Use simple_select_many_batch in get_rooms_for_users

Author: Fizzadar

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 collections import defaultdict
 from typing import (
     TYPE_CHECKING,
     Collection,
@@ -681,38 +682,27 @@ async def get_rooms_for_users(
         Returns:
             Map from user_id to set of rooms that is currently in.
         """
-        return await self.db_pool.runInteraction(
-            "get_rooms_for_users",
-            self._get_rooms_for_users_txn,
-            user_ids,
-        )
-
-    def _get_rooms_for_users_txn(
-        self, txn: LoggingTransaction, user_ids: Collection[str]
-    ) -> Dict[str, FrozenSet[str]]:
 
-        clause, args = make_in_list_sql_clause(
-            self.database_engine,
-            "c.state_key",
-            user_ids,
+        rows = await self.db_pool.simple_select_many_batch(
+            table="current_state_events",
+            column="state_key",
+            iterable=user_ids,
+            retcols=(
+                "user_id",
+                "room_id",
+            ),
+            keyvalues={
+                "type": EventTypes.Member,
+                "membership": Membership.JOIN,
+            },
+            desc="get_rooms_for_users",
         )
 
-        sql = f"""
-            SELECT c.state_key, room_id
-            FROM current_state_events AS c
-            WHERE
-                c.type = 'm.room.member'
-                AND c.membership = ?
-                AND {clause}
-        """
-
-        txn.execute(sql, [Membership.JOIN] + args)
-
-        result: Dict[str, Set[str]] = {user_id: set() for user_id in user_ids}
-        for user_id, room_id in txn:
-            result[user_id].add(room_id)
+        user_rooms: Dict[str, Set[str]] = defaultdict(set)
+        for row in rows:
+            user_rooms[row["user_id"]].add(row["room_id"])
 
-        return {user_id: frozenset(v) for user_id, v in result.items()}
+        return {key: frozenset(rooms) for key, rooms in user_rooms.items()}
 
     @cached(max_entries=10000)
     async def does_pair_of_users_share_a_room(