Sliding Sync: Add cache to get_tags_for_room(...) (#17730)

Add cache to `get_tags_for_room(...)`

This helps Sliding Sync because `get_tags_for_room(...)` is going to be
used in #17695

Essentially, we're just trying to match `get_account_data_for_room(...)`
which already has a tree cache.

changelog.d/17730.misc

@@ -0,0 +1 @@
+Add cache to `get_tags_for_room(...)`.

synapse/handlers/account_data.py

@@ -33,7 +33,7 @@
  ReplicationRemoveUserAccountDataRestServlet,
 )
 from synapse.streams import EventSource
-from synapse.types import JsonDict, StrCollection, StreamKeyType, UserID
+from synapse.types import JsonDict, JsonMapping, StrCollection, StreamKeyType, UserID
 
 if TYPE_CHECKING:
  from synapse.server import HomeServer
@@ -253,7 +253,7 @@ async def remove_account_data_for_user(
  return response["max_stream_id"]
 
  async def add_tag_to_room(
- self, user_id: str, room_id: str, tag: str, content: JsonDict
+ self, user_id: str, room_id: str, tag: str, content: JsonMapping
  ) -> int:
  """Add a tag to a room for a user.
 

synapse/storage/databases/main/cache.py

@@ -471,6 +471,7 @@ def _invalidate_caches_for_room(self, room_id: str) -> None:
 
  self._attempt_to_invalidate_cache("get_account_data_for_room", None)
  self._attempt_to_invalidate_cache("get_account_data_for_room_and_type", None)
+ self._attempt_to_invalidate_cache("get_tags_for_room", None)
  self._attempt_to_invalidate_cache("get_aliases_for_room", (room_id,))
  self._attempt_to_invalidate_cache("get_latest_event_ids_in_room", (room_id,))
  self._attempt_to_invalidate_cache("_get_forward_extremeties_for_room", None)

synapse/storage/databases/main/tags.py

@@ -158,9 +158,10 @@ def get_updated_tags_txn(txn: LoggingTransaction) -> List[str]:
 
  return results
 
+ @cached(num_args=2, tree=True)
  async def get_tags_for_room(
  self, user_id: str, room_id: str
- ) -> Dict[str, JsonDict]:
+ ) -> Mapping[str, JsonMapping]:
  """Get all the tags for the given room
 
  Args:
@@ -182,7 +183,7 @@ async def get_tags_for_room(
  return {tag: db_to_json(content) for tag, content in rows}
 
  async def add_tag_to_room(
- self, user_id: str, room_id: str, tag: str, content: JsonDict
+ self, user_id: str, room_id: str, tag: str, content: JsonMapping
  ) -> int:
  """Add a tag to a room for a user.
 
@@ -213,6 +214,7 @@ def add_tag_txn(txn: LoggingTransaction, next_id: int) -> None:
  await self.db_pool.runInteraction("add_tag", add_tag_txn, next_id)
 
  self.get_tags_for_user.invalidate((user_id,))
+ self.get_tags_for_room.invalidate((user_id, room_id))
 
  return self._account_data_id_gen.get_current_token()
 
@@ -237,6 +239,7 @@ def remove_tag_txn(txn: LoggingTransaction, next_id: int) -> None:
  await self.db_pool.runInteraction("remove_tag", remove_tag_txn, next_id)
 
  self.get_tags_for_user.invalidate((user_id,))
+ self.get_tags_for_room.invalidate((user_id, room_id))
 
  return self._account_data_id_gen.get_current_token()
 
@@ -290,9 +293,19 @@ def process_replication_rows(
  rows: Iterable[Any],
  ) -> None:
  if stream_name == AccountDataStream.NAME:
- for row in rows:
+ # Cast is safe because the `AccountDataStream` should only be giving us
+ # `AccountDataStreamRow`
+ account_data_stream_rows: List[AccountDataStream.AccountDataStreamRow] = (
+ cast(List[AccountDataStream.AccountDataStreamRow], rows)
+ )
+
+ for row in account_data_stream_rows:
  if row.data_type == AccountDataTypes.TAG:
  self.get_tags_for_user.invalidate((row.user_id,))
+ if row.room_id:
+ self.get_tags_for_room.invalidate((row.user_id, row.room_id))
+ else:
+ self.get_tags_for_room.invalidate((row.user_id,))
  self._account_data_stream_cache.entity_has_changed(
  row.user_id, token
  )

tests/server_notices/test_resource_limits_server_notices.py

@@ -89,7 +89,7 @@ def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
  return_value="!something:localhost"
  )
  self._rlsn._store.add_tag_to_room = AsyncMock(return_value=None) # type: ignore[method-assign]
- self._rlsn._store.get_tags_for_room = AsyncMock(return_value={}) # type: ignore[method-assign]
+ self._rlsn._store.get_tags_for_room = AsyncMock(return_value={})
 
  @override_config({"hs_disabled": True})
  def test_maybe_send_server_notice_disabled_hs(self) -> None: