Don't call SQLBaseStore methods from outside stores

synapse/storage/data_stores/main/roommember.py

@@ -15,6 +15,7 @@
 # limitations under the License.
 
 import logging
+from typing import Iterable, List
 
 from six import iteritems, itervalues
 
@@ -813,6 +814,22 @@ class RoomMemberWorkerStore(EventsWorkerStore):
 
         return set(room_ids)
 
+    def get_membership_from_event_ids(
+        self, member_event_ids: Iterable[str]
+    ) -> List[dict]:
+        """Get user_id and membership of a set of event IDs.
+        """
+
+        return self._simple_select_many_batch(
+            table="room_memberships",
+            column="event_id",
+            iterable=member_event_ids,
+            retcols=("user_id", "membership", "event_id"),
+            keyvalues={},
+            batch_size=500,
+            desc="get_membership_from_event_ids",
+        )
+
 
 class RoomMemberBackgroundUpdateStore(BackgroundUpdateStore):
     def __init__(self, db_conn, hs):