private Task <Log> SendAppendEntriesInParallel(string log, bool heartBeat)
{
if (!heartBeat)
{
LocalLog.Add(Term, log);
}
var tcs = new TaskCompletionSource <Log>();
var successCount = 0;
Peers.ForEach(peer => Task.Run(async() =>
{
AppendEntriesResult result;
Debug.WriteLine("{0}: sending append entries to {1}", NodeInfo(), peer.Id);
result = await AppendAllTheEntries(heartBeat, peer);
Debug.WriteLine("{0}: Got a result {1}", NodeInfo(), peer.Id);
return(result);
})
.ContinueWith(async t =>
{
Debug.WriteLine("{0}: ContinueingWith {1}", NodeInfo(), t.Result.Success);
if (t.Result.Success)
{
Interlocked.Increment(ref successCount);
}
if (successCount >= PeerAgreementsNeededForConcensus())
{
await CommitToServerLog(log);
tcs.SetResult(ServerLog);
}
}));
return(tcs.Task);
}
private async Task <LogResult> SendAppendEntries(string log, bool heartBeat)
{
if (!heartBeat)
{
LocalLog.Add(Term, log);
}
var results = new List <AppendEntriesResult>();
Peers.ForEach(async peer =>
{
Debug.WriteLine("{0}: sending append entries to {1}", NodeInfo(), peer.Id);
var result = (await AppendAllTheEntries(heartBeat, peer)
.ToObservable()
.Timeout(TimeSpan.FromSeconds(5))
.Catch <AppendEntriesResult, TimeoutException>(e => Observable.Return(new AppendEntriesResult(0, false))));
if (result.CurrentTerm > Term)
{
StepDown(result.CurrentTerm, peer.Id);
}
results.Add(result);
Debug.WriteLine("{0}: Got a result {1}", NodeInfo(), peer.Id);
});
if (results.Count(r => r.Success) >= PeerAgreementsNeededForConcensus())
{
await CommitToServerLog(log);
}
return(new LogCommited
{
ServerLog = ServerLog
});
}
public virtual async Task <AppendEntriesResult> AppendEntries(AppendEntriesRequest request)
{
Debug.WriteLine("{0}: GOT APPEND ENTRIES CALL {1}: leader commit {2} : entries: {3}", NodeInfo(), request.Id, request.CommitIndex, String.Concat(request.Entries.Select(e => e.Log + " ")));
HeartBeat(request.Id, request.Term);
if (request.Entries == null || !request.Entries.Any()) //heartbeat
{
if (request.CommitIndex > ServerLog.LastIndex)
{
Debug.WriteLine("{0}: HeartBeat Adding To Server Log up to index {1} leaderCommitIndex {2}", NodeInfo(), request.PreviousLogIndex, request.CommitIndex);
LocalLog.Entries.Where(e => e.Index > ServerLog.LastIndex && e.Index <= request.CommitIndex).ForEach(e => ServerLog.Add(e.Term, e.Log));
}
return(new AppendEntriesResult(Term, true));
}
if (Term < request.Term) //servers term is behind. we need to ensure we are in follower state and reset who we have voted for
{
StepDown(request.Term, request.Id);
return(new AppendEntriesResult(Term, false));
}
if (request.Term < Term)
{
return(new AppendEntriesResult(Term, false));
}
if (request.PreviousLogIndex == 0 || (request.PreviousLogIndex <= ServerLog.LastIndex &&
ServerLog.LastTerm == request.PreviousLogTerm))
{
Debug.WriteLine("{0}: huh");
}
//reply false if log doesnt contain an entry at prevLogIndex whose term matches prevlogTerm
if (!LocalLog.Entries.Any(e => e.Index == request.PreviousLogIndex && e.Term == request.PreviousLogTerm)) //not to sure about this line yet
{
return(new AppendEntriesResult(Term, false));
}
if (LocalLog.Entries.Any(e => e.Index == request.PreviousLogIndex && e.Term != request.PreviousLogTerm))
{
//delete the entry and all that follow it
LocalLog.RemoveEntryAndThoseAfterIt(request.PreviousLogIndex);
}
if (request.Entries.Max(e => e.Index) > LocalLog.LastIndex)
{
Debug.WriteLine("{0}: Adding To Local Log up to index {1} leaderCommitIndex {2}", NodeInfo(), request.Entries.Max(e => e.Index), request.CommitIndex);
request.Entries.Where(e => e.Index > LocalLog.LastIndex).ForEach(e => LocalLog.Add(e.Term, e.Log));
}
if (request.CommitIndex > ServerLog.LastIndex)
{
Debug.WriteLine("{0}: Adding To Server Log up to index {1} leaderCommitIndex {2}", NodeInfo(), request.PreviousLogIndex, request.CommitIndex);
request.Entries.Where(e => e.Index > ServerLog.LastIndex && e.Index <= request.CommitIndex).ForEach(e => ServerLog.Add(e.Term, e.Log));
}
if (request.CommitIndex > CommitIndex)
{
CommitIndex = Math.Min(request.CommitIndex, LocalLog.LastIndex);
}
return(new AppendEntriesResult(Term, true));
}