From dc11b5c55e2888a7a3dac51fedc3864d112136ce Mon Sep 17 00:00:00 2001
From: zelig <viktor.tron@gmail.com>
Date: Mon, 14 Jul 2014 18:40:18 +0100
Subject: [PATCH] fix reactor channel blocking

---
 ethreact/reactor.go | 53 +++++++++++++++++++++++----------------------
 1 file changed, 27 insertions(+), 26 deletions(-)

diff --git a/ethreact/reactor.go b/ethreact/reactor.go
index 8e72ca903..a26f82a97 100644
--- a/ethreact/reactor.go
+++ b/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 {
@@ -63,22 +67,20 @@ type Event struct {
 // The reactor basic engine. Acts as bridge
 // between the events and the subscribers/posters
 type ReactorEngine struct {
-	lock            sync.RWMutex
-	eventChannel    chan Event
-	eventHandlers   map[string]*EventHandler
-	quit            chan bool
-	shutdownChannel chan bool
-	running         bool
-	drained         chan bool
+	lock          sync.RWMutex
+	eventChannel  chan Event
+	eventHandlers map[string]*EventHandler
+	quit          chan chan error
+	running       bool
+	drained       chan bool
 }
 
 func New() *ReactorEngine {
 	return &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),
+		eventHandlers: make(map[string]*EventHandler),
+		eventChannel:  make(chan Event, eventBufferSize),
+		quit:          make(chan chan error, 1),
+		drained:       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 status := <-reactor.quit:
+					reactor.lock.Lock()
+					defer reactor.lock.Unlock()
+					reactor.running = false
+					logger.Infoln("stopped")
+					status <- nil
+					return
 				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
 				}
 			}
-			reactor.lock.Lock()
-			defer reactor.lock.Unlock()
-			reactor.running = false
-			logger.Infoln("stopped")
-			close(reactor.shutdownChannel)
 		}()
 		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:
 		}
 	}
 }