fix reactor channel blocking

ethreact/reactor.go

@@ -7,6 +7,10 @@ import (
 
 var logger = ethlog.NewLogger("REACTOR")
 
+const (
+	eventBufferSize int = 10
+)
+
 type EventHandler struct {
 	lock  sync.RWMutex
 	name  string
@@ -21,7 +25,7 @@ func (e *EventHandler) Post(event Event) {
 
 	// if we want to preserve order pushing to subscibed channels
 	// dispatching should be syncrounous
-	// this means if subscribed event channel is blocked (closed or has fixed capacity)
+	// this means if subscribed event channel is blocked
 	// the reactor dispatch will be blocked, so we need to mitigate by skipping
 	// rogue blocking subscribers
 	for i, ch := range e.chans {
@@ -66,8 +70,7 @@ type ReactorEngine struct {
 	lock          sync.RWMutex
 	eventChannel  chan Event
 	eventHandlers map[string]*EventHandler
-	quit            chan bool
-	shutdownChannel chan bool
+	quit          chan chan error
 	running       bool
 	drained       chan bool
 }
@@ -75,10 +78,9 @@ type ReactorEngine struct {
 func New() *ReactorEngine {
 	return &ReactorEngine{
 		eventHandlers: make(map[string]*EventHandler),
-		eventChannel:    make(chan Event),
-		quit:            make(chan bool, 1),
+		eventChannel:  make(chan Event, eventBufferSize),
+		quit:          make(chan chan error, 1),
 		drained:       make(chan bool, 1),
-		shutdownChannel: make(chan bool, 1),
 	}
 }
 
@@ -87,24 +89,22 @@ func (reactor *ReactorEngine) Start() {
 	defer reactor.lock.Unlock()
 	if !reactor.running {
 		go func() {
-		out:
 			for {
 				select {
-				case <-reactor.quit:
-					break out
-				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 // blocking till message is coming in
-				}
-			}
+				case status := <-reactor.quit:
 					reactor.lock.Lock()
 					defer reactor.lock.Unlock()
 					reactor.running = false
 					logger.Infoln("stopped")
-			close(reactor.shutdownChannel)
+					status <- nil
+					return
+				case event := <-reactor.eventChannel:
+					// needs to be called syncronously to keep order of events
+					reactor.dispatch(event)
+				default:
+					reactor.drained <- true // blocking till message is coming in
+				}
+			}
 		}()
 		reactor.running = true
 		logger.Infoln("started")
@@ -112,15 +112,15 @@ func (reactor *ReactorEngine) Start() {
 }
 
 func (reactor *ReactorEngine) Stop() {
-	reactor.lock.RLock()
 	if reactor.running {
-		reactor.quit <- true
+		status := make(chan error)
+		reactor.quit <- status
 		select {
 		case <-reactor.drained:
+		default:
 		}
+		<-status
 	}
-	reactor.lock.RUnlock()
-	<-reactor.shutdownChannel
 }
 
 func (reactor *ReactorEngine) Flush() {
@@ -165,6 +165,7 @@ func (reactor *ReactorEngine) Post(event string, resource interface{}) {
 		reactor.eventChannel <- Event{Resource: resource, Name: event}
 		select {
 		case <-reactor.drained:
+		default:
 		}
 	}
 }