public Node MakeNode(ActorSystem system)
{
var cluster = Cluster.Get(system);
int uid = cluster.SelfUniqueAddress.Uid;
var node = new Node(uid);
ActionBroker.SetLeader(system.ActorOf <LeaderActor>("leader"));
ActionBroker.SetFollower(system.ActorOf <FollowerActor>("follower"));
ActionBroker.SetCandidate(system.ActorOf <CandidateActor>("candidate"));
ActionBroker.SetElection(system.ActorOf <ElectionCycleActor>("electionCycle"));
ActionBroker.SetHeartbeat(system.ActorOf <HeartbeatActor>("heartbeat"));
ActionBroker.SetStatusBroadcast(system.ActorOf <StatusBroadcastActor>("status"));
return(node);
}
public Node(int clusterUniqueId)
{
ProcessId = Process.GetCurrentProcess().Id;
ClusterUid = clusterUniqueId;
Log.Information("{0}", $"My Uid is {ClusterUid}");
LogEntries = new List <LogEntry>();
NodeEvents.OnElectionDurationChanged = dur => ElectionDuration = dur;
NodeEvents.OnElectionElapsed = el => ElectionElapsed = el;
NodeEvents.OnElectionTimeout = () => {
//step up as candidate
//ask for vote
if (Role == Roles.Follower)
{
Role = Roles.Candidate;
Term++;
Votes = 0;
Log.Information("{0}", $"Starting election for term {Term}");
ActionBroker.StopElectionTimer();
ActionBroker.AskForVote(Term);
ActionBroker.StartWaitForVote();
}
};
NodeEvents.OnGotVote = (uid, term) =>
{
//if got more than majority vote, then becomes leader
//start sending heartbeat
if (term == Term)
{
Votes++;
}
Log.Information("{0}", $"Got {Votes}/{Majority} votes for term {term} from {uid}");
if (Votes >= Majority)
{
Log.Information("{0}", "Elected!");
Role = Roles.Leader;
CurrentLeaderId = ClusterUid;
ActionBroker.StopWaitForVote();
ActionBroker.StartHeartbeat();
}
};
NodeEvents.OnHeartbeat = (senderpath, hb) => {
//resets election time
//otherwise becomes candidate and send request for votes
ActionBroker.ResetElectionTimer();
//if heartbeat has term equal or bigger than self, then step down
if (hb.Term >= Term)
{
//need to roll back changes and take match leader's log entries
if (Role != Roles.Follower)
{
Log.Information("{0}", "Stepping down");
Role = Roles.Follower;
ActionBroker.StopHeartbeat();
ActionBroker.StartElectionTimer();
}
if (hb.Term != Term)
{
Log.Information("{0}", $"Updating from term {Term} to {hb.Term}");
Term = hb.Term;
}
}
CurrentLeaderId = hb.SenderId;
if (Role == Roles.Follower)
{
ActionBroker.SendHeartbeatResponse(hb.Id, hb.SenderId, senderpath, hb.Term, hb.LogIndex);
}
};
NodeEvents.OnJoinedCluster = () => {
if (Role != Roles.Leader)
{
Log.Information("{0}", "Starting election timer");
ActionBroker.StartElectionTimer();
}
};
NodeEvents.OnVoteRequest = vr =>
{
//if not voted this term and is not a leader, then vote for the candidate
if (_votedForTerm < vr.Term && Role != Roles.Leader)
{
if (vr.SenderId != ClusterUid)
{
Log.Information("{0}", $"Vote request from candidate {vr.SenderId} for term {vr.Term}");
}
else
{
Log.Information("{0}", $"Vote request from self in term {vr.Term}");
}
_votedForTerm = vr.Term;
return(true);
}
else
{
Log.Information("{0}", $"Not voting. {vr.SenderId} asking for term {vr.Term}, last voted for {_votedForTerm} and role is {Role.ToString()}");
return(false);
}
};
NodeEvents.OnWaitForVoteTimeout = () =>
{
//restart election time
Role = Roles.Follower;
ActionBroker.ResetElectionTimer();
ActionBroker.StartElectionTimer();
};
NodeEvents.OnMemberChanged = count => {
//update majority
Majority = (count + 1) / 2;
Log.Information("{0}", $"Majority is now {Majority}");
};
}
public void Stop(TimeSpan timeSpan)
{
ActionBroker.Stop(timeSpan);
}
public void OnKill()
{
ActionBroker.SendTerminateSignal();
}