Support ListenBucketNotificationV2 streaming (#8622)

cmd/peer-rest-client.go

@@ -677,6 +677,60 @@ func (client *peerRESTClient) doTrace(traceCh chan interface{}, doneCh chan stru
 	}
 }
 
+func (client *peerRESTClient) doListen(listenCh chan interface{}, doneCh chan struct{}) {
+	// To cancel the REST request in case doneCh gets closed.
+	ctx, cancel := context.WithCancel(context.Background())
+
+	cancelCh := make(chan struct{})
+	defer close(cancelCh)
+	go func() {
+		select {
+		case <-doneCh:
+		case <-cancelCh:
+			// There was an error in the REST request.
+		}
+		cancel()
+	}()
+
+	respBody, err := client.callWithContext(ctx, peerRESTMethodListen, nil, nil, -1)
+	defer http.DrainBody(respBody)
+
+	if err != nil {
+		return
+	}
+
+	dec := gob.NewDecoder(respBody)
+	for {
+		var ev event.Event
+		if err = dec.Decode(&ev); err != nil {
+			return
+		}
+		if len(ev.EventVersion) > 0 {
+			select {
+			case listenCh <- ev:
+			default:
+				// Do not block on slow receivers.
+			}
+		}
+	}
+}
+
+// Listen - listen on peers.
+func (client *peerRESTClient) Listen(listenCh chan interface{}, doneCh chan struct{}) {
+	go func() {
+		for {
+			client.doListen(listenCh, doneCh)
+			select {
+			case <-doneCh:
+				return
+			default:
+				// There was error in the REST request, retry after sometime as probably the peer is down.
+				time.Sleep(5 * time.Second)
+			}
+		}
+	}()
+}
+
 // Trace - send http trace request to peer nodes
 func (client *peerRESTClient) Trace(traceCh chan interface{}, doneCh chan struct{}, trcAll, trcErr bool) {
 	go func() {