Rename `_auth_and_persist_fetched_events` (#11116)

... to `_auth_and_persist_outliers`, since that reflects its purpose better.

changelog.d/11116.misc

@@ -0,0 +1 @@
+Clean up some of the federation event authentication code for clarity.

synapse/handlers/federation_event.py

@@ -1116,14 +1116,12 @@ class FederationEventHandler:
 
         await concurrently_execute(get_event, event_ids, 5)
         logger.info("Fetched %i events of %i requested", len(events), len(event_ids))
-        await self._auth_and_persist_fetched_events(destination, room_id, events)
+        await self._auth_and_persist_outliers(room_id, events)
 
-    async def _auth_and_persist_fetched_events(
-        self, origin: str, room_id: str, events: Iterable[EventBase]
+    async def _auth_and_persist_outliers(
+        self, room_id: str, events: Iterable[EventBase]
     ) -> None:
-        """Persist the events fetched by _get_events_and_persist or _get_remote_auth_chain_for_event
-
-        The events to be persisted must be outliers.
+        """Persist a batch of outlier events fetched from remote servers.
 
         We first sort the events to make sure that we process each event's auth_events
         before the event itself, and then auth and persist them.
@@ -1131,7 +1129,6 @@ class FederationEventHandler:
         Notifies about the events where appropriate.
 
         Params:
-            origin: where the events came from
             room_id: the room that the events are meant to be in (though this has
                not yet been checked)
             events: the events that have been fetched
@@ -1167,15 +1164,15 @@ class FederationEventHandler:
                 shortstr(e.event_id for e in roots),
             )
 
-            await self._auth_and_persist_fetched_events_inner(origin, room_id, roots)
+            await self._auth_and_persist_outliers_inner(room_id, roots)
 
             for ev in roots:
                 del event_map[ev.event_id]
 
-    async def _auth_and_persist_fetched_events_inner(
-        self, origin: str, room_id: str, fetched_events: Collection[EventBase]
+    async def _auth_and_persist_outliers_inner(
+        self, room_id: str, fetched_events: Collection[EventBase]
     ) -> None:
-        """Helper for _auth_and_persist_fetched_events
+        """Helper for _auth_and_persist_outliers
 
         Persists a batch of events where we have (theoretically) already persisted all
         of their auth events.
@@ -1719,9 +1716,7 @@ class FederationEventHandler:
         for s in seen_remotes:
             remote_event_map.pop(s, None)
 
-        await self._auth_and_persist_fetched_events(
-            destination, room_id, remote_event_map.values()
-        )
+        await self._auth_and_persist_outliers(room_id, remote_event_map.values())
 
     async def _update_context_for_auth_events(
         self, event: EventBase, context: EventContext, auth_events: StateMap[EventBase]