From d0c713cc85f094c323b2ba3f02d8ac411a7f0705 Mon Sep 17 00:00:00 2001
From: Sean Quah <8349537+squahtx@users.noreply.github.com>
Date: Fri, 10 Feb 2023 23:29:00 +0000
Subject: Return read-only collections from `@cached` methods (#13755)

It's important that collections returned from `@cached` methods are not
modified, otherwise future retrievals from the cache will return the
modified collection.

This applies to the return values from `@cached` methods and the values
inside the dictionaries returned by `@cachedList` methods. It's not
necessary for the dictionaries returned by `@cachedList` methods
themselves to be read-only.

Signed-off-by: Sean Quah <seanq@matrix.org>
Co-authored-by: David Robertson <davidr@element.io>
---
 synapse/storage/databases/main/roommember.py | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

(limited to 'synapse/storage/databases/main/roommember.py')

diff --git a/synapse/storage/databases/main/roommember.py b/synapse/storage/databases/main/roommember.py
index ea6a5e2f34..694a5b802c 100644
--- a/synapse/storage/databases/main/roommember.py
+++ b/synapse/storage/databases/main/roommember.py
@@ -24,6 +24,7 @@ from typing import (
     List,
     Mapping,
     Optional,
+    Sequence,
     Set,
     Tuple,
     Union,
@@ -153,7 +154,7 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         return self._known_servers_count
 
     @cached(max_entries=100000, iterable=True)
-    async def get_users_in_room(self, room_id: str) -> List[str]:
+    async def get_users_in_room(self, room_id: str) -> Sequence[str]:
         """Returns a list of users in the room.
 
         Will return inaccurate results for rooms with partial state, since the state for
@@ -190,9 +191,7 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         )
 
     @cached()
-    def get_user_in_room_with_profile(
-        self, room_id: str, user_id: str
-    ) -> Dict[str, ProfileInfo]:
+    def get_user_in_room_with_profile(self, room_id: str, user_id: str) -> ProfileInfo:
         raise NotImplementedError()
 
     @cachedList(
@@ -246,7 +245,7 @@ class RoomMemberWorkerStore(EventsWorkerStore):
     @cached(max_entries=100000, iterable=True)
     async def get_users_in_room_with_profiles(
         self, room_id: str
-    ) -> Dict[str, ProfileInfo]:
+    ) -> Mapping[str, ProfileInfo]:
         """Get a mapping from user ID to profile information for all users in a given room.
 
         The profile information comes directly from this room's `m.room.member`
@@ -285,7 +284,7 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         )
 
     @cached(max_entries=100000)
-    async def get_room_summary(self, room_id: str) -> Dict[str, MemberSummary]:
+    async def get_room_summary(self, room_id: str) -> Mapping[str, MemberSummary]:
         """Get the details of a room roughly suitable for use by the room
         summary extension to /sync. Useful when lazy loading room members.
         Args:
@@ -357,7 +356,7 @@ class RoomMemberWorkerStore(EventsWorkerStore):
     @cached()
     async def get_invited_rooms_for_local_user(
         self, user_id: str
-    ) -> List[RoomsForUser]:
+    ) -> Sequence[RoomsForUser]:
         """Get all the rooms the *local* user is invited to.
 
         Args:
@@ -475,7 +474,7 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         return results
 
     @cached(iterable=True)
-    async def get_local_users_in_room(self, room_id: str) -> List[str]:
+    async def get_local_users_in_room(self, room_id: str) -> Sequence[str]:
         """
         Retrieves a list of the current roommembers who are local to the server.
         """
@@ -791,7 +790,7 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         """Returns the set of users who share a room with `user_id`"""
         room_ids = await self.get_rooms_for_user(user_id)
 
-        user_who_share_room = set()
+        user_who_share_room: Set[str] = set()
         for room_id in room_ids:
             user_ids = await self.get_users_in_room(room_id)
             user_who_share_room.update(user_ids)
@@ -953,7 +952,7 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         return True
 
     @cached(iterable=True, max_entries=10000)
-    async def get_current_hosts_in_room(self, room_id: str) -> Set[str]:
+    async def get_current_hosts_in_room(self, room_id: str) -> AbstractSet[str]:
         """Get current hosts in room based on current state."""
 
         # First we check if we already have `get_users_in_room` in the cache, as
-- 
cgit 1.5.1