1 files changed, 22 insertions, 35 deletions

diff --git a/syncapi/streams/stream_pdu.go b/syncapi/streams/stream_pdu.go
index 2818aad8..fa4c722c 100644
--- a/syncapi/streams/stream_pdu.go
+++ b/syncapi/streams/stream_pdu.go
@@ -209,11 +209,27 @@ func (p *PDUStreamProvider) IncrementalSync(
 
 	newPos = from
 	for _, delta := range stateDeltas {
+		newRange := r
+		// If this room was joined in this sync, try to fetch
+		// as much timeline events as allowed by the filter.
+		if delta.NewlyJoined {
+			// Reverse the range, so we get the most recent first.
+			// This will be limited by the eventFilter.
+			newRange = types.Range{
+				From:      r.To,
+				To:        0,
+				Backwards: true,
+			}
+		}
 		var pos types.StreamPosition
-		if pos, err = p.addRoomDeltaToResponse(ctx, req.Device, r, delta, &eventFilter, &stateFilter, req.Response); err != nil {
+		if pos, err = p.addRoomDeltaToResponse(ctx, req.Device, newRange, delta, &eventFilter, &stateFilter, req.Response); err != nil {
 			req.Log.WithError(err).Error("d.addRoomDeltaToResponse failed")
 			return to
 		}
+		// Reset the position, as it is only for the special case of newly joined rooms
+		if delta.NewlyJoined {
+			pos = newRange.From
+		}
 		switch {
 		case r.Backwards && pos < newPos:
 			fallthrough
@@ -222,37 +238,6 @@ func (p *PDUStreamProvider) IncrementalSync(
 		}
 	}
 
-	// If we joined a new room in this sync, make sure we add enough information about it.
-	// This does an "initial sync" for the newly joined rooms
-	newlyJoinedRooms := joinedRooms(req.Response, req.Device.UserID)
-	if len(newlyJoinedRooms) > 0 {
-		// remove already added rooms, as we're doing an "initial sync"
-		for _, x := range newlyJoinedRooms {
-			delete(req.Response.Rooms.Join, x)
-		}
-		r = types.Range{
-			From:      to,
-			To:        0,
-			Backwards: true,
-		}
-		// We only care about the newly joined rooms, so update the stateFilter to reflect that
-		stateFilter.Rooms = &newlyJoinedRooms
-		if stateDeltas, _, err = p.DB.GetStateDeltas(ctx, req.Device, r, req.Device.UserID, &stateFilter); err != nil {
-			req.Log.WithError(err).Error("p.DB.GetStateDeltas failed")
-			return newPos
-		}
-		for _, delta := range stateDeltas {
-			// Ignore deltas for rooms we didn't newly join
-			if _, ok := req.Response.Rooms.Join[delta.RoomID]; ok {
-				continue
-			}
-			if _, err = p.addRoomDeltaToResponse(ctx, req.Device, r, delta, &eventFilter, &stateFilter, req.Response); err != nil {
-				req.Log.WithError(err).Error("d.addRoomDeltaToResponse failed")
-				return newPos
-			}
-		}
-	}
-
 	return newPos
 }
 
@@ -340,12 +325,12 @@ func (p *PDUStreamProvider) addRoomDeltaToResponse(
 		logrus.WithError(err).Error("unable to apply history visibility filter")
 	}
 
-	if len(events) > 0 {
-		updateLatestPosition(events[len(events)-1].EventID())
-	}
 	if len(delta.StateEvents) > 0 {
 		updateLatestPosition(delta.StateEvents[len(delta.StateEvents)-1].EventID())
 	}
+	if len(events) > 0 {
+		updateLatestPosition(events[len(events)-1].EventID())
+	}
 
 	switch delta.Membership {
 	case gomatrixserverlib.Join:
@@ -418,6 +403,8 @@ func applyHistoryVisibilityFilter(
 	logrus.WithFields(logrus.Fields{
 		"duration": time.Since(startTime),
 		"room_id":  roomID,
+		"before":   len(recentEvents),
+		"after":    len(events),
 	}).Debug("applied history visibility (sync)")
 	return events, nil
 }