private async Task Candidacy(CancellationToken c)
{
while (_role == Role.Candidate)
{
var forMe = 1; // vote for yourself
var againstMe = 0;
var peers = _peerManager.GetPeers().ToArray();
var concensus = (peers.Length / 2) + 1;
var proxies = peers.Select(x => _peerManager.GetProxy(x.Address));
var retry = TheTrace.LogPolicy(_meAsAPeer.ShortName).WaitAndRetryAsync(3, (i) => TimeSpan.FromMilliseconds(i * i * 30));
var policy = Policy.TimeoutAsync(_settings.CandidacyTimeout).WrapAsync(retry);
var request = new RequestVoteRequest()
{
CandidateId = State.Id,
CurrentTerm = State.CurrentTerm,
LastLogIndex = _logPersister.LastIndex,
LastLogTerm = _logPersister.LastEntryTerm
};
var all = await Task.WhenAll(proxies.Select(p => policy.ExecuteAndCaptureAsync(() => p.RequestVoteAsync(request))));
var maxTerm = 0L;
foreach (var r in all)
{
if (r.Outcome == OutcomeType.Successful)
{
if (r.Result.CurrentTerm > maxTerm)
{
maxTerm = r.Result.CurrentTerm;
}
if (r.Result != null && r.Result.VoteGranted)
{
forMe++;
}
else
{
againstMe++;
}
}
}
if (againstMe >= concensus)
{
TheTrace.TraceInformation($"[{_meAsAPeer.ShortName}] Result of the candidacy for term {State.CurrentTerm}. I got rejected with {againstMe} votes :/");
BecomeFollower(maxTerm);
}
else if (forMe >= concensus)
{
TheTrace.TraceInformation($"[{_meAsAPeer.ShortName}] Result of the candidacy for term {State.CurrentTerm}. I got elected with {forMe} votes! :)");
BecomeLeader();
}
else
{
TheTrace.TraceInformation($"[{_meAsAPeer.ShortName}] Result of the candidacy for term {State.CurrentTerm}. Non-conclusive with {forMe} for me and {againstMe} against me.");
}
}
}
/// <inheritdoc />
public Task <RequestVoteResponse> RequestVoteAsync(RequestVoteRequest request)
{
var peers = _peerManager.GetPeers();
var peer = peers.Where(x => x.Id == request.CandidateId).FirstOrDefault();
var peerName = peer?.ShortName ?? request.CandidateId.ToString();
lock (State)
{
if (request.CurrentTerm > State.CurrentTerm)
{
BecomeFollower(request.CurrentTerm);
}
// Reply false if term < currentTerm
if (State.CurrentTerm > request.CurrentTerm)
{
TheTrace.TraceInformation($"[{_meAsAPeer.ShortName}] Rejecting vote of {peerName} due to backward term");
return(Task.FromResult(new RequestVoteResponse()
{
CurrentTerm = State.CurrentTerm,
VoteGranted = false
}));
}
// 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)
if (!State.LastVotedForId.HasValue && _logPersister.LastIndex <= request.LastLogIndex)
{
State.LastVotedForId = request.CandidateId;
// If election timeout elapses without receiving AppendEntries RPC from current leader OR GRANTING VOTE TO CANDIDATE: convert to candidate
_lastHeartbeat.Set();
TheTrace.TraceInformation($"[{_meAsAPeer.ShortName}] Voting for {peerName} for term {request.CurrentTerm}");
return(Task.FromResult(new RequestVoteResponse()
{
CurrentTerm = State.CurrentTerm,
VoteGranted = true
}));
}
TheTrace.TraceInformation($"[{_meAsAPeer.ShortName}] Rejecting vote of {peerName} for term {request.CurrentTerm} as it did not fulfil");
// assume the rest we send back no
return(Task.FromResult(new RequestVoteResponse()
{
CurrentTerm = State.CurrentTerm,
VoteGranted = false
}));
}
}
