diff --git a/changelog.d/17191.misc b/changelog.d/17191.misc
deleted file mode 100644
index bd55eeaa33..0000000000
--- a/changelog.d/17191.misc
+++ /dev/null
@@ -1 +0,0 @@
-Improve performance of calculating device lists changes in `/sync`.
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 659499af75..2bd1b8de88 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -1854,13 +1854,38 @@ class SyncHandler:
# Step 1a, check for changes in devices of users we share a room
# with
- users_that_have_changed = (
- await self._device_handler.get_device_changes_in_shared_rooms(
- user_id,
- sync_result_builder.joined_room_ids,
- from_token=since_token,
- )
+ #
+ # We do this in two different ways depending on what we have cached.
+ # If we already have a list of all the user that have changed since
+ # the last sync then it's likely more efficient to compare the rooms
+ # they're in with the rooms the syncing user is in.
+ #
+ # If we don't have that info cached then we get all the users that
+ # share a room with our user and check if those users have changed.
+ cache_result = self.store.get_cached_device_list_changes(
+ since_token.device_list_key
)
+ if cache_result.hit:
+ changed_users = cache_result.entities
+
+ result = await self.store.get_rooms_for_users(changed_users)
+
+ for changed_user_id, entries in result.items():
+ # Check if the changed user shares any rooms with the user,
+ # or if the changed user is the syncing user (as we always
+ # want to include device list updates of their own devices).
+ if user_id == changed_user_id or any(
+ rid in joined_rooms for rid in entries
+ ):
+ users_that_have_changed.add(changed_user_id)
+ else:
+ users_that_have_changed = (
+ await self._device_handler.get_device_changes_in_shared_rooms(
+ user_id,
+ sync_result_builder.joined_room_ids,
+ from_token=since_token,
+ )
+ )
# Step 1b, check for newly joined rooms
for room_id in newly_joined_rooms:
diff --git a/synapse/storage/databases/main/devices.py b/synapse/storage/databases/main/devices.py
index d98f0593bc..8dbcb3f5a0 100644
--- a/synapse/storage/databases/main/devices.py
+++ b/synapse/storage/databases/main/devices.py
@@ -70,7 +70,10 @@ from synapse.types import (
from synapse.util import json_decoder, json_encoder
from synapse.util.caches.descriptors import cached, cachedList
from synapse.util.caches.lrucache import LruCache
-from synapse.util.caches.stream_change_cache import StreamChangeCache
+from synapse.util.caches.stream_change_cache import (
+ AllEntitiesChangedResult,
+ StreamChangeCache,
+)
from synapse.util.cancellation import cancellable
from synapse.util.iterutils import batch_iter
from synapse.util.stringutils import shortstr
@@ -829,6 +832,16 @@ class DeviceWorkerStore(RoomMemberWorkerStore, EndToEndKeyWorkerStore):
)
return {device[0]: db_to_json(device[1]) for device in devices}
+ def get_cached_device_list_changes(
+ self,
+ from_key: int,
+ ) -> AllEntitiesChangedResult:
+ """Get set of users whose devices have changed since `from_key`, or None
+ if that information is not in our cache.
+ """
+
+ return self._device_list_stream_cache.get_all_entities_changed(from_key)
+
@cancellable
async def get_all_devices_changed(
self,
@@ -1462,7 +1475,7 @@ class DeviceWorkerStore(RoomMemberWorkerStore, EndToEndKeyWorkerStore):
sql = """
SELECT DISTINCT user_id FROM device_lists_changes_in_room
- WHERE {clause} AND stream_id > ?
+ WHERE {clause} AND stream_id >= ?
"""
def _get_device_list_changes_in_rooms_txn(
|
