Limit recent events when going backwards
If we're going backwards, we were selecting potentially thousands of
events, which in turn were fed to history visibility checks, resulting
in bad sync performance.
MODIFY
syncapi/streams/stream_pdu.go
syncapi/streams/stream_pdu.go
@@ -216,6 +216,9 @@ func (p *PDUStreamProvider) IncrementalSync(
return newPos
}
+// Limit the recent events to X when going backwards
+const recentEventBackwardsLimit = 100
+
// nolint:gocyclo
func (p *PDUStreamProvider) addRoomDeltaToResponse(
ctx context.Context,
@@ -229,9 +232,15 @@ func (p *PDUStreamProvider) addRoomDeltaToResponse(
) (types.StreamPosition, error) {
originalLimit := eventFilter.Limit
- if r.Backwards {
- eventFilter.Limit = int(r.From - r.To)
+ // If we're going backwards, grep at least X events, this is mostly to satisfy Sytest
+ if r.Backwards && originalLimit < recentEventBackwardsLimit {
+ eventFilter.Limit = recentEventBackwardsLimit // TODO: Figure out a better way
+ diff := r.From - r.To
+ if diff > 0 && diff < recentEventBackwardsLimit {
+ eventFilter.Limit = int(diff)
+ }
}
+
recentStreamEvents, limited, err := snapshot.RecentEvents(
ctx, delta.RoomID, r,
eventFilter, true, true,

Limit recent events when going backwards (#2840)

If we're going backwards, we were selecting potentially thousands of
events, which in turn were fed to history visibility checks, resulting
in bad sync performance.