Leader election sends LEADER state change event twice

[Benjamin Jaton]

https://gist.github.com/benji/ea93ac90697f5503f515583be4c7475e

15:25:09.472 [copycat-server-/127.0.0.1:5001-copycat] DEBUG i.a.c.server.state.CandidateState - /127.0.0.1:5001 - Single member cluster. Transitioning directly to leader.
15:25:09.473 [copycat-server-/127.0.0.1:5001-copycat] INFO  i.a.c.server.state.ServerContext - /127.0.0.1:5001 - Transitioning to LEADER
15:25:09.473 [copycat-server-/127.0.0.1:5001-copycat] DEBUG i.a.c.server.state.CandidateState - /127.0.0.1:5001 - Cancelling election
15:25:09.477 [copycat-server-/127.0.0.1:5001-copycat] INFO  i.a.c.server.state.ServerContext - /127.0.0.1:5001 - Found leader /127.0.0.1:5001
15:25:09.478 [copycat-server-/127.0.0.1:5001-copycat] DEBUG i.a.c.s.storage.system.MetaStore - Store vote 0
15:25:09.480 [copycat-server-/127.0.0.1:5001-copycat] DEBUG i.a.copycat.server.state.LeaderState - /127.0.0.1:5001 - Appended InitializeEntry[index=1, term=1, timestamp=1489789509477]
15:25:09.481 [copycat-server-/127.0.0.1:5001-copycat] DEBUG i.a.copycat.server.state.LeaderState - /127.0.0.1:5001 - Appended ConfigurationEntry[index=2, term=1, timestamp=1489789509480, members=[ServerMember[type=ACTIVE, status=AVAILABLE, serverAddress=/127.0.0.1:5001, clientAddress=/127.0.0.1:5001]]]
15:25:09.482 [copycat-server-/127.0.0.1:5001-copycat] DEBUG i.a.c.s.storage.system.MetaStore - Store configuration Configuration[index=2, time=1489789509480, members=[ServerMember[type=ACTIVE, status=AVAILABLE, serverAddress=/127.0.0.1:5001, clientAddress=/127.0.0.1:5001]]]
15:25:09.484 [copycat-server-/127.0.0.1:5001-copycat] DEBUG i.a.c.s.state.ServerStateMachine - /127.0.0.1:5001 - Applying InitializeEntry[index=1, term=1, timestamp=1489789509477]
15:25:09.487 [copycat-server-/127.0.0.1:5001-copycat] DEBUG i.a.copycat.server.state.LeaderState - /127.0.0.1:5001 - Starting append timer
State changed to LEADER
State changed to LEADER
15:25:09.488 [copycat-server-/127.0.0.1:5001-copycat] INFO  i.a.copycat.server.CopycatServer - Server started successfully!

First time callback is invoked through:

at TwoLeaderEvents.lambda$0(TwoLeaderEvents.java:29)
at io.atomix.catalyst.concurrent.Listeners$ListenerHolder.accept(Listeners.java:104)
at io.atomix.copycat.server.state.ServerContext.lambda$23(ServerContext.java:612)
at java.lang.Iterable.forEach(Iterable.java:75)
at io.atomix.copycat.server.state.ServerContext.transition(ServerContext.java:612)
at io.atomix.copycat.server.state.CandidateState.sendVoteRequests(CandidateState.java:106)
at io.atomix.copycat.server.state.CandidateState.startElection(CandidateState.java:65)
at java.util.concurrent.CompletableFuture.uniRun(CompletableFuture.java:705)
at java.util.concurrent.CompletableFuture.uniRunStage(CompletableFuture.java:717)
at java.util.concurrent.CompletableFuture.thenRun(CompletableFuture.java:2010)
at io.atomix.copycat.server.state.CandidateState.open(CandidateState.java:57)
at io.atomix.copycat.server.state.ServerContext.transition(ServerContext.java:607)
at io.atomix.copycat.server.state.FollowerState.sendPollRequests(FollowerState.java:107)
at io.atomix.copycat.server.state.FollowerState.lambda$1(FollowerState.java:86)
at io.atomix.catalyst.concurrent.Runnables.lambda$logFailure$2(Runnables.java:20)

Second time invoked through:

at TwoLeaderEvents.lambda$0(TwoLeaderEvents.java:29)
at io.atomix.catalyst.concurrent.Listeners$ListenerHolder.accept(Listeners.java:104)
at io.atomix.copycat.server.state.ServerContext.lambda$23(ServerContext.java:612)
at java.lang.Iterable.forEach(Iterable.java:75)
at io.atomix.copycat.server.state.ServerContext.transition(ServerContext.java:612)
at io.atomix.copycat.server.state.FollowerState.sendPollRequests(FollowerState.java:107)
at io.atomix.copycat.server.state.FollowerState.lambda$1(FollowerState.java:86)
at io.atomix.catalyst.concurrent.Runnables.lambda$logFailure$2(Runnables.java:20)