Prevent duplicate events from being sent...

* Strip event content if it doesn't contain anything

Signed-off-by: Andrew Morgan <andrewm@matrix.org>

src/github.com/matrix-org/dendrite/appservice/appservice.go

@@ -50,7 +50,7 @@ func SetupAppServiceAPIComponent(
 	// a sync.Cond object that can be used to notify workers when there are new
 	// events to be sent out.
 	workerStates := make([]types.ApplicationServiceWorkerState, len(base.Cfg.Derived.ApplicationServices))
-	for _, appservice := range base.Cfg.Derived.ApplicationServices {
+	for i, appservice := range base.Cfg.Derived.ApplicationServices {
 		eventCount := 0
 
 		m := sync.Mutex{}
@@ -59,7 +59,7 @@ func SetupAppServiceAPIComponent(
 			Cond:        sync.NewCond(&m),
 			EventsReady: &eventCount,
 		}
-		workerStates = append(workerStates, ws)
+		workerStates[i] = ws
 	}
 
 	consumer := consumers.NewOutputRoomEventConsumer(

src/github.com/matrix-org/dendrite/appservice/consumers/roomserver.go

@@ -116,6 +116,10 @@ func (s *OutputRoomEventConsumer) onMessage(msg *sarama.ConsumerMessage) error {
 	}
 
 	// Check if any events need to passed on to external application services
+	if len(events) > 0 {
+		// Check if this was a membership event
+		return s.filterRoomserverEvents(ctx, events)
+	}
 	return s.filterRoomserverEvents(ctx, append(events, ev))
 }
 

src/github.com/matrix-org/dendrite/appservice/storage/appservice_events_table.go

@@ -210,6 +210,12 @@ func (s *eventsStatements) insertEvent(
 	appServiceID string,
 	event *gomatrixserverlib.Event,
 ) (err error) {
+	// If event has no content, strip the json
+	content := event.Content()
+	if string(content) == "{\"disable\":true}" {
+		content = []byte("{}")
+	}
+
 	_, err = s.insertEventStmt.ExecContext(
 		ctx,
 		appServiceID,
@@ -218,7 +224,7 @@ func (s *eventsStatements) insertEvent(
 		event.RoomID(),
 		event.Type(),
 		event.Sender(),
-		event.Content(),
+		content,
 		-1, // No transaction ID yet
 	)
 	return