From c3516e9decc355b75a297d72a13b98a43d312e66 Mon Sep 17 00:00:00 2001
From: reivilibre <oliverw@matrix.org>
Date: Tue, 16 Aug 2022 12:16:56 +0000
Subject: [PATCH] Faster room joins: make `/joined_members` block whilst the
 room is partial stated. (#13514)

---
 changelog.d/13514.bugfix                     |  1 +
 synapse/handlers/message.py                  |  6 +++++-
 synapse/storage/controllers/state.py         | 13 +++++++++++++
 synapse/storage/databases/main/roommember.py |  3 +++
 4 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 changelog.d/13514.bugfix

diff --git a/changelog.d/13514.bugfix b/changelog.d/13514.bugfix
new file mode 100644
index 0000000000..7498af0e47
--- /dev/null
+++ b/changelog.d/13514.bugfix
@@ -0,0 +1 @@
+Faster room joins: make `/joined_members` block whilst the room is partial stated.
\ No newline at end of file
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 6b03603598..8f29ee9a87 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -331,7 +331,11 @@ class MessageHandler:
                     msg="Getting joined members while not being a current member of the room is forbidden.",
                 )
 
-        users_with_profile = await self.store.get_users_in_room_with_profiles(room_id)
+        users_with_profile = (
+            await self._state_storage_controller.get_users_in_room_with_profiles(
+                room_id
+            )
+        )
 
         # If this is an AS, double check that they are allowed to see the members.
         # This can either be because the AS user is in the room or because there
diff --git a/synapse/storage/controllers/state.py b/synapse/storage/controllers/state.py
index 0d480f1014..0c78eb735e 100644
--- a/synapse/storage/controllers/state.py
+++ b/synapse/storage/controllers/state.py
@@ -30,6 +30,7 @@ from typing import (
 from synapse.api.constants import EventTypes
 from synapse.events import EventBase
 from synapse.logging.opentracing import trace
+from synapse.storage.roommember import ProfileInfo
 from synapse.storage.state import StateFilter
 from synapse.storage.util.partial_state_events_tracker import (
     PartialCurrentStateTracker,
@@ -506,3 +507,15 @@ class StateStorageController:
         await self._partial_state_room_tracker.await_full_state(room_id)
 
         return await self.stores.main.get_current_hosts_in_room(room_id)
+
+    async def get_users_in_room_with_profiles(
+        self, room_id: str
+    ) -> Dict[str, ProfileInfo]:
+        """
+        Get the current users in the room with their profiles.
+        If the room is currently partial-stated, this will block until the room has
+        full state.
+        """
+        await self._partial_state_room_tracker.await_full_state(room_id)
+
+        return await self.stores.main.get_users_in_room_with_profiles(room_id)
diff --git a/synapse/storage/databases/main/roommember.py b/synapse/storage/databases/main/roommember.py
index 93ff4816c8..5e5f607a14 100644
--- a/synapse/storage/databases/main/roommember.py
+++ b/synapse/storage/databases/main/roommember.py
@@ -283,6 +283,9 @@ class RoomMemberWorkerStore(EventsWorkerStore):
 
         Returns:
             A mapping from user ID to ProfileInfo.
+
+        Preconditions:
+          - There is full state available for the room (it is not partial-stated).
         """
 
         def _get_users_in_room_with_profiles(