FIFO ordering of input events (#1386)

* Initial FIFOing of roomserver inputs

* Remove EventID response from api.InputRoomEventsResponse

* Don't send back event ID unnecessarily

* Fix ordering hopefully

* Reduce copies, use buffered task channel to reduce contention on other rooms

* Fix error handling

6 files changed, 11 insertions, 16 deletions

diff --git a/clientapi/routing/createroom.go b/clientapi/routing/createroom.go
index 57fc3f33..af43064f 100644
--- a/clientapi/routing/createroom.go
+++ b/clientapi/routing/createroom.go
@@ -342,8 +342,7 @@ func createRoom(
 	}
 
 	// send events to the room server
-	_, err = roomserverAPI.SendEvents(req.Context(), rsAPI, builtEvents, cfg.Matrix.ServerName, nil)
-	if err != nil {
+	if err = roomserverAPI.SendEvents(req.Context(), rsAPI, builtEvents, cfg.Matrix.ServerName, nil); err != nil {
 		util.GetLogger(req.Context()).WithError(err).Error("SendEvents failed")
 		return jsonerror.InternalServerError()
 	}
diff --git a/clientapi/routing/membership.go b/clientapi/routing/membership.go
index cba19a24..202662ab 100644
--- a/clientapi/routing/membership.go
+++ b/clientapi/routing/membership.go
@@ -75,13 +75,12 @@ func sendMembership(ctx context.Context, accountDB accounts.Database, device *us
 		return jsonerror.InternalServerError()
 	}
 
-	_, err = roomserverAPI.SendEvents(
+	if err = roomserverAPI.SendEvents(
 		ctx, rsAPI,
 		[]gomatrixserverlib.HeaderedEvent{event.Event.Headered(roomVer)},
 		cfg.Matrix.ServerName,
 		nil,
-	)
-	if err != nil {
+	); err != nil {
 		util.GetLogger(ctx).WithError(err).Error("SendEvents failed")
 		return jsonerror.InternalServerError()
 	}
diff --git a/clientapi/routing/profile.go b/clientapi/routing/profile.go
index 4c7895bd..bc51b0b5 100644
--- a/clientapi/routing/profile.go
+++ b/clientapi/routing/profile.go
@@ -171,7 +171,7 @@ func SetAvatarURL(
 		return jsonerror.InternalServerError()
 	}
 
-	if _, err := api.SendEvents(req.Context(), rsAPI, events, cfg.Matrix.ServerName, nil); err != nil {
+	if err := api.SendEvents(req.Context(), rsAPI, events, cfg.Matrix.ServerName, nil); err != nil {
 		util.GetLogger(req.Context()).WithError(err).Error("SendEvents failed")
 		return jsonerror.InternalServerError()
 	}
@@ -289,7 +289,7 @@ func SetDisplayName(
 		return jsonerror.InternalServerError()
 	}
 
-	if _, err := api.SendEvents(req.Context(), rsAPI, events, cfg.Matrix.ServerName, nil); err != nil {
+	if err := api.SendEvents(req.Context(), rsAPI, events, cfg.Matrix.ServerName, nil); err != nil {
 		util.GetLogger(req.Context()).WithError(err).Error("SendEvents failed")
 		return jsonerror.InternalServerError()
 	}
diff --git a/clientapi/routing/redaction.go b/clientapi/routing/redaction.go
index a825da64..178bfafc 100644
--- a/clientapi/routing/redaction.go
+++ b/clientapi/routing/redaction.go
@@ -122,8 +122,7 @@ func SendRedaction(
 			JSON: jsonerror.NotFound("Room does not exist"),
 		}
 	}
-	_, err = roomserverAPI.SendEvents(context.Background(), rsAPI, []gomatrixserverlib.HeaderedEvent{*e}, cfg.Matrix.ServerName, nil)
-	if err != nil {
+	if err = roomserverAPI.SendEvents(context.Background(), rsAPI, []gomatrixserverlib.HeaderedEvent{*e}, cfg.Matrix.ServerName, nil); err != nil {
 		util.GetLogger(req.Context()).WithError(err).Errorf("failed to SendEvents")
 		return jsonerror.InternalServerError()
 	}
diff --git a/clientapi/routing/sendevent.go b/clientapi/routing/sendevent.go
index a25979ea..9744a564 100644
--- a/clientapi/routing/sendevent.go
+++ b/clientapi/routing/sendevent.go
@@ -90,27 +90,26 @@ func SendEvent(
 
 	// pass the new event to the roomserver and receive the correct event ID
 	// event ID in case of duplicate transaction is discarded
-	eventID, err := api.SendEvents(
+	if err := api.SendEvents(
 		req.Context(), rsAPI,
 		[]gomatrixserverlib.HeaderedEvent{
 			e.Headered(verRes.RoomVersion),
 		},
 		cfg.Matrix.ServerName,
 		txnAndSessionID,
-	)
-	if err != nil {
+	); err != nil {
 		util.GetLogger(req.Context()).WithError(err).Error("SendEvents failed")
 		return jsonerror.InternalServerError()
 	}
 	util.GetLogger(req.Context()).WithFields(logrus.Fields{
-		"event_id":     eventID,
+		"event_id":     e.EventID(),
 		"room_id":      roomID,
 		"room_version": verRes.RoomVersion,
 	}).Info("Sent event to roomserver")
 
 	res := util.JSONResponse{
 		Code: http.StatusOK,
-		JSON: sendEventResponse{eventID},
+		JSON: sendEventResponse{e.EventID()},
 	}
 	// Add response to transactionsCache
 	if txnID != nil {
diff --git a/clientapi/threepid/invites.go b/clientapi/threepid/invites.go
index 2ffb6bb0..b9575a28 100644
--- a/clientapi/threepid/invites.go
+++ b/clientapi/threepid/invites.go
@@ -359,7 +359,7 @@ func emit3PIDInviteEvent(
 		return err
 	}
 
-	_, err = api.SendEvents(
+	return api.SendEvents(
 		ctx, rsAPI,
 		[]gomatrixserverlib.HeaderedEvent{
 			(*event).Headered(queryRes.RoomVersion),
@@ -367,5 +367,4 @@ func emit3PIDInviteEvent(
 		cfg.Matrix.ServerName,
 		nil,
 	)
-	return err
 }