From 244ff0dccb64fbdf29b6cbf8a7e02a81b92c7330 Mon Sep 17 00:00:00 2001 From: Neil Alexander Date: Mon, 18 Jan 2021 13:21:33 +0000 Subject: [PATCH] Don't create so many state snapshots when updating forward extremities (#1718) * Light-weight checking of state changes when updating forward extremities * Only do this for non-state events, since state events will always result in state change at extremities --- .../internal/input/input_latest_events.go | 40 +++++++++++++++++-- roomserver/state/state.go | 4 +- 2 files changed, 38 insertions(+), 6 deletions(-) diff --git a/roomserver/internal/input/input_latest_events.go b/roomserver/internal/input/input_latest_events.go index e5ec8c4d7..c9264a27d 100644 --- a/roomserver/internal/input/input_latest_events.go +++ b/roomserver/internal/input/input_latest_events.go @@ -100,7 +100,8 @@ type latestEventsUpdater struct { // The eventID of the event that was processed before this one. lastEventIDSent string // The latest events in the room after processing this event. - latest []types.StateAtEventAndReference + oldLatest []types.StateAtEventAndReference + latest []types.StateAtEventAndReference // The state entries removed from and added to the current state of the // room as a result of processing this event. They are sorted lists. removed []types.StateEntry @@ -123,10 +124,10 @@ func (u *latestEventsUpdater) doUpdateLatestEvents() error { // state snapshot from somewhere else, e.g. a federated room join, // then start with an empty set - none of the forward extremities // that we knew about before matter anymore. - oldLatest := []types.StateAtEventAndReference{} + u.oldLatest = []types.StateAtEventAndReference{} if !u.rewritesState { u.oldStateNID = u.updater.CurrentStateSnapshotNID() - oldLatest = u.updater.LatestEvents() + u.oldLatest = u.updater.LatestEvents() } // If the event has already been written to the output log then we @@ -140,7 +141,7 @@ func (u *latestEventsUpdater) doUpdateLatestEvents() error { // Work out what the latest events are. This will include the new // event if it is not already referenced. extremitiesChanged, err := u.calculateLatest( - oldLatest, u.event, + u.oldLatest, u.event, types.StateAtEventAndReference{ EventReference: u.event.EventReference(), StateAtEvent: u.stateAtEvent, @@ -200,6 +201,37 @@ func (u *latestEventsUpdater) latestState() error { var err error roomState := state.NewStateResolution(u.api.DB, *u.roomInfo) + // Work out if the state at the extremities has actually changed + // or not. If they haven't then we won't bother doing all of the + // hard work. + if u.event.StateKey() == nil { + stateChanged := false + oldStateNIDs := make([]types.StateSnapshotNID, 0, len(u.oldLatest)) + newStateNIDs := make([]types.StateSnapshotNID, 0, len(u.latest)) + for _, old := range u.oldLatest { + oldStateNIDs = append(oldStateNIDs, old.BeforeStateSnapshotNID) + } + for _, new := range u.latest { + newStateNIDs = append(newStateNIDs, new.BeforeStateSnapshotNID) + } + oldStateNIDs = state.UniqueStateSnapshotNIDs(oldStateNIDs) + newStateNIDs = state.UniqueStateSnapshotNIDs(newStateNIDs) + if len(oldStateNIDs) != len(newStateNIDs) { + stateChanged = true + } else { + for i := range oldStateNIDs { + if oldStateNIDs[i] != newStateNIDs[i] { + stateChanged = true + break + } + } + } + if !stateChanged { + u.newStateNID = u.oldStateNID + return nil + } + } + // Get a list of the current latest events. This may or may not // include the new event from the input path, depending on whether // it is a forward extremity or not. diff --git a/roomserver/state/state.go b/roomserver/state/state.go index 87715af42..953276b24 100644 --- a/roomserver/state/state.go +++ b/roomserver/state/state.go @@ -116,7 +116,7 @@ func (v StateResolution) LoadCombinedStateAfterEvents( // Deduplicate the IDs before passing them to the database. // There could be duplicates because the events could be state events where // the snapshot of the room state before them was the same. - stateBlockNIDLists, err := v.db.StateBlockNIDs(ctx, uniqueStateSnapshotNIDs(stateNIDs)) + stateBlockNIDLists, err := v.db.StateBlockNIDs(ctx, UniqueStateSnapshotNIDs(stateNIDs)) if err != nil { return nil, fmt.Errorf("v.db.StateBlockNIDs: %w", err) } @@ -1103,7 +1103,7 @@ func (s stateNIDSorter) Len() int { return len(s) } func (s stateNIDSorter) Less(i, j int) bool { return s[i] < s[j] } func (s stateNIDSorter) Swap(i, j int) { s[i], s[j] = s[j], s[i] } -func uniqueStateSnapshotNIDs(nids []types.StateSnapshotNID) []types.StateSnapshotNID { +func UniqueStateSnapshotNIDs(nids []types.StateSnapshotNID) []types.StateSnapshotNID { return nids[:util.SortAndUnique(stateNIDSorter(nids))] }