Merge branch 'master' into neilalexander/rsconcurrency

roomserver/internal/input/input_membership.go

@@ -107,6 +107,23 @@ func (r *Inputer) updateMembership(
 		return updates, nil
 	}
 
+	// In an ideal world, we shouldn't ever have "add" be nil and "remove" be
+	// set, as this implies that we're deleting a state event without replacing
+	// it (a thing that ordinarily shouldn't happen in Matrix). However, state
+	// resets are sadly a thing occasionally and we have to account for that.
+	// Beforehand there used to be a check here which stopped dead if we hit
+	// this scenario, but that meant that the membership table got out of sync
+	// after a state reset, often thinking that the user was still joined to
+	// the room even though the room state said otherwise, and this would prevent
+	// the user from being able to attempt to rejoin the room without modifying
+	// the database. So instead what we'll do is we'll just update the membership
+	// table to say that the user is "leave" and we'll use the old event to
+	// avoid nil pointer exceptions on the code path that follows.
+	if add == nil {
+		add = remove
+		newMembership = gomatrixserverlib.Leave
+	}
+
 	mu, err := updater.MembershipUpdater(targetUserNID, r.isLocalTarget(add))
 	if err != nil {
 		return nil, err

roomserver/internal/query/query.go

@@ -112,7 +112,7 @@ func (r *Queryer) QueryStateAfterEvents(
 			return fmt.Errorf("getAuthChain: %w", err)
 		}
 
-		stateEvents, err = state.ResolveConflictsAdhoc(info.RoomVersion, stateEvents, authEvents)
+		stateEvents, err = gomatrixserverlib.ResolveConflicts(info.RoomVersion, stateEvents, authEvents)
 		if err != nil {
 			return fmt.Errorf("state.ResolveConflictsAdhoc: %w", err)
 		}
@@ -469,7 +469,7 @@ func (r *Queryer) QueryStateAndAuthChain(
 	}
 
 	if request.ResolveState {
-		if stateEvents, err = state.ResolveConflictsAdhoc(
+		if stateEvents, err = gomatrixserverlib.ResolveConflicts(
 			info.RoomVersion, stateEvents, authEvents,
 		); err != nil {
 			return err

roomserver/state/state.go

@@ -683,79 +683,6 @@ func (v *StateResolution) calculateStateAfterManyEvents(
 	return
 }
 
-// ResolveConflictsAdhoc is a helper function to assist the query API in
-// performing state resolution when requested. This is a different code
-// path to the rest of state.go because this assumes you already have
-// gomatrixserverlib.Event objects and not just a bunch of NIDs like
-// elsewhere in the state resolution.
-// TODO: Some of this can possibly be deduplicated
-func ResolveConflictsAdhoc(
-	version gomatrixserverlib.RoomVersion,
-	events []*gomatrixserverlib.Event,
-	authEvents []*gomatrixserverlib.Event,
-) ([]*gomatrixserverlib.Event, error) {
-	type stateKeyTuple struct {
-		Type     string
-		StateKey string
-	}
-
-	// Prepare our data structures.
-	eventMap := make(map[stateKeyTuple][]*gomatrixserverlib.Event)
-	var conflicted, notConflicted, resolved []*gomatrixserverlib.Event
-
-	// Run through all of the events that we were given and sort them
-	// into a map, sorted by (event_type, state_key) tuple. This means
-	// that we can easily spot events that are "conflicted", e.g.
-	// there are duplicate values for the same tuple key.
-	for _, event := range events {
-		if event.StateKey() == nil {
-			// Ignore events that are not state events.
-			continue
-		}
-		// Append the events if there is already a conflicted list for
-		// this tuple key, create it if not.
-		tuple := stateKeyTuple{event.Type(), *event.StateKey()}
-		eventMap[tuple] = append(eventMap[tuple], event)
-	}
-
-	// Split out the events in the map into conflicted and unconflicted
-	// buckets. The conflicted events will be ran through state res,
-	// whereas unconfliced events will always going to appear in the
-	// final resolved state.
-	for _, list := range eventMap {
-		if len(list) > 1 {
-			conflicted = append(conflicted, list...)
-		} else {
-			notConflicted = append(notConflicted, list...)
-		}
-	}
-
-	// Work out which state resolution algorithm we want to run for
-	// the room version.
-	stateResAlgo, err := version.StateResAlgorithm()
-	if err != nil {
-		return nil, err
-	}
-	switch stateResAlgo {
-	case gomatrixserverlib.StateResV1:
-		// Currently state res v1 doesn't handle unconflicted events
-		// for us, like state res v2 does, so we will need to add the
-		// unconflicted events into the state ourselves.
-		// TODO: Fix state res v1 so this is handled for the caller.
-		resolved = gomatrixserverlib.ResolveStateConflicts(conflicted, authEvents)
-		resolved = append(resolved, notConflicted...)
-	case gomatrixserverlib.StateResV2:
-		// TODO: auth difference here?
-		resolved = gomatrixserverlib.ResolveStateConflictsV2(conflicted, notConflicted, authEvents, authEvents)
-	default:
-		return nil, fmt.Errorf("unsupported state resolution algorithm %v", stateResAlgo)
-	}
-
-	// Return the final resolved state events, including both the
-	// resolved set of conflicted events, and the unconflicted events.
-	return resolved, nil
-}
-
 func (v *StateResolution) resolveConflicts(
 	ctx context.Context, version gomatrixserverlib.RoomVersion,
 	notConflicted, conflicted []types.StateEntry,