Remove more usages of cursor_to_dict

synapse/rest/admin/rooms.py

@@ -724,7 +724,17 @@ async def on_GET(
         room_id, _ = await self.resolve_room_id(room_identifier)
 
         extremities = await self.store.get_forward_extremities_for_room(room_id)
-        return HTTPStatus.OK, {"count": len(extremities), "results": extremities}
+        result = [
+            {
+                "event_id": ex[0],
+                "state_group": ex[1],
+                "depth": ex[2],
+                "received_ts": ex[3],
+            }
+            for ex in extremities
+        ]
+
+        return HTTPStatus.OK, {"count": len(extremities), "results": result}
 
 
 class RoomEventContextServlet(RestServlet):

synapse/storage/databases/main/events_forward_extremities.py

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 import logging
-from typing import Any, Dict, List
+from typing import Any, Dict, List, Optional, Tuple, cast
 
 from synapse.api.errors import SynapseError
 from synapse.storage.database import LoggingTransaction
@@ -91,12 +91,17 @@ def delete_forward_extremities_for_room_txn(txn: LoggingTransaction) -> int:
 
     async def get_forward_extremities_for_room(
         self, room_id: str
-    ) -> List[Dict[str, Any]]:
-        """Get list of forward extremities for a room."""
+    ) -> List[Tuple[str, int, int, int]]:
+        """
+        Get list of forward extremities for a room.
+
+        Returns:
+            A list of tuples of event_id, state_group, depth, and received_ts.
+        """
 
         def get_forward_extremities_for_room_txn(
             txn: LoggingTransaction,
-        ) -> List[Dict[str, Any]]:
+        ) -> List[Tuple[str, int, int, int]]:
             sql = """
                 SELECT event_id, state_group, depth, received_ts
                 FROM event_forward_extremities
@@ -106,7 +111,7 @@ def get_forward_extremities_for_room_txn(
             """
 
             txn.execute(sql, (room_id,))
-            return self.db_pool.cursor_to_dict(txn)
+            return cast(List[Tuple[str, int, int, int]], txn.fetchall())
 
         return await self.db_pool.runInteraction(
             "get_forward_extremities_for_room",