fix delete_existing for _persist_events (#6300)

this is part of _retry_on_integrity_error, so should only be on _persist_events_and_state_updates

changelog.d/6300.misc

@@ -0,0 +1 @@
+Move `persist_events` out from main data store.

synapse/storage/data_stores/main/events.py

@@ -82,7 +82,7 @@ def _retry_on_integrity_error(func):
     @defer.inlineCallbacks
     def f(self, *args, **kwargs):
         try:
-            res = yield func(self, *args, **kwargs)
+            res = yield func(self, *args, delete_existing=False, **kwargs)
         except self.database_engine.module.IntegrityError:
             logger.exception("IntegrityError, retrying.")
             res = yield func(self, *args, delete_existing=True, **kwargs)

synapse/storage/persist_events.py

@@ -260,9 +260,7 @@ class EventsPersistenceStorage(object):
         self._event_persist_queue.handle_queue(room_id, persisting_queue)
 
     @defer.inlineCallbacks
-    def _persist_events(
-        self, events_and_contexts, backfilled=False, delete_existing=False
-    ):
+    def _persist_events(self, events_and_contexts, backfilled=False):
         """Calculates the change to current state and forward extremities, and
         persists the given events and with those updates.
 
@@ -412,7 +410,6 @@ class EventsPersistenceStorage(object):
                 state_delta_for_room=state_delta_for_room,
                 new_forward_extremeties=new_forward_extremeties,
                 backfilled=backfilled,
-                delete_existing=delete_existing,
             )
 
     @defer.inlineCallbacks