Modernize invertergui: MQTT write support, HA integration, UI updates

vendor/github.com/eclipse/paho.mqtt.golang/router.go

@@ -136,60 +136,41 @@ func (r *router) setDefaultHandler(handler MessageHandler) {
 // associated callback (or the defaultHandler, if one exists and no other route matched). If
 // anything is sent down the stop channel the function will end.
 func (r *router) matchAndDispatch(messages <-chan *packets.PublishPacket, order bool, client *client) <-chan *PacketAndToken {
-	var wg sync.WaitGroup
-	ackOutChan := make(chan *PacketAndToken) // Channel returned to caller; closed when messages channel closed
-	var ackInChan chan *PacketAndToken       // ACKs generated by ackFunc get put onto this channel
+	ackChan := make(chan *PacketAndToken) // Channel returned to caller; closed when goroutine terminates
 
-	stopAckCopy := make(chan struct{})    // Closure requests stop of go routine copying ackInChan to ackOutChan
-	ackCopyStopped := make(chan struct{}) // Closure indicates that it is safe to close ackOutChan
-	goRoutinesDone := make(chan struct{}) // closed on wg.Done()
-	if order {
-		ackInChan = ackOutChan // When order = true no go routines are used so safe to use one channel and close when done
-	} else {
-		// When order = false ACK messages are sent in go routines so ackInChan cannot be closed until all goroutines done
-		ackInChan = make(chan *PacketAndToken)
-		go func() { // go routine to copy from ackInChan to ackOutChan until stopped
-			for {
-				select {
-				case a := <-ackInChan:
-					ackOutChan <- a
-				case <-stopAckCopy:
-					close(ackCopyStopped) // Signal main go routine that it is safe to close ackOutChan
-					for {
-						select {
-						case <-ackInChan: // drain ackInChan to ensure all goRoutines can complete cleanly (ACK dropped)
-							DEBUG.Println(ROU, "matchAndDispatch received acknowledgment after processing stopped (ACK dropped).")
-						case <-goRoutinesDone:
-							close(ackInChan) // Nothing further should be sent (a panic is probably better than silent failure)
-							DEBUG.Println(ROU, "matchAndDispatch order=false copy goroutine exiting.")
-							return
-						}
-					}
-				}
-			}
-		}()
+	// In some cases message acknowledgments may come through after shutdown (connection is down etc). Where this is the
+	// case we need to accept any such requests and then ignore them. Note that this is not a perfect solution, if we
+	// have reconnected, and the session is still live, then the Ack really should be sent (see Issus #726)
+	var ackMutex sync.RWMutex
+	sendAckChan := ackChan // This will be set to nil before ackChan is closed
+	sendAck := func(ack *PacketAndToken) {
+		ackMutex.RLock()
+		defer ackMutex.RUnlock()
+		if sendAckChan != nil {
+			sendAckChan <- ack
+		} else {
+			DEBUG.Println(ROU, "matchAndDispatch received acknowledgment after processing stopped (ACK dropped).")
+		}
 	}
 
 	go func() { // Main go routine handling inbound messages
+		var handlers []MessageHandler
 		for message := range messages {
 			// DEBUG.Println(ROU, "matchAndDispatch received message")
 			sent := false
 			r.RLock()
-			m := messageFromPublish(message, ackFunc(ackInChan, client.persist, message))
-			var handlers []MessageHandler
+			m := messageFromPublish(message, ackFunc(sendAck, client.persist, message))
 			for e := r.routes.Front(); e != nil; e = e.Next() {
 				if e.Value.(*route).match(message.TopicName) {
 					if order {
 						handlers = append(handlers, e.Value.(*route).callback)
 					} else {
 						hd := e.Value.(*route).callback
-						wg.Add(1)
 						go func() {
 							hd(client, m)
 							if !client.options.AutoAckDisabled {
 								m.Ack()
 							}
-							wg.Done()
 						}()
 					}
 					sent = true
@@ -200,13 +181,11 @@ func (r *router) matchAndDispatch(messages <-chan *packets.PublishPacket, order
 					if order {
 						handlers = append(handlers, r.defaultHandler)
 					} else {
-						wg.Add(1)
 						go func() {
 							r.defaultHandler(client, m)
 							if !client.options.AutoAckDisabled {
 								m.Ack()
 							}
-							wg.Done()
 						}()
 					}
 				} else {
@@ -214,26 +193,22 @@ func (r *router) matchAndDispatch(messages <-chan *packets.PublishPacket, order
 				}
 			}
 			r.RUnlock()
-			for _, handler := range handlers {
-				handler(client, m)
-				if !client.options.AutoAckDisabled {
-					m.Ack()
+			if order {
+				for _, handler := range handlers {
+					handler(client, m)
+					if !client.options.AutoAckDisabled {
+						m.Ack()
+					}
 				}
+				handlers = handlers[:0]
 			}
 			// DEBUG.Println(ROU, "matchAndDispatch handled message")
 		}
-		if order {
-			close(ackOutChan)
-		} else { // Ensure that nothing further will be written to ackOutChan before closing it
-			close(stopAckCopy)
-			<-ackCopyStopped
-			close(ackOutChan)
-			go func() {
-				wg.Wait() // Note: If this remains running then the user has handlers that are not returning
-				close(goRoutinesDone)
-			}()
-		}
+		ackMutex.Lock()
+		sendAckChan = nil
+		ackMutex.Unlock()
+		close(ackChan) // as sendAckChan is now nil nothing further will be sent on this
 		DEBUG.Println(ROU, "matchAndDispatch exiting")
 	}()
-	return ackOutChan
+	return ackChan
 }