Minor perf/debugging improvements (#1121)

* Minor perf/debugging improvements

- publicroomsapi: Don't call QueryEventsByID with no event IDs
- appservice: Consume only if there are 1 or more ASes
- roomserver: don't keep a copy of the request "for debugging" - we trace now

* fedsender: return early if we have no destinations

* Unbreak tests

6 files changed, 19 insertions, 27 deletions

diff --git a/appservice/appservice.go b/appservice/appservice.go
index 0fbe3f20..bd261ff9 100644
--- a/appservice/appservice.go
+++ b/appservice/appservice.go
@@ -86,12 +86,16 @@ func NewInternalAPI(
 		Cfg: base.Cfg,
 	}
 
-	consumer := consumers.NewOutputRoomEventConsumer(
-		base.Cfg, base.KafkaConsumer, accountsDB, appserviceDB,
-		rsAPI, workerStates,
-	)
-	if err := consumer.Start(); err != nil {
-		logrus.WithError(err).Panicf("failed to start appservice roomserver consumer")
+	// Only consume if we actually have ASes to track, else we'll just chew cycles needlessly.
+	// We can't add ASes at runtime so this is safe to do.
+	if len(workerStates) > 0 {
+		consumer := consumers.NewOutputRoomEventConsumer(
+			base.Cfg, base.KafkaConsumer, accountsDB, appserviceDB,
+			rsAPI, workerStates,
+		)
+		if err := consumer.Start(); err != nil {
+			logrus.WithError(err).Panicf("failed to start appservice roomserver consumer")
+		}
 	}
 
 	// Create application service transaction workers
diff --git a/federationapi/routing/send_test.go b/federationapi/routing/send_test.go
index adae7c22..3123b55c 100644
--- a/federationapi/routing/send_test.go
+++ b/federationapi/routing/send_test.go
@@ -128,7 +128,6 @@ func (t *testRoomserverAPI) QueryLatestEventsAndState(
 	response *api.QueryLatestEventsAndStateResponse,
 ) error {
 	r := t.queryLatestEventsAndState(request)
-	response.QueryLatestEventsAndStateRequest = *request
 	response.RoomExists = r.RoomExists
 	response.RoomVersion = testRoomVersion
 	response.LatestEvents = r.LatestEvents
@@ -144,7 +143,6 @@ func (t *testRoomserverAPI) QueryStateAfterEvents(
 	response *api.QueryStateAfterEventsResponse,
 ) error {
 	response.RoomVersion = testRoomVersion
-	response.QueryStateAfterEventsRequest = *request
 	res := t.queryStateAfterEvents(request)
 	response.PrevEventsExist = res.PrevEventsExist
 	response.RoomExists = res.RoomExists
@@ -612,7 +610,6 @@ func TestTransactionFetchMissingStateByStateIDs(t *testing.T) {
 					}
 				}
 			}
-			res.QueryEventsByIDRequest = *req
 			return res
 		},
 	}
diff --git a/federationsender/queue/queue.go b/federationsender/queue/queue.go
index 5b8fc3c5..24034355 100644
--- a/federationsender/queue/queue.go
+++ b/federationsender/queue/queue.go
@@ -107,6 +107,9 @@ func (oqs *OutgoingQueues) SendEvent(
 
 	// Remove our own server from the list of destinations.
 	destinations = filterAndDedupeDests(oqs.origin, destinations)
+	if len(destinations) == 0 {
+		return nil
+	}
 
 	log.WithFields(log.Fields{
 		"destinations": destinations, "event": ev.EventID(),
diff --git a/publicroomsapi/consumers/roomserver.go b/publicroomsapi/consumers/roomserver.go
index ba187cb1..b9686d56 100644
--- a/publicroomsapi/consumers/roomserver.go
+++ b/publicroomsapi/consumers/roomserver.go
@@ -78,18 +78,19 @@ func (s *OutputRoomEventConsumer) onMessage(msg *sarama.ConsumerMessage) error {
 		return nil
 	}
 
-	remQueryReq := api.QueryEventsByIDRequest{EventIDs: output.NewRoomEvent.RemovesStateEventIDs}
 	var remQueryRes api.QueryEventsByIDResponse
-	if err := s.rsAPI.QueryEventsByID(context.TODO(), &remQueryReq, &remQueryRes); err != nil {
-		log.Warn(err)
-		return err
+	if len(output.NewRoomEvent.RemovesStateEventIDs) > 0 {
+		remQueryReq := api.QueryEventsByIDRequest{EventIDs: output.NewRoomEvent.RemovesStateEventIDs}
+		if err := s.rsAPI.QueryEventsByID(context.TODO(), &remQueryReq, &remQueryRes); err != nil {
+			log.Warn(err)
+			return err
+		}
 	}
 
 	var addQueryEvents, remQueryEvents []gomatrixserverlib.Event
 	for _, headeredEvent := range output.NewRoomEvent.AddsState() {
 		addQueryEvents = append(addQueryEvents, headeredEvent.Event)
 	}
-	addQueryEvents = append(addQueryEvents, output.NewRoomEvent.Event.Unwrap())
 	for _, headeredEvent := range remQueryRes.Events {
 		remQueryEvents = append(remQueryEvents, headeredEvent.Event)
 	}
diff --git a/roomserver/api/query.go b/roomserver/api/query.go
index b1525342..6586b1af 100644
--- a/roomserver/api/query.go
+++ b/roomserver/api/query.go
@@ -33,8 +33,6 @@ type QueryLatestEventsAndStateRequest struct {
 // This is used when sending events to set the prev_events, auth_events and depth.
 // It is also used to tell whether the event is allowed by the event auth rules.
 type QueryLatestEventsAndStateResponse struct {
-	// Copy of the request for debugging.
-	QueryLatestEventsAndStateRequest
 	// Does the room exist?
 	// If the room doesn't exist this will be false and LatestEvents will be empty.
 	RoomExists bool `json:"room_exists"`
@@ -66,8 +64,6 @@ type QueryStateAfterEventsRequest struct {
 
 // QueryStateAfterEventsResponse is a response to QueryStateAfterEvents
 type QueryStateAfterEventsResponse struct {
-	// Copy of the request for debugging.
-	QueryStateAfterEventsRequest
 	// Does the room exist on this roomserver?
 	// If the room doesn't exist this will be false and StateEvents will be empty.
 	RoomExists bool `json:"room_exists"`
@@ -89,8 +85,6 @@ type QueryEventsByIDRequest struct {
 
 // QueryEventsByIDResponse is a response to QueryEventsByID
 type QueryEventsByIDResponse struct {
-	// Copy of the request for debugging.
-	QueryEventsByIDRequest
 	// A list of events with the requested IDs.
 	// If the roomserver does not have a copy of a requested event
 	// then it will omit that event from the list.
@@ -187,8 +181,6 @@ type QueryStateAndAuthChainRequest struct {
 
 // QueryStateAndAuthChainResponse is a response to QueryStateAndAuthChain
 type QueryStateAndAuthChainResponse struct {
-	// Copy of the request for debugging.
-	QueryStateAndAuthChainRequest
 	// Does the room exist on this roomserver?
 	// If the room doesn't exist this will be false and StateEvents will be empty.
 	RoomExists bool `json:"room_exists"`
diff --git a/roomserver/internal/query.go b/roomserver/internal/query.go
index 375ddc23..4fc8e4c2 100644
--- a/roomserver/internal/query.go
+++ b/roomserver/internal/query.go
@@ -45,7 +45,6 @@ func (r *RoomserverInternalAPI) QueryLatestEventsAndState(
 
 	roomState := state.NewStateResolution(r.DB)
 
-	response.QueryLatestEventsAndStateRequest = *request
 	roomNID, err := r.DB.RoomNIDExcludingStubs(ctx, request.RoomID)
 	if err != nil {
 		return err
@@ -105,7 +104,6 @@ func (r *RoomserverInternalAPI) QueryStateAfterEvents(
 
 	roomState := state.NewStateResolution(r.DB)
 
-	response.QueryStateAfterEventsRequest = *request
 	roomNID, err := r.DB.RoomNIDExcludingStubs(ctx, request.RoomID)
 	if err != nil {
 		return err
@@ -153,8 +151,6 @@ func (r *RoomserverInternalAPI) QueryEventsByID(
 	request *api.QueryEventsByIDRequest,
 	response *api.QueryEventsByIDResponse,
 ) error {
-	response.QueryEventsByIDRequest = *request
-
 	eventNIDMap, err := r.DB.EventNIDs(ctx, request.EventIDs)
 	if err != nil {
 		return err
@@ -734,7 +730,6 @@ func (r *RoomserverInternalAPI) QueryStateAndAuthChain(
 	request *api.QueryStateAndAuthChainRequest,
 	response *api.QueryStateAndAuthChainResponse,
 ) error {
-	response.QueryStateAndAuthChainRequest = *request
 	roomNID, err := r.DB.RoomNIDExcludingStubs(ctx, request.RoomID)
 	if err != nil {
 		return err