From 1124111a12c3ab35f8b68d9031695aec8b2c7c50 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Wed, 13 May 2020 17:15:40 +0100
Subject: [PATCH] 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                             | 1 +
 synapse/app/generic_worker.py                     | 2 ++
 synapse/handlers/message.py                       | 2 --
 synapse/storage/data_stores/main/censor_events.py | 7 +------
 4 files changed, 4 insertions(+), 8 deletions(-)
 create mode 100644 changelog.d/7492.misc

diff --git a/changelog.d/7492.misc b/changelog.d/7492.misc
new file mode 100644
index 000000000..5ad31819d
--- /dev/null
+++ b/changelog.d/7492.misc
@@ -0,0 +1 @@
+Allow censoring of events to happen on workers.
diff --git a/synapse/app/generic_worker.py b/synapse/app/generic_worker.py
index 667ad2042..bccb1140b 100644
--- a/synapse/app/generic_worker.py
+++ b/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,
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index a622a600b..0242521cc 100644
--- a/synapse/handlers/message.py
+++ b/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():
diff --git a/synapse/storage/data_stores/main/censor_events.py b/synapse/storage/data_stores/main/censor_events.py
index 49683b4d5..2d4826172 100644
--- a/synapse/storage/data_stores/main/censor_events.py
+++ b/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