private LogLengthNegotiation CheckIfValidLeader()
{
using (_engine.ContextPool.AllocateOperationContext(out TransactionOperationContext context))
{
var logLength = _connection.Read <LogLengthNegotiation>(context);
if (logLength.Term < _engine.CurrentTerm)
{
var msg = $"The incoming term {logLength.Term} is smaller than current term {_engine.CurrentTerm} and is therefor rejected";
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info(msg);
}
_connection.Send(context, new LogLengthNegotiationResponse
{
Status = LogLengthNegotiationResponse.ResponseStatus.Rejected,
Message = msg,
CurrentTerm = _engine.CurrentTerm
});
_connection.Dispose();
return(null);
}
_engine.Timeout.Defer(_connection.Source);
return(logLength);
}
}
public static bool CheckIfValidLeader(RachisConsensus engine, RemoteConnection connection, out LogLengthNegotiation negotiation)
{
negotiation = null;
using (engine.ContextPool.AllocateOperationContext(out ClusterOperationContext context))
{
var logLength = connection.Read <LogLengthNegotiation>(context);
if (logLength.Term < engine.CurrentTerm)
{
var msg = $"The incoming term {logLength.Term} is smaller than current term {engine.CurrentTerm} and is therefor rejected (From thread: {logLength.SendingThread})";
if (engine.Log.IsInfoEnabled)
{
engine.Log.Info(msg);
}
connection.Send(context, new LogLengthNegotiationResponse
{
Status = LogLengthNegotiationResponse.ResponseStatus.Rejected,
Message = msg,
CurrentTerm = engine.CurrentTerm
});
connection.Dispose();
return(false);
}
if (engine.Log.IsInfoEnabled)
{
engine.Log.Info($"The incoming term { logLength.Term} is from a valid leader (From thread: {logLength.SendingThread})");
}
engine.FoundAboutHigherTerm(logLength.Term, "Setting the term of the new leader");
engine.Timeout.Defer(connection.Source);
negotiation = logLength;
}
return(true);
}
public void Dispose()
{
_connection?.Dispose();
if (_thread != null &&
_thread.ManagedThreadId != Thread.CurrentThread.ManagedThreadId)
{
_thread.Join();
}
}
public void Dispose()
{
_disposed = true;
if (_candidate.ElectionResult != ElectionResult.Won)
{
Connection?.Dispose();
if (_thread != null && _thread.ManagedThreadId != Thread.CurrentThread.ManagedThreadId)
{
while (_thread.Join(16) == false)
{
Connection?.Dispose();
}
}
}
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"CandidateAmbassador {_tag}: Dispose after the elections were {_candidate.ElectionResult}");
}
}
public void Dispose()
{
_connection.Dispose();
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"{ToString()}: Disposing");
}
if (_followerLongRunningWork != null && _followerLongRunningWork.ManagedThreadId != Thread.CurrentThread.ManagedThreadId)
{
_followerLongRunningWork.Join(int.MaxValue);
}
_engine.InMemoryDebug.RemoveRecorderOlderThan(DateTime.UtcNow.AddMinutes(-5));
}
public void Dispose()
{
_connection.Dispose();
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"{ToString()}: Disposing");
}
if (_followerLongRunningWork != null && _followerLongRunningWork.ManagedThreadId != Thread.CurrentThread.ManagedThreadId)
{
_followerLongRunningWork.Join(int.MaxValue);
}
_engine.InMemoryDebug.RemoveRecorder(_debugName);
}
public void Dispose()
{
if (_electionWon == false)
{
_connection.Dispose();
}
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"{ToString()}: Disposing");
}
if (_electorLongRunningWork != null && _electorLongRunningWork.ManagedThreadId != Thread.CurrentThread.ManagedThreadId)
{
_electorLongRunningWork.Join(int.MaxValue);
}
}
/// <summary>
/// This method may run for a long while, as we are trying to get agreement
/// from a majority of the cluster
/// </summary>
private void Run()
{
try
{
while (_candidate.Running && _disposed == false)
{
try
{
Stream stream;
try
{
using (_engine.ContextPool.AllocateOperationContext(out TransactionOperationContext context))
{
stream = _engine.ConnectToPeer(_url, _certificate, context).Result;
}
if (_candidate.Running == false)
{
break;
}
}
catch (Exception e)
{
Status = AmbassadorStatus.FailedToConnect;
StatusMessage = $"Failed to connect with {_tag}.{Environment.NewLine} " + e.Message;
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"CandidateAmbassador {_engine.Tag}: Failed to connect to remote peer: " + _url, e);
}
// wait a bit
_candidate.WaitForChangeInState();
continue; // we'll retry connecting
}
Status = AmbassadorStatus.Connected;
StatusMessage = $"Connected to {_tag}";
Connection = new RemoteConnection(_tag, _engine.Tag, stream);
using (_engine.ContextPool.AllocateOperationContext(out TransactionOperationContext context))
{
ClusterTopology topology;
long lastLogIndex;
long lastLogTerm;
using (context.OpenReadTransaction())
{
topology = _engine.GetTopology(context);
lastLogIndex = _engine.GetLastEntryIndex(context);
lastLogTerm = _engine.GetTermForKnownExisting(context, lastLogIndex);
}
Debug.Assert(topology.TopologyId != null);
Connection.Send(context, new RachisHello
{
TopologyId = topology.TopologyId,
DebugSourceIdentifier = _engine.Tag,
DebugDestinationIdentifier = _tag,
InitialMessageType = InitialMessageType.RequestVote
});
while (_candidate.Running)
{
RequestVoteResponse rvr;
var currentElectionTerm = _candidate.ElectionTerm;
var engineCurrentTerm = _engine.CurrentTerm;
if (_candidate.IsForcedElection == false ||
_candidate.RunRealElectionAtTerm != currentElectionTerm)
{
Connection.Send(context, new RequestVote
{
Source = _engine.Tag,
Term = currentElectionTerm,
IsForcedElection = false,
IsTrialElection = true,
LastLogIndex = lastLogIndex,
LastLogTerm = lastLogTerm
});
rvr = Connection.Read <RequestVoteResponse>(context);
if (rvr.Term > currentElectionTerm)
{
var message = $"Candidate ambassador {_engine.Tag}: found election term {rvr.Term} that is higher than ours {currentElectionTerm}";
// we need to abort the current elections
_engine.SetNewState(RachisState.Follower, null, engineCurrentTerm, message);
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"CandidateAmbassador {_engine.Tag}: {message}");
}
_engine.FoundAboutHigherTerm(rvr.Term);
throw new InvalidOperationException(message);
}
NotInTopology = rvr.NotInTopology;
if (rvr.VoteGranted == false)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"CandidateAmbassador {_engine.Tag}: Got a negative response from {_tag} reason: {rvr.Message}");
}
// we go a negative response here, so we can't proceed
// we'll need to wait until the candidate has done something, like
// change term or given up
_candidate.WaitForChangeInState();
continue;
}
TrialElectionWonAtTerm = rvr.Term;
_candidate.WaitForChangeInState();
}
Connection.Send(context, new RequestVote
{
Source = _engine.Tag,
Term = currentElectionTerm,
IsForcedElection = _candidate.IsForcedElection,
IsTrialElection = false,
LastLogIndex = lastLogIndex,
LastLogTerm = lastLogTerm
});
rvr = Connection.Read <RequestVoteResponse>(context);
if (rvr.Term > currentElectionTerm)
{
var message = $"Candidate ambassador {_engine.Tag}: found election term {rvr.Term} that is higher than ours {currentElectionTerm}";
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"CandidateAmbassador {_engine.Tag}: {message}");
}
// we need to abort the current elections
_engine.SetNewState(RachisState.Follower, null, engineCurrentTerm, message);
_engine.FoundAboutHigherTerm(rvr.Term);
throw new InvalidOperationException(message);
}
NotInTopology = rvr.NotInTopology;
if (rvr.VoteGranted == false)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"CandidateAmbassador {_engine.Tag}: Got a negative response from {_tag} reason: {rvr.Message}");
}
// we go a negative response here, so we can't proceed
// we'll need to wait until the candidate has done something, like
// change term or given up
_candidate.WaitForChangeInState();
continue;
}
RealElectionWonAtTerm = rvr.Term;
_candidate.WaitForChangeInState();
}
SendElectionResult();
}
}
catch (OperationCanceledException)
{
Status = AmbassadorStatus.Closed;
StatusMessage = "Closed";
SendElectionResult();
break;
}
catch (ObjectDisposedException)
{
Status = AmbassadorStatus.Closed;
StatusMessage = "Closed";
SendElectionResult();
break;
}
catch (AggregateException ae)
when(ae.InnerException is OperationCanceledException || ae.InnerException is ObjectDisposedException)
{
Status = AmbassadorStatus.Closed;
StatusMessage = "Closed";
SendElectionResult();
break;
}
catch (Exception e)
{
Status = AmbassadorStatus.FailedToConnect;
StatusMessage = $"Failed to get vote from {_tag}.{Environment.NewLine}" + e.Message;
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"CandidateAmbassador {_engine.Tag}: Failed to get vote from remote peer url={_url} tag={_tag}", e);
}
Connection?.Dispose();
_candidate.WaitForChangeInState();
}
}
}
catch (Exception e)
{
Status = AmbassadorStatus.FailedToConnect;
StatusMessage = $"Failed to talk to {_url}.{Environment.NewLine}" + e;
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info("Failed to talk to remote peer: " + _url, e);
}
}
finally
{
if (_candidate.ElectionResult != ElectionResult.Won)
{
Connection?.Dispose();
}
}
}
public void HandleVoteRequest()
{
try
{
while (true)
{
using (_engine.ContextPool.AllocateOperationContext(out TransactionOperationContext context))
{
var rv = _connection.Read <RequestVote>(context);
if (_engine.Log.IsInfoEnabled)
{
var election = rv.IsTrialElection ? "Trial" : "Real";
_engine.Log.Info($"Received ({election}) 'RequestVote' from {rv.Source}: Election is {rv.ElectionResult} in term {rv.Term} while our current term is {_engine.CurrentTerm}, " +
$"Forced election is {rv.IsForcedElection}. (Sent from:{rv.SendingThread})");
}
//We are getting a request to vote for our known leader
if (_engine.LeaderTag == rv.Source)
{
_engine.LeaderTag = null;
//If we are followers we want to drop the connection with the leader right away.
//We shouldn't be in any other state since if we are candidate our leaderTag should be null but its safer to verify.
if (_engine.CurrentState == RachisState.Follower)
{
_engine.SetNewState(RachisState.Follower, null, _engine.CurrentTerm, $"We got a vote request from our leader {rv.Source} so we switch to leaderless state.");
}
}
ClusterTopology clusterTopology;
long lastIndex;
long lastTerm;
string whoGotMyVoteIn;
long lastVotedTerm;
using (context.OpenReadTransaction())
{
lastIndex = _engine.GetLastEntryIndex(context);
lastTerm = _engine.GetTermForKnownExisting(context, lastIndex);
(whoGotMyVoteIn, lastVotedTerm) = _engine.GetWhoGotMyVoteIn(context, rv.Term);
clusterTopology = _engine.GetTopology(context);
}
// this should be only the case when we where once in a cluster, then we were brought down and our data was wiped.
if (clusterTopology.TopologyId == null)
{
_connection.Send(context, new RequestVoteResponse
{
Term = rv.Term,
VoteGranted = true,
Message = "I might vote for you, because I'm not part of any cluster."
});
continue;
}
if (clusterTopology.Members.ContainsKey(rv.Source) == false &&
clusterTopology.Promotables.ContainsKey(rv.Source) == false &&
clusterTopology.Watchers.ContainsKey(rv.Source) == false)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
// we only report to the node asking for our vote if we are the leader, this gives
// the oust node a authorotative confirmation that they were removed from the cluster
NotInTopology = _engine.CurrentState == RachisState.Leader,
Message = $"Node {rv.Source} is not in my topology, cannot vote for it"
});
_connection.Dispose();
return;
}
var currentTerm = _engine.CurrentTerm;
if (rv.Term == currentTerm && rv.ElectionResult == ElectionResult.Won)
{
_electionWon = true;
if (Follower.CheckIfValidLeader(_engine, _connection, out var negotiation))
{
var follower = new Follower(_engine, negotiation.Term, _connection);
follower.AcceptConnection(negotiation);
}
return;
}
if (rv.ElectionResult != ElectionResult.InProgress)
{
_connection.Dispose();
return;
}
if (rv.Term <= _engine.CurrentTerm)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
Message = "My term is higher or equals to yours"
});
_connection.Dispose();
return;
}
if (rv.IsForcedElection == false &&
(
_engine.CurrentState == RachisState.Leader ||
_engine.CurrentState == RachisState.LeaderElect
)
)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentLeader.Term,
VoteGranted = false,
Message = "I'm a leader in good standing, coup will be resisted"
});
_connection.Dispose();
return;
}
if (whoGotMyVoteIn != null && whoGotMyVoteIn != rv.Source)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
Message = $"Already voted in {rv.LastLogTerm}, for {whoGotMyVoteIn}"
});
continue;
}
if (lastVotedTerm > rv.Term)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
Message = $"Already voted for another node in {lastVotedTerm}"
});
continue;
}
if (lastTerm > rv.LastLogTerm)
{
// we aren't going to vote for this guy, but we need to check if it is more up to date
// in the state of the cluster than we are
if (rv.Term > _engine.CurrentTerm + 1)
{
// trail election is often done on the current term + 1, but if there is any
// election on a term that is greater than the current term plus one, we should
// consider this an indication that the cluster was able to move past our term
// and update the term accordingly
using (context.OpenWriteTransaction())
{
// double checking things under the transaction lock
if (rv.Term > _engine.CurrentTerm + 1)
{
_engine.CastVoteInTerm(context, rv.Term - 1, null, "Noticed that the term in the cluster grew beyond what I was familiar with, increasing it");
}
context.Transaction.Commit();
}
}
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
Message = $"My last log entry is of term {lastTerm} / {lastIndex} while yours is {rv.LastLogTerm}, so I'm more up to date"
});
continue;
}
if (rv.IsTrialElection)
{
if (_engine.Timeout.ExpiredLastDeferral(_engine.ElectionTimeout.TotalMilliseconds / 2, out string currentLeader) == false &&
string.IsNullOrEmpty(currentLeader) == false) // if we are leaderless we can't refuse to cast our vote.
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
Message = $"My leader {currentLeader} is keeping me up to date, so I don't want to vote for you"
});
continue;
}
if (lastTerm == rv.LastLogTerm && lastIndex > rv.LastLogIndex)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
Message = $"My log {lastIndex} is more up to date than yours {rv.LastLogIndex}"
});
continue;
}
_connection.Send(context, new RequestVoteResponse
{
Term = rv.Term,
VoteGranted = true,
Message = "I might vote for you"
});
continue;
}
HandleVoteResult result;
using (context.OpenWriteTransaction())
{
result = ShouldGrantVote(context, lastIndex, rv, lastTerm);
if (result.DeclineVote == false)
{
_engine.CastVoteInTerm(context, rv.Term, rv.Source, "Casting vote as elector");
context.Transaction.Commit();
}
}
if (result.DeclineVote)
{
_connection.Send(context, new RequestVoteResponse
{
Term = result.VotedTerm,
VoteGranted = false,
Message = result.DeclineReason
});
}
else
{
_connection.Send(context, new RequestVoteResponse
{
Term = rv.Term,
VoteGranted = true,
Message = "I've voted for you"
});
}
}
}
}
catch (OperationCanceledException)
{
}
catch (ObjectDisposedException)
{
}
catch (AggregateException ae)
when(ae.InnerException is OperationCanceledException || ae.InnerException is ObjectDisposedException)
{
}
catch (Exception e)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"Failed to talk to candidate: {_engine.Tag}", e);
}
}
finally
{
if (_electionWon == false)
{
_connection.Dispose();
}
}
}
public void HandleVoteRequest()
{
try
{
while (true)
{
using (_engine.ContextPool.AllocateOperationContext(out TransactionOperationContext context))
{
var rv = _connection.Read <RequestVote>(context);
ClusterTopology clusterTopology;
long lastIndex;
long lastTerm;
string whoGotMyVoteIn;
using (context.OpenReadTransaction())
{
lastIndex = _engine.GetLastEntryIndex(context);
lastTerm = _engine.GetTermForKnownExisting(context, lastIndex);
whoGotMyVoteIn = _engine.GetWhoGotMyVoteIn(context, rv.Term);
clusterTopology = _engine.GetTopology(context);
}
if (clusterTopology.Members.ContainsKey(rv.Source) == false &&
clusterTopology.Promotables.ContainsKey(rv.Source) == false &&
clusterTopology.Watchers.ContainsKey(rv.Source) == false)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
// we only report to the node asking for our vote if we are the leader, this gives
// the oust node a authorotative confirmation that they were removed from the cluster
NotInTopology = _engine.CurrentState == RachisConsensus.State.Leader,
Message = $"Node {rv.Source} is not in my topology, cannot vote for it"
});
_connection.Dispose();
return;
}
if (rv.Term <= _engine.CurrentTerm)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
Message = "My term is higher or equals to yours"
});
_connection.Dispose();
return;
}
if (rv.IsForcedElection == false &&
(
_engine.CurrentState == RachisConsensus.State.Leader ||
_engine.CurrentState == RachisConsensus.State.LeaderElect
)
)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
Message = "I'm a leader in good standing, coup will be resisted"
});
_connection.Dispose();
return;
}
if (whoGotMyVoteIn != null && whoGotMyVoteIn != rv.Source)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
Message = $"Already voted in {rv.LastLogTerm}, for {whoGotMyVoteIn}"
});
_connection.Dispose();
return;
}
if (lastTerm > rv.LastLogTerm)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
Message = $"My last log entry is of term {lastTerm} / {lastIndex} while yours is {rv.LastLogTerm}, so I'm more up to date"
});
_connection.Dispose();
return;
}
if (lastIndex > rv.LastLogIndex)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
Message = $"My last log entry is of term {lastTerm} / {lastIndex} while yours is {rv.LastLogTerm} / {rv.LastLogIndex}, so I'm more up to date"
});
_connection.Dispose();
return;
}
if (rv.IsTrialElection)
{
if (_engine.Timeout.ExpiredLastDeferral(_engine.ElectionTimeout.TotalMilliseconds / 2, out string currentLeader) == false)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
Message = $"My leader {currentLeader} is keeping me up to date, so I don't want to vote for you"
});
_connection.Dispose();
return;
}
_connection.Send(context, new RequestVoteResponse
{
Term = rv.Term,
VoteGranted = true,
Message = "I might vote for you"
});
if (_thread == null) // let's wait for this in another thread
{
_thread = new Thread(HandleVoteRequest)
{
Name =
$"Elector thread for {rv.Source} > {_engine.Tag}",
IsBackground = true
};
_thread.Start();
return;
}
continue;
}
bool alreadyVoted = false;
using (context.OpenWriteTransaction())
{
whoGotMyVoteIn = _engine.GetWhoGotMyVoteIn(context, rv.Term);
if (whoGotMyVoteIn != null && whoGotMyVoteIn != rv.Source)
{
alreadyVoted = true;
}
else
{
_engine.CastVoteInTerm(context, rv.Term, rv.Source);
}
context.Transaction.Commit();
}
if (alreadyVoted)
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = false,
Message = $"Already voted in {rv.LastLogTerm}, for {whoGotMyVoteIn}"
});
}
else
{
_connection.Send(context, new RequestVoteResponse
{
Term = _engine.CurrentTerm,
VoteGranted = true,
Message = "I've voted for you"
});
}
_connection.Dispose();
}
}
}
catch (OperationCanceledException)
{
}
catch (ObjectDisposedException)
{
}
catch (AggregateException ae)
when(ae.InnerException is OperationCanceledException || ae.InnerException is ObjectDisposedException)
{
}
catch (Exception e)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info("Failed to talk to candidate: " + _engine.Tag, e);
}
}
}