diff --git a/synapse/storage/databases/main/roommember.py b/synapse/storage/databases/main/roommember.py
index 8e2ba7b7b4..ea6a5e2f34 100644
--- a/synapse/storage/databases/main/roommember.py
+++ b/synapse/storage/databases/main/roommember.py
@@ -13,6 +13,7 @@
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
+from itertools import chain
from typing import (
TYPE_CHECKING,
AbstractSet,
@@ -1131,12 +1132,33 @@ class RoomMemberWorkerStore(EventsWorkerStore):
else:
# The cache doesn't match the state group or prev state group,
# so we calculate the result from first principles.
+ #
+ # We need to fetch all hosts joined to the room according to `state` by
+ # inspecting all join memberships in `state`. However, if the `state` is
+ # relatively recent then many of its events are likely to be held in
+ # the current state of the room, which is easily available and likely
+ # cached.
+ #
+ # We therefore compute the set of `state` events not in the
+ # current state and only fetch those.
+ current_memberships = (
+ await self._get_approximate_current_memberships_in_room(room_id)
+ )
+ unknown_state_events = {}
+ joined_users_in_current_state = []
+
+ for (type, state_key), event_id in state.items():
+ if event_id not in current_memberships:
+ unknown_state_events[type, state_key] = event_id
+ elif current_memberships[event_id] == Membership.JOIN:
+ joined_users_in_current_state.append(state_key)
+
joined_user_ids = await self.get_joined_user_ids_from_state(
- room_id, state
+ room_id, unknown_state_events
)
cache.hosts_to_joined_users = {}
- for user_id in joined_user_ids:
+ for user_id in chain(joined_user_ids, joined_users_in_current_state):
host = intern_string(get_domain_from_id(user_id))
cache.hosts_to_joined_users.setdefault(host, set()).add(user_id)
@@ -1147,6 +1169,26 @@ class RoomMemberWorkerStore(EventsWorkerStore):
return frozenset(cache.hosts_to_joined_users)
+ async def _get_approximate_current_memberships_in_room(
+ self, room_id: str
+ ) -> Mapping[str, Optional[str]]:
+ """Build a map from event id to membership, for all events in the current state.
+
+ The event ids of non-memberships events (e.g. `m.room.power_levels`) are present
+ in the result, mapped to values of `None`.
+
+ The result is approximate for partially-joined rooms. It is fully accurate
+ for fully-joined rooms.
+ """
+
+ rows = await self.db_pool.simple_select_list(
+ "current_state_events",
+ keyvalues={"room_id": room_id},
+ retcols=("event_id", "membership"),
+ desc="has_completed_background_updates",
+ )
+ return {row["event_id"]: row["membership"] for row in rows}
+
@cached(max_entries=10000)
def _get_joined_hosts_cache(self, room_id: str) -> "_JoinedHostsCache":
return _JoinedHostsCache()
|
