public async Task StartElection()
{
var now = node.settings.Scheduler.Now;
if (node.lastHeartBeat <= now - node.electionTimeout)
{
lock (node.grantVoteLocker)
{
node.requestHandler = new Candidate(node);
Debug.WriteLine("{0}: Starting a new Election. current term {1}. election Timout {2}ms", node.NodeInfo(), node.Term, node.electionTimeout.TotalMilliseconds);
node.Term++;
node.CurrentLeader = node.Id;
}
var successCount = 0;
var blah = node.Peers.Select(async p =>
{
var vote = await p.RequestVote(new VoteRequest(node.Id, node.Term, node.LocalLog.LastTerm, node.LocalLog.LastIndex));
if (vote.VoteGranted)
{
Debug.WriteLine("{0}: Vote granted from {1}", node.NodeInfo(), p.Id);
Interlocked.Increment(ref successCount);
}
else
{
if (vote.CurrentTerm > node.Term)
{
Debug.WriteLine("{0}: stepping down as vote returned had higher term {1}", node.NodeInfo(), vote.CurrentTerm);
node.StepDown(vote.CurrentTerm, p.Id);
}
}
});
foreach (var task in blah)
{
await task;
}
if (node.ConcencusIsReached(successCount) && node.State == State.Candidate)
{
node.requestHandler = new Leader(node);
Debug.WriteLine("{0}: Elected as Leader. votes {1}. needed {2}", node.NodeInfo(), successCount, node.PeerAgreementsNeededForConcensus());
await SendHeartBeat();
}
else
{
Debug.WriteLine("{0}: Not elected. votes {1}. needed {2}", node.NodeInfo(), successCount, node.PeerAgreementsNeededForConcensus());
node.randomizeElectionDelays = true;
}
}
else
{
Debug.WriteLine("{0}: election was attempted before election timeout. lastHeartBeat {1} < now {2} - electionTimeout {3}", node.NodeInfo(), node.lastHeartBeat, now, node.electionTimeout.TotalSeconds);
Debug.WriteLine("{0}: need {1}ms more.", node.NodeInfo(), ((now - node.electionTimeout) - node.lastHeartBeat).TotalMilliseconds, now, node.electionTimeout.TotalSeconds);
}
}
public async Task <VoteResult> Vote(VoteRequest request)
{
if (request.Term < node.Term)
{
return(new VoteResult(node.Term, false));
}
//this needs some sort of lock around it. although it would be very rare in a deployed system, the nodes in unit tests have hit
//this block at the exact same time, resulting in both nodes getting the vote.
//using a lock for now. should be replaced at some point with interlocked for perf
lock (node.grantVoteLocker)
{
if (request.Term > node.Term)
{
node.StepDown(node.Term, request.Id);
}
return(new VoteResult(node.Term, false));
}
}