Wrap a number of things that run in the background

This will reduce the number of "Starting db connection from sentinel context"
warnings, and will help with our metrics.

synapse/storage/event_push_actions.py

@@ -22,6 +22,7 @@ from canonicaljson import json
 
 from twisted.internet import defer
 
+from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.storage._base import LoggingTransaction, SQLBaseStore
 from synapse.util.caches.descriptors import cachedInlineCallbacks
 
@@ -458,11 +459,12 @@ class EventPushActionsWorkerStore(SQLBaseStore):
                 "Error removing push actions after event persistence failure",
             )
 
-    @defer.inlineCallbacks
     def _find_stream_orderings_for_times(self):
-        yield self.runInteraction(
+        run_as_background_process(
+            "event_push_action_stream_orderings",
+            self.runInteraction,
             "_find_stream_orderings_for_times",
-            self._find_stream_orderings_for_times_txn
+            self._find_stream_orderings_for_times_txn,
         )
 
     def _find_stream_orderings_for_times_txn(self, txn):
@@ -604,7 +606,7 @@ class EventPushActionsStore(EventPushActionsWorkerStore):
 
         self._doing_notif_rotation = False
         self._rotate_notif_loop = self._clock.looping_call(
-            self._rotate_notifs, 30 * 60 * 1000
+            self._start_rotate_notifs, 30 * 60 * 1000,
         )
 
     def _set_push_actions_for_event_and_users_txn(self, txn, events_and_contexts,
@@ -787,6 +789,9 @@ class EventPushActionsStore(EventPushActionsWorkerStore):
             WHERE room_id = ? AND user_id = ? AND stream_ordering <= ?
         """, (room_id, user_id, stream_ordering))
 
+    def _start_rotate_notifs(self):
+        run_as_background_process("rotate_notifs", self._rotate_notifs)
+
     @defer.inlineCallbacks
     def _rotate_notifs(self):
         if self._doing_notif_rotation or self.stream_ordering_day_ago is None: