Comments

src/github.com/matrix-org/dendrite/federationsender/queue/queue.go

@@ -65,6 +65,8 @@ func (oqs *OutgoingQueues) SendEvent(
 	return nil
 }
 
+// filterDestinations removes our own server from the list of destinations.
+// Otherwise we could end up trying to talk to ourselves.
 func filterDestinations(origin gomatrixserverlib.ServerName, destinations []gomatrixserverlib.ServerName) []gomatrixserverlib.ServerName {
 	var result []gomatrixserverlib.ServerName
 	for _, destination := range destinations {
@@ -76,6 +78,10 @@ func filterDestinations(origin gomatrixserverlib.ServerName, destinations []goma
 	return result
 }
 
+// outgoingQueue is a queue of events for a single destination.
+// It is responsible for sending the events to the destination and
+// ensures that only one request is in flight to a given destination
+// at a time.
 type outgoingQueue struct {
 	mutex              sync.Mutex
 	client             *gomatrixserverlib.FederationClient
@@ -87,6 +93,9 @@ type outgoingQueue struct {
 	pendingEvents      []*gomatrixserverlib.Event
 }
 
+// Send event adds the event to the pending queue for the destination.
+// If the queue is empty then it starts a background goroutine to
+// start sending events to that destination.
 func (oq *outgoingQueue) sendEvent(ev *gomatrixserverlib.Event) {
 	oq.mutex.Lock()
 	defer oq.mutex.Unlock()
@@ -118,6 +127,9 @@ func (oq *outgoingQueue) backgroundSend() {
 	}
 }
 
+// next creates a new transaction from the pending event queue
+// and flushes the queue.
+// Returns nil if the queue was empty.
 func (oq *outgoingQueue) next() *gomatrixserverlib.Transaction {
 	oq.mutex.Lock()
 	defer oq.mutex.Unlock()