Review comments

sync3/handler/txn_id_waiter.go

@@ -60,7 +60,6 @@ func (t *TxnIDWaiter) Ingest(up caches.Update) {
 	// TODO: bound the queue size?
 	t.queues[ed.RoomID] = append(queue, eventUpdate)
 
-	// TODO: if t gets gced, will this function still run? If so, will things explode?
 	time.AfterFunc(t.maxDelay, func() { t.PublishUpToNID(ed.RoomID, ed.NID) })
 }
 

v3.go

@@ -39,6 +39,7 @@ type Opts struct {
 	TestingSynchronousPubsub bool
 	// MaxTransactionIDDelay is the longest amount of time that we will wait for
 	// confirmation of an event's transaction_id before sending it to its sender.
+	// Set to 0 to disable this delay mechanism entirely.
 	MaxTransactionIDDelay time.Duration
 
 	DBMaxConns        int