private void SendProposal()
{
_acceptsReceived.Clear();
_masterProposal = null;
var master = GetBestMasterCandidate();
if (master == null)
{
Log.Trace("ELECTIONS: (V={lastAttemptedView}) NO MASTER CANDIDATE WHEN TRYING TO SEND PROPOSAL.",
_lastAttemptedView);
return;
}
_masterProposal = master;
Log.Debug("ELECTIONS: (V={lastAttemptedView}) SENDING PROPOSAL CANDIDATE: {formatNodeInfo}, ME: {ownInfo}.",
_lastAttemptedView, FormatNodeInfo(master), FormatNodeInfo(GetOwnInfo()));
var proposal = new ElectionMessage.Proposal(_nodeInfo.InstanceId, _nodeInfo.InternalHttp,
master.InstanceId, master.InternalHttp,
_lastInstalledView,
master.EpochNumber, master.EpochPosition, master.EpochId,
master.LastCommitPosition, master.WriterCheckpoint, master.ChaserCheckpoint);
Handle(new ElectionMessage.Accept(_nodeInfo.InstanceId, _nodeInfo.InternalHttp,
master.InstanceId, master.InternalHttp, _lastInstalledView));
SendToAllExceptMe(proposal);
}
public void Handle(ElectionMessage.Proposal message)
{
if (_state == ElectionsState.Shutdown)
{
return;
}
if (message.ServerId == _nodeInfo.InstanceId)
{
return;
}
if (_state != ElectionsState.NonLeader)
{
return;
}
if (message.View != _lastInstalledView)
{
return;
}
if (_servers.All(x => x.InstanceId != message.ServerId))
{
return;
}
if (_servers.All(x => x.InstanceId != message.MasterId))
{
return;
}
var candidate = new MasterCandidate(message.MasterId, message.MasterInternalHttp,
message.EpochNumber, message.EpochPosition, message.EpochId,
message.LastCommitPosition, message.WriterCheckpoint, message.ChaserCheckpoint, 0);
if (!IsLegitimateMaster(message.View, message.ServerInternalHttp, message.ServerId, candidate))
{
return;
}
Log.Debug(
"ELECTIONS: (V={lastAttemptedView}) PROPOSAL FROM [{serverInternalHttp},{serverId:B}] M={candidateInfo}. ME={ownInfo}.",
_lastAttemptedView,
message.ServerInternalHttp, message.ServerId, FormatNodeInfo(candidate), FormatNodeInfo(GetOwnInfo()));
if (_masterProposal == null)
{
_masterProposal = candidate;
_acceptsReceived.Clear();
}
if (_masterProposal.InstanceId == message.MasterId)
{
// NOTE: proposal from other server is also implicit Accept from that server
Handle(new ElectionMessage.Accept(message.ServerId, message.ServerInternalHttp,
message.MasterId, message.MasterInternalHttp, message.View));
var accept = new ElectionMessage.Accept(_nodeInfo.InstanceId, _nodeInfo.InternalHttp,
message.MasterId, message.MasterInternalHttp, message.View);
Handle(accept); // implicitly sent accept to ourselves
SendToAllExceptMe(accept);
}
}
private bool IsCandidateGoodEnough(MasterCandidate candidate, MasterCandidate ownInfo)
{
if (candidate.EpochNumber != ownInfo.EpochNumber)
{
return(candidate.EpochNumber > ownInfo.EpochNumber);
}
if (candidate.LastCommitPosition != ownInfo.LastCommitPosition)
{
return(candidate.LastCommitPosition > ownInfo.LastCommitPosition);
}
if (candidate.WriterCheckpoint != ownInfo.WriterCheckpoint)
{
return(candidate.WriterCheckpoint > ownInfo.WriterCheckpoint);
}
if (candidate.ChaserCheckpoint != ownInfo.ChaserCheckpoint)
{
return(candidate.ChaserCheckpoint > ownInfo.ChaserCheckpoint);
}
return(true);
}
private bool IsLegitimateMaster(int view, IPEndPoint proposingServerEndPoint, Guid proposingServerId,
MasterCandidate candidate)
{
var master = _servers.FirstOrDefault(x =>
x.IsAlive && x.InstanceId == _lastElectedMaster && x.State == VNodeState.Master);
if (master != null)
{
if (candidate.InstanceId == master.InstanceId ||
candidate.EpochNumber > master.EpochNumber ||
(candidate.EpochNumber == master.EpochNumber && candidate.EpochId != master.EpochId))
{
return(true);
}
Log.Debug(
"ELECTIONS: (V={view}) NOT LEGITIMATE MASTER PROPOSAL FROM [{proposingServerEndPoint},{proposingServerId:B}] M={candidateInfo}. "
+ "PREVIOUS MASTER IS ALIVE: [{masterInternalHttp},{masterId:B}].",
view, proposingServerEndPoint, proposingServerId, FormatNodeInfo(candidate),
master.InternalHttpEndPoint, master.InstanceId);
return(false);
}
if (candidate.InstanceId == _nodeInfo.InstanceId)
{
return(true);
}
var ownInfo = GetOwnInfo();
if (!IsCandidateGoodEnough(candidate, ownInfo))
{
Log.Debug(
"ELECTIONS: (V={view}) NOT LEGITIMATE MASTER PROPOSAL FROM [{proposingServerEndPoint},{proposingServerId:B}] M={candidateInfo}. ME={ownInfo}.",
view, proposingServerEndPoint, proposingServerId, FormatNodeInfo(candidate),
FormatNodeInfo(ownInfo));
return(false);
}
return(true);
}
private void ShiftToLeaderElection(int view)
{
Log.Debug("ELECTIONS: (V={view}) SHIFT TO LEADER ELECTION.", view);
_state = ElectionsState.ElectingLeader;
_vcReceived.Clear();
_prepareOkReceived.Clear();
_lastAttemptedView = view;
_masterProposal = null;
_master = null;
_acceptsReceived.Clear();
var viewChangeMsg = new ElectionMessage.ViewChange(_nodeInfo.InstanceId, _nodeInfo.InternalHttp, view);
Handle(viewChangeMsg);
SendToAllExceptMe(viewChangeMsg);
_publisher.Publish(TimerMessage.Schedule.Create(LeaderElectionProgressTimeout,
_publisherEnvelope,
new ElectionMessage.ElectionsTimedOut(view)));
}
private static string FormatNodeInfo(MasterCandidate candidate)
{
return(FormatNodeInfo(candidate.InternalHttp, candidate.InstanceId,
candidate.LastCommitPosition, candidate.WriterCheckpoint, candidate.ChaserCheckpoint,
candidate.EpochNumber, candidate.EpochPosition, candidate.EpochId));
}
