Un-yuck the server side of the presenter API

main.go

@@ -98,14 +98,7 @@ type room struct {
 	roomId     string
 	timerStart time.Time
 	clientById map[string]*client
-	present    map[*presentState]bool
-}
-
-type presentState struct {
-	responseWriter http.ResponseWriter
-	flusher        http.Flusher
-	room           *room
-	controlChan    chan *controlEvent
+	present    map[chan *controlEvent]bool
 }
 
 var key []byte
@@ -363,8 +356,14 @@ func create(w http.ResponseWriter, r *http.Request) {
 }
 
 func present(w http.ResponseWriter, r *http.Request) {
-	ps := newPresentState(w, r)
-	if ps == nil {
+	flusher, ok := w.(http.Flusher)
+	if !ok {
+		http.Error(w, "streaming unsupported", http.StatusBadRequest)
+		return
+	}
+
+	room, controlChan := registerPresent(w, r)
+	if controlChan == nil {
 		return
 	}
 
@@ -374,18 +373,16 @@ func present(w http.ResponseWriter, r *http.Request) {
 	for {
 		select {
 		case <-closeChan:
-			ps.close()
-			return
+			mu.Lock()
+			delete(room.present, controlChan)
+			close(controlChan)
+			mu.Unlock()
 
 		case <-ticker.C:
-			mu.Lock()
-			ps.sendHeartbeat()
-			mu.Unlock()
+			writePresentHeartbeat(w, flusher)
 
-		case ctrl := <-ps.controlChan:
-			mu.Lock()
-			ps.sendEvent(ctrl)
-			mu.Unlock()
+		case ctrl := <-controlChan:
+			writePresentEvent(ctrl, w, flusher)
 		}
 	}
 }
@@ -450,12 +447,11 @@ func watch(w http.ResponseWriter, r *http.Request) {
 	for {
 		select {
 		case <-closeChan:
-			close(eventChan)
-
 			mu.Lock()
 			if client.eventChan == eventChan {
 				client.eventChan = nil
 			}
+			close(eventChan)
 			mu.Unlock()
 
 		case <-ticker.C:
@@ -509,7 +505,7 @@ func newRoom(roomId string) *room {
 		roomId:     roomId,
 		timerStart: time.Now(),
 		clientById: map[string]*client{},
-		present:    map[*presentState]bool{},
+		present:    map[chan *controlEvent]bool{},
 	}
 }
 
@@ -559,7 +555,7 @@ func (rm *room) sendAdminEvent(ae *adminEvent) {
 
 func (rm *room) sendControlEvent(ce *controlEvent) {
 	for present, _ := range rm.present {
-		present.sendEvent(ce)
+		present <- ce
 	}
 }
 
@@ -635,52 +631,33 @@ func writeEvent(e *event, w http.ResponseWriter, flusher http.Flusher) {
 	flusher.Flush()
 }
 
-func newPresentState(w http.ResponseWriter, r *http.Request) *presentState {
+func registerPresent(w http.ResponseWriter, r *http.Request) (*room, chan *controlEvent) {
 	mu.Lock()
 	defer mu.Unlock()
 
-	ps := &presentState{
-		responseWriter: w,
-		controlChan:    make(chan *controlEvent, 100),
-	}
-
-	var ok bool
-	ps.flusher, ok = w.(http.Flusher)
-	if !ok {
-		http.Error(ps.responseWriter, "streaming unsupported", http.StatusBadRequest)
-		return nil
-	}
+	controlChan := make(chan *controlEvent, 100)
 
 	roomId := r.URL.Query().Get("room_id")
-	ps.room = getRoom(roomId)
+	room := getRoom(roomId)
 
-	ps.room.present[ps] = true
+	room.present[controlChan] = true
 
 	w.Header().Set("Content-Type", "text/event-stream")
 	w.Header().Set("Cache-Control", "no-cache")
 	w.Header().Set("Connection", "keep-alive")
 
-	return ps
+	return room, controlChan
 }
 
-func (ps *presentState) sendHeartbeat() {
-	fmt.Fprintf(ps.responseWriter, ":\n\n")
-	ps.flusher.Flush()
+func writePresentHeartbeat(w http.ResponseWriter, flusher http.Flusher) {
+	writePresentEvent(&controlEvent{}, w, flusher)
 }
 
-func (ps *presentState) sendEvent(e *controlEvent) {
+func writePresentEvent(e *controlEvent, w http.ResponseWriter, flusher http.Flusher) {
 	j, err := json.Marshal(e)
 	if err != nil {
 		log.Fatal(err)
 	}
-	fmt.Fprintf(ps.responseWriter, "data: %s\n\n", j)
-	ps.flusher.Flush()
-}
-
-func (ps *presentState) close() {
-	mu.Lock()
-	defer mu.Unlock()
-
-	delete(ps.room.present, ps)
-	close(ps.controlChan)
+	fmt.Fprintf(w, "data: %s\n\n", j)
+	flusher.Flush()
 }