Linting

roomserver/query/backfill.go

@@ -49,40 +49,12 @@ func (b *backfillRequester) StateIDsBeforeEvent(ctx context.Context, targetEvent
 		if !ok {
 			goto FederationHit
 		}
-		// The state IDs BEFORE the target event are the state IDs BEFORE the prev_event PLUS the prev_event itself
+		newStateIDs := b.calculateNewStateIDs(targetEvent.Unwrap(), prevEvent, prevEventStateIDs)
-		newStateIDs := prevEventStateIDs[:]
+		if newStateIDs != nil {
-		if prevEvent.StateKey() == nil {
-			// state is the same as the previous event
 			b.eventIDToBeforeStateIDs[targetEvent.EventID()] = newStateIDs
 			return newStateIDs, nil
 		}
-
+		// else we failed to calculate the new state, so fallthrough
-		missingState := false // true if we are missing the info for a state event ID
-		foundEvent := false   // true if we found a (type, state_key) match
-		// find which state ID to replace, if any
-		for i, id := range newStateIDs {
-			ev, ok := b.eventIDMap[id]
-			if !ok {
-				missingState = true
-				continue
-			}
-			if ev.Type() == prevEvent.Type() && ev.StateKey() != nil && ev.StateKey() == prevEvent.StateKey() {
-				newStateIDs[i] = prevEvent.EventID()
-				foundEvent = true
-				break
-			}
-		}
-		if !foundEvent && !missingState {
-			// we can be certain that this is new state
-			newStateIDs = append(newStateIDs, prevEvent.EventID())
-			foundEvent = true
-		}
-
-		if foundEvent {
-			b.eventIDToBeforeStateIDs[targetEvent.EventID()] = newStateIDs
-			return newStateIDs, nil
-		}
-		// else fallthrough because we don't know if one of the missing state IDs was the one we could replace.
 	}
 
 FederationHit:
@@ -105,6 +77,43 @@ FederationHit:
 	return nil, lastErr
 }
 
+func (b *backfillRequester) calculateNewStateIDs(targetEvent, prevEvent gomatrixserverlib.Event, prevEventStateIDs []string) []string {
+	newStateIDs := prevEventStateIDs[:]
+	if prevEvent.StateKey() == nil {
+		// state is the same as the previous event
+		b.eventIDToBeforeStateIDs[targetEvent.EventID()] = newStateIDs
+		return newStateIDs
+	}
+
+	missingState := false // true if we are missing the info for a state event ID
+	foundEvent := false   // true if we found a (type, state_key) match
+	// find which state ID to replace, if any
+	for i, id := range newStateIDs {
+		ev, ok := b.eventIDMap[id]
+		if !ok {
+			missingState = true
+			continue
+		}
+		// The state IDs BEFORE the target event are the state IDs BEFORE the prev_event PLUS the prev_event itself
+		if ev.Type() == prevEvent.Type() && ev.StateKey() != nil && ev.StateKey() == prevEvent.StateKey() {
+			newStateIDs[i] = prevEvent.EventID()
+			foundEvent = true
+			break
+		}
+	}
+	if !foundEvent && !missingState {
+		// we can be certain that this is new state
+		newStateIDs = append(newStateIDs, prevEvent.EventID())
+		foundEvent = true
+	}
+
+	if foundEvent {
+		b.eventIDToBeforeStateIDs[targetEvent.EventID()] = newStateIDs
+		return newStateIDs
+	}
+	return nil
+}
+
 func (b *backfillRequester) StateBeforeEvent(ctx context.Context, roomVer gomatrixserverlib.RoomVersion, event gomatrixserverlib.HeaderedEvent, eventIDs []string) (map[string]*gomatrixserverlib.Event, error) {
 	// try to fetch the events from the database first
 	events, err := b.ProvideEvents(roomVer, eventIDs)

roomserver/query/query.go

@@ -551,37 +551,18 @@ func (r *RoomserverQueryAPI) backfillViaFederation(ctx context.Context, req *api
 	}
 	logrus.WithField("room_id", req.RoomID).Infof("backfilled %d events", len(events))
 
-	backfilledEventMap := make(map[string]types.Event)
-	var roomNID types.RoomNID
 	// persist these new events - auth checks have already been done
-	for _, ev := range events {
+	roomNID, backfilledEventMap := persistEvents(ctx, r.DB, events)
-		nidMap, err := r.DB.EventNIDs(ctx, ev.AuthEventIDs())
-		if err != nil { // this shouldn't happen as RequestBackill already found them
-			logrus.WithError(err).WithField("auth_events", ev.AuthEventIDs()).Error("Failed to find one or more auth events")
-			continue
-		}
-		authNids := make([]types.EventNID, len(nidMap))
-		i := 0
-		for _, nid := range nidMap {
-			authNids[i] = nid
-			i++
-		}
-		var stateAtEvent types.StateAtEvent
-		roomNID, stateAtEvent, err = r.DB.StoreEvent(ctx, ev.Unwrap(), nil, authNids)
 	if err != nil {
-			logrus.WithError(err).WithField("event_id", ev.EventID()).Error("Failed to store backfilled event")
+		return err
-			continue
-		}
-		backfilledEventMap[ev.EventID()] = types.Event{
-			EventNID: stateAtEvent.StateEntry.EventNID,
-			Event:    ev.Unwrap(),
-		}
 	}
 
 	for _, ev := range backfilledEventMap {
 		// now add state for these events
 		stateIDs, ok := requester.eventIDToBeforeStateIDs[ev.EventID()]
 		if !ok {
+			// this should be impossible as all events returned must have pass Step 5 of the PDU checks
+			// which requires a list of state IDs.
 			logrus.WithError(err).WithField("event_id", ev.EventID()).Error("Failed to find state IDs for event which passed auth checks")
 			continue
 		}
@@ -858,6 +839,35 @@ func getAuthChain(
 	return authEvents, nil
 }
 
+func persistEvents(ctx context.Context, db storage.Database, events []gomatrixserverlib.HeaderedEvent) (types.RoomNID, map[string]types.Event) {
+	var roomNID types.RoomNID
+	backfilledEventMap := make(map[string]types.Event)
+	for _, ev := range events {
+		nidMap, err := db.EventNIDs(ctx, ev.AuthEventIDs())
+		if err != nil { // this shouldn't happen as RequestBackfill already found them
+			logrus.WithError(err).WithField("auth_events", ev.AuthEventIDs()).Error("Failed to find one or more auth events")
+			continue
+		}
+		authNids := make([]types.EventNID, len(nidMap))
+		i := 0
+		for _, nid := range nidMap {
+			authNids[i] = nid
+			i++
+		}
+		var stateAtEvent types.StateAtEvent
+		roomNID, stateAtEvent, err = db.StoreEvent(ctx, ev.Unwrap(), nil, authNids)
+		if err != nil {
+			logrus.WithError(err).WithField("event_id", ev.EventID()).Error("Failed to store backfilled event")
+			continue
+		}
+		backfilledEventMap[ev.EventID()] = types.Event{
+			EventNID: stateAtEvent.StateEntry.EventNID,
+			Event:    ev.Unwrap(),
+		}
+	}
+	return roomNID, backfilledEventMap
+}
+
 // QueryRoomVersionCapabilities implements api.RoomserverQueryAPI
 func (r *RoomserverQueryAPI) QueryRoomVersionCapabilities(
 	ctx context.Context,