Use buffered channel (0xPolygon#1361)

blockchain/subscription.go

@@ -42,19 +42,7 @@ type subscription struct {
 
 // GetEventCh creates a new event channel, and returns it
 func (s *subscription) GetEventCh() chan *Event {
-	eventCh := make(chan *Event)
-
-	go func() {
-		for {
-			evnt := s.GetEvent()
-			if evnt == nil {
-				return
-			}
-			eventCh <- evnt
-		}
-	}()
-
-	return eventCh
+	return s.updateCh
 }
 
 // GetEvent returns the event from the subscription (BLOCKING)
@@ -161,11 +149,7 @@ func (e *eventStream) newUpdateCh() chan *Event {
 	e.Lock()
 	defer e.Unlock()
 
-	ch := make(chan *Event, 1)
-
-	if e.updateCh == nil {
-		e.updateCh = make([]chan *Event, 0)
-	}
+	ch := make(chan *Event, 5)
 
 	e.updateCh = append(e.updateCh, ch)
 
@@ -179,9 +163,6 @@ func (e *eventStream) push(event *Event) {
 
 	// Notify the listeners
 	for _, update := range e.updateCh {
-		select {
-		case update <- event:
-		default:
-		}
+		update <- event
 	}
 }

blockchain/subscription_test.go

@@ -51,3 +51,61 @@ func TestSubscription(t *testing.T) {
 
 	assert.Equal(t, event.NewChain[0].Number, caughtEventNum)
 }
+
+func TestSubscription_BufferedChannel_MultipleSubscriptions(t *testing.T) {
+	t.Parallel()
+
+	var (
+		e                  = &eventStream{}
+		wg                 sync.WaitGroup
+		numOfEvents        = 100000
+		numOfSubscriptions = 10
+	)
+
+	subscriptions := make([]*subscription, numOfSubscriptions)
+	wg.Add(numOfSubscriptions)
+
+	worker := func(id int, sub *subscription) {
+		updateCh := sub.GetEventCh()
+		caughtEvents := 0
+
+		defer wg.Done()
+
+		for {
+			select {
+			case <-updateCh:
+				caughtEvents++
+				if caughtEvents == numOfEvents {
+					return
+				}
+			case <-time.After(10 * time.Second):
+				t.Errorf("subscription %d did not caught all events", id)
+			}
+		}
+	}
+
+	for i := 0; i < numOfSubscriptions; i++ {
+		sub := e.subscribe()
+		subscriptions[i] = sub
+
+		go worker(i, sub)
+	}
+
+	// Send the events to the channels
+	for i := 0; i < numOfEvents; i++ {
+		e.push(&Event{
+			NewChain: []*types.Header{
+				{
+					Number: uint64(i),
+				},
+			},
+		})
+	}
+
+	// Wait for the events to be processed
+	wg.Wait()
+
+	for _, s := range subscriptions {
+		s.Close()
+	}
+}