FIXUP

This makes it so we can always `upsert` to avoid duplicates otherwise
I'm not sure of how to not insert duplicates in certain situations
(see FIXME in the diff) which would cause problems down the line
for the unique index being added later.

changelog.d/17512.misc

@@ -0,0 +1 @@
+Pre-populate room data used in experimental [MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575) Sliding Sync `/sync` endpoint for quick filtering/sorting.

changelog.d/17599.misc

@@ -0,0 +1 @@
+Store sliding sync per-connection state in the database.

changelog.d/17600.misc

@@ -0,0 +1 @@
+Make the sliding sync `PerConnectionState` class immutable.

scripts-dev/mypy_synapse_plugin.py

@@ -38,6 +38,7 @@ from mypy.types import (
     NoneType,
     TupleType,
     TypeAliasType,
+    TypeVarType,
     UninhabitedType,
     UnionType,
 )
@@ -233,6 +234,7 @@ IMMUTABLE_CUSTOM_TYPES = {
     "synapse.synapse_rust.push.FilteredPushRules",
     # This is technically not immutable, but close enough.
     "signedjson.types.VerifyKey",
+    "synapse.types.StrCollection",
 }
 
 # Immutable containers only if the values are also immutable.
@@ -298,7 +300,7 @@ def is_cacheable(
 
         elif rt.type.fullname in MUTABLE_CONTAINER_TYPES:
             # Mutable containers are mutable regardless of their underlying type.
-            return False, None
+            return False, f"container {rt.type.fullname} is mutable"
 
         elif "attrs" in rt.type.metadata:
             # attrs classes are only cachable iff it is frozen (immutable itself)
@@ -318,6 +320,9 @@ def is_cacheable(
             else:
                 return False, "non-frozen attrs class"
 
+        elif rt.type.is_enum:
+            # We assume Enum values are immutable
+            return True, None
         else:
             # Ensure we fail for unknown types, these generally means that the
             # above code is not complete.
@@ -326,6 +331,18 @@ def is_cacheable(
                 f"Don't know how to handle {rt.type.fullname} return type instance",
             )
 
+    elif isinstance(rt, TypeVarType):
+        # We consider TypeVars immutable if they are bound to a set of immutable
+        # types.
+        if rt.values:
+            for value in rt.values:
+                ok, note = is_cacheable(value, signature, verbose)
+                if not ok:
+                    return False, f"TypeVar bound not cacheable {value}"
+            return True, None
+
+        return False, "TypeVar is unbound"
+
     elif isinstance(rt, NoneType):
         # None is cachable.
         return True, None

synapse/_scripts/synapse_port_db.py

@@ -129,6 +129,11 @@ BOOLEAN_COLUMNS = {
     "remote_media_cache": ["authenticated"],
     "room_stats_state": ["is_federatable"],
     "rooms": ["is_public", "has_auth_chain_index"],
+    "sliding_sync_joined_rooms": ["is_encrypted"],
+    "sliding_sync_membership_snapshots": [
+        "has_known_state",
+        "is_encrypted",
+    ],
     "users": ["shadow_banned", "approved", "locked", "suspended"],
     "un_partial_stated_event_stream": ["rejection_status_changed"],
     "users_who_share_rooms": ["share_private"],

synapse/api/constants.py

@@ -245,6 +245,8 @@ class EventContentFields:
     # `m.room.encryption`` algorithm field
     ENCRYPTION_ALGORITHM: Final = "algorithm"
 
+    TOMBSTONE_SUCCESSOR_ROOM: Final = "replacement_room"
+
 
 class EventUnsignedContentFields:
     """Fields found inside the 'unsigned' data on events"""

synapse/app/generic_worker.py

@@ -98,6 +98,7 @@ from synapse.storage.databases.main.roommember import RoomMemberWorkerStore
 from synapse.storage.databases.main.search import SearchStore
 from synapse.storage.databases.main.session import SessionStore
 from synapse.storage.databases.main.signatures import SignatureWorkerStore
+from synapse.storage.databases.main.sliding_sync import SlidingSyncStore
 from synapse.storage.databases.main.state import StateGroupWorkerStore
 from synapse.storage.databases.main.stats import StatsStore
 from synapse.storage.databases.main.stream import StreamWorkerStore
@@ -159,6 +160,7 @@ class GenericWorkerStore(
     SessionStore,
     TaskSchedulerWorkerStore,
     ExperimentalFeaturesStore,
+    SlidingSyncStore,
 ):
     # Properties that multiple storage classes define. Tell mypy what the
     # expected type is.

synapse/handlers/sliding_sync/__init__.py

@@ -17,6 +17,7 @@ import logging
 from itertools import chain
 from typing import (
     TYPE_CHECKING,
+    AbstractSet,
     Any,
     Dict,
     List,
@@ -45,13 +46,6 @@ from synapse.events.utils import parse_stripped_state_event, strip_event
 from synapse.handlers.relations import BundledAggregations
 from synapse.handlers.sliding_sync.extensions import SlidingSyncExtensionHandler
 from synapse.handlers.sliding_sync.store import SlidingSyncConnectionStore
-from synapse.handlers.sliding_sync.types import (
-    HaveSentRoomFlag,
-    MutablePerConnectionState,
-    PerConnectionState,
-    RoomSyncConfig,
-    StateValues,
-)
 from synapse.logging.opentracing import (
     SynapseTags,
     log_kv,
@@ -83,7 +77,17 @@ from synapse.types import (
     StreamToken,
     UserID,
 )
-from synapse.types.handlers import OperationType, SlidingSyncConfig, SlidingSyncResult
+from synapse.types.handlers.sliding_sync import (
+    SLIDING_SYNC_DEFAULT_BUMP_EVENT_TYPES,
+    HaveSentRoomFlag,
+    MutablePerConnectionState,
+    OperationType,
+    PerConnectionState,
+    RoomSyncConfig,
+    SlidingSyncConfig,
+    SlidingSyncResult,
+    StateValues,
+)
 from synapse.types.state import StateFilter
 from synapse.util.async_helpers import concurrently_execute
 from synapse.visibility import filter_events_for_client
@@ -107,18 +111,6 @@ class Sentinel(enum.Enum):
     UNSET_SENTINEL = object()
 
 
-# The event types that clients should consider as new activity.
-DEFAULT_BUMP_EVENT_TYPES = {
-    EventTypes.Create,
-    EventTypes.Message,
-    EventTypes.Encrypted,
-    EventTypes.Sticker,
-    EventTypes.CallInvite,
-    EventTypes.PollStart,
-    EventTypes.LiveLocationShareStart,
-}
-
-
 @attr.s(slots=True, frozen=True, auto_attribs=True)
 class _RoomMembershipForUser:
     """
@@ -206,7 +198,7 @@ class SlidingSyncHandler:
         self.rooms_to_exclude_globally = hs.config.server.rooms_to_exclude_from_sync
         self.is_mine_id = hs.is_mine_id
 
-        self.connection_store = SlidingSyncConnectionStore()
+        self.connection_store = SlidingSyncConnectionStore(self.store)
         self.extensions = SlidingSyncExtensionHandler(hs)
 
     async def wait_for_sync_for_user(
@@ -330,11 +322,7 @@ class SlidingSyncHandler:
                 sync_config, from_token
             )
         )
-
-        await self.connection_store.mark_token_seen(
-            sync_config=sync_config,
-            from_token=from_token,
-        )
+        new_connection_state = previous_connection_state.get_mutable()
 
         # Get all of the room IDs that the user should be able to see in the sync
         # response
@@ -352,6 +340,10 @@ class SlidingSyncHandler:
                 )
             )
 
+        lists_to_rooms: Mapping[str, AbstractSet[str]] = {}
+        if previous_connection_state is not None:
+            lists_to_rooms = previous_connection_state.list_to_rooms
+
         # Assemble sliding window lists
         lists: Dict[str, SlidingSyncResult.SlidingWindowList] = {}
         # Keep track of the rooms that we can display and need to fetch more info about
@@ -368,13 +360,26 @@ class SlidingSyncHandler:
 
                 for list_key, list_config in sync_config.lists.items():
                     # Apply filters
-                    filtered_sync_room_map = sync_room_map
-                    if list_config.filters is not None:
-                        filtered_sync_room_map = await self.filter_rooms(
-                            sync_config.user,
-                            sync_room_map,
-                            list_config.filters,
-                            to_token,
+                    previous_found_rooms = lists_to_rooms.get(list_key)
+                    if previous_found_rooms:
+                        filtered_sync_room_map = {
+                            room_id: sync_room_map[room_id]
+                            for room_id in previous_found_rooms
+                        }
+
+                        # TODO: Record changes to the list.
+                    else:
+                        filtered_sync_room_map = sync_room_map
+                        if list_config.filters is not None:
+                            filtered_sync_room_map = await self.filter_rooms(
+                                sync_config.user,
+                                sync_room_map,
+                                list_config.filters,
+                                to_token,
+                            )
+
+                        new_connection_state.list_to_rooms[list_key] = set(
+                            filtered_sync_room_map.keys()
                         )
 
                     # Find which rooms are partially stated and may need to be filtered out
@@ -430,15 +435,11 @@ class SlidingSyncHandler:
                                     room_id
                                 )
                                 if existing_room_sync_config is not None:
-                                    existing_room_sync_config.combine_room_sync_config(
+                                    room_sync_config = existing_room_sync_config.combine_room_sync_config(
                                         room_sync_config
                                     )
-                                else:
-                                    # Make a copy so if we modify it later, it doesn't
-                                    # affect all references.
-                                    relevant_room_map[room_id] = (
-                                        room_sync_config.deep_copy()
-                                    )
+
+                                relevant_room_map[room_id] = room_sync_config
 
                                 room_ids_in_list.append(room_id)
 
@@ -503,11 +504,13 @@ class SlidingSyncHandler:
                     # and need to fetch more info about.
                     existing_room_sync_config = relevant_room_map.get(room_id)
                     if existing_room_sync_config is not None:
-                        existing_room_sync_config.combine_room_sync_config(
-                            room_sync_config
+                        room_sync_config = (
+                            existing_room_sync_config.combine_room_sync_config(
+                                room_sync_config
+                            )
                         )
-                    else:
-                        relevant_room_map[room_id] = room_sync_config
+
+                    relevant_room_map[room_id] = room_sync_config
 
         # Fetch room data
         rooms: Dict[str, SlidingSyncResult.RoomResult] = {}
@@ -569,8 +572,6 @@ class SlidingSyncHandler:
                     if room_id in rooms_should_send
                 }
 
-        new_connection_state = previous_connection_state.get_mutable()
-
         @trace
         @tag_args
         async def handle_room(room_id: str) -> None:
@@ -2229,7 +2230,9 @@ class SlidingSyncHandler:
         # Figure out the last bump event in the room
         last_bump_event_result = (
             await self.store.get_last_event_pos_in_room_before_stream_ordering(
-                room_id, to_token.room_key, event_types=DEFAULT_BUMP_EVENT_TYPES
+                room_id,
+                to_token.room_key,
+                event_types=SLIDING_SYNC_DEFAULT_BUMP_EVENT_TYPES,
             )
         )
 

synapse/handlers/sliding_sync/extensions.py

@@ -19,11 +19,6 @@ from typing_extensions import assert_never
 
 from synapse.api.constants import AccountDataTypes
 from synapse.handlers.receipts import ReceiptEventSource
-from synapse.handlers.sliding_sync.types import (
-    HaveSentRoomFlag,
-    MutablePerConnectionState,
-    PerConnectionState,
-)
 from synapse.logging.opentracing import trace
 from synapse.types import (
     DeviceListUpdates,
@@ -32,7 +27,14 @@ from synapse.types import (
     SlidingSyncStreamToken,
     StreamToken,
 )
-from synapse.types.handlers import OperationType, SlidingSyncConfig, SlidingSyncResult
+from synapse.types.handlers.sliding_sync import (
+    HaveSentRoomFlag,
+    MutablePerConnectionState,
+    OperationType,
+    PerConnectionState,
+    SlidingSyncConfig,
+    SlidingSyncResult,
+)
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer

synapse/handlers/sliding_sync/store.py

@@ -13,18 +13,18 @@
 #
 
 import logging
-from typing import TYPE_CHECKING, Dict, Optional, Tuple
+from typing import TYPE_CHECKING, Optional
 
 import attr
 
-from synapse.api.errors import SlidingSyncUnknownPosition
-from synapse.handlers.sliding_sync.types import (
+from synapse.logging.opentracing import trace
+from synapse.storage.databases.main import DataStore
+from synapse.types import SlidingSyncStreamToken
+from synapse.types.handlers.sliding_sync import (
     MutablePerConnectionState,
     PerConnectionState,
+    SlidingSyncConfig,
 )
-from synapse.logging.opentracing import trace
-from synapse.types import SlidingSyncStreamToken
-from synapse.types.handlers import SlidingSyncConfig
 
 if TYPE_CHECKING:
     pass
@@ -61,20 +61,7 @@ class SlidingSyncConnectionStore:
             to mapping of room ID to `HaveSentRoom`.
     """
 
-    # `(user_id, conn_id)` -> `connection_position` -> `PerConnectionState`
-    _connections: Dict[Tuple[str, str], Dict[int, PerConnectionState]] = attr.Factory(
-        dict
-    )
-
-    async def is_valid_token(
-        self, sync_config: SlidingSyncConfig, connection_token: int
-    ) -> bool:
-        """Return whether the connection token is valid/recognized"""
-        if connection_token == 0:
-            return True
-
-        conn_key = self._get_connection_key(sync_config)
-        return connection_token in self._connections.get(conn_key, {})
+    store: "DataStore"
 
     async def get_per_connection_state(
         self,
@@ -86,23 +73,20 @@ class SlidingSyncConnectionStore:
         Raises:
             SlidingSyncUnknownPosition if the connection_token is unknown
         """
-        if from_token is None:
+        if from_token is None or from_token.connection_position == 0:
             return PerConnectionState()
 
-        connection_position = from_token.connection_position
-        if connection_position == 0:
-            # Initial sync (request without a `from_token`) starts at `0` so
-            # there is no existing per-connection state
-            return PerConnectionState()
+        conn_id = sync_config.conn_id or ""
 
-        conn_key = self._get_connection_key(sync_config)
-        sync_statuses = self._connections.get(conn_key, {})
-        connection_state = sync_statuses.get(connection_position)
+        device_id = sync_config.requester.device_id
+        assert device_id is not None
 
-        if connection_state is None:
-            raise SlidingSyncUnknownPosition()
-
-        return connection_state
+        return await self.store.get_per_connection_state(
+            sync_config.user.to_string(),
+            device_id,
+            conn_id,
+            from_token.connection_position,
+        )
 
     @trace
     async def record_new_state(
@@ -116,85 +100,24 @@ class SlidingSyncConnectionStore:
         If there are no changes to the state this may return the same token as
         the existing per-connection state.
         """
-        prev_connection_token = 0
-        if from_token is not None:
-            prev_connection_token = from_token.connection_position
-
         if not new_connection_state.has_updates():
-            return prev_connection_token
+            if from_token is not None:
+                return from_token.connection_position
+            else:
+                return 0
 
-        conn_key = self._get_connection_key(sync_config)
-        sync_statuses = self._connections.setdefault(conn_key, {})
+        if from_token is not None and from_token.connection_position == 0:
+            from_token = None
 
-        # Generate a new token, removing any existing entries in that token
-        # (which can happen if requests get resent).
-        new_store_token = prev_connection_token + 1
-        sync_statuses.pop(new_store_token, None)
-
-        # We copy the `MutablePerConnectionState` so that the inner `ChainMap`s
-        # don't grow forever.
-        sync_statuses[new_store_token] = new_connection_state.copy()
-
-        return new_store_token
-
-    @trace
-    async def mark_token_seen(
-        self,
-        sync_config: SlidingSyncConfig,
-        from_token: Optional[SlidingSyncStreamToken],
-    ) -> None:
-        """We have received a request with the given token, so we can clear out
-        any other tokens associated with the connection.
-
-        If there is no from token then we have started afresh, and so we delete
-        all tokens associated with the device.
-        """
-        # Clear out any tokens for the connection that doesn't match the one
-        # from the request.
-
-        conn_key = self._get_connection_key(sync_config)
-        sync_statuses = self._connections.pop(conn_key, {})
-        if from_token is None:
-            return
-
-        sync_statuses = {
-            connection_token: room_statuses
-            for connection_token, room_statuses in sync_statuses.items()
-            if connection_token == from_token.connection_position
-        }
-        if sync_statuses:
-            self._connections[conn_key] = sync_statuses
-
-    @staticmethod
-    def _get_connection_key(sync_config: SlidingSyncConfig) -> Tuple[str, str]:
-        """Return a unique identifier for this connection.
-
-        The first part is simply the user ID.
-
-        The second part is generally a combination of device ID and conn_id.
-        However, both these two are optional (e.g. puppet access tokens don't
-        have device IDs), so this handles those edge cases.
-
-        We use this over the raw `conn_id` to avoid clashes between different
-        clients that use the same `conn_id`. Imagine a user uses a web client
-        that uses `conn_id: main_sync_loop` and an Android client that also has
-        a `conn_id: main_sync_loop`.
-        """
-
-        user_id = sync_config.user.to_string()
-
-        # Only one sliding sync connection is allowed per given conn_id (empty
-        # or not).
         conn_id = sync_config.conn_id or ""
 
-        if sync_config.requester.device_id:
-            return (user_id, f"D/{sync_config.requester.device_id}/{conn_id}")
+        device_id = sync_config.requester.device_id
+        assert device_id is not None
 
-        if sync_config.requester.access_token_id:
-            # If we don't have a device, then the access token ID should be a
-            # stable ID.
-            return (user_id, f"A/{sync_config.requester.access_token_id}/{conn_id}")
-
-        # If we have neither then its likely an AS or some weird token. Either
-        # way we can just fail here.
-        raise Exception("Cannot use sliding sync with access token type")
+        return await self.store.persist_per_connection_state(
+            sync_config.user.to_string(),
+            device_id,
+            conn_id,
+            from_token.connection_position if from_token else None,
+            new_connection_state,
+        )

synapse/storage/controllers/persist_events.py

@@ -502,8 +502,15 @@ class EventsPersistenceStorageController:
         """
         state = await self._calculate_current_state(room_id)
         delta = await self._calculate_state_delta(room_id, state)
+        sliding_sync_table_changes = (
+            await self.persist_events_store._calculate_sliding_sync_table_changes(
+                room_id, [], delta
+            )
+        )
 
-        await self.persist_events_store.update_current_state(room_id, delta)
+        await self.persist_events_store.update_current_state(
+            room_id, delta, sliding_sync_table_changes
+        )
 
     async def _calculate_current_state(self, room_id: str) -> StateMap[str]:
         """Calculate the current state of a room, based on the forward extremities

synapse/storage/database.py

@@ -35,6 +35,7 @@ from typing import (
     Iterable,
     Iterator,
     List,
+    Mapping,
     Optional,
     Sequence,
     Tuple,
@@ -64,6 +65,7 @@ from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.storage.background_updates import BackgroundUpdater
 from synapse.storage.engines import BaseDatabaseEngine, PostgresEngine, Sqlite3Engine
 from synapse.storage.types import Connection, Cursor, SQLQueryParameters
+from synapse.types import StrCollection
 from synapse.util.async_helpers import delay_cancellation
 from synapse.util.iterutils import batch_iter
 
@@ -1095,6 +1097,50 @@ class DatabasePool:
 
         txn.execute(sql, vals)
 
+    @staticmethod
+    def simple_insert_returning_txn(
+        txn: LoggingTransaction,
+        table: str,
+        values: Dict[str, Any],
+        returning: StrCollection,
+    ) -> Tuple[Any, ...]:
+        """Executes a `INSERT INTO... RETURNING...` statement (or equivalent for
+        SQLite versions that don't support it).
+        """
+
+        if txn.database_engine.supports_returning:
+            keys, vals = zip(*values.items())
+
+            sql = "INSERT INTO %s (%s) VALUES(%s) RETURNING %s" % (
+                table,
+                ", ".join(k for k in keys),
+                ", ".join("?" for _ in keys),
+                ", ".join(k for k in returning),
+            )
+
+            txn.execute(sql, vals)
+            row = txn.fetchone()
+            assert row is not None
+            return row
+        else:
+            # For old versions of SQLite we do a standard insert and then can
+            # use `last_insert_rowid` to get at the row we just inserted
+            DatabasePool.simple_insert_txn(
+                txn,
+                table=table,
+                values=values,
+            )
+            txn.execute("SELECT last_insert_rowid()")
+            row = txn.fetchone()
+            assert row is not None
+            (rowid,) = row
+
+            row = DatabasePool.simple_select_one_txn(
+                txn, table=table, keyvalues={"rowid": rowid}, retcols=returning
+            )
+            assert row is not None
+            return row
+
     async def simple_insert_many(
         self,
         table: str,
@@ -1254,9 +1300,9 @@ class DatabasePool:
         self,
         txn: LoggingTransaction,
         table: str,
-        keyvalues: Dict[str, Any],
-        values: Dict[str, Any],
-        insertion_values: Optional[Dict[str, Any]] = None,
+        keyvalues: Mapping[str, Any],
+        values: Mapping[str, Any],
+        insertion_values: Optional[Mapping[str, Any]] = None,
         where_clause: Optional[str] = None,
     ) -> bool:
         """
@@ -1299,9 +1345,9 @@ class DatabasePool:
         self,
         txn: LoggingTransaction,
         table: str,
-        keyvalues: Dict[str, Any],
-        values: Dict[str, Any],
-        insertion_values: Optional[Dict[str, Any]] = None,
+        keyvalues: Mapping[str, Any],
+        values: Mapping[str, Any],
+        insertion_values: Optional[Mapping[str, Any]] = None,
         where_clause: Optional[str] = None,
         lock: bool = True,
     ) -> bool:
@@ -1322,7 +1368,7 @@ class DatabasePool:
 
         if lock:
             # We need to lock the table :(
-            self.engine.lock_table(txn, table)
+            txn.database_engine.lock_table(txn, table)
 
         def _getwhere(key: str) -> str:
             # If the value we're passing in is None (aka NULL), we need to use
@@ -1376,13 +1422,13 @@ class DatabasePool:
         # successfully inserted
         return True
 
+    @staticmethod
     def simple_upsert_txn_native_upsert(
-        self,
         txn: LoggingTransaction,
         table: str,
-        keyvalues: Dict[str, Any],
-        values: Dict[str, Any],
-        insertion_values: Optional[Dict[str, Any]] = None,
+        keyvalues: Mapping[str, Any],
+        values: Mapping[str, Any],
+        insertion_values: Optional[Mapping[str, Any]] = None,
         where_clause: Optional[str] = None,
     ) -> bool:
         """
@@ -1535,8 +1581,8 @@ class DatabasePool:
 
             self.simple_upsert_txn_emulated(txn, table, _keys, _vals, lock=False)
 
+    @staticmethod
     def simple_upsert_many_txn_native_upsert(
-        self,
         txn: LoggingTransaction,
         table: str,
         key_names: Collection[str],
@@ -1966,8 +2012,8 @@ class DatabasePool:
     def simple_update_txn(
         txn: LoggingTransaction,
         table: str,
-        keyvalues: Dict[str, Any],
-        updatevalues: Dict[str, Any],
+        keyvalues: Mapping[str, Any],
+        updatevalues: Mapping[str, Any],
     ) -> int:
         """
         Update rows in the given database table.

synapse/storage/databases/main/__init__.py

@@ -33,6 +33,7 @@ from synapse.storage.database import (
     LoggingDatabaseConnection,
     LoggingTransaction,
 )
+from synapse.storage.databases.main.sliding_sync import SlidingSyncStore
 from synapse.storage.databases.main.stats import UserSortOrder
 from synapse.storage.engines import BaseDatabaseEngine
 from synapse.storage.types import Cursor
@@ -156,6 +157,7 @@ class DataStore(
     LockStore,
     SessionStore,
     TaskSchedulerWorkerStore,
+    SlidingSyncStore,
 ):
     def __init__(
         self,

synapse/storage/databases/main/cache.py

@@ -313,6 +313,8 @@ class CacheInvalidationWorkerStore(SQLBaseStore):
             "get_unread_event_push_actions_by_room_for_user", (room_id,)
         )
 
+        self._attempt_to_invalidate_cache("_get_max_event_pos", (room_id,))
+
         # The `_get_membership_from_event_id` is immutable, except for the
         # case where we look up an event *before* persisting it.
         self._attempt_to_invalidate_cache("_get_membership_from_event_id", (event_id,))

synapse/storage/databases/main/events_worker.py

@@ -457,6 +457,8 @@ class EventsWorkerStore(SQLBaseStore):
     ) -> Optional[EventBase]:
         """Get an event from the database by event_id.
 
+        Events for unknown room versions will also be filtered out.
+
         Args:
             event_id: The event_id of the event to fetch
 
@@ -511,6 +513,10 @@ class EventsWorkerStore(SQLBaseStore):
     ) -> Dict[str, EventBase]:
         """Get events from the database
 
+        Unknown events will be omitted from the response.
+
+        Events for unknown room versions will also be filtered out.
+
         Args:
             event_ids: The event_ids of the events to fetch
 
@@ -553,6 +559,8 @@ class EventsWorkerStore(SQLBaseStore):
 
         Unknown events will be omitted from the response.
 
+        Events for unknown room versions will also be filtered out.
+
         Args:
             event_ids: The event_ids of the events to fetch
 

synapse/storage/databases/main/purge_events.py

@@ -454,6 +454,10 @@ class PurgeEventsStore(StateGroupWorkerStore, CacheInvalidationWorkerStore):
             # so must be deleted first.
             "local_current_membership",
             "room_memberships",
+            # Note: the sliding_sync_ tables have foreign keys to the `events` table
+            # so must be deleted first.
+            "sliding_sync_joined_rooms",
+            "sliding_sync_membership_snapshots",
             "events",
             "federation_inbound_events_staging",
             "receipts_graph",

synapse/storage/databases/main/roommember.py

@@ -1337,6 +1337,12 @@ class RoomMemberWorkerStore(EventsWorkerStore, CacheInvalidationWorkerStore):
                 keyvalues={"user_id": user_id, "room_id": room_id},
                 updatevalues={"forgotten": 1},
             )
+            self.db_pool.simple_update_txn(
+                txn,
+                table="sliding_sync_membership_snapshots",
+                keyvalues={"user_id": user_id, "room_id": room_id},
+                updatevalues={"forgotten": 1},
+            )
 
             self._invalidate_cache_and_stream(txn, self.did_forget, (user_id, room_id))
             self._invalidate_cache_and_stream(

synapse/storage/databases/main/sliding_sync.py

@@ -0,0 +1,506 @@
+#
+# This file is licensed under the Affero General Public License (AGPL) version 3.
+#
+# Copyright (C) 2023 New Vector, Ltd
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# See the GNU Affero General Public License for more details:
+# <https://www.gnu.org/licenses/agpl-3.0.html>.
+#
+
+
+from typing import TYPE_CHECKING, AbstractSet, Dict, List, Mapping, Optional, Set, cast
+
+import attr
+
+from synapse.api.errors import SlidingSyncUnknownPosition
+from synapse.logging.opentracing import log_kv
+from synapse.storage._base import SQLBaseStore, db_to_json
+from synapse.storage.database import LoggingTransaction
+from synapse.types import MultiWriterStreamToken, RoomStreamToken
+from synapse.types.handlers.sliding_sync import (
+    HaveSentRoom,
+    HaveSentRoomFlag,
+    MutablePerConnectionState,
+    PerConnectionState,
+    RoomStatusMap,
+    RoomSyncConfig,
+)
+from synapse.util import json_encoder
+from synapse.util.caches.descriptors import cached
+
+if TYPE_CHECKING:
+    from synapse.storage.databases.main import DataStore
+
+
+class SlidingSyncStore(SQLBaseStore):
+    async def persist_per_connection_state(
+        self,
+        user_id: str,
+        device_id: str,
+        conn_id: str,
+        previous_connection_position: Optional[int],
+        per_connection_state: "MutablePerConnectionState",
+    ) -> int:
+        """Persist updates to the per-connection state for a sliding sync
+        connection.
+
+        Returns:
+            The connection position of the newly persisted state.
+        """
+
+        store = cast("DataStore", self)
+        return await self.db_pool.runInteraction(
+            "persist_per_connection_state",
+            self.persist_per_connection_state_txn,
+            user_id=user_id,
+            device_id=device_id,
+            conn_id=conn_id,
+            previous_connection_position=previous_connection_position,
+            per_connection_state=await PerConnectionStateDB.from_state(
+                per_connection_state, store
+            ),
+        )
+
+    def persist_per_connection_state_txn(
+        self,
+        txn: LoggingTransaction,
+        user_id: str,
+        device_id: str,
+        conn_id: str,
+        previous_connection_position: Optional[int],
+        per_connection_state: "PerConnectionStateDB",
+    ) -> int:
+        # First we fetch the (or create) the connection key associated with the
+        # previous connection position.
+        if previous_connection_position is not None:
+            # The `previous_connection_position` is a user-supplied value, so we
+            # need to make sure that the one they supplied is actually theirs.
+            sql = """
+                SELECT connection_key
+                FROM sliding_sync_connection_positions
+                INNER JOIN sliding_sync_connections USING (connection_key)
+                WHERE
+                    connection_position = ?
+                    AND user_id = ? AND device_id = ? AND conn_id = ?
+            """
+            txn.execute(
+                sql, (previous_connection_position, user_id, device_id, conn_id)
+            )
+            row = txn.fetchone()
+            if row is None:
+                raise SlidingSyncUnknownPosition()
+
+            (connection_key,) = row
+        else:
+            # We're restarting the connection, so we clear all existing
+            # connections. We do this here to ensure that if we get lots of
+            # one-shot requests we don't stack up lots of entries.
+            self.db_pool.simple_delete_txn(
+                txn,
+                table="sliding_sync_connections",
+                keyvalues={
+                    "user_id": user_id,
+                    "device_id": device_id,
+                    "conn_id": conn_id,
+                },
+            )
+
+            (connection_key,) = self.db_pool.simple_insert_returning_txn(
+                txn,
+                table="sliding_sync_connections",
+                values={
+                    "user_id": user_id,
+                    "device_id": device_id,
+                    "conn_id": conn_id,
+                    "created_ts": self._clock.time_msec(),
+                },
+                returning=("connection_key",),
+            )
+
+        # Define a new connection position for the updates
+        (connection_position,) = self.db_pool.simple_insert_returning_txn(
+            txn,
+            table="sliding_sync_connection_positions",
+            values={
+                "connection_key": connection_key,
+                "created_ts": self._clock.time_msec(),
+            },
+            returning=("connection_position",),
+        )
+
+        # We need to deduplicate the `required_state` JSON. We do this by
+        # fetching all JSON associated with the connection and comparing that
+        # with the updates to `required_state`
+
+        # Dict from required state json -> required state ID
+        required_state_to_id: Dict[str, int] = {}
+        if previous_connection_position is not None:
+            rows = self.db_pool.simple_select_list_txn(
+                txn,
+                table="sliding_sync_connection_required_state",
+                keyvalues={"connection_key": connection_key},
+                retcols=("required_state_id", "required_state"),
+            )
+            for required_state_id, required_state in rows:
+                required_state_to_id[required_state] = required_state_id
+
+        room_to_state_ids: Dict[str, int] = {}
+        unique_required_state: Dict[str, List[str]] = {}
+        for room_id, room_state in per_connection_state.room_configs.items():
+            serialized_state = json_encoder.encode(
+                # We store the required state as a sorted list of event type /
+                # state key tuples.
+                sorted(
+                    (event_type, state_key)
+                    for event_type, state_keys in room_state.required_state_map.items()
+                    for state_key in state_keys
+                )
+            )
+
+            existing_state_id = required_state_to_id.get(serialized_state)
+            if existing_state_id is not None:
+                room_to_state_ids[room_id] = existing_state_id
+            else:
+                unique_required_state.setdefault(serialized_state, []).append(room_id)
+
+        # Insert any new `required_state` json we haven't previously seen.
+        for serialized_required_state, room_ids in unique_required_state.items():
+            (required_state_id,) = self.db_pool.simple_insert_returning_txn(
+                txn,
+                table="sliding_sync_connection_required_state",
+                values={
+                    "connection_key": connection_key,
+                    "required_state": serialized_required_state,
+                },
+                returning=("required_state_id",),
+            )
+            for room_id in room_ids:
+                room_to_state_ids[room_id] = required_state_id
+
+        # Copy over state from the previous connection position (we'll overwrite
+        # these rows with any changes).
+        if previous_connection_position is not None:
+            sql = """
+                INSERT INTO sliding_sync_connection_streams
+                (connection_position, stream, room_id, room_status, last_position)
+                SELECT ?, stream, room_id, room_status, last_position
+                FROM sliding_sync_connection_streams
+                WHERE connection_position = ?
+            """
+            txn.execute(sql, (connection_position, previous_connection_position))
+
+            sql = """
+                INSERT INTO sliding_sync_connection_room_configs
+                (connection_position, room_id, timeline_limit, required_state_id)
+                SELECT ?, room_id, timeline_limit, required_state_id
+                FROM sliding_sync_connection_room_configs
+                WHERE connection_position = ?
+            """
+            txn.execute(sql, (connection_position, previous_connection_position))
+
+        # We now upsert the changes to the various streams.
+        key_values = []
+        value_values = []
+        for room_id, have_sent_room in per_connection_state.rooms._statuses.items():
+            key_values.append((connection_position, "rooms", room_id))
+            value_values.append(
+                (have_sent_room.status.value, have_sent_room.last_token)
+            )
+
+        for room_id, have_sent_room in per_connection_state.receipts._statuses.items():
+            key_values.append((connection_position, "receipts", room_id))
+            value_values.append(
+                (have_sent_room.status.value, have_sent_room.last_token)
+            )
+
+        self.db_pool.simple_upsert_many_txn(
+            txn,
+            table="sliding_sync_connection_streams",
+            key_names=(
+                "connection_position",
+                "stream",
+                "room_id",
+            ),
+            key_values=key_values,
+            value_names=(
+                "room_status",
+                "last_position",
+            ),
+            value_values=value_values,
+        )
+
+        # ... and upsert changes to the room configs.
+        keys = []
+        values = []
+        for room_id, room_config in per_connection_state.room_configs.items():
+            keys.append((connection_position, room_id))
+            values.append((room_config.timeline_limit, room_to_state_ids[room_id]))
+
+        self.db_pool.simple_upsert_many_txn(
+            txn,
+            table="sliding_sync_connection_room_configs",
+            key_names=(
+                "connection_position",
+                "room_id",
+            ),
+            key_values=keys,
+            value_names=(
+                "timeline_limit",
+                "required_state_id",
+            ),
+            value_values=values,
+        )
+
+        # Persist changes to the room lists
+        for list_name, list_room_ids in per_connection_state.list_to_rooms.items():
+            self.db_pool.simple_delete_txn(
+                txn,
+                table="sliding_sync_connection_room_lists",
+                keyvalues={"connection_key": connection_key, "list_name": list_name},
+            )
+            self.db_pool.simple_insert_many_txn(
+                txn,
+                table="sliding_sync_connection_room_lists",
+                keys=("connection_key", "list_name", "room_id"),
+                values=[
+                    (connection_key, list_name, room_id) for room_id in list_room_ids
+                ],
+            )
+
+        return connection_position
+
+    @cached(iterable=True, max_entries=100000)
+    async def get_per_connection_state(
+        self, user_id: str, device_id: str, conn_id: str, connection_position: int
+    ) -> "PerConnectionState":
+        """Get the per-connection state for the given connection position."""
+
+        per_connection_state_db = await self.db_pool.runInteraction(
+            "get_per_connection_state",
+            self._get_per_connection_state_txn,
+            user_id=user_id,
+            device_id=device_id,
+            conn_id=conn_id,
+            connection_position=connection_position,
+        )
+        store = cast("DataStore", self)
+        return await per_connection_state_db.to_state(store)
+
+    def _get_per_connection_state_txn(
+        self,
+        txn: LoggingTransaction,
+        user_id: str,
+        device_id: str,
+        conn_id: str,
+        connection_position: int,
+    ) -> "PerConnectionStateDB":
+        # The `previous_connection_position` is a user-supplied value, so we
+        # need to make sure that the one they supplied is actually theirs.
+        sql = """
+            SELECT connection_key
+            FROM sliding_sync_connection_positions
+            INNER JOIN sliding_sync_connections USING (connection_key)
+            WHERE
+                connection_position = ?
+                AND user_id = ? AND device_id = ? AND conn_id = ?
+        """
+        txn.execute(sql, (connection_position, user_id, device_id, conn_id))
+        row = txn.fetchone()
+        if row is None:
+            raise SlidingSyncUnknownPosition()
+
+        (connection_key,) = row
+
+        # Now that we have seen the client has received and used the connection
+        # position, we can delete all the other connection positions.
+        sql = """
+            DELETE FROM sliding_sync_connection_positions
+            WHERE connection_key = ? AND connection_position != ?
+        """
+        txn.execute(sql, (connection_key, connection_position))
+
+        # Fetch and create a mapping from required state ID to the actual
+        # required state for the connection.
+        rows = self.db_pool.simple_select_list_txn(
+            txn,
+            table="sliding_sync_connection_required_state",
+            keyvalues={"connection_key": connection_key},
+            retcols=(
+                "required_state_id",
+                "required_state",
+            ),
+        )
+
+        required_state_map: Dict[int, Dict[str, Set[str]]] = {}
+        for row in rows:
+            state = required_state_map[row[0]] = {}
+            for event_type, state_keys in db_to_json(row[1]):
+                state[event_type] = set(state_keys)
+
+        # Get all the room configs, looking up the required state from the map
+        # above.
+        room_config_rows = self.db_pool.simple_select_list_txn(
+            txn,
+            table="sliding_sync_connection_room_configs",
+            keyvalues={"connection_position": connection_position},
+            retcols=(
+                "room_id",
+                "timeline_limit",
+                "required_state_id",
+            ),
+        )
+
+        room_configs: Dict[str, RoomSyncConfig] = {}
+        for (
+            room_id,
+            timeline_limit,
+            required_state_id,
+        ) in room_config_rows:
+            room_configs[room_id] = RoomSyncConfig(
+                timeline_limit=timeline_limit,
+                required_state_map=required_state_map[required_state_id],
+            )
+
+        # Now look up the per-room stream data.
+        rooms: Dict[str, HaveSentRoom[str]] = {}
+        receipts: Dict[str, HaveSentRoom[str]] = {}
+
+        receipt_rows = self.db_pool.simple_select_list_txn(
+            txn,
+            table="sliding_sync_connection_streams",
+            keyvalues={"connection_position": connection_position},
+            retcols=(
+                "stream",
+                "room_id",
+                "room_status",
+                "last_position",
+            ),
+        )
+        for stream, room_id, room_status, last_position in receipt_rows:
+            have_sent_room: HaveSentRoom[str] = HaveSentRoom(
+                status=HaveSentRoomFlag(room_status), last_token=last_position
+            )
+            if stream == "rooms":
+                rooms[room_id] = have_sent_room
+            elif stream == "receipts":
+                receipts[room_id] = have_sent_room
+
+        # Fetch any stored lists for the connection
+        rows = self.db_pool.simple_select_list_txn(
+            txn,
+            table="sliding_sync_connection_room_lists",
+            keyvalues={
+                connection_key: connection_key,
+            },
+            retcols=("list_name", "room_id"),
+        )
+        list_to_rooms: Dict[str, Set[str]] = {}
+        for list_name, room_id in rows:
+            list_to_rooms.setdefault(list_name, set()).add(room_id)
+
+        return PerConnectionStateDB(
+            rooms=RoomStatusMap(rooms),
+            receipts=RoomStatusMap(receipts),
+            room_configs=room_configs,
+            list_to_rooms=list_to_rooms,
+        )
+
+
+@attr.s(auto_attribs=True, frozen=True)
+class PerConnectionStateDB:
+    """An equivalent to `PerConnectionState` that holds data in a format stored
+    in the DB.
+
+    The principle difference is that the tokens for the different streams are
+    serialized to strings.
+
+    When persisting this *only* contains updates to the state.
+    """
+
+    rooms: "RoomStatusMap[str]"
+    receipts: "RoomStatusMap[str]"
+
+    room_configs: Mapping[str, "RoomSyncConfig"]
+    list_to_rooms: Mapping[str, AbstractSet[str]]
+
+    @staticmethod
+    async def from_state(
+        per_connection_state: "MutablePerConnectionState", store: "DataStore"
+    ) -> "PerConnectionStateDB":
+        """Convert from a standard `PerConnectionState`"""
+        rooms = {
+            room_id: HaveSentRoom(
+                status=status.status,
+                last_token=(
+                    await status.last_token.to_string(store)
+                    if status.last_token is not None
+                    else None
+                ),
+            )
+            for room_id, status in per_connection_state.rooms.get_updates().items()
+        }
+
+        receipts = {
+            room_id: HaveSentRoom(
+                status=status.status,
+                last_token=(
+                    await status.last_token.to_string(store)
+                    if status.last_token is not None
+                    else None
+                ),
+            )
+            for room_id, status in per_connection_state.receipts.get_updates().items()
+        }
+
+        log_kv(
+            {
+                "rooms": rooms,
+                "receipts": receipts,
+                "room_configs": per_connection_state.room_configs.maps[0],
+            }
+        )
+
+        return PerConnectionStateDB(
+            rooms=RoomStatusMap(rooms),
+            receipts=RoomStatusMap(receipts),
+            room_configs=per_connection_state.room_configs.maps[0],
+            list_to_rooms=per_connection_state.list_to_rooms.maps[0],
+        )
+
+    async def to_state(self, store: "DataStore") -> "PerConnectionState":
+        """Convert into a standard `PerConnectionState`"""
+        rooms = {
+            room_id: HaveSentRoom(
+                status=status.status,
+                last_token=(
+                    await RoomStreamToken.parse(store, status.last_token)
+                    if status.last_token is not None
+                    else None
+                ),
+            )
+            for room_id, status in self.rooms._statuses.items()
+        }
+
+        receipts = {
+            room_id: HaveSentRoom(
+                status=status.status,
+                last_token=(
+                    await MultiWriterStreamToken.parse(store, status.last_token)
+                    if status.last_token is not None
+                    else None
+                ),
+            )
+            for room_id, status in self.receipts._statuses.items()
+        }
+
+        return PerConnectionState(
+            rooms=RoomStatusMap(rooms),
+            receipts=RoomStatusMap(receipts),
+            room_configs=self.room_configs,
+            list_to_rooms=self.list_to_rooms,
+        )

synapse/storage/databases/main/state_deltas.py

@@ -161,45 +161,80 @@ class StateDeltasStore(SQLBaseStore):
             self._get_max_stream_id_in_current_state_deltas_txn,
         )
 
+    def get_current_state_deltas_for_room_txn(
+        self,
+        txn: LoggingTransaction,
+        room_id: str,
+        *,
+        from_token: Optional[RoomStreamToken],
+        to_token: Optional[RoomStreamToken],
+    ) -> List[StateDelta]:
+        """
+        Get the state deltas between two tokens.
+
+        (> `from_token` and <= `to_token`)
+        """
+        from_clause = ""
+        from_args = []
+        if from_token is not None:
+            from_clause = "AND ? < stream_id"
+            from_args = [from_token.stream]
+
+        to_clause = ""
+        to_args = []
+        if to_token is not None:
+            to_clause = "AND stream_id <= ?"
+            to_args = [to_token.get_max_stream_pos()]
+
+        sql = f"""
+                SELECT instance_name, stream_id, type, state_key, event_id, prev_event_id
+                FROM current_state_delta_stream
+                WHERE room_id = ? {from_clause} {to_clause}
+                ORDER BY stream_id ASC
+            """
+        txn.execute(sql, [room_id] + from_args + to_args)
+
+        return [
+            StateDelta(
+                stream_id=row[1],
+                room_id=room_id,
+                event_type=row[2],
+                state_key=row[3],
+                event_id=row[4],
+                prev_event_id=row[5],
+            )
+            for row in txn
+            if _filter_results_by_stream(from_token, to_token, row[0], row[1])
+        ]
+
     @trace
     async def get_current_state_deltas_for_room(
-        self, room_id: str, from_token: RoomStreamToken, to_token: RoomStreamToken
+        self,
+        room_id: str,
+        *,
+        from_token: Optional[RoomStreamToken],
+        to_token: Optional[RoomStreamToken],
     ) -> List[StateDelta]:
-        """Get the state deltas between two tokens."""
+        """
+        Get the state deltas between two tokens.
 
-        if not self._curr_state_delta_stream_cache.has_entity_changed(
-            room_id, from_token.stream
+        (> `from_token` and <= `to_token`)
+        """
+
+        if (
+            from_token is not None
+            and not self._curr_state_delta_stream_cache.has_entity_changed(
+                room_id, from_token.stream
+            )
         ):
             return []
 
-        def get_current_state_deltas_for_room_txn(
-            txn: LoggingTransaction,
-        ) -> List[StateDelta]:
-            sql = """
-                SELECT instance_name, stream_id, type, state_key, event_id, prev_event_id
-                FROM current_state_delta_stream
-                WHERE room_id = ? AND ? < stream_id AND stream_id <= ?
-                ORDER BY stream_id ASC
-            """
-            txn.execute(
-                sql, (room_id, from_token.stream, to_token.get_max_stream_pos())
-            )
-
-            return [
-                StateDelta(
-                    stream_id=row[1],
-                    room_id=room_id,
-                    event_type=row[2],
-                    state_key=row[3],
-                    event_id=row[4],
-                    prev_event_id=row[5],
-                )
-                for row in txn
-                if _filter_results_by_stream(from_token, to_token, row[0], row[1])
-            ]
-
         return await self.db_pool.runInteraction(
-            "get_current_state_deltas_for_room", get_current_state_deltas_for_room_txn
+            "get_current_state_deltas_for_room",
+            self.get_current_state_deltas_for_room_txn,
+            room_id,
+            from_token=from_token,
+            to_token=to_token,
         )
 
     @trace

synapse/storage/databases/main/stream.py

@@ -50,6 +50,7 @@ from typing import (
     Dict,
     Iterable,
     List,
+    Mapping,
     Optional,
     Protocol,
     Set,
@@ -80,7 +81,7 @@ from synapse.storage.databases.main.events_worker import EventsWorkerStore
 from synapse.storage.engines import BaseDatabaseEngine, PostgresEngine, Sqlite3Engine
 from synapse.storage.util.id_generators import MultiWriterIdGenerator
 from synapse.types import PersistedEventPosition, RoomStreamToken, StrCollection
-from synapse.util.caches.descriptors import cached
+from synapse.util.caches.descriptors import cached, cachedList
 from synapse.util.caches.stream_change_cache import StreamChangeCache
 from synapse.util.cancellation import cancellable
 from synapse.util.iterutils import batch_iter
@@ -1263,12 +1264,76 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
 
         return None
 
+    async def get_last_event_pos_in_room(
+        self,
+        room_id: str,
+        event_types: Optional[StrCollection] = None,
+    ) -> Optional[Tuple[str, PersistedEventPosition]]:
+        """
+        Returns the ID and event position of the last event in a room.
+
+        Based on `get_last_event_pos_in_room_before_stream_ordering(...)`
+
+        Args:
+            room_id
+            event_types: Optional allowlist of event types to filter by
+
+        Returns:
+            The ID of the most recent event and it's position, or None if there are no
+            events in the room that match the given event types.
+        """
+
+        def _get_last_event_pos_in_room_txn(
+            txn: LoggingTransaction,
+        ) -> Optional[Tuple[str, PersistedEventPosition]]:
+            event_type_clause = ""
+            event_type_args: List[str] = []
+            if event_types is not None and len(event_types) > 0:
+                event_type_clause, event_type_args = make_in_list_sql_clause(
+                    txn.database_engine, "type", event_types
+                )
+                event_type_clause = f"AND {event_type_clause}"
+
+            sql = f"""
+            SELECT event_id, stream_ordering, instance_name
+            FROM events
+            LEFT JOIN rejections USING (event_id)
+            WHERE room_id = ?
+                {event_type_clause}
+                AND NOT outlier
+                AND rejections.event_id IS NULL
+            ORDER BY stream_ordering DESC
+            LIMIT 1
+            """
+
+            txn.execute(
+                sql,
+                [room_id] + event_type_args,
+            )
+
+            row = cast(Optional[Tuple[str, int, str]], txn.fetchone())
+            if row is not None:
+                event_id, stream_ordering, instance_name = row
+
+                return event_id, PersistedEventPosition(
+                    # If instance_name is null we default to "master"
+                    instance_name or "master",
+                    stream_ordering,
+                )
+
+            return None
+
+        return await self.db_pool.runInteraction(
+            "get_last_event_pos_in_room",
+            _get_last_event_pos_in_room_txn,
+        )
+
     @trace
     async def get_last_event_pos_in_room_before_stream_ordering(
         self,
         room_id: str,
         end_token: RoomStreamToken,
-        event_types: Optional[Collection[str]] = None,
+        event_types: Optional[StrCollection] = None,
     ) -> Optional[Tuple[str, PersistedEventPosition]]:
         """
         Returns the ID and event position of the last event in a room at or before a
@@ -1382,7 +1447,6 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
         """
 
         min_token = end_token.stream
-        max_token = end_token.get_max_stream_pos()
         results: Dict[str, int] = {}
 
         # First, we check for the rooms in the stream change cache to see if we
@@ -1395,26 +1459,76 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
             else:
                 missing_room_ids.add(room_id)
 
+        if not missing_room_ids:
+            return results
+
         # Next, we query the stream position from the DB. At first we fetch all
         # positions less than the *max* stream pos in the token, then filter
         # them down. We do this as a) this is a cheaper query, and b) the vast
         # majority of rooms will have a latest token from before the min stream
         # pos.
 
-        def bulk_get_last_event_pos_txn(
-            txn: LoggingTransaction, batch_room_ids: StrCollection
+        uncapped_results = await self._bulk_get_max_event_pos(missing_room_ids)
+
+        # Check that the stream position for the rooms are from before the
+        # minimum position of the token. If not then we need to fetch more
+        # rows.
+        recheck_rooms: Set[str] = set()
+        for room_id, stream in uncapped_results.items():
+            if stream <= min_token:
+                results[room_id] = stream
+            else:
+                recheck_rooms.add(room_id)
+
+        if not recheck_rooms:
+            return results
+
+        for room_id in recheck_rooms:
+            result = await self.get_last_event_pos_in_room_before_stream_ordering(
+                room_id, end_token
+            )
+            if result is not None:
+                results[room_id] = result[1].stream
+
+        return results
+
+    @cached()
+    async def _get_max_event_pos(self, room_id: str) -> int:
+        raise NotImplementedError()
+
+    @cachedList(cached_method_name="_get_max_event_pos", list_name="room_ids")
+    async def _bulk_get_max_event_pos(
+        self, room_ids: StrCollection
+    ) -> Mapping[str, int]:
+        """Fetch the max position of a persisted event in the room."""
+
+        now_token = self.get_room_max_token()
+        max_pos = now_token.get_max_stream_pos()
+
+        results: Dict[str, int] = {}
+        missing_room_ids: Set[str] = set()
+        for room_id in room_ids:
+            stream_pos = self._events_stream_cache.get_max_pos_of_last_change(room_id)
+            if stream_pos is not None:
+                results[room_id] = stream_pos
+            else:
+                missing_room_ids.add(room_id)
+
+        if not missing_room_ids:
+            return results
+
+        def bulk_get_max_event_pos_txn(
+            txn: LoggingTransaction, batched_room_ids: StrCollection
         ) -> Dict[str, int]:
-            # This query fetches the latest stream position in the rooms before
-            # the given max position.
             clause, args = make_in_list_sql_clause(
-                self.database_engine, "room_id", batch_room_ids
+                self.database_engine, "room_id", batched_room_ids
             )
             sql = f"""
                 SELECT room_id, (
                     SELECT stream_ordering FROM events AS e
                     LEFT JOIN rejections USING (event_id)
                     WHERE e.room_id = r.room_id
-                        AND stream_ordering <= ?
+                        AND e.stream_ordering <= ?
                         AND NOT outlier
                         AND rejection_reason IS NULL
                     ORDER BY stream_ordering DESC
@@ -1423,72 +1537,26 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
                 FROM rooms AS r
                 WHERE {clause}
             """
-            txn.execute(sql, [max_token] + args)
+            txn.execute(sql, [max_pos] + args)
             return {row[0]: row[1] for row in txn}
 
         recheck_rooms: Set[str] = set()
-        for batched in batch_iter(missing_room_ids, 1000):
-            result = await self.db_pool.runInteraction(
-                "bulk_get_last_event_pos_in_room_before_stream_ordering",
-                bulk_get_last_event_pos_txn,
-                batched,
+        for batched in batch_iter(room_ids, 1000):
+            batch_results = await self.db_pool.runInteraction(
+                "_bulk_get_max_event_pos", bulk_get_max_event_pos_txn, batched
             )
-
-            # Check that the stream position for the rooms are from before the
-            # minimum position of the token. If not then we need to fetch more
-            # rows.
-            for room_id, stream in result.items():
-                if stream <= min_token:
-                    results[room_id] = stream
+            for room_id, stream_ordering in batch_results.items():
+                if stream_ordering <= now_token.stream:
+                    results.update(batch_results)
                 else:
                     recheck_rooms.add(room_id)
 
-        if not recheck_rooms:
-            return results
-
-        # For the remaining rooms we need to fetch all rows between the min and
-        # max stream positions in the end token, and filter out the rows that
-        # are after the end token.
-        #
-        # This query should be fast as the range between the min and max should
-        # be small.
-
-        def bulk_get_last_event_pos_recheck_txn(
-            txn: LoggingTransaction, batch_room_ids: StrCollection
-        ) -> Dict[str, int]:
-            clause, args = make_in_list_sql_clause(
-                self.database_engine, "room_id", batch_room_ids
+        for room_id in recheck_rooms:
+            result = await self.get_last_event_pos_in_room_before_stream_ordering(
+                room_id, now_token
             )
-            sql = f"""
-                SELECT room_id, instance_name, stream_ordering
-                FROM events
-                WHERE ? < stream_ordering AND stream_ordering <= ?
-                    AND NOT outlier
-                    AND rejection_reason IS NULL
-                    AND {clause}
-                ORDER BY stream_ordering ASC
-            """
-            txn.execute(sql, [min_token, max_token] + args)
-
-            # We take the max stream ordering that is less than the token. Since
-            # we ordered by stream ordering we just need to iterate through and
-            # take the last matching stream ordering.
-            txn_results: Dict[str, int] = {}
-            for row in txn:
-                room_id = row[0]
-                event_pos = PersistedEventPosition(row[1], row[2])
-                if not event_pos.persisted_after(end_token):
-                    txn_results[room_id] = event_pos.stream
-
-            return txn_results
-
-        for batched in batch_iter(recheck_rooms, 1000):
-            recheck_result = await self.db_pool.runInteraction(
-                "bulk_get_last_event_pos_in_room_before_stream_ordering_recheck",
-                bulk_get_last_event_pos_recheck_txn,
-                batched,
-            )
-            results.update(recheck_result)
+            if result is not None:
+                results[room_id] = result[1].stream
 
         return results
 

synapse/storage/engines/_base.py

@@ -28,6 +28,11 @@ if TYPE_CHECKING:
     from synapse.storage.database import LoggingDatabaseConnection
 
 
+# A string that will be replaced with the appropriate auto increment directive
+# for the database engine, expands to an auto incrementing integer primary key.
+AUTO_INCREMENT_PRIMARY_KEYPLACEHOLDER = "$%AUTO_INCREMENT_PRIMARY_KEY%$"
+
+
 class IsolationLevel(IntEnum):
     READ_COMMITTED: int = 1
     REPEATABLE_READ: int = 2

synapse/storage/engines/postgres.py

@@ -25,6 +25,7 @@ from typing import TYPE_CHECKING, Any, Mapping, NoReturn, Optional, Tuple, cast
 import psycopg2.extensions
 
 from synapse.storage.engines._base import (
+    AUTO_INCREMENT_PRIMARY_KEYPLACEHOLDER,
     BaseDatabaseEngine,
     IncorrectDatabaseSetup,
     IsolationLevel,
@@ -256,4 +257,10 @@ class PostgresEngine(
         executing the script in its own transaction. The script transaction is
         left open and it is the responsibility of the caller to commit it.
         """
+        # Replace auto increment placeholder with the appropriate directive
+        script = script.replace(
+            AUTO_INCREMENT_PRIMARY_KEYPLACEHOLDER,
+            "BIGINT PRIMARY KEY GENERATED ALWAYS AS IDENTITY",
+        )
+
         cursor.execute(f"COMMIT; BEGIN TRANSACTION; {script}")

synapse/storage/engines/sqlite.py

@@ -25,6 +25,7 @@ import threading
 from typing import TYPE_CHECKING, Any, List, Mapping, Optional
 
 from synapse.storage.engines import BaseDatabaseEngine
+from synapse.storage.engines._base import AUTO_INCREMENT_PRIMARY_KEYPLACEHOLDER
 from synapse.storage.types import Cursor
 
 if TYPE_CHECKING:
@@ -168,6 +169,11 @@ class Sqlite3Engine(BaseDatabaseEngine[sqlite3.Connection, sqlite3.Cursor]):
         > first. No other implicit transaction control is performed; any transaction
         > control must be added to sql_script.
         """
+        # Replace auto increment placeholder with the appropriate directive
+        script = script.replace(
+            AUTO_INCREMENT_PRIMARY_KEYPLACEHOLDER, "INTEGER PRIMARY KEY AUTOINCREMENT"
+        )
+
         # The implementation of `executescript` can be found at
         # https://github.com/python/cpython/blob/3.11/Modules/_sqlite/cursor.c#L1035.
         cursor.executescript(f"BEGIN TRANSACTION; {script}")

synapse/storage/schema/__init__.py

@@ -19,7 +19,7 @@
 #
 #
 
-SCHEMA_VERSION = 86  # remember to update the list below when updating
+SCHEMA_VERSION = 87  # remember to update the list below when updating
 """Represents the expectations made by the codebase about the database schema
 
 This should be incremented whenever the codebase changes its requirements on the
@@ -142,6 +142,10 @@ Changes in SCHEMA_VERSION = 85
 
 Changes in SCHEMA_VERSION = 86
     - Add a column `authenticated` to the tables `local_media_repository` and `remote_media_cache`
+
+Changes in SCHEMA_VERSION = 87
+    - Add tables to store Sliding Sync data for quick filtering/sorting
+      (`sliding_sync_joined_rooms`, `sliding_sync_membership_snapshots`)
 """
 
 

synapse/storage/schema/main/delta/87/01_sliding_sync_memberships.sql

@@ -0,0 +1,153 @@
+--
+-- This file is licensed under the Affero General Public License (AGPL) version 3.
+--
+-- Copyright (C) 2024 New Vector, Ltd
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU Affero General Public License as
+-- published by the Free Software Foundation, either version 3 of the
+-- License, or (at your option) any later version.
+--
+-- See the GNU Affero General Public License for more details:
+-- <https://www.gnu.org/licenses/agpl-3.0.html>.
+
+-- This table is a list/queue used to keep track of which rooms need to be inserted into
+-- `sliding_sync_joined_rooms`. We do this to avoid reading from `current_state_events`
+-- during the background update to populate `sliding_sync_joined_rooms` which works but
+-- it takes a lot of work for the database to grab `DISTINCT` room_ids given how many
+-- state events there are for each room.
+CREATE TABLE IF NOT EXISTS sliding_sync_joined_rooms_to_recalculate(
+    room_id TEXT NOT NULL REFERENCES rooms(room_id),
+    PRIMARY KEY (room_id)
+);
+
+-- A table for storing room meta data (current state relevant to sliding sync) that the
+-- local server is still participating in (someone local is joined to the room).
+--
+-- We store the joined rooms in separate table from `sliding_sync_membership_snapshots`
+-- because we need up-to-date information for joined rooms and it can be shared across
+-- everyone who is joined.
+--
+-- This table is kept in sync with `current_state_events` which means if the server is
+-- no longer participating in a room, the row will be deleted.
+CREATE TABLE IF NOT EXISTS sliding_sync_joined_rooms(
+    room_id TEXT NOT NULL REFERENCES rooms(room_id),
+    -- The `stream_ordering` of the most-recent/latest event in the room
+    event_stream_ordering BIGINT NOT NULL REFERENCES events(stream_ordering),
+    -- The `stream_ordering` of the last event according to the `bump_event_types`
+    bump_stamp BIGINT,
+    -- `m.room.create` -> `content.type` (current state)
+    --
+    -- Useful for the `spaces`/`not_spaces` filter in the Sliding Sync API
+    room_type TEXT,
+    -- `m.room.name` -> `content.name` (current state)
+    --
+    -- Useful for the room meta data and `room_name_like` filter in the Sliding Sync API
+    room_name TEXT,
+    -- `m.room.encryption` -> `content.algorithm` (current state)
+    --
+    -- Useful for the `is_encrypted` filter in the Sliding Sync API
+    is_encrypted BOOLEAN DEFAULT FALSE NOT NULL,
+    -- `m.room.tombstone` -> `content.replacement_room` (according to the current state at the
+    -- time of the membership).
+    --
+    -- Useful for the `include_old_rooms` functionality in the Sliding Sync API
+    tombstone_successor_room_id TEXT,
+    PRIMARY KEY (room_id)
+);
+
+-- So we can purge rooms easily.
+--
+-- The primary key is already `room_id`
+
+-- So we can sort by `stream_ordering
+CREATE UNIQUE INDEX IF NOT EXISTS sliding_sync_joined_rooms_event_stream_ordering ON sliding_sync_joined_rooms(event_stream_ordering);
+
+-- A table for storing a snapshot of room meta data (historical current state relevant
+-- for sliding sync) at the time of a local user's membership. Only has rows for the
+-- latest membership event for a given local user in a room which matches
+-- `local_current_membership` .
+--
+-- We store all memberships including joins. This makes it easy to reference this table
+-- to find all membership for a given user and shares the same semantics as
+-- `local_current_membership`. And we get to avoid some table maintenance; if we only
+-- stored non-joins, we would have to delete the row for the user when the user joins
+-- the room. Stripped state doesn't include the `m.room.tombstone` event, so we just
+-- assume that the room doesn't have a tombstone.
+--
+-- For remote invite/knocks where the server is not participating in the room, we will
+-- use stripped state events to populate this table. We assume that if any stripped
+-- state is given, it will include all possible stripped state events types. For
+-- example, if stripped state is given but `m.room.encryption` isn't included, we will
+-- assume that the room is not encrypted.
+--
+-- We don't include `bump_stamp` here because we can just use the `stream_ordering` from
+-- the membership event itself as the `bump_stamp`.
+CREATE TABLE IF NOT EXISTS sliding_sync_membership_snapshots(
+    room_id TEXT NOT NULL REFERENCES rooms(room_id),
+    user_id TEXT NOT NULL,
+    -- Useful to be able to tell leaves from kicks (where the `user_id` is different from the `sender`)
+    sender TEXT NOT NULL,
+    membership_event_id TEXT NOT NULL REFERENCES events(event_id),
+    membership TEXT NOT NULL,
+    -- This is an integer just to match `room_memberships` and also means we don't need
+    -- to do any casting.
+    forgotten INTEGER DEFAULT 0 NOT NULL,
+    -- `stream_ordering` of the `membership_event_id`
+    event_stream_ordering BIGINT NOT NULL REFERENCES events(stream_ordering),
+    -- For remote invites/knocks that don't include any stripped state, we want to be
+    -- able to distinguish between a room with `None` as valid value for some state and
+    -- room where the state is completely unknown. Basically, this should be True unless
+    -- no stripped state was provided for a remote invite/knock (False).
+    has_known_state BOOLEAN DEFAULT FALSE NOT NULL,
+    -- `m.room.create` -> `content.type` (according to the current state at the time of
+    -- the membership).
+    --
+    -- Useful for the `spaces`/`not_spaces` filter in the Sliding Sync API
+    room_type TEXT,
+    -- `m.room.name` -> `content.name` (according to the current state at the time of
+    -- the membership).
+    --
+    -- Useful for the room meta data and `room_name_like` filter in the Sliding Sync API
+    room_name TEXT,
+    -- `m.room.encryption` -> `content.algorithm` (according to the current state at the
+    -- time of the membership).
+    --
+    -- Useful for the `is_encrypted` filter in the Sliding Sync API
+    is_encrypted BOOLEAN DEFAULT FALSE NOT NULL,
+    -- `m.room.tombstone` -> `content.replacement_room` (according to the current state at the
+    -- time of the membership).
+    --
+    -- Useful for the `include_old_rooms` functionality in the Sliding Sync API
+    tombstone_successor_room_id TEXT,
+    PRIMARY KEY (room_id, user_id)
+);
+
+-- So we can purge rooms easily.
+--
+-- Since we're using a multi-column index as the primary key (room_id, user_id), the
+-- first index column (room_id) is always usable for searching so we don't need to
+-- create a separate index for it.
+--
+-- CREATE INDEX IF NOT EXISTS sliding_sync_membership_snapshots_room_id ON sliding_sync_membership_snapshots(room_id);
+
+-- So we can fetch all rooms for a given user
+CREATE INDEX IF NOT EXISTS sliding_sync_membership_snapshots_user_id ON sliding_sync_membership_snapshots(user_id);
+-- So we can sort by `stream_ordering
+CREATE UNIQUE INDEX IF NOT EXISTS sliding_sync_membership_snapshots_event_stream_ordering ON sliding_sync_membership_snapshots(event_stream_ordering);
+
+
+-- Add a series of background updates to populate the new `sliding_sync_joined_rooms` table:
+--
+--   1. Add a background update to prefill `sliding_sync_joined_rooms_to_recalculate`.
+--      We do a one-shot bulk insert from the `rooms` table to prefill.
+--   2. Add a background update to populate the new `sliding_sync_joined_rooms` table
+--
+INSERT INTO background_updates (ordering, update_name, progress_json) VALUES
+  (8701, 'sliding_sync_prefill_joined_rooms_to_recalculate_table_bg_update', '{}');
+INSERT INTO background_updates (ordering, update_name, progress_json, depends_on) VALUES
+  (8701, 'sliding_sync_joined_rooms_bg_update', '{}', 'sliding_sync_prefill_joined_rooms_to_recalculate_table_bg_update');
+
+-- Add a background updates to populate the new `sliding_sync_membership_snapshots` table
+INSERT INTO background_updates (ordering, update_name, progress_json) VALUES
+  (8701, 'sliding_sync_membership_snapshots_bg_update', '{}');

synapse/storage/schema/main/delta/87/02_per_connection_state.sql

@@ -0,0 +1,78 @@
+--
+-- This file is licensed under the Affero General Public License (AGPL) version 3.
+--
+-- Copyright (C) 2024 New Vector, Ltd
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU Affero General Public License as
+-- published by the Free Software Foundation, either version 3 of the
+-- License, or (at your option) any later version.
+--
+-- See the GNU Affero General Public License for more details:
+-- <https://www.gnu.org/licenses/agpl-3.0.html>.
+
+
+-- Table to track active sliding sync connections.
+--
+-- A new connection will be created for every sliding sync request without a
+-- `since` token for a given `conn_id` for a device.#
+--
+-- Once a new connection is created and used we delete all other connections for
+-- the `conn_id`.
+CREATE TABLE sliding_sync_connections(
+    connection_key $%AUTO_INCREMENT_PRIMARY_KEY%$,
+    user_id TEXT NOT NULL,
+    device_id TEXT NOT NULL,
+    conn_id TEXT NOT NULL,
+    created_ts BIGINT NOT NULL
+);
+
+CREATE INDEX sliding_sync_connections_idx ON sliding_sync_connections(user_id, device_id, conn_id);
+
+-- We track per-connection state by associating changes to the state with
+-- connection positions. This ensures that we correctly track state even if we
+-- see retries of requests.
+--
+-- If the client starts a "new" connection (by not specifying a since token),
+-- we'll clear out the other connections (to ensure that we don't end up with
+-- lots of connection keys).
+CREATE TABLE sliding_sync_connection_positions(
+    connection_position $%AUTO_INCREMENT_PRIMARY_KEY%$,
+    connection_key BIGINT NOT NULL REFERENCES sliding_sync_connections(connection_key) ON DELETE CASCADE,
+    created_ts BIGINT NOT NULL
+);
+
+CREATE INDEX sliding_sync_connection_positions_key ON sliding_sync_connection_positions(connection_key);
+
+
+-- To save space we deduplicate the `required_state` json by assigning IDs to
+-- different values.
+CREATE TABLE sliding_sync_connection_required_state(
+    required_state_id $%AUTO_INCREMENT_PRIMARY_KEY%$,
+    connection_key BIGINT NOT NULL REFERENCES sliding_sync_connections(connection_key) ON DELETE CASCADE,
+    required_state TEXT NOT NULL  -- We store this as a json list of event type / state key tuples.
+);
+
+CREATE INDEX sliding_sync_connection_required_state_conn_pos ON sliding_sync_connections(connection_key);
+
+
+-- Stores the room configs we have seen for rooms in a connection.
+CREATE TABLE sliding_sync_connection_room_configs(
+    connection_position BIGINT NOT NULL REFERENCES sliding_sync_connection_positions(connection_position) ON DELETE CASCADE,
+    room_id TEXT NOT NULL,
+    timeline_limit BIGINT NOT NULL,
+    required_state_id BIGINT NOT NULL REFERENCES sliding_sync_connection_required_state(required_state_id)
+);
+
+CREATE UNIQUE INDEX sliding_sync_connection_room_configs_idx ON sliding_sync_connection_room_configs(connection_position, room_id);
+
+-- Stores what data we have sent for given streams down given connections.
+CREATE TABLE sliding_sync_connection_streams(
+    connection_position BIGINT NOT NULL REFERENCES sliding_sync_connection_positions(connection_position) ON DELETE CASCADE,
+    stream TEXT NOT NULL,  -- e.g. "events" or "receipts"
+    room_id TEXT NOT NULL,
+    room_status TEXT NOT NULL,  -- "live" or "previously", i.e. the `HaveSentRoomFlag` value
+    last_position TEXT  -- For "previously" the token for the stream we have sent up to.
+);
+
+CREATE UNIQUE INDEX sliding_sync_connection_streams_idx ON sliding_sync_connection_streams(connection_position, room_id, stream);

synapse/storage/schema/main/delta/87/03_per_connection_lists.sql

@@ -0,0 +1,22 @@
+--
+-- This file is licensed under the Affero General Public License (AGPL) version 3.
+--
+-- Copyright (C) 2024 New Vector, Ltd
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU Affero General Public License as
+-- published by the Free Software Foundation, either version 3 of the
+-- License, or (at your option) any later version.
+--
+-- See the GNU Affero General Public License for more details:
+-- <https://www.gnu.org/licenses/agpl-3.0.html>.
+
+
+-- Stores the room lists for a connection
+CREATE TABLE sliding_sync_connection_room_lists(
+    connection_key BIGINT NOT NULL REFERENCES sliding_sync_connections(connection_key) ON DELETE CASCADE,
+    list_name TEXT NOT NULL,
+    room_id TEXT NOT NULL
+);
+
+CREATE INDEX sliding_sync_connection_room_lists_idx ON sliding_sync_connection_room_lists(connection_key);

synapse/types/handlers/__init__.py

@@ -17,33 +17,9 @@
 # [This file includes modifications made by New Vector Limited]
 #
 #
-from enum import Enum
-from typing import TYPE_CHECKING, Dict, Final, List, Mapping, Optional, Sequence, Tuple
 
-import attr
-from typing_extensions import TypedDict
 
-from synapse._pydantic_compat import HAS_PYDANTIC_V2
-
-if TYPE_CHECKING or HAS_PYDANTIC_V2:
-    from pydantic.v1 import Extra
-else:
-    from pydantic import Extra
-
-from synapse.events import EventBase
-from synapse.types import (
-    DeviceListUpdates,
-    JsonDict,
-    JsonMapping,
-    Requester,
-    SlidingSyncStreamToken,
-    StreamToken,
-    UserID,
-)
-from synapse.types.rest.client import SlidingSyncBody
-
-if TYPE_CHECKING:
-    from synapse.handlers.relations import BundledAggregations
+from typing import List, Optional, TypedDict
 
 
 class ShutdownRoomParams(TypedDict):
@@ -101,335 +77,3 @@ class ShutdownRoomResponse(TypedDict):
     failed_to_kick_users: List[str]
     local_aliases: List[str]
     new_room_id: Optional[str]
-
-
-class SlidingSyncConfig(SlidingSyncBody):
-    """
-    Inherit from `SlidingSyncBody` since we need all of the same fields and add a few
-    extra fields that we need in the handler
-    """
-
-    user: UserID
-    requester: Requester
-
-    # Pydantic config
-    class Config:
-        # By default, ignore fields that we don't recognise.
-        extra = Extra.ignore
-        # By default, don't allow fields to be reassigned after parsing.
-        allow_mutation = False
-        # Allow custom types like `UserID` to be used in the model
-        arbitrary_types_allowed = True
-
-
-class OperationType(Enum):
-    """
-    Represents the operation types in a Sliding Sync window.
-
-    Attributes:
-        SYNC: Sets a range of entries. Clients SHOULD discard what they previous knew about
-            entries in this range.
-        INSERT: Sets a single entry. If the position is not empty then clients MUST move
-            entries to the left or the right depending on where the closest empty space is.
-        DELETE: Remove a single entry. Often comes before an INSERT to allow entries to move
-            places.
-        INVALIDATE: Remove a range of entries. Clients MAY persist the invalidated range for
-            offline support, but they should be treated as empty when additional operations
-            which concern indexes in the range arrive from the server.
-    """
-
-    SYNC: Final = "SYNC"
-    INSERT: Final = "INSERT"
-    DELETE: Final = "DELETE"
-    INVALIDATE: Final = "INVALIDATE"
-
-
-@attr.s(slots=True, frozen=True, auto_attribs=True)
-class SlidingSyncResult:
-    """
-    The Sliding Sync result to be serialized to JSON for a response.
-
-    Attributes:
-        next_pos: The next position token in the sliding window to request (next_batch).
-        lists: Sliding window API. A map of list key to list results.
-        rooms: Room subscription API. A map of room ID to room results.
-        extensions: Extensions API. A map of extension key to extension results.
-    """
-
-    @attr.s(slots=True, frozen=True, auto_attribs=True)
-    class RoomResult:
-        """
-        Attributes:
-            name: Room name or calculated room name.
-            avatar: Room avatar
-            heroes: List of stripped membership events (containing `user_id` and optionally
-                `avatar_url` and `displayname`) for the users used to calculate the room name.
-            is_dm: Flag to specify whether the room is a direct-message room (most likely
-                between two people).
-            initial: Flag which is set when this is the first time the server is sending this
-                data on this connection. Clients can use this flag to replace or update
-                their local state. When there is an update, servers MUST omit this flag
-                entirely and NOT send "initial":false as this is wasteful on bandwidth. The
-                absence of this flag means 'false'.
-            unstable_expanded_timeline: Flag which is set if we're returning more historic
-                events due to the timeline limit having increased. See "XXX: Odd behavior"
-                comment ing `synapse.handlers.sliding_sync`.
-            required_state: The current state of the room
-            timeline: Latest events in the room. The last event is the most recent.
-            bundled_aggregations: A mapping of event ID to the bundled aggregations for
-                the timeline events above. This allows clients to show accurate reaction
-                counts (or edits, threads), even if some of the reaction events were skipped
-                over in a gappy sync.
-            stripped_state: Stripped state events (for rooms where the usre is
-                invited/knocked). Same as `rooms.invite.$room_id.invite_state` in sync v2,
-                absent on joined/left rooms
-            prev_batch: A token that can be passed as a start parameter to the
-                `/rooms/<room_id>/messages` API to retrieve earlier messages.
-            limited: True if there are more events than `timeline_limit` looking
-                backwards from the `response.pos` to the `request.pos`.
-            num_live: The number of timeline events which have just occurred and are not historical.
-                The last N events are 'live' and should be treated as such. This is mostly
-                useful to determine whether a given @mention event should make a noise or not.
-                Clients cannot rely solely on the absence of `initial: true` to determine live
-                events because if a room not in the sliding window bumps into the window because
-                of an @mention it will have `initial: true` yet contain a single live event
-                (with potentially other old events in the timeline).
-            bump_stamp: The `stream_ordering` of the last event according to the
-                `bump_event_types`. This helps clients sort more readily without them
-                needing to pull in a bunch of the timeline to determine the last activity.
-                `bump_event_types` is a thing because for example, we don't want display
-                name changes to mark the room as unread and bump it to the top. For
-                encrypted rooms, we just have to consider any activity as a bump because we
-                can't see the content and the client has to figure it out for themselves.
-            joined_count: The number of users with membership of join, including the client's
-                own user ID. (same as sync `v2 m.joined_member_count`)
-            invited_count: The number of users with membership of invite. (same as sync v2
-                `m.invited_member_count`)
-            notification_count: The total number of unread notifications for this room. (same
-                as sync v2)
-            highlight_count: The number of unread notifications for this room with the highlight
-                flag set. (same as sync v2)
-        """
-
-        @attr.s(slots=True, frozen=True, auto_attribs=True)
-        class StrippedHero:
-            user_id: str
-            display_name: Optional[str]
-            avatar_url: Optional[str]
-
-        name: Optional[str]
-        avatar: Optional[str]
-        heroes: Optional[List[StrippedHero]]
-        is_dm: bool
-        initial: bool
-        unstable_expanded_timeline: bool
-        # Should be empty for invite/knock rooms with `stripped_state`
-        required_state: List[EventBase]
-        # Should be empty for invite/knock rooms with `stripped_state`
-        timeline_events: List[EventBase]
-        bundled_aggregations: Optional[Dict[str, "BundledAggregations"]]
-        # Optional because it's only relevant to invite/knock rooms
-        stripped_state: List[JsonDict]
-        # Only optional because it won't be included for invite/knock rooms with `stripped_state`
-        prev_batch: Optional[StreamToken]
-        # Only optional because it won't be included for invite/knock rooms with `stripped_state`
-        limited: Optional[bool]
-        # Only optional because it won't be included for invite/knock rooms with `stripped_state`
-        num_live: Optional[int]
-        bump_stamp: int
-        joined_count: int
-        invited_count: int
-        notification_count: int
-        highlight_count: int
-
-        def __bool__(self) -> bool:
-            return (
-                # If this is the first time the client is seeing the room, we should not filter it out
-                # under any circumstance.
-                self.initial
-                # We need to let the client know if there are any new events
-                or bool(self.required_state)
-                or bool(self.timeline_events)
-                or bool(self.stripped_state)
-            )
-
-    @attr.s(slots=True, frozen=True, auto_attribs=True)
-    class SlidingWindowList:
-        """
-        Attributes:
-            count: The total number of entries in the list. Always present if this list
-                is.
-            ops: The sliding list operations to perform.
-        """
-
-        @attr.s(slots=True, frozen=True, auto_attribs=True)
-        class Operation:
-            """
-            Attributes:
-                op: The operation type to perform.
-                range: Which index positions are affected by this operation. These are
-                    both inclusive.
-                room_ids: Which room IDs are affected by this operation. These IDs match
-                    up to the positions in the `range`, so the last room ID in this list
-                    matches the 9th index. The room data is held in a separate object.
-            """
-
-            op: OperationType
-            range: Tuple[int, int]
-            room_ids: List[str]
-
-        count: int
-        ops: List[Operation]
-
-    @attr.s(slots=True, frozen=True, auto_attribs=True)
-    class Extensions:
-        """Responses for extensions
-
-        Attributes:
-            to_device: The to-device extension (MSC3885)
-            e2ee: The E2EE device extension (MSC3884)
-        """
-
-        @attr.s(slots=True, frozen=True, auto_attribs=True)
-        class ToDeviceExtension:
-            """The to-device extension (MSC3885)
-
-            Attributes:
-                next_batch: The to-device stream token the client should use
-                    to get more results
-                events: A list of to-device messages for the client
-            """
-
-            next_batch: str
-            events: Sequence[JsonMapping]
-
-            def __bool__(self) -> bool:
-                return bool(self.events)
-
-        @attr.s(slots=True, frozen=True, auto_attribs=True)
-        class E2eeExtension:
-            """The E2EE device extension (MSC3884)
-
-            Attributes:
-                device_list_updates: List of user_ids whose devices have changed or left (only
-                    present on incremental syncs).
-                device_one_time_keys_count: Map from key algorithm to the number of
-                    unclaimed one-time keys currently held on the server for this device. If
-                    an algorithm is unlisted, the count for that algorithm is assumed to be
-                    zero. If this entire parameter is missing, the count for all algorithms
-                    is assumed to be zero.
-                device_unused_fallback_key_types: List of unused fallback key algorithms
-                    for this device.
-            """
-
-            # Only present on incremental syncs
-            device_list_updates: Optional[DeviceListUpdates]
-            device_one_time_keys_count: Mapping[str, int]
-            device_unused_fallback_key_types: Sequence[str]
-
-            def __bool__(self) -> bool:
-                # Note that "signed_curve25519" is always returned in key count responses
-                # regardless of whether we uploaded any keys for it. This is necessary until
-                # https://github.com/matrix-org/matrix-doc/issues/3298 is fixed.
-                #
-                # Also related:
-                # https://github.com/element-hq/element-android/issues/3725 and
-                # https://github.com/matrix-org/synapse/issues/10456
-                default_otk = self.device_one_time_keys_count.get("signed_curve25519")
-                more_than_default_otk = len(self.device_one_time_keys_count) > 1 or (
-                    default_otk is not None and default_otk > 0
-                )
-
-                return bool(
-                    more_than_default_otk
-                    or self.device_list_updates
-                    or self.device_unused_fallback_key_types
-                )
-
-        @attr.s(slots=True, frozen=True, auto_attribs=True)
-        class AccountDataExtension:
-            """The Account Data extension (MSC3959)
-
-            Attributes:
-                global_account_data_map: Mapping from `type` to `content` of global account
-                    data events.
-                account_data_by_room_map: Mapping from room_id to mapping of `type` to
-                    `content` of room account data events.
-            """
-
-            global_account_data_map: Mapping[str, JsonMapping]
-            account_data_by_room_map: Mapping[str, Mapping[str, JsonMapping]]
-
-            def __bool__(self) -> bool:
-                return bool(
-                    self.global_account_data_map or self.account_data_by_room_map
-                )
-
-        @attr.s(slots=True, frozen=True, auto_attribs=True)
-        class ReceiptsExtension:
-            """The Receipts extension (MSC3960)
-
-            Attributes:
-                room_id_to_receipt_map: Mapping from room_id to `m.receipt` ephemeral
-                    event (type, content)
-            """
-
-            room_id_to_receipt_map: Mapping[str, JsonMapping]
-
-            def __bool__(self) -> bool:
-                return bool(self.room_id_to_receipt_map)
-
-        @attr.s(slots=True, frozen=True, auto_attribs=True)
-        class TypingExtension:
-            """The Typing Notification extension (MSC3961)
-
-            Attributes:
-                room_id_to_typing_map: Mapping from room_id to `m.typing` ephemeral
-                    event (type, content)
-            """
-
-            room_id_to_typing_map: Mapping[str, JsonMapping]
-
-            def __bool__(self) -> bool:
-                return bool(self.room_id_to_typing_map)
-
-        to_device: Optional[ToDeviceExtension] = None
-        e2ee: Optional[E2eeExtension] = None
-        account_data: Optional[AccountDataExtension] = None
-        receipts: Optional[ReceiptsExtension] = None
-        typing: Optional[TypingExtension] = None
-
-        def __bool__(self) -> bool:
-            return bool(
-                self.to_device
-                or self.e2ee
-                or self.account_data
-                or self.receipts
-                or self.typing
-            )
-
-    next_pos: SlidingSyncStreamToken
-    lists: Dict[str, SlidingWindowList]
-    rooms: Dict[str, RoomResult]
-    extensions: Extensions
-
-    def __bool__(self) -> bool:
-        """Make the result appear empty if there are no updates. This is used
-        to tell if the notifier needs to wait for more events when polling for
-        events.
-        """
-        # We don't include `self.lists` here, as a) `lists` is always non-empty even if
-        # there are no changes, and b) since we're sorting rooms by `stream_ordering` of
-        # the latest activity, anything that would cause the order to change would end
-        # up in `self.rooms` and cause us to send down the change.
-        return bool(self.rooms or self.extensions)
-
-    @staticmethod
-    def empty(next_pos: SlidingSyncStreamToken) -> "SlidingSyncResult":
-        "Return a new empty result"
-        return SlidingSyncResult(
-            next_pos=next_pos,
-            lists={},
-            rooms={},
-            extensions=SlidingSyncResult.Extensions(),
-        )

synapse/types/handlers/sliding_sync.py

@@ -18,29 +18,393 @@ from collections import ChainMap
 from enum import Enum
 from typing import (
     TYPE_CHECKING,
+    AbstractSet,
     Callable,
     Dict,
     Final,
     Generic,
+    List,
     Mapping,
     MutableMapping,
     Optional,
+    Sequence,
     Set,
+    Tuple,
     TypeVar,
     cast,
 )
 
 import attr
 
+from synapse._pydantic_compat import HAS_PYDANTIC_V2
 from synapse.api.constants import EventTypes
 from synapse.types import MultiWriterStreamToken, RoomStreamToken, StrCollection, UserID
-from synapse.types.handlers import SlidingSyncConfig
+
+if TYPE_CHECKING or HAS_PYDANTIC_V2:
+    from pydantic.v1 import Extra
+else:
+    from pydantic import Extra
+
+from synapse.events import EventBase
+from synapse.types import (
+    DeviceListUpdates,
+    JsonDict,
+    JsonMapping,
+    Requester,
+    SlidingSyncStreamToken,
+    StreamToken,
+)
+from synapse.types.rest.client import SlidingSyncBody
 
 if TYPE_CHECKING:
-    pass
+    from synapse.handlers.relations import BundledAggregations
 
 logger = logging.getLogger(__name__)
 
+# Sliding Sync: The event types that clients should consider as new activity and affect
+# the `bump_stamp`
+SLIDING_SYNC_DEFAULT_BUMP_EVENT_TYPES = {
+    EventTypes.Create,
+    EventTypes.Message,
+    EventTypes.Encrypted,
+    EventTypes.Sticker,
+    EventTypes.CallInvite,
+    EventTypes.PollStart,
+    EventTypes.LiveLocationShareStart,
+}
+
+
+class SlidingSyncConfig(SlidingSyncBody):
+    """
+    Inherit from `SlidingSyncBody` since we need all of the same fields and add a few
+    extra fields that we need in the handler
+    """
+
+    user: UserID
+    requester: Requester
+
+    # Pydantic config
+    class Config:
+        # By default, ignore fields that we don't recognise.
+        extra = Extra.ignore
+        # By default, don't allow fields to be reassigned after parsing.
+        allow_mutation = False
+        # Allow custom types like `UserID` to be used in the model
+        arbitrary_types_allowed = True
+
+
+class OperationType(Enum):
+    """
+    Represents the operation types in a Sliding Sync window.
+
+    Attributes:
+        SYNC: Sets a range of entries. Clients SHOULD discard what they previous knew about
+            entries in this range.
+        INSERT: Sets a single entry. If the position is not empty then clients MUST move
+            entries to the left or the right depending on where the closest empty space is.
+        DELETE: Remove a single entry. Often comes before an INSERT to allow entries to move
+            places.
+        INVALIDATE: Remove a range of entries. Clients MAY persist the invalidated range for
+            offline support, but they should be treated as empty when additional operations
+            which concern indexes in the range arrive from the server.
+    """
+
+    SYNC: Final = "SYNC"
+    INSERT: Final = "INSERT"
+    DELETE: Final = "DELETE"
+    INVALIDATE: Final = "INVALIDATE"
+
+
+@attr.s(slots=True, frozen=True, auto_attribs=True)
+class SlidingSyncResult:
+    """
+    The Sliding Sync result to be serialized to JSON for a response.
+
+    Attributes:
+        next_pos: The next position token in the sliding window to request (next_batch).
+        lists: Sliding window API. A map of list key to list results.
+        rooms: Room subscription API. A map of room ID to room results.
+        extensions: Extensions API. A map of extension key to extension results.
+    """
+
+    @attr.s(slots=True, frozen=True, auto_attribs=True)
+    class RoomResult:
+        """
+        Attributes:
+            name: Room name or calculated room name.
+            avatar: Room avatar
+            heroes: List of stripped membership events (containing `user_id` and optionally
+                `avatar_url` and `displayname`) for the users used to calculate the room name.
+            is_dm: Flag to specify whether the room is a direct-message room (most likely
+                between two people).
+            initial: Flag which is set when this is the first time the server is sending this
+                data on this connection. Clients can use this flag to replace or update
+                their local state. When there is an update, servers MUST omit this flag
+                entirely and NOT send "initial":false as this is wasteful on bandwidth. The
+                absence of this flag means 'false'.
+            unstable_expanded_timeline: Flag which is set if we're returning more historic
+                events due to the timeline limit having increased. See "XXX: Odd behavior"
+                comment ing `synapse.handlers.sliding_sync`.
+            required_state: The current state of the room
+            timeline: Latest events in the room. The last event is the most recent.
+            bundled_aggregations: A mapping of event ID to the bundled aggregations for
+                the timeline events above. This allows clients to show accurate reaction
+                counts (or edits, threads), even if some of the reaction events were skipped
+                over in a gappy sync.
+            stripped_state: Stripped state events (for rooms where the usre is
+                invited/knocked). Same as `rooms.invite.$room_id.invite_state` in sync v2,
+                absent on joined/left rooms
+            prev_batch: A token that can be passed as a start parameter to the
+                `/rooms/<room_id>/messages` API to retrieve earlier messages.
+            limited: True if there are more events than `timeline_limit` looking
+                backwards from the `response.pos` to the `request.pos`.
+            num_live: The number of timeline events which have just occurred and are not historical.
+                The last N events are 'live' and should be treated as such. This is mostly
+                useful to determine whether a given @mention event should make a noise or not.
+                Clients cannot rely solely on the absence of `initial: true` to determine live
+                events because if a room not in the sliding window bumps into the window because
+                of an @mention it will have `initial: true` yet contain a single live event
+                (with potentially other old events in the timeline).
+            bump_stamp: The `stream_ordering` of the last event according to the
+                `bump_event_types`. This helps clients sort more readily without them
+                needing to pull in a bunch of the timeline to determine the last activity.
+                `bump_event_types` is a thing because for example, we don't want display
+                name changes to mark the room as unread and bump it to the top. For
+                encrypted rooms, we just have to consider any activity as a bump because we
+                can't see the content and the client has to figure it out for themselves.
+            joined_count: The number of users with membership of join, including the client's
+                own user ID. (same as sync `v2 m.joined_member_count`)
+            invited_count: The number of users with membership of invite. (same as sync v2
+                `m.invited_member_count`)
+            notification_count: The total number of unread notifications for this room. (same
+                as sync v2)
+            highlight_count: The number of unread notifications for this room with the highlight
+                flag set. (same as sync v2)
+        """
+
+        @attr.s(slots=True, frozen=True, auto_attribs=True)
+        class StrippedHero:
+            user_id: str
+            display_name: Optional[str]
+            avatar_url: Optional[str]
+
+        name: Optional[str]
+        avatar: Optional[str]
+        heroes: Optional[List[StrippedHero]]
+        is_dm: bool
+        initial: bool
+        unstable_expanded_timeline: bool
+        # Should be empty for invite/knock rooms with `stripped_state`
+        required_state: List[EventBase]
+        # Should be empty for invite/knock rooms with `stripped_state`
+        timeline_events: List[EventBase]
+        bundled_aggregations: Optional[Dict[str, "BundledAggregations"]]
+        # Optional because it's only relevant to invite/knock rooms
+        stripped_state: List[JsonDict]
+        # Only optional because it won't be included for invite/knock rooms with `stripped_state`
+        prev_batch: Optional[StreamToken]
+        # Only optional because it won't be included for invite/knock rooms with `stripped_state`
+        limited: Optional[bool]
+        # Only optional because it won't be included for invite/knock rooms with `stripped_state`
+        num_live: Optional[int]
+        bump_stamp: int
+        joined_count: int
+        invited_count: int
+        notification_count: int
+        highlight_count: int
+
+        def __bool__(self) -> bool:
+            return (
+                # If this is the first time the client is seeing the room, we should not filter it out
+                # under any circumstance.
+                self.initial
+                # We need to let the client know if there are any new events
+                or bool(self.required_state)
+                or bool(self.timeline_events)
+                or bool(self.stripped_state)
+            )
+
+    @attr.s(slots=True, frozen=True, auto_attribs=True)
+    class SlidingWindowList:
+        """
+        Attributes:
+            count: The total number of entries in the list. Always present if this list
+                is.
+            ops: The sliding list operations to perform.
+        """
+
+        @attr.s(slots=True, frozen=True, auto_attribs=True)
+        class Operation:
+            """
+            Attributes:
+                op: The operation type to perform.
+                range: Which index positions are affected by this operation. These are
+                    both inclusive.
+                room_ids: Which room IDs are affected by this operation. These IDs match
+                    up to the positions in the `range`, so the last room ID in this list
+                    matches the 9th index. The room data is held in a separate object.
+            """
+
+            op: OperationType
+            range: Tuple[int, int]
+            room_ids: List[str]
+
+        count: int
+        ops: List[Operation]
+
+    @attr.s(slots=True, frozen=True, auto_attribs=True)
+    class Extensions:
+        """Responses for extensions
+
+        Attributes:
+            to_device: The to-device extension (MSC3885)
+            e2ee: The E2EE device extension (MSC3884)
+        """
+
+        @attr.s(slots=True, frozen=True, auto_attribs=True)
+        class ToDeviceExtension:
+            """The to-device extension (MSC3885)
+
+            Attributes:
+                next_batch: The to-device stream token the client should use
+                    to get more results
+                events: A list of to-device messages for the client
+            """
+
+            next_batch: str
+            events: Sequence[JsonMapping]
+
+            def __bool__(self) -> bool:
+                return bool(self.events)
+
+        @attr.s(slots=True, frozen=True, auto_attribs=True)
+        class E2eeExtension:
+            """The E2EE device extension (MSC3884)
+
+            Attributes:
+                device_list_updates: List of user_ids whose devices have changed or left (only
+                    present on incremental syncs).
+                device_one_time_keys_count: Map from key algorithm to the number of
+                    unclaimed one-time keys currently held on the server for this device. If
+                    an algorithm is unlisted, the count for that algorithm is assumed to be
+                    zero. If this entire parameter is missing, the count for all algorithms
+                    is assumed to be zero.
+                device_unused_fallback_key_types: List of unused fallback key algorithms
+                    for this device.
+            """
+
+            # Only present on incremental syncs
+            device_list_updates: Optional[DeviceListUpdates]
+            device_one_time_keys_count: Mapping[str, int]
+            device_unused_fallback_key_types: Sequence[str]
+
+            def __bool__(self) -> bool:
+                # Note that "signed_curve25519" is always returned in key count responses
+                # regardless of whether we uploaded any keys for it. This is necessary until
+                # https://github.com/matrix-org/matrix-doc/issues/3298 is fixed.
+                #
+                # Also related:
+                # https://github.com/element-hq/element-android/issues/3725 and
+                # https://github.com/matrix-org/synapse/issues/10456
+                default_otk = self.device_one_time_keys_count.get("signed_curve25519")
+                more_than_default_otk = len(self.device_one_time_keys_count) > 1 or (
+                    default_otk is not None and default_otk > 0
+                )
+
+                return bool(
+                    more_than_default_otk
+                    or self.device_list_updates
+                    or self.device_unused_fallback_key_types
+                )
+
+        @attr.s(slots=True, frozen=True, auto_attribs=True)
+        class AccountDataExtension:
+            """The Account Data extension (MSC3959)
+
+            Attributes:
+                global_account_data_map: Mapping from `type` to `content` of global account
+                    data events.
+                account_data_by_room_map: Mapping from room_id to mapping of `type` to
+                    `content` of room account data events.
+            """
+
+            global_account_data_map: Mapping[str, JsonMapping]
+            account_data_by_room_map: Mapping[str, Mapping[str, JsonMapping]]
+
+            def __bool__(self) -> bool:
+                return bool(
+                    self.global_account_data_map or self.account_data_by_room_map
+                )
+
+        @attr.s(slots=True, frozen=True, auto_attribs=True)
+        class ReceiptsExtension:
+            """The Receipts extension (MSC3960)
+
+            Attributes:
+                room_id_to_receipt_map: Mapping from room_id to `m.receipt` ephemeral
+                    event (type, content)
+            """
+
+            room_id_to_receipt_map: Mapping[str, JsonMapping]
+
+            def __bool__(self) -> bool:
+                return bool(self.room_id_to_receipt_map)
+
+        @attr.s(slots=True, frozen=True, auto_attribs=True)
+        class TypingExtension:
+            """The Typing Notification extension (MSC3961)
+
+            Attributes:
+                room_id_to_typing_map: Mapping from room_id to `m.typing` ephemeral
+                    event (type, content)
+            """
+
+            room_id_to_typing_map: Mapping[str, JsonMapping]
+
+            def __bool__(self) -> bool:
+                return bool(self.room_id_to_typing_map)
+
+        to_device: Optional[ToDeviceExtension] = None
+        e2ee: Optional[E2eeExtension] = None
+        account_data: Optional[AccountDataExtension] = None
+        receipts: Optional[ReceiptsExtension] = None
+        typing: Optional[TypingExtension] = None
+
+        def __bool__(self) -> bool:
+            return bool(
+                self.to_device
+                or self.e2ee
+                or self.account_data
+                or self.receipts
+                or self.typing
+            )
+
+    next_pos: SlidingSyncStreamToken
+    lists: Dict[str, SlidingWindowList]
+    rooms: Dict[str, RoomResult]
+    extensions: Extensions
+
+    def __bool__(self) -> bool:
+        """Make the result appear empty if there are no updates. This is used
+        to tell if the notifier needs to wait for more events when polling for
+        events.
+        """
+        # We don't include `self.lists` here, as a) `lists` is always non-empty even if
+        # there are no changes, and b) since we're sorting rooms by `stream_ordering` of
+        # the latest activity, anything that would cause the order to change would end
+        # up in `self.rooms` and cause us to send down the change.
+        return bool(self.rooms or self.extensions)
+
+    @staticmethod
+    def empty(next_pos: SlidingSyncStreamToken) -> "SlidingSyncResult":
+        "Return a new empty result"
+        return SlidingSyncResult(
+            next_pos=next_pos,
+            lists={},
+            rooms={},
+            extensions=SlidingSyncResult.Extensions(),
+        )
+
 
 class StateValues:
     """
@@ -60,7 +424,7 @@ class StateValues:
 
 # We can't freeze this class because we want to update it in place with the
 # de-duplicated data.
-@attr.s(slots=True, auto_attribs=True)
+@attr.s(slots=True, auto_attribs=True, frozen=True)
 class RoomSyncConfig:
     """
     Holds the config for what data we should fetch for a room in the sync response.
@@ -74,7 +438,7 @@ class RoomSyncConfig:
     """
 
     timeline_limit: int
-    required_state_map: Dict[str, Set[str]]
+    required_state_map: Mapping[str, AbstractSet[str]]
 
     @classmethod
     def from_room_config(
@@ -148,7 +512,7 @@ class RoomSyncConfig:
 
     def deep_copy(self) -> "RoomSyncConfig":
         required_state_map: Dict[str, Set[str]] = {
-            state_type: state_key_set.copy()
+            state_type: set(state_key_set)
             for state_type, state_key_set in self.required_state_map.items()
         }
 
@@ -159,14 +523,20 @@ class RoomSyncConfig:
 
     def combine_room_sync_config(
         self, other_room_sync_config: "RoomSyncConfig"
-    ) -> None:
+    ) -> "RoomSyncConfig":
         """
-        Combine this `RoomSyncConfig` with another `RoomSyncConfig` and take the
+        Combine this `RoomSyncConfig` with another `RoomSyncConfig` and return the
         superset union of the two.
         """
+        timeline_limit = self.timeline_limit
+        required_state_map = {
+            event_type: set(state_keys)
+            for event_type, state_keys in self.required_state_map.items()
+        }
+
         # Take the highest timeline limit
         if self.timeline_limit < other_room_sync_config.timeline_limit:
-            self.timeline_limit = other_room_sync_config.timeline_limit
+            timeline_limit = other_room_sync_config.timeline_limit
 
         # Union the required state
         for (
@@ -175,14 +545,14 @@ class RoomSyncConfig:
         ) in other_room_sync_config.required_state_map.items():
             # If we already have a wildcard for everything, we don't need to add
             # anything else
-            if StateValues.WILDCARD in self.required_state_map.get(
+            if StateValues.WILDCARD in required_state_map.get(
                 StateValues.WILDCARD, set()
             ):
                 break
 
             # If we already have a wildcard `state_key` for this `state_type`, we don't need
             # to add anything else
-            if StateValues.WILDCARD in self.required_state_map.get(state_type, set()):
+            if StateValues.WILDCARD in required_state_map.get(state_type, set()):
                 continue
 
             # If we're getting wildcards for the `state_type` and `state_key`, that's
@@ -191,16 +561,14 @@ class RoomSyncConfig:
                 state_type == StateValues.WILDCARD
                 and StateValues.WILDCARD in state_key_set
             ):
-                self.required_state_map = {state_type: {StateValues.WILDCARD}}
+                required_state_map = {state_type: {StateValues.WILDCARD}}
                 # We can break, since we don't need to add anything else
                 break
 
             for state_key in state_key_set:
                 # If we already have a wildcard for this specific `state_key`, we don't need
                 # to add it since the wildcard already covers it.
-                if state_key in self.required_state_map.get(
-                    StateValues.WILDCARD, set()
-                ):
+                if state_key in required_state_map.get(StateValues.WILDCARD, set()):
                     continue
 
                 # If we're getting a wildcard for the `state_type`, get rid of any other
@@ -211,7 +579,7 @@ class RoomSyncConfig:
                     # Make a copy so we don't run into an error: `dictionary changed size
                     # during iteration`, when we remove items
                     for existing_state_type, existing_state_key_set in list(
-                        self.required_state_map.items()
+                        required_state_map.items()
                     ):
                         # Make a copy so we don't run into an error: `Set changed size during
                         # iteration`, when we filter out and remove items
@@ -221,19 +589,21 @@ class RoomSyncConfig:
 
                         # If we've the left the `set()` empty, remove it from the map
                         if existing_state_key_set == set():
-                            self.required_state_map.pop(existing_state_type, None)
+                            required_state_map.pop(existing_state_type, None)
 
                 # If we're getting a wildcard `state_key`, get rid of any other state_keys
                 # for this `state_type` since the wildcard will cover it already.
                 if state_key == StateValues.WILDCARD:
-                    self.required_state_map[state_type] = {state_key}
+                    required_state_map[state_type] = {state_key}
                     break
                 # Otherwise, just add it to the set
                 else:
-                    if self.required_state_map.get(state_type) is None:
-                        self.required_state_map[state_type] = {state_key}
+                    if required_state_map.get(state_type) is None:
+                        required_state_map[state_type] = {state_key}
                     else:
-                        self.required_state_map[state_type].add(state_key)
+                        required_state_map[state_type].add(state_key)
+
+        return RoomSyncConfig(timeline_limit, required_state_map)
 
     def must_await_full_state(
         self,
@@ -324,7 +694,7 @@ class HaveSentRoomFlag(Enum):
     LIVE = "live"
 
 
-T = TypeVar("T")
+T = TypeVar("T", str, RoomStreamToken, MultiWriterStreamToken)
 
 
 @attr.s(auto_attribs=True, slots=True, frozen=True)
@@ -383,6 +753,9 @@ class RoomStatusMap(Generic[T]):
 
         return RoomStatusMap(statuses=dict(self._statuses))
 
+    def __len__(self) -> int:
+        return len(self._statuses)
+
 
 class MutableRoomStatusMap(RoomStatusMap[T]):
     """A mutable version of `RoomStatusMap`"""
@@ -439,7 +812,7 @@ class MutableRoomStatusMap(RoomStatusMap[T]):
             self._statuses[room_id] = HaveSentRoom.previously(from_token)
 
 
-@attr.s(auto_attribs=True)
+@attr.s(auto_attribs=True, frozen=True)
 class PerConnectionState:
     """The per-connection state. A snapshot of what we've sent down the
     connection before.
@@ -467,14 +840,18 @@ class PerConnectionState:
 
     room_configs: Mapping[str, RoomSyncConfig] = attr.Factory(dict)
 
+    list_to_rooms: Mapping[str, AbstractSet[str]] = attr.Factory(dict)
+
     def get_mutable(self) -> "MutablePerConnectionState":
         """Get a mutable copy of this state."""
         room_configs = cast(MutableMapping[str, RoomSyncConfig], self.room_configs)
+        list_to_rooms = cast(MutableMapping[str, Set[str]], self.list_to_rooms)
 
         return MutablePerConnectionState(
             rooms=self.rooms.get_mutable(),
             receipts=self.receipts.get_mutable(),
             room_configs=ChainMap({}, room_configs),
+            list_to_rooms=ChainMap({}, list_to_rooms),
         )
 
     def copy(self) -> "PerConnectionState":
@@ -482,6 +859,15 @@ class PerConnectionState:
             rooms=self.rooms.copy(),
             receipts=self.receipts.copy(),
             room_configs=dict(self.room_configs),
+            list_to_rooms=dict(self.list_to_rooms),
+        )
+
+    def __len__(self) -> int:
+        return (
+            len(self.rooms)
+            + len(self.receipts)
+            + len(self.room_configs)
+            + len(self.list_to_rooms)
         )
 
 
@@ -494,13 +880,20 @@ class MutablePerConnectionState(PerConnectionState):
 
     room_configs: typing.ChainMap[str, RoomSyncConfig]
 
+    list_to_rooms: typing.ChainMap[str, Set[str]]
+
     def has_updates(self) -> bool:
         return (
             bool(self.rooms.get_updates())
             or bool(self.receipts.get_updates())
             or bool(self.get_room_config_updates())
+            or bool(self.list_to_rooms.maps[0])
         )
 
     def get_room_config_updates(self) -> Mapping[str, RoomSyncConfig]:
         """Get updates to the room sync config"""
         return self.room_configs.maps[0]
+
+    def get_list_to_rooms_updates(self) -> Mapping[str, StrCollection]:
+        """Get updates to the `list_to_rooms`"""
+        return self.list_to_rooms.maps[0]

tests/handlers/test_sliding_sync.py

@@ -18,7 +18,6 @@
 #
 #
 import logging
-from copy import deepcopy
 from typing import Dict, List, Optional
 from unittest.mock import patch
 
@@ -47,7 +46,7 @@ from synapse.rest.client import knock, login, room
 from synapse.server import HomeServer
 from synapse.storage.util.id_generators import MultiWriterIdGenerator
 from synapse.types import JsonDict, StreamToken, UserID
-from synapse.types.handlers import SlidingSyncConfig
+from synapse.types.handlers.sliding_sync import SlidingSyncConfig
 from synapse.util import Clock
 
 from tests.replication._base import BaseMultiWorkerStreamTestCase
@@ -566,23 +565,11 @@ class RoomSyncConfigTestCase(TestCase):
         """
         Combine A into B and B into A to make sure we get the same result.
         """
-        # Since we're mutating these in place, make a copy for each of our trials
-        room_sync_config_a = deepcopy(a)
-        room_sync_config_b = deepcopy(b)
+        combined_config = a.combine_room_sync_config(b)
+        self._assert_room_config_equal(combined_config, expected, "B into A")
 
-        # Combine B into A
-        room_sync_config_a.combine_room_sync_config(room_sync_config_b)
-
-        self._assert_room_config_equal(room_sync_config_a, expected, "B into A")
-
-        # Since we're mutating these in place, make a copy for each of our trials
-        room_sync_config_a = deepcopy(a)
-        room_sync_config_b = deepcopy(b)
-
-        # Combine A into B
-        room_sync_config_b.combine_room_sync_config(room_sync_config_a)
-
-        self._assert_room_config_equal(room_sync_config_b, expected, "A into B")
+        combined_config = a.combine_room_sync_config(b)
+        self._assert_room_config_equal(combined_config, expected, "A into B")
 
 
 class GetRoomMembershipForUserAtToTokenTestCase(HomeserverTestCase):

tests/rest/client/sliding_sync/test_rooms_meta.py

@@ -16,7 +16,7 @@ import logging
 from twisted.test.proto_helpers import MemoryReactor
 
 import synapse.rest.admin
-from synapse.api.constants import EventTypes, Membership
+from synapse.api.constants import EventContentFields, EventTypes, Membership
 from synapse.api.room_versions import RoomVersions
 from synapse.rest.client import login, room, sync
 from synapse.server import HomeServer
@@ -44,6 +44,10 @@ class SlidingSyncRoomsMetaTestCase(SlidingSyncBase):
     def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
         self.store = hs.get_datastores().main
         self.storage_controllers = hs.get_storage_controllers()
+        self.state_handler = self.hs.get_state_handler()
+        persistence = self.hs.get_storage_controllers().persistence
+        assert persistence is not None
+        self.persistence = persistence
 
     def test_rooms_meta_when_joined(self) -> None:
         """
@@ -600,16 +604,16 @@ class SlidingSyncRoomsMetaTestCase(SlidingSyncBase):
         Test that `bump_stamp` ignores backfilled events, i.e. events with a
         negative stream ordering.
         """
-
         user1_id = self.register_user("user1", "pass")
         user1_tok = self.login(user1_id, "pass")
 
         # Create a remote room
         creator = "@user:other"
         room_id = "!foo:other"
+        room_version = RoomVersions.V10
         shared_kwargs = {
             "room_id": room_id,
-            "room_version": "10",
+            "room_version": room_version.identifier,
         }
 
         create_tuple = self.get_success(
@@ -618,6 +622,12 @@ class SlidingSyncRoomsMetaTestCase(SlidingSyncBase):
                 prev_event_ids=[],
                 type=EventTypes.Create,
                 state_key="",
+                content={
+                    # The `ROOM_CREATOR` field could be removed if we used a room
+                    # version > 10 (in favor of relying on `sender`)
+                    EventContentFields.ROOM_CREATOR: creator,
+                    EventContentFields.ROOM_VERSION: room_version.identifier,
+                },
                 sender=creator,
                 **shared_kwargs,
             )
@@ -667,22 +677,29 @@ class SlidingSyncRoomsMetaTestCase(SlidingSyncBase):
         ]
 
         # Ensure the local HS knows the room version
-        self.get_success(
-            self.store.store_room(room_id, creator, False, RoomVersions.V10)
-        )
+        self.get_success(self.store.store_room(room_id, creator, False, room_version))
 
         # Persist these events as backfilled events.
-        persistence = self.hs.get_storage_controllers().persistence
-        assert persistence is not None
-
         for event, context in remote_events_and_contexts:
-            self.get_success(persistence.persist_event(event, context, backfilled=True))
+            self.get_success(
+                self.persistence.persist_event(event, context, backfilled=True)
+            )
 
-        # Now we join the local user to the room
-        join_tuple = self.get_success(
+        # Now we join the local user to the room. We want to make this feel as close to
+        # the real `process_remote_join()` as possible but we'd like to avoid some of
+        # the auth checks that would be done in the real code.
+        #
+        # FIXME: The test was originally written using this less-real
+        # `persist_event(...)` shortcut but it would be nice to use the real remote join
+        # process in a `FederatingHomeserverTestCase`.
+        flawed_join_tuple = self.get_success(
             create_event(
                 self.hs,
                 prev_event_ids=[invite_tuple[0].event_id],
+                # This doesn't work correctly to create an `EventContext` that includes
+                # both of these state events. I assume it's because we're working on our
+                # local homeserver which has the remote state set as `outlier`. We have
+                # to create our own EventContext below to get this right.
                 auth_event_ids=[create_tuple[0].event_id, invite_tuple[0].event_id],
                 type=EventTypes.Member,
                 state_key=user1_id,
@@ -691,7 +708,22 @@ class SlidingSyncRoomsMetaTestCase(SlidingSyncBase):
                 **shared_kwargs,
             )
         )
-        self.get_success(persistence.persist_event(*join_tuple))
+        # We have to create our own context to get the state set correctly. If we use
+        # the `EventContext` from the `flawed_join_tuple`, the `current_state_events`
+        # table will only have the join event in it which should never happen in our
+        # real server.
+        join_event = flawed_join_tuple[0]
+        join_context = self.get_success(
+            self.state_handler.compute_event_context(
+                join_event,
+                state_ids_before_event={
+                    (e.type, e.state_key): e.event_id
+                    for e in [create_tuple[0], invite_tuple[0]]
+                },
+                partial_state=False,
+            )
+        )
+        self.get_success(self.persistence.persist_event(join_event, join_context))
 
         # Doing an SS request should return a positive `bump_stamp`, even though
         # the only event that matches the bump types has as negative stream

tests/rest/client/sliding_sync/test_rooms_required_state.py

@@ -191,8 +191,14 @@ class SlidingSyncRoomsRequiredStateTestCase(SlidingSyncBase):
         }
         _, from_token = self.do_sync(sync_body, tok=user1_tok)
 
-        # Reset the in-memory cache
-        self.hs.get_sliding_sync_handler().connection_store._connections.clear()
+        # Reset the positions
+        self.get_success(
+            self.store.db_pool.simple_delete(
+                table="sliding_sync_connections",
+                keyvalues={"user_id": user1_id},
+                desc="clear_cache",
+            )
+        )
 
         # Make the Sliding Sync request
         channel = self.make_request(

tests/storage/test__base.py

@@ -112,6 +112,24 @@ class UpdateUpsertManyTests(unittest.HomeserverTestCase):
             {(1, "user1", "hello"), (2, "user2", "bleb")},
         )
 
+        self.get_success(
+            self.storage.db_pool.runInteraction(
+                "test",
+                self.storage.db_pool.simple_upsert_many_txn,
+                self.table_name,
+                key_names=key_names,
+                key_values=[[2, "user2"]],
+                value_names=[],
+                value_values=[],
+            )
+        )
+
+        # Check results are what we expect
+        self.assertEqual(
+            set(self._dump_table_to_tuple()),
+            {(1, "user1", "hello"), (2, "user2", "bleb")},
+        )
+
     def test_simple_update_many(self) -> None:
         """
         simple_update_many performs many updates at once.

tests/storage/test_events.py

@@ -19,6 +19,7 @@
 #
 #
 
+import logging
 from typing import List, Optional
 
 from twisted.test.proto_helpers import MemoryReactor
@@ -35,6 +36,8 @@ from synapse.util import Clock
 
 from tests.unittest import HomeserverTestCase
 
+logger = logging.getLogger(__name__)
+
 
 class ExtremPruneTestCase(HomeserverTestCase):
     servlets = [

tests/storage/test_roommember.py

@@ -24,7 +24,7 @@ from typing import List, Optional, Tuple, cast
 
 from twisted.test.proto_helpers import MemoryReactor
 
-from synapse.api.constants import EventTypes, JoinRules, Membership
+from synapse.api.constants import EventContentFields, EventTypes, JoinRules, Membership
 from synapse.api.room_versions import RoomVersions
 from synapse.rest import admin
 from synapse.rest.admin import register_servlets_for_client_rest_resource
@@ -38,6 +38,7 @@ from synapse.util import Clock
 from tests import unittest
 from tests.server import TestHomeServer
 from tests.test_utils import event_injection
+from tests.test_utils.event_injection import create_event
 from tests.unittest import skip_unless
 
 logger = logging.getLogger(__name__)
@@ -54,6 +55,10 @@ class RoomMemberStoreTestCase(unittest.HomeserverTestCase):
         # We can't test the RoomMemberStore on its own without the other event
         # storage logic
         self.store = hs.get_datastores().main
+        self.state_handler = self.hs.get_state_handler()
+        persistence = self.hs.get_storage_controllers().persistence
+        assert persistence is not None
+        self.persistence = persistence
 
         self.u_alice = self.register_user("alice", "pass")
         self.t_alice = self.login("alice", "pass")
@@ -220,31 +225,166 @@ class RoomMemberStoreTestCase(unittest.HomeserverTestCase):
         )
 
     def test_join_locally_forgotten_room(self) -> None:
-        """Tests if a user joins a forgotten room the room is not forgotten anymore."""
-        self.room = self.helper.create_room_as(self.u_alice, tok=self.t_alice)
-        self.assertFalse(
-            self.get_success(self.store.is_locally_forgotten_room(self.room))
-        )
+        """
+        Tests if a user joins a forgotten room, the room is not forgotten anymore.
 
-        # after leaving and forget the room, it is forgotten
-        self.get_success(
-            event_injection.inject_member_event(
-                self.hs, self.room, self.u_alice, "leave"
+        Since a room can't be re-joined if everyone has left. This can only happen with
+        a room with remote users in it.
+        """
+        user1_id = self.register_user("user1", "pass")
+        user1_tok = self.login(user1_id, "pass")
+
+        # Create a remote room
+        creator = "@user:other"
+        room_id = "!foo:other"
+        room_version = RoomVersions.V10
+        shared_kwargs = {
+            "room_id": room_id,
+            "room_version": room_version.identifier,
+        }
+
+        create_tuple = self.get_success(
+            create_event(
+                self.hs,
+                prev_event_ids=[],
+                type=EventTypes.Create,
+                state_key="",
+                content={
+                    # The `ROOM_CREATOR` field could be removed if we used a room
+                    # version > 10 (in favor of relying on `sender`)
+                    EventContentFields.ROOM_CREATOR: creator,
+                    EventContentFields.ROOM_VERSION: room_version.identifier,
+                },
+                sender=creator,
+                **shared_kwargs,
             )
         )
-        self.get_success(self.store.forget(self.u_alice, self.room))
-        self.assertTrue(
-            self.get_success(self.store.is_locally_forgotten_room(self.room))
-        )
-
-        # after rejoin the room is not forgotten anymore
-        self.get_success(
-            event_injection.inject_member_event(
-                self.hs, self.room, self.u_alice, "join"
+        creator_tuple = self.get_success(
+            create_event(
+                self.hs,
+                prev_event_ids=[create_tuple[0].event_id],
+                auth_event_ids=[create_tuple[0].event_id],
+                type=EventTypes.Member,
+                state_key=creator,
+                content={"membership": Membership.JOIN},
+                sender=creator,
+                **shared_kwargs,
             )
         )
+
+        remote_events_and_contexts = [
+            create_tuple,
+            creator_tuple,
+        ]
+
+        # Ensure the local HS knows the room version
+        self.get_success(self.store.store_room(room_id, creator, False, room_version))
+
+        # Persist these events as backfilled events.
+        for event, context in remote_events_and_contexts:
+            self.get_success(
+                self.persistence.persist_event(event, context, backfilled=True)
+            )
+
+        # Now we join the local user to the room. We want to make this feel as close to
+        # the real `process_remote_join()` as possible but we'd like to avoid some of
+        # the auth checks that would be done in the real code.
+        #
+        # FIXME: The test was originally written using this less-real
+        # `persist_event(...)` shortcut but it would be nice to use the real remote join
+        # process in a `FederatingHomeserverTestCase`.
+        flawed_join_tuple = self.get_success(
+            create_event(
+                self.hs,
+                prev_event_ids=[creator_tuple[0].event_id],
+                # This doesn't work correctly to create an `EventContext` that includes
+                # both of these state events. I assume it's because we're working on our
+                # local homeserver which has the remote state set as `outlier`. We have
+                # to create our own EventContext below to get this right.
+                auth_event_ids=[create_tuple[0].event_id],
+                type=EventTypes.Member,
+                state_key=user1_id,
+                content={"membership": Membership.JOIN},
+                sender=user1_id,
+                **shared_kwargs,
+            )
+        )
+        # We have to create our own context to get the state set correctly. If we use
+        # the `EventContext` from the `flawed_join_tuple`, the `current_state_events`
+        # table will only have the join event in it which should never happen in our
+        # real server.
+        join_event = flawed_join_tuple[0]
+        join_context = self.get_success(
+            self.state_handler.compute_event_context(
+                join_event,
+                state_ids_before_event={
+                    (e.type, e.state_key): e.event_id for e in [create_tuple[0]]
+                },
+                partial_state=False,
+            )
+        )
+        self.get_success(self.persistence.persist_event(join_event, join_context))
+
+        # The room shouldn't be forgotten because the local user just joined
         self.assertFalse(
-            self.get_success(self.store.is_locally_forgotten_room(self.room))
+            self.get_success(self.store.is_locally_forgotten_room(room_id))
+        )
+
+        # After all of the local users (there is only user1) leave and forgetting the
+        # room, it is forgotten
+        user1_leave_response = self.helper.leave(room_id, user1_id, tok=user1_tok)
+        user1_leave_event = self.get_success(
+            self.store.get_event(user1_leave_response["event_id"])
+        )
+        self.get_success(self.store.forget(user1_id, room_id))
+        self.assertTrue(self.get_success(self.store.is_locally_forgotten_room(room_id)))
+
+        # Join the local user to the room (again). We want to make this feel as close to
+        # the real `process_remote_join()` as possible but we'd like to avoid some of
+        # the auth checks that would be done in the real code.
+        #
+        # FIXME: The test was originally written using this less-real
+        # `event_injection.inject_member_event(...)` shortcut but it would be nice to
+        # use the real remote join process in a `FederatingHomeserverTestCase`.
+        flawed_join_tuple = self.get_success(
+            create_event(
+                self.hs,
+                prev_event_ids=[user1_leave_response["event_id"]],
+                # This doesn't work correctly to create an `EventContext` that includes
+                # both of these state events. I assume it's because we're working on our
+                # local homeserver which has the remote state set as `outlier`. We have
+                # to create our own EventContext below to get this right.
+                auth_event_ids=[
+                    create_tuple[0].event_id,
+                    user1_leave_response["event_id"],
+                ],
+                type=EventTypes.Member,
+                state_key=user1_id,
+                content={"membership": Membership.JOIN},
+                sender=user1_id,
+                **shared_kwargs,
+            )
+        )
+        # We have to create our own context to get the state set correctly. If we use
+        # the `EventContext` from the `flawed_join_tuple`, the `current_state_events`
+        # table will only have the join event in it which should never happen in our
+        # real server.
+        join_event = flawed_join_tuple[0]
+        join_context = self.get_success(
+            self.state_handler.compute_event_context(
+                join_event,
+                state_ids_before_event={
+                    (e.type, e.state_key): e.event_id
+                    for e in [create_tuple[0], user1_leave_event]
+                },
+                partial_state=False,
+            )
+        )
+        self.get_success(self.persistence.persist_event(join_event, join_context))
+
+        # After the local user rejoins the remote room, it isn't forgotten anymore
+        self.assertFalse(
+            self.get_success(self.store.is_locally_forgotten_room(room_id))
         )
 
 

tests/unittest.py

@@ -272,8 +272,8 @@ class TestCase(unittest.TestCase):
 
     def assertIncludes(
         self,
-        actual_items: AbstractSet[str],
-        expected_items: AbstractSet[str],
+        actual_items: AbstractSet[TV],
+        expected_items: AbstractSet[TV],
         exact: bool = False,
         message: Optional[str] = None,
     ) -> None: