subscribe before state emits NewRoundStep

I had to alter events package for that. Hope that's fine.
Refs #847

consensus/reactor.go

@@ -43,7 +43,8 @@ type ConsensusReactor struct {
 	eventBus *types.EventBus
 }
 
-// NewConsensusReactor returns a new ConsensusReactor with the given consensusState.
+// NewConsensusReactor returns a new ConsensusReactor with the given
+// consensusState.
 func NewConsensusReactor(consensusState *ConsensusState, fastSync bool) *ConsensusReactor {
 	conR := &ConsensusReactor{
 		conS:     consensusState,
@@ -53,27 +54,31 @@ func NewConsensusReactor(consensusState *ConsensusState, fastSync bool) *Consens
 	return conR
 }
 
-// OnStart implements BaseService.
+// OnStart implements BaseService by subscribing to events, which later will be
+// broadcasted to other peers and starting state if we're not in fast sync.
 func (conR *ConsensusReactor) OnStart() error {
 	conR.Logger.Info("ConsensusReactor ", "fastSync", conR.FastSync())
 	if err := conR.BaseReactor.OnStart(); err != nil {
 		return err
 	}
 
+	conR.subscribeToBroadcastEvents()
+
 	if !conR.FastSync() {
 		err := conR.conS.Start()
 		if err != nil {
 			return err
 		}
-		conR.subscribeToBroadcastEvents()
 	}
 
 	return nil
 }
 
-// OnStop implements BaseService
+// OnStop implements BaseService by unsubscribing from events and stopping
+// state.
 func (conR *ConsensusReactor) OnStop() {
 	conR.BaseReactor.OnStop()
+	conR.unsubscribeFromBroadcastEvents()
 	conR.conS.Stop()
 }
 
@@ -99,7 +104,6 @@ func (conR *ConsensusReactor) SwitchToConsensus(state sm.State, blocksSynced int
 		conR.Logger.Error("Error starting conS", "err", err)
 		return
 	}
-	conR.subscribeToBroadcastEvents()
 }
 
 // GetChannels implements Reactor
@@ -347,11 +351,6 @@ func (conR *ConsensusReactor) FastSync() bool {
 // proposal heartbeats using internal pubsub defined on state to broadcast
 // them to peers upon receiving.
 func (conR *ConsensusReactor) subscribeToBroadcastEvents() {
-	// assert consensus state is running
-	if !conR.conS.IsRunning() {
-		panic("consensus state must be running at this point")
-	}
-
 	const subscriber = "consensus-reactor"
 	conR.conS.evsw.AddListenerForEvent(subscriber, types.EventNewRoundStep,
 		func(data tmevents.EventData) {
@@ -369,6 +368,11 @@ func (conR *ConsensusReactor) subscribeToBroadcastEvents() {
 		})
 }
 
+func (conR *ConsensusReactor) unsubscribeFromBroadcastEvents() {
+	const subscriber = "consensus-reactor"
+	conR.conS.evsw.RemoveListener(subscriber)
+}
+
 func (conR *ConsensusReactor) broadcastProposalHeartbeatMessage(hb *types.Heartbeat) {
 	conR.Logger.Debug("Broadcasting proposal heartbeat message",
 		"height", hb.Height, "round", hb.Round, "sequence", hb.Sequence)