");
State = RaftState.Candidate;
LeaderLostTimerTask?.Cancel();
LeaderLostTimerTask = null;
LogSequence.SetVoteFor(string.Empty); // 先清除，在真正自荐前可以给别人投票。
StartRequestVote();
return;
case RaftState.Leader:
// 并发的RequestVote的结果如果没有判断当前状态，可能会到达这里。
// 不是什么大问题。see ProcessRequestVoteResult
logger.Info($"RaftState {Name} Impossible! Follower->Leader");
return;
}
}
private void ConvertStateFromCandidateTo(RaftState newState)
{
switch (newState)
{
case RaftState.Follower:
logger.Info($"RaftState {Name}: Candidate->Follower");
State = RaftState.Follower;
VoteSuccess.Clear(); // 选举结束清除。
LogSequence.SetVoteFor(string.Empty);
StartRequestVoteDelayTask?.Cancel();
StartRequestVoteDelayTask = null;
WaitMajorityVoteTimoutTask?.Cancel();
WaitMajorityVoteTimoutTask = null;
StartLeaderLostTimerTask();
return;
case RaftState.Candidate:
logger.Info($"RaftState {Name}: Candidate->Candidate");
LogSequence.SetVoteFor(string.Empty); // 先清除，在真正自荐前可以给别人投票。
StartRequestVote();
return;
case RaftState.Leader:
StartRequestVoteDelayTask?.Cancel();
StartRequestVoteDelayTask = null;
WaitMajorityVoteTimoutTask?.Cancel();
WaitMajorityVoteTimoutTask = null;
VoteSuccess.Clear(); // 选举结束清除。
logger.Info($"RaftState {Name}: Candidate->Leader");
State = RaftState.Leader;
LogSequence.SetVoteFor(string.Empty);
LeaderId = Name; // set to self
// (Reinitialized after election)
var nextIndex = LogSequence.LastIndex + 1;
Server.Config.ForEachConnector(
(c) =>
{
var cex = c as Server.ConnectorEx;
cex.NextIndex = nextIndex;
cex.MatchIndex = 0;
});
// Upon election:
// send initial empty AppendEntries RPCs
// (heartbeat)to each server; repeat during
// idle periods to prevent election timeouts(§5.2)
LogSequence.AppendLog(new HeartbeatLog(HeartbeatLog.SetLeaderReadyEvent), false);
HearbeatTimerTask = Scheduler.Instance.Schedule(
(ThisTask) =>
{
var elapse = Util.Time.NowUnixMillis - LogSequence.AppendLogActiveTime;
if (elapse < RaftConfig.LeaderHeartbeatTimer)
{
LogSequence.AppendLog(new HeartbeatLog(), false);
}
},
1000,
1000);
return;
}
}
