From 6bc6184d70614a9ba2cc585c88f66e6a780ddb98 Mon Sep 17 00:00:00 2001 From: Neil Alexander Date: Fri, 6 May 2022 15:52:44 +0100 Subject: [PATCH] Simplify `calculateLatest` (#2430) * Simplify `calculateLatest` * Comments --- .../internal/input/input_latest_events.go | 26 ++++++------------- 1 file changed, 8 insertions(+), 18 deletions(-) diff --git a/roomserver/internal/input/input_latest_events.go b/roomserver/internal/input/input_latest_events.go index 7e58ef9d0..9ad8b0422 100644 --- a/roomserver/internal/input/input_latest_events.go +++ b/roomserver/internal/input/input_latest_events.go @@ -316,40 +316,30 @@ func (u *latestEventsUpdater) calculateLatest( // Then let's see if any of the existing forward extremities now // have entries in the previous events table. If they do then we // will no longer include them as forward extremities. - existingPrevs := make(map[string]struct{}) - for _, l := range existingRefs { + for k, l := range existingRefs { referenced, err := u.updater.IsReferenced(l.EventReference) if err != nil { return false, fmt.Errorf("u.updater.IsReferenced: %w", err) } else if referenced { - existingPrevs[l.EventID] = struct{}{} + delete(existingRefs, k) } } - // Include our new event in the extremities. - newLatest := []types.StateAtEventAndReference{newStateAndRef} + // Start off with our new unreferenced event. We're reusing the backing + // array here rather than allocating a new one. + u.latest = append(u.latest[:0], newStateAndRef) - // Then run through and see if the other extremities are still valid. - // If our new event references them then they are no longer good - // candidates. + // If our new event references any of the existing forward extremities + // then they are no longer forward extremities, so remove them. for _, prevEventID := range newEvent.PrevEventIDs() { delete(existingRefs, prevEventID) } - // Ensure that we don't add any candidate forward extremities from - // the old set that are, themselves, referenced by the old set of - // forward extremities. This shouldn't happen but guards against - // the possibility anyway. - for prevEventID := range existingPrevs { - delete(existingRefs, prevEventID) - } - // Then re-add any old extremities that are still valid after all. for _, old := range existingRefs { - newLatest = append(newLatest, *old) + u.latest = append(u.latest, *old) } - u.latest = newLatest return true, nil }