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.
This commit is contained in:
Till 2022-10-28 13:40:51 +02:00 committed by GitHub
parent 0782011f54
commit 69aff372f3
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@ -216,6 +216,9 @@ func (p *PDUStreamProvider) IncrementalSync(
return newPos return newPos
} }
// Limit the recent events to X when going backwards
const recentEventBackwardsLimit = 100
// nolint:gocyclo // nolint:gocyclo
func (p *PDUStreamProvider) addRoomDeltaToResponse( func (p *PDUStreamProvider) addRoomDeltaToResponse(
ctx context.Context, ctx context.Context,
@ -229,9 +232,15 @@ func (p *PDUStreamProvider) addRoomDeltaToResponse(
) (types.StreamPosition, error) { ) (types.StreamPosition, error) {
originalLimit := eventFilter.Limit originalLimit := eventFilter.Limit
if r.Backwards { // If we're going backwards, grep at least X events, this is mostly to satisfy Sytest
eventFilter.Limit = int(r.From - r.To) 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( recentStreamEvents, limited, err := snapshot.RecentEvents(
ctx, delta.RoomID, r, ctx, delta.RoomID, r,
eventFilter, true, true, eventFilter, true, true,