Tidy up a bit

federationsender/queue/destinationqueue.go

@@ -33,7 +33,7 @@ const (
 	// How many times should we tolerate consecutive failures before we
 	// just blacklist the host altogether? Bear in mind that the backoff
 	// is exponential, so the max time here to attempt is 2**failures.
-	FailuresUntilBlacklist = 16
+	FailuresUntilBlacklist = 16 // 16 equates to roughly 18 hours.
 )
 
 // destinationQueue is a queue of events for a single destination.
@@ -41,13 +41,13 @@ const (
 // ensures that only one request is in flight to a given destination
 // at a time.
 type destinationQueue struct {
-	rsProducer         *producers.RoomserverProducer        //
-	client             *gomatrixserverlib.FederationClient  //
-	origin             gomatrixserverlib.ServerName         //
-	destination        gomatrixserverlib.ServerName         //
-	running            atomic.Bool                          // is the queue worke running?
+	rsProducer         *producers.RoomserverProducer        // roomserver producer
+	client             *gomatrixserverlib.FederationClient  // federation client
+	origin             gomatrixserverlib.ServerName         // origin of requests
+	destination        gomatrixserverlib.ServerName         // destination of requests
+	running            atomic.Bool                          // is the queue worker running?
 	blacklisted        atomic.Bool                          // is the remote side dead?
-	backoffUntil       atomic.Value                         // time.Time
+	backoffUntil       atomic.Value                         // time.Time to wait until before sending requests
 	idleCounter        atomic.Uint32                        // how many ticks have we done nothing?
 	failCounter        atomic.Uint32                        // how many times have we failed?
 	sentCounter        atomic.Uint32                        // how many times have we succeeded?
@@ -124,11 +124,9 @@ func (oq *destinationQueue) sendEvent(ev *gomatrixserverlib.HeaderedEvent) {
 		// If the destination is blacklisted then drop the event.
 		return
 	}
-	fmt.Println("Queuing event", ev.EventID())
 	oq.runningMutex.Lock()
 	oq.pendingPDUs = append(oq.pendingPDUs, ev)
 	oq.runningMutex.Unlock()
-	fmt.Println("Queued event", ev.EventID())
 	oq.wake()
 }
 
@@ -206,8 +204,16 @@ func (oq *destinationQueue) backgroundSend() {
 			// the pending events and EDUs.
 			if transaction {
 				oq.runningMutex.Lock()
-				oq.pendingPDUs = oq.pendingPDUs[len(pendingPDUs):]
-				oq.pendingEDUs = oq.pendingEDUs[len(pendingEDUs):]
+				// Reallocate so that the underlying arrays can be GC'd, as
+				// opposed to growing forever.
+				oq.pendingPDUs = append(
+					[]*gomatrixserverlib.HeaderedEvent{},
+					oq.pendingPDUs[len(pendingPDUs):]...,
+				)
+				oq.pendingEDUs = append(
+					[]*gomatrixserverlib.EDU{},
+					oq.pendingEDUs[len(pendingEDUs):]...,
+				)
 				oq.runningMutex.Unlock()
 			}
 		}
@@ -226,7 +232,12 @@ func (oq *destinationQueue) backgroundSend() {
 			// the pending invites.
 			if invites {
 				oq.runningMutex.Lock()
-				oq.pendingInvites = oq.pendingInvites[len(pendingInvites):]
+				// Reallocate so that the underlying array can be GC'd, as
+				// opposed to growing forever.
+				oq.pendingInvites = append(
+					[]*gomatrixserverlib.InviteV2Request{},
+					oq.pendingInvites[len(pendingInvites):]...,
+				)
 				oq.runningMutex.Unlock()
 			}
 		}