Return event NID from StoreEvent, match PSQL vs SQLite behaviour, tweak backfill persistence (#2071)

roomserver/internal/input/input_events.go

@@ -122,7 +122,7 @@ func (r *Inputer) processRoomEvent(
 	}
 
 	// Store the event.
-	_, stateAtEvent, redactionEvent, redactedEventID, err := r.DB.StoreEvent(ctx, event, authEventNIDs, isRejected)
+	_, _, stateAtEvent, redactionEvent, redactedEventID, err := r.DB.StoreEvent(ctx, event, authEventNIDs, isRejected)
 	if err != nil {
 		return "", fmt.Errorf("r.DB.StoreEvent: %w", err)
 	}

roomserver/internal/perform/perform_backfill.go

@@ -546,6 +546,7 @@ func joinEventsFromHistoryVisibility(
 
 func persistEvents(ctx context.Context, db storage.Database, events []*gomatrixserverlib.HeaderedEvent) (types.RoomNID, map[string]types.Event) {
 	var roomNID types.RoomNID
+	var eventNID types.EventNID
 	backfilledEventMap := make(map[string]types.Event)
 	for j, ev := range events {
 		nidMap, err := db.EventNIDs(ctx, ev.AuthEventIDs())
@@ -559,10 +560,9 @@ func persistEvents(ctx context.Context, db storage.Database, events []*gomatrixs
 			authNids[i] = nid
 			i++
 		}
-		var stateAtEvent types.StateAtEvent
 		var redactedEventID string
 		var redactionEvent *gomatrixserverlib.Event
-		roomNID, stateAtEvent, redactionEvent, redactedEventID, err = db.StoreEvent(ctx, ev.Unwrap(), authNids, false)
+		eventNID, roomNID, _, redactionEvent, redactedEventID, err = db.StoreEvent(ctx, ev.Unwrap(), authNids, false)
 		if err != nil {
 			logrus.WithError(err).WithField("event_id", ev.EventID()).Error("Failed to persist event")
 			continue
@@ -581,7 +581,7 @@ func persistEvents(ctx context.Context, db storage.Database, events []*gomatrixs
 			events[j] = ev
 		}
 		backfilledEventMap[ev.EventID()] = types.Event{
-			EventNID: stateAtEvent.StateEntry.EventNID,
+			EventNID: eventNID,
 			Event:    ev.Unwrap(),
 		}
 	}

roomserver/storage/interface.go

@@ -70,7 +70,7 @@ type Database interface {
 	StoreEvent(
 		ctx context.Context, event *gomatrixserverlib.Event, authEventNIDs []types.EventNID,
 		isRejected bool,
-	) (types.RoomNID, types.StateAtEvent, *gomatrixserverlib.Event, string, error)
+	) (types.EventNID, types.RoomNID, types.StateAtEvent, *gomatrixserverlib.Event, string, error)
 	// Look up the state entries for a list of string event IDs
 	// Returns an error if the there is an error talking to the database
 	// Returns a types.MissingEventError if the event IDs aren't in the database.

roomserver/storage/shared/storage.go

@@ -461,7 +461,7 @@ func (d *Database) GetLatestEventsForUpdate(
 func (d *Database) StoreEvent(
 	ctx context.Context, event *gomatrixserverlib.Event,
 	authEventNIDs []types.EventNID, isRejected bool,
-) (types.RoomNID, types.StateAtEvent, *gomatrixserverlib.Event, string, error) {
+) (types.EventNID, types.RoomNID, types.StateAtEvent, *gomatrixserverlib.Event, string, error) {
 	var (
 		roomNID          types.RoomNID
 		eventTypeNID     types.EventTypeNID
@@ -538,7 +538,7 @@ func (d *Database) StoreEvent(
 		return nil
 	})
 	if err != nil {
-		return 0, types.StateAtEvent{}, nil, "", fmt.Errorf("d.Writer.Do: %w", err)
+		return 0, 0, types.StateAtEvent{}, nil, "", fmt.Errorf("d.Writer.Do: %w", err)
 	}
 
 	// We should attempt to update the previous events table with any
@@ -551,10 +551,10 @@ func (d *Database) StoreEvent(
 	if prevEvents := event.PrevEvents(); len(prevEvents) > 0 {
 		roomInfo, err = d.RoomInfo(ctx, event.RoomID())
 		if err != nil {
-			return 0, types.StateAtEvent{}, nil, "", fmt.Errorf("d.RoomInfo: %w", err)
+			return 0, 0, types.StateAtEvent{}, nil, "", fmt.Errorf("d.RoomInfo: %w", err)
 		}
 		if roomInfo == nil && len(prevEvents) > 0 {
-			return 0, types.StateAtEvent{}, nil, "", fmt.Errorf("expected room %q to exist", event.RoomID())
+			return 0, 0, types.StateAtEvent{}, nil, "", fmt.Errorf("expected room %q to exist", event.RoomID())
 		}
 		// Create an updater - NB: on sqlite this WILL create a txn as we are directly calling the shared DB form of
 		// GetLatestEventsForUpdate - not via the SQLiteDatabase form which has `nil` txns. This
@@ -563,7 +563,7 @@ func (d *Database) StoreEvent(
 		// to do writes however then this will need to go inside `Writer.Do`.
 		updater, err = d.GetLatestEventsForUpdate(ctx, *roomInfo)
 		if err != nil {
-			return 0, types.StateAtEvent{}, nil, "", fmt.Errorf("NewLatestEventsUpdater: %w", err)
+			return 0, 0, types.StateAtEvent{}, nil, "", fmt.Errorf("NewLatestEventsUpdater: %w", err)
 		}
 		// Ensure that we atomically store prev events AND commit them. If we don't wrap StorePreviousEvents
 		// and EndTransaction in a writer then it's possible for a new write txn to be made between the two
@@ -580,11 +580,11 @@ func (d *Database) StoreEvent(
 			return err
 		})
 		if err != nil {
-			return 0, types.StateAtEvent{}, nil, "", err
+			return 0, 0, types.StateAtEvent{}, nil, "", err
 		}
 	}
 
-	return roomNID, types.StateAtEvent{
+	return eventNID, roomNID, types.StateAtEvent{
 		BeforeStateSnapshotNID: stateNID,
 		StateEntry: types.StateEntry{
 			StateKeyTuple: types.StateKeyTuple{

roomserver/storage/sqlite3/events_table.go

@@ -49,7 +49,8 @@ const eventsSchema = `
 const insertEventSQL = `
 	INSERT INTO roomserver_events (room_nid, event_type_nid, event_state_key_nid, event_id, reference_sha256, auth_event_nids, depth, is_rejected)
 	  VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
-	  ON CONFLICT DO NOTHING;
+	  ON CONFLICT DO NOTHING
+	  RETURNING event_nid, state_snapshot_nid;
 `
 
 const selectEventSQL = "" +
@@ -161,20 +162,13 @@ func (s *eventStatements) InsertEvent(
 ) (types.EventNID, types.StateSnapshotNID, error) {
 	// attempt to insert: the last_row_id is the event NID
 	var eventNID int64
+	var stateNID int64
 	insertStmt := sqlutil.TxStmt(txn, s.insertEventStmt)
-	result, err := insertStmt.ExecContext(
+	err := insertStmt.QueryRowContext(
 		ctx, int64(roomNID), int64(eventTypeNID), int64(eventStateKeyNID),
 		eventID, referenceSHA256, eventNIDsAsArray(authEventNIDs), depth, isRejected,
-	)
+	).Scan(&eventNID, &stateNID)
-	if err != nil {
+	return types.EventNID(eventNID), types.StateSnapshotNID(stateNID), err
-		return 0, 0, err
-	}
-	modified, err := result.RowsAffected()
-	if modified == 0 && err == nil {
-		return 0, 0, sql.ErrNoRows
-	}
-	eventNID, err = result.LastInsertId()
-	return types.EventNID(eventNID), 0, err
 }
 
 func (s *eventStatements) SelectEvent(