Deduplicate `is_server_notices_room`. (#13780)

4 files changed, 20 insertions, 18 deletions

diff --git a/changelog.d/13780.misc b/changelog.d/13780.misc
new file mode 100644
index 0000000000..1bcac51cad
--- /dev/null
+++ b/changelog.d/13780.misc
@@ -0,0 +1 @@
+Deduplicate `is_server_notices_room`.
\ No newline at end of file
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 72157d5a36..e07cda133a 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -752,20 +752,12 @@ class EventCreationHandler:
         if builder.type == EventTypes.Member:
             membership = builder.content.get("membership", None)
             if membership == Membership.JOIN:
-                return await self._is_server_notices_room(builder.room_id)
+                return await self.store.is_server_notice_room(builder.room_id)
             elif membership == Membership.LEAVE:
                 # the user is always allowed to leave (but not kick people)
                 return builder.state_key == requester.user.to_string()
         return False
 
-    async def _is_server_notices_room(self, room_id: str) -> bool:
-        if self.config.servernotices.server_notices_mxid is None:
-            return False
-        is_server_notices_room = await self.store.check_local_user_in_room(
-            user_id=self.config.servernotices.server_notices_mxid, room_id=room_id
-        )
-        return is_server_notices_room
-
     async def assert_accepted_privacy_policy(self, requester: Requester) -> None:
         """Check if a user has accepted the privacy policy
 
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 5d4adf5bfd..8d01f4bf2b 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -837,7 +837,7 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
                 old_membership == Membership.INVITE
                 and effective_membership_state == Membership.LEAVE
             ):
-                is_blocked = await self._is_server_notice_room(room_id)
+                is_blocked = await self.store.is_server_notice_room(room_id)
                 if is_blocked:
                     raise SynapseError(
                         HTTPStatus.FORBIDDEN,
@@ -1617,14 +1617,6 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
 
         return False
 
-    async def _is_server_notice_room(self, room_id: str) -> bool:
-        if self._server_notices_mxid is None:
-            return False
-        is_server_notices_room = await self.store.check_local_user_in_room(
-            user_id=self._server_notices_mxid, room_id=room_id
-        )
-        return is_server_notices_room
-
 
 class RoomMemberMasterHandler(RoomMemberHandler):
     def __init__(self, hs: "HomeServer"):
diff --git a/synapse/storage/databases/main/roommember.py b/synapse/storage/databases/main/roommember.py
index fdb4684e12..a8d224602a 100644
--- a/synapse/storage/databases/main/roommember.py
+++ b/synapse/storage/databases/main/roommember.py
@@ -88,6 +88,8 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         # at a time. Keyed by room_id.
         self._joined_host_linearizer = Linearizer("_JoinedHostsCache")
 
+        self._server_notices_mxid = hs.config.servernotices.server_notices_mxid
+
         if (
             self.hs.config.worker.run_background_tasks
             and self.hs.config.metrics.metrics_flags.known_servers
@@ -504,6 +506,21 @@ class RoomMemberWorkerStore(EventsWorkerStore):
 
         return membership == Membership.JOIN
 
+    async def is_server_notice_room(self, room_id: str) -> bool:
+        """
+        Determines whether the given room is a 'Server Notices' room, used for
+        sending server notices to a user.
+
+        This is determined by seeing whether the server notices user is present
+        in the room.
+        """
+        if self._server_notices_mxid is None:
+            return False
+        is_server_notices_room = await self.check_local_user_in_room(
+            user_id=self._server_notices_mxid, room_id=room_id
+        )
+        return is_server_notices_room
+
     async def get_local_current_membership_for_user_in_room(
         self, user_id: str, room_id: str
     ) -> Tuple[Optional[str], Optional[str]]: