Allow censoring of events to happen on workers. (#7492)

This is safe as we can now write to cache invalidation stream on workers, and is required for when we move event persistence off master.

changelog.d/7492.misc

@@ -0,0 +1 @@
+Allow censoring of events to happen on workers.

synapse/app/generic_worker.py

@@ -122,6 +122,7 @@ from synapse.rest.client.v2_alpha.register import RegisterRestServlet
 from synapse.rest.client.versions import VersionsRestServlet
 from synapse.rest.key.v2 import KeyApiV2Resource
 from synapse.server import HomeServer
+from synapse.storage.data_stores.main.censor_events import CensorEventsStore
 from synapse.storage.data_stores.main.media_repository import MediaRepositoryStore
 from synapse.storage.data_stores.main.monthly_active_users import (
     MonthlyActiveUsersWorkerStore,
@@ -442,6 +443,7 @@ class GenericWorkerSlavedStore(
     SlavedGroupServerStore,
     SlavedAccountDataStore,
     SlavedPusherStore,
+    CensorEventsStore,
     SlavedEventStore,
     SlavedKeyStore,
     RoomStore,

synapse/handlers/message.py

@@ -72,7 +72,6 @@ class MessageHandler(object):
         self.state_store = self.storage.state
         self._event_serializer = hs.get_event_client_serializer()
         self._ephemeral_events_enabled = hs.config.enable_ephemeral_messages
-        self._is_worker_app = bool(hs.config.worker_app)
 
         # The scheduled call to self._expire_event. None if no call is currently
         # scheduled.
@@ -260,7 +259,6 @@ class MessageHandler(object):
         Args:
             event (EventBase): The event to schedule the expiry of.
         """
-        assert not self._is_worker_app
 
         expiry_ts = event.content.get(EventContentFields.SELF_DESTRUCT_AFTER)
         if not isinstance(expiry_ts, int) or event.is_state():

synapse/storage/data_stores/main/censor_events.py

@@ -33,15 +33,10 @@ if TYPE_CHECKING:
 logger = logging.getLogger(__name__)
 
 
-class CensorEventsStore(CacheInvalidationWorkerStore, EventsWorkerStore, SQLBaseStore):
+class CensorEventsStore(EventsWorkerStore, CacheInvalidationWorkerStore, SQLBaseStore):
     def __init__(self, database: Database, db_conn, hs: "HomeServer"):
         super().__init__(database, db_conn, hs)
 
-        # This should only exist on master for now
-        assert (
-            hs.config.worker.worker_app is None
-        ), "Can only instantiate CensorEventsStore on master"
-
         def _censor_redactions():
             return run_as_background_process(
                 "_censor_redactions", self._censor_redactions