Tweaks

syncapi/routing/messages.go

@@ -336,7 +336,15 @@ func (r *messagesReq) retrieveEvents(ctx context.Context, rsAPI api.SyncRoomserv
 		// removed all of them. This means there are no events for this user
 		// anymore. Let them know.
 		if errors.Is(err, shared.ErrNoEventsForFilter) {
-			return []synctypes.ClientEvent{}, *r.from, emptyToken, nil
+			if len(streamEvents) == 0 {
+				return []synctypes.ClientEvent{}, *r.from, emptyToken, nil
+			}
+			// We possibly received events, try to get start/end from them
+			start, end, err = r.getStartEnd(r.snapshot.StreamEventsToEvents(ctx, r.device, streamEvents, rsAPI))
+			if err != nil {
+				return []synctypes.ClientEvent{}, *r.from, *r.to, err
+			}
+			return []synctypes.ClientEvent{}, start, end, nil
 		}
 		err = fmt.Errorf("GetEventsInRange: %w", err)
 		return []synctypes.ClientEvent{}, *r.from, emptyToken, err

syncapi/storage/interface.go

@@ -81,7 +81,10 @@ type DatabaseTransaction interface {
 	// If no data is retrieved, returns an empty map
 	// If there was an issue with the retrieval, returns an error
 	GetAccountDataInRange(ctx context.Context, userID string, r types.Range, accountDataFilterPart *synctypes.EventFilter) (map[string][]string, types.StreamPosition, error)
-	// GetEventsInTopologicalRange retrieves all of the events on a given ordering using the given extremities and limit. If backwardsOrdering is true, the most recent event must be first, else last.
+	// GetEventsInTopologicalRange retrieves all of the events on a given ordering using the given extremities and limit.
+	// If backwardsOrdering is true, the most recent event must be first, else last.
+	// Returns the filtered StreamEvents on success. Returns **unfiltered** StreamEvents and ErrNoEventsForFilter if
+	// the provided filter removed all events, this can be used to still calculate the start/end position. (e.g for `/messages`)
 	GetEventsInTopologicalRange(ctx context.Context, from, to *types.TopologyToken, roomID string, filter *synctypes.RoomEventFilter, backwardOrdering bool) (events []types.StreamEvent, err error)
 	// EventPositionInTopology returns the depth and stream position of the given event.
 	EventPositionInTopology(ctx context.Context, eventID string) (types.TopologyToken, error)

syncapi/storage/shared/storage_sync.go

@@ -273,7 +273,13 @@ func (d *DatabaseTransaction) GetEventsInTopologicalRange(
 	// Check if we should be able to return events.
 	// If we received 0 events, this most likely means that the provided filter removed them.
 	if len(eIDs) > 0 && len(events) == 0 {
-		return nil, ErrNoEventsForFilter
+		// We try to fetch the events without a filter, so we can tell the client if there
+		// are more events earlier than the requested and filtered.
+		events, err = d.OutputEvents.SelectEvents(ctx, d.txn, eIDs, nil, true)
+		if err != nil {
+			return
+		}
+		return events, ErrNoEventsForFilter
 	}
 
 	return

syncapi/storage/storage_test.go

@@ -250,7 +250,8 @@ func TestGetEventsInRangeWithTopologyTokenNoEventsForFilter(t *testing.T) {
 			filter := &synctypes.RoomEventFilter{Limit: 20, NotTypes: &notTypes, Senders: &senders}
 			paginatedEvents, err := snapshot.GetEventsInTopologicalRange(ctx, &from, &to, r.ID, filter, true)
 			assert.Equal(t, shared.ErrNoEventsForFilter, err)
-			assert.Nil(t, paginatedEvents)
+			gots := snapshot.StreamEventsToEvents(context.Background(), nil, paginatedEvents, nil)
+			test.AssertEventsEqual(t, gots, test.Reversed(events[len(events)-15:]))
 		})
 	})
 }