fix reactor engine main loop blocked to wait if drained

ethreact/reactor.go

@@ -28,7 +28,7 @@ func (e *EventHandler) Post(event Event) {
 		select {
 		case ch <- event:
 		default:
-			logger.Warnln("subscribing channel %d to event %s blocked. skipping", i, event.Name)
+			logger.Warnf("subscribing channel %d to event %s blocked. skipping\n", i, event.Name)
 		}
 	}
 }
@@ -69,7 +69,7 @@ type ReactorEngine struct {
 	quit            chan bool
 	shutdownChannel chan bool
 	running         bool
-	drained         bool
+	drained         chan bool
 }
 
 func New() *ReactorEngine {
@@ -77,6 +77,7 @@ func New() *ReactorEngine {
 		eventHandlers:   make(map[string]*EventHandler),
 		eventChannel:    make(chan Event),
 		quit:            make(chan bool, 1),
+		drained:         make(chan bool, 1),
 		shutdownChannel: make(chan bool, 1),
 	}
 }
@@ -94,8 +95,9 @@ func (reactor *ReactorEngine) Start() {
 				case event := <-reactor.eventChannel:
 					// needs to be called syncronously to keep order of events
 					reactor.dispatch(event)
+				case reactor.drained <- true:
 				default:
-					reactor.drained = true
+					reactor.drained <- true // blocking till message is coming in
 				}
 			}
 			reactor.lock.Lock()
@@ -113,14 +115,16 @@ func (reactor *ReactorEngine) Stop() {
 	reactor.lock.RLock()
 	if reactor.running {
 		reactor.quit <- true
+		select {
+		case <-reactor.drained:
+		}
 	}
 	reactor.lock.RUnlock()
 	<-reactor.shutdownChannel
 }
 
 func (reactor *ReactorEngine) Flush() {
-	for !reactor.drained {
-	}
+	<-reactor.drained
 }
 
 // Subscribe a channel to the specified event
@@ -136,7 +140,7 @@ func (reactor *ReactorEngine) Subscribe(event string, eventChannel chan Event) {
 	}
 	// Add the events channel to reactor event handler
 	eventHandler.Add(eventChannel)
-	logger.Debugln("added new subscription to %s", event)
+	logger.Debugf("added new subscription to %s", event)
 }
 
 func (reactor *ReactorEngine) Unsubscribe(event string, eventChannel chan Event) {
@@ -149,7 +153,7 @@ func (reactor *ReactorEngine) Unsubscribe(event string, eventChannel chan Event)
 		if len == 0 {
 			reactor.eventHandlers[event] = nil
 		}
-		logger.Debugln("removed subscription to %s", event)
+		logger.Debugf("removed subscription to %s", event)
 	}
 }
 
@@ -158,8 +162,10 @@ func (reactor *ReactorEngine) Post(event string, resource interface{}) {
 	defer reactor.lock.Unlock()
 
 	if reactor.running {
-		reactor.drained = false
 		reactor.eventChannel <- Event{Resource: resource, Name: event}
+		select {
+		case <-reactor.drained:
+		}
 	}
 }