Optimise calculating device_list changes in `/sync`. (#11974)

For users with large accounts it is inefficient to calculate the set of
users they share a room with (and takes a lot of space in the cache).
Instead we can look at users whose devices have changed since the last
sync and check if they share a room with the syncing user.
This commit is contained in:
Erik Johnston 2022-02-15 15:01:00 +00:00 committed by GitHub
parent bab2394aa9
commit 2b5643b3af
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4 changed files with 125 additions and 14 deletions

1
changelog.d/11974.misc Normal file
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@ -0,0 +1 @@
Optimise calculating device_list changes in `/sync`.

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@ -1289,23 +1289,54 @@ class SyncHandler:
# room with by looking at all users that have left a room plus users
# that were in a room we've left.
users_who_share_room = await self.store.get_users_who_share_room_with_user(
user_id
users_that_have_changed = set()
joined_rooms = sync_result_builder.joined_room_ids
# Step 1a, check for changes in devices of users we share a room
# with
#
# 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.
changed_users = self.store.get_cached_device_list_changes(
since_token.device_list_key
)
if changed_users is not None:
result = await self.store.get_rooms_for_users_with_stream_ordering(
changed_users
)
# Always tell the user about their own devices. We check as the user
# ID is almost certainly already included (unless they're not in any
# rooms) and taking a copy of the set is relatively expensive.
if user_id not in users_who_share_room:
users_who_share_room = set(users_who_share_room)
users_who_share_room.add(user_id)
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(
e.room_id in joined_rooms for e in entries
):
users_that_have_changed.add(changed_user_id)
else:
users_who_share_room = (
await self.store.get_users_who_share_room_with_user(user_id)
)
tracked_users = users_who_share_room
# Always tell the user about their own devices. We check as the user
# ID is almost certainly already included (unless they're not in any
# rooms) and taking a copy of the set is relatively expensive.
if user_id not in users_who_share_room:
users_who_share_room = set(users_who_share_room)
users_who_share_room.add(user_id)
# Step 1a, check for changes in devices of users we share a room with
users_that_have_changed = await self.store.get_users_whose_devices_changed(
since_token.device_list_key, tracked_users
)
tracked_users = users_who_share_room
users_that_have_changed = (
await self.store.get_users_whose_devices_changed(
since_token.device_list_key, tracked_users
)
)
# Step 1b, check for newly joined rooms
for room_id in newly_joined_rooms:
@ -1329,7 +1360,14 @@ class SyncHandler:
newly_left_users.update(left_users)
# Remove any users that we still share a room with.
newly_left_users -= users_who_share_room
left_users_rooms = (
await self.store.get_rooms_for_users_with_stream_ordering(
newly_left_users
)
)
for user_id, entries in left_users_rooms.items():
if any(e.room_id in joined_rooms for e in entries):
newly_left_users.discard(user_id)
return DeviceLists(changed=users_that_have_changed, left=newly_left_users)
else:

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@ -670,6 +670,16 @@ class DeviceWorkerStore(SQLBaseStore):
device["device_id"]: db_to_json(device["content"]) for device in devices
}
def get_cached_device_list_changes(
self,
from_key: int,
) -> Optional[Set[str]]:
"""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)
async def get_users_whose_devices_changed(
self, from_key: int, user_ids: Iterable[str]
) -> Set[str]:

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@ -504,6 +504,68 @@ class RoomMemberWorkerStore(EventsWorkerStore):
for room_id, instance, stream_id in txn
)
@cachedList(
cached_method_name="get_rooms_for_user_with_stream_ordering",
list_name="user_ids",
)
async def get_rooms_for_users_with_stream_ordering(
self, user_ids: Collection[str]
) -> Dict[str, FrozenSet[GetRoomsForUserWithStreamOrdering]]:
"""A batched version of `get_rooms_for_user_with_stream_ordering`.
Returns:
Map from user_id to set of rooms that is currently in.
"""
return await self.db_pool.runInteraction(
"get_rooms_for_users_with_stream_ordering",
self._get_rooms_for_users_with_stream_ordering_txn,
user_ids,
)
def _get_rooms_for_users_with_stream_ordering_txn(
self, txn, user_ids: Collection[str]
) -> Dict[str, FrozenSet[GetRoomsForUserWithStreamOrdering]]:
clause, args = make_in_list_sql_clause(
self.database_engine,
"c.state_key",
user_ids,
)
if self._current_state_events_membership_up_to_date:
sql = f"""
SELECT c.state_key, room_id, e.instance_name, e.stream_ordering
FROM current_state_events AS c
INNER JOIN events AS e USING (room_id, event_id)
WHERE
c.type = 'm.room.member'
AND c.membership = ?
AND {clause}
"""
else:
sql = f"""
SELECT c.state_key, room_id, e.instance_name, e.stream_ordering
FROM current_state_events AS c
INNER JOIN room_memberships AS m USING (room_id, event_id)
INNER JOIN events AS e USING (room_id, event_id)
WHERE
c.type = 'm.room.member'
AND m.membership = ?
AND {clause}
"""
txn.execute(sql, [Membership.JOIN] + args)
result = {user_id: set() for user_id in user_ids}
for user_id, room_id, instance, stream_id in txn:
result[user_id].add(
GetRoomsForUserWithStreamOrdering(
room_id, PersistedEventPosition(instance, stream_id)
)
)
return {user_id: frozenset(v) for user_id, v in result.items()}
async def get_users_server_still_shares_room_with(
self, user_ids: Collection[str]
) -> Set[str]: