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

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"`

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