Don't limit "state" (#2849)

This is apparently some incorrect behaviour that we built as a result of
a spec bug (matrix-org/matrix-spec#1314) where we were applying a filter
to the `"state"` section of the `/sync` response incorrectly. The client
then has no way to know that the state was limited.

This PR removes the state limiting, which probably also helps #2842.

syncapi/routing/context.go

@@ -93,7 +93,6 @@ func Context(
 	}
 
 	stateFilter := gomatrixserverlib.StateFilter{
-		Limit:                   100,
 		NotSenders:              filter.NotSenders,
 		NotTypes:                filter.NotTypes,
 		Senders:                 filter.Senders,

syncapi/routing/search.go

@@ -294,7 +294,7 @@ type SearchRequest struct {
 				BeforeLimit    int  `json:"before_limit,omitempty"`
 				IncludeProfile bool `json:"include_profile,omitempty"`
 			} `json:"event_context"`
-			Filter    gomatrixserverlib.StateFilter `json:"filter"`
+			Filter    gomatrixserverlib.RoomEventFilter `json:"filter"`
 			Groupings struct {
 				GroupBy []struct {
 					Key string `json:"key"`

syncapi/storage/postgres/current_room_state_table.go

@@ -91,8 +91,7 @@ const selectCurrentStateSQL = "" +
 	" AND ( $4::text[] IS NULL OR     type LIKE ANY($4)  )" +
 	" AND ( $5::text[] IS NULL OR NOT(type LIKE ANY($5)) )" +
 	" AND ( $6::bool IS NULL   OR     contains_url = $6  )" +
-	" AND (event_id = ANY($7)) IS NOT TRUE" +
+	" AND (event_id = ANY($7)) IS NOT TRUE"
-	" LIMIT $8"
 
 const selectJoinedUsersSQL = "" +
 	"SELECT room_id, state_key FROM syncapi_current_room_state WHERE type = 'm.room.member' AND membership = 'join'"
@@ -290,7 +289,6 @@ func (s *currentRoomStateStatements) SelectCurrentState(
 		pq.StringArray(filterConvertTypeWildcardToSQL(stateFilter.NotTypes)),
 		stateFilter.ContainsURL,
 		pq.StringArray(excludeEventIDs),
-		stateFilter.Limit,
 	)
 	if err != nil {
 		return nil, err

syncapi/storage/postgres/output_room_events_table.go

@@ -144,8 +144,7 @@ const selectStateInRangeFilteredSQL = "" +
 	" AND ( $6::text[] IS NULL OR     type LIKE ANY($6)  )" +
 	" AND ( $7::text[] IS NULL OR NOT(type LIKE ANY($7)) )" +
 	" AND ( $8::bool IS NULL   OR     contains_url = $8  )" +
-	" ORDER BY id ASC" +
+	" ORDER BY id ASC"
-	" LIMIT $9"
 
 // In order for us to apply the state updates correctly, rows need to be ordered in the order they were received (id).
 const selectStateInRangeSQL = "" +
@@ -153,8 +152,7 @@ const selectStateInRangeSQL = "" +
 	" FROM syncapi_output_room_events" +
 	" WHERE (id > $1 AND id <= $2) AND (add_state_ids IS NOT NULL OR remove_state_ids IS NOT NULL)" +
 	" AND room_id = ANY($3)" +
-	" ORDER BY id ASC" +
+	" ORDER BY id ASC"
-	" LIMIT $4"
 
 const deleteEventsForRoomSQL = "" +
 	"DELETE FROM syncapi_output_room_events WHERE room_id = $1"
@@ -264,13 +262,11 @@ func (s *outputRoomEventsStatements) SelectStateInRange(
 			pq.StringArray(filterConvertTypeWildcardToSQL(stateFilter.Types)),
 			pq.StringArray(filterConvertTypeWildcardToSQL(stateFilter.NotTypes)),
 			stateFilter.ContainsURL,
-			stateFilter.Limit,
 		)
 	} else {
 		stmt := sqlutil.TxStmt(txn, s.selectStateInRangeStmt)
 		rows, err = stmt.QueryContext(
 			ctx, r.Low(), r.High(), pq.StringArray(roomIDs),
-			r.High()-r.Low(),
 		)
 	}
 

syncapi/storage/sqlite3/current_room_state_table.go

@@ -277,7 +277,8 @@ func (s *currentRoomStateStatements) SelectCurrentState(
 		},
 		stateFilter.Senders, stateFilter.NotSenders,
 		stateFilter.Types, stateFilter.NotTypes,
-		excludeEventIDs, stateFilter.ContainsURL, stateFilter.Limit, FilterOrderNone,
+		excludeEventIDs, stateFilter.ContainsURL, 0,
+		FilterOrderNone,
 	)
 	if err != nil {
 		return nil, fmt.Errorf("s.prepareWithFilters: %w", err)

syncapi/storage/sqlite3/filtering.go

@@ -84,8 +84,10 @@ func prepareWithFilters(
 	case FilterOrderDesc:
 		query += " ORDER BY id DESC"
 	}
+	if limit > 0 {
 		query += fmt.Sprintf(" LIMIT $%d", offset+1)
 		params = append(params, limit)
+	}
 
 	var stmt *sql.Stmt
 	var err error

syncapi/storage/sqlite3/output_room_events_table.go

@@ -200,7 +200,7 @@ func (s *outputRoomEventsStatements) SelectStateInRange(
 			s.db, txn, stmtSQL, inputParams,
 			stateFilter.Senders, stateFilter.NotSenders,
 			stateFilter.Types, stateFilter.NotTypes,
-			nil, stateFilter.ContainsURL, stateFilter.Limit, FilterOrderAsc,
+			nil, stateFilter.ContainsURL, 0, FilterOrderAsc,
 		)
 	} else {
 		stmt, params, err = prepareWithFilters(

syncapi/streams/stream_pdu.go

@@ -301,7 +301,7 @@ func (p *PDUStreamProvider) addRoomDeltaToResponse(
 	}
 
 	// Applies the history visibility rules
-	events, err := applyHistoryVisibilityFilter(ctx, snapshot, p.rsAPI, delta.RoomID, device.UserID, eventFilter.Limit, recentEvents)
+	events, err := applyHistoryVisibilityFilter(ctx, snapshot, p.rsAPI, delta.RoomID, device.UserID, recentEvents)
 	if err != nil {
 		logrus.WithError(err).Error("unable to apply history visibility filter")
 	}
@@ -378,12 +378,12 @@ func applyHistoryVisibilityFilter(
 	snapshot storage.DatabaseTransaction,
 	rsAPI roomserverAPI.SyncRoomserverAPI,
 	roomID, userID string,
-	limit int,
 	recentEvents []*gomatrixserverlib.HeaderedEvent,
 ) ([]*gomatrixserverlib.HeaderedEvent, error) {
 	// We need to make sure we always include the latest states events, if they are in the timeline.
 	// We grep at least limit * 2 events, to ensure we really get the needed events.
-	stateEvents, err := snapshot.CurrentState(ctx, roomID, &gomatrixserverlib.StateFilter{Limit: limit * 2}, nil)
+	filter := gomatrixserverlib.DefaultStateFilter()
+	stateEvents, err := snapshot.CurrentState(ctx, roomID, &filter, nil)
 	if err != nil {
 		// Not a fatal error, we can continue without the stateEvents,
 		// they are only needed if there are state events in the timeline.
@@ -521,7 +521,7 @@ func (p *PDUStreamProvider) getJoinResponseForCompleteSync(
 	events := recentEvents
 	// Only apply history visibility checks if the response is for joined rooms
 	if !isPeek {
-		events, err = applyHistoryVisibilityFilter(ctx, snapshot, p.rsAPI, roomID, device.UserID, eventFilter.Limit, recentEvents)
+		events, err = applyHistoryVisibilityFilter(ctx, snapshot, p.rsAPI, roomID, device.UserID, recentEvents)
 		if err != nil {
 			logrus.WithError(err).Error("unable to apply history visibility filter")
 		}
@@ -601,7 +601,6 @@ func (p *PDUStreamProvider) lazyLoadMembers(
 	}
 	// Query missing membership events
 	filter := gomatrixserverlib.DefaultStateFilter()
-	filter.Limit = stateFilter.Limit
 	filter.Senders = &wantUsers
 	filter.Types = &[]string{gomatrixserverlib.MRoomMember}
 	memberships, err := snapshot.GetStateEventsForRoom(ctx, roomID, &filter)

syncapi/sync/request.go

@@ -79,7 +79,6 @@ func newSyncRequest(req *http.Request, device userapi.Device, syncDB storage.Dat
 		// for the rest of the data to trickle down.
 		filter.AccountData.Limit = math.MaxInt32
 		filter.Room.AccountData.Limit = math.MaxInt32
-		filter.Room.State.Limit = math.MaxInt32
 	}
 
 	logger := util.GetLogger(req.Context()).WithFields(logrus.Fields{