When restarting a partial join resync, prioritise the server which actioned a partial join (#14126)

This commit is contained in:
David Robertson 2022-10-18 12:33:18 +01:00 committed by GitHub
parent 4af93bd7f6
commit c3a4780080
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
6 changed files with 95 additions and 31 deletions

1
changelog.d/14126.misc Normal file
View File

@ -0,0 +1 @@
Faster joins: prioritise the server we joined by when restarting a partial join resync.

View File

@ -937,7 +937,10 @@ class DeviceListUpdater:
# Check if we are partially joining any rooms. If so we need to store
# all device list updates so that we can handle them correctly once we
# know who is in the room.
partial_rooms = await self.store.get_partial_state_rooms_and_servers()
# TODO(faster joins): this fetches and processes a bunch of data that we don't
# use. Could be replaced by a tighter query e.g.
# SELECT EXISTS(SELECT 1 FROM partial_state_rooms)
partial_rooms = await self.store.get_partial_state_room_resync_info()
if partial_rooms:
await self.store.add_remote_device_list_to_pending(
user_id,

View File

@ -632,6 +632,7 @@ class FederationHandler:
room_id=room_id,
servers=ret.servers_in_room,
device_lists_stream_id=self.store.get_device_stream_token(),
joined_via=origin,
)
try:
@ -1615,13 +1616,13 @@ class FederationHandler:
"""Resumes resyncing of all partial-state rooms after a restart."""
assert not self.config.worker.worker_app
partial_state_rooms = await self.store.get_partial_state_rooms_and_servers()
for room_id, servers_in_room in partial_state_rooms.items():
partial_state_rooms = await self.store.get_partial_state_room_resync_info()
for room_id, resync_info in partial_state_rooms.items():
run_as_background_process(
desc="sync_partial_state_room",
func=self._sync_partial_state_room,
initial_destination=None,
other_destinations=servers_in_room,
initial_destination=resync_info.joined_via,
other_destinations=resync_info.servers_in_room,
room_id=room_id,
)
@ -1650,28 +1651,12 @@ class FederationHandler:
# really leave, that might mean we have difficulty getting the room state over
# federation.
# https://github.com/matrix-org/synapse/issues/12802
#
# TODO(faster_joins): we need some way of prioritising which homeservers in
# `other_destinations` to try first, otherwise we'll spend ages trying dead
# homeservers for large rooms.
# https://github.com/matrix-org/synapse/issues/12999
if initial_destination is None and len(other_destinations) == 0:
raise ValueError(
f"Cannot resync state of {room_id}: no destinations provided"
)
# Make an infinite iterator of destinations to try. Once we find a working
# destination, we'll stick with it until it flakes.
destinations: Collection[str]
if initial_destination is not None:
# Move `initial_destination` to the front of the list.
destinations = list(other_destinations)
if initial_destination in destinations:
destinations.remove(initial_destination)
destinations = [initial_destination] + destinations
else:
destinations = other_destinations
destinations = _prioritise_destinations_for_partial_state_resync(
initial_destination, other_destinations, room_id
)
destination_iter = itertools.cycle(destinations)
# `destination` is the current remote homeserver we're pulling from.
@ -1769,3 +1754,29 @@ class FederationHandler:
room_id,
destination,
)
def _prioritise_destinations_for_partial_state_resync(
initial_destination: Optional[str],
other_destinations: Collection[str],
room_id: str,
) -> Collection[str]:
"""Work out the order in which we should ask servers to resync events.
If an `initial_destination` is given, it takes top priority. Otherwise
all servers are treated equally.
:raises ValueError: if no destination is provided at all.
"""
if initial_destination is None and len(other_destinations) == 0:
raise ValueError(f"Cannot resync state of {room_id}: no destinations provided")
if initial_destination is None:
return other_destinations
# Move `initial_destination` to the front of the list.
destinations = list(other_destinations)
if initial_destination in destinations:
destinations.remove(initial_destination)
destinations = [initial_destination] + destinations
return destinations

View File

@ -1658,7 +1658,7 @@ class DatabasePool:
table: string giving the table name
keyvalues: dict of column names and values to select the row with
retcol: string giving the name of the column to return
allow_none: If true, return None instead of failing if the SELECT
allow_none: If true, return None instead of raising StoreError if the SELECT
statement returns no rows
desc: description of the transaction, for logging and metrics
"""

View File

@ -97,6 +97,12 @@ class RoomSortOrder(Enum):
STATE_EVENTS = "state_events"
@attr.s(slots=True, frozen=True, auto_attribs=True)
class PartialStateResyncInfo:
joined_via: Optional[str]
servers_in_room: List[str] = attr.ib(factory=list)
class RoomWorkerStore(CacheInvalidationWorkerStore):
def __init__(
self,
@ -1160,17 +1166,29 @@ class RoomWorkerStore(CacheInvalidationWorkerStore):
desc="get_partial_state_servers_at_join",
)
async def get_partial_state_rooms_and_servers(
async def get_partial_state_room_resync_info(
self,
) -> Mapping[str, Collection[str]]:
"""Get all rooms containing events with partial state, and the servers known
to be in the room.
) -> Mapping[str, PartialStateResyncInfo]:
"""Get all rooms containing events with partial state, and the information
needed to restart a "resync" of those rooms.
Returns:
A dictionary of rooms with partial state, with room IDs as keys and
lists of servers in rooms as values.
"""
room_servers: Dict[str, List[str]] = {}
room_servers: Dict[str, PartialStateResyncInfo] = {}
rows = await self.db_pool.simple_select_list(
table="partial_state_rooms",
keyvalues={},
retcols=("room_id", "joined_via"),
desc="get_server_which_served_partial_join",
)
for row in rows:
room_id = row["room_id"]
joined_via = row["joined_via"]
room_servers[room_id] = PartialStateResyncInfo(joined_via=joined_via)
rows = await self.db_pool.simple_select_list(
"partial_state_rooms_servers",
@ -1182,7 +1200,15 @@ class RoomWorkerStore(CacheInvalidationWorkerStore):
for row in rows:
room_id = row["room_id"]
server_name = row["server_name"]
room_servers.setdefault(room_id, []).append(server_name)
entry = room_servers.get(room_id)
if entry is None:
# There is a foreign key constraint which enforces that every room_id in
# partial_state_rooms_servers appears in partial_state_rooms. So we
# expect `entry` to be non-null. (This reasoning fails if we've
# partial-joined between the two SELECTs, but this is unlikely to happen
# in practice.)
continue
entry.servers_in_room.append(server_name)
return room_servers
@ -1827,6 +1853,7 @@ class RoomStore(RoomBackgroundUpdateStore, RoomWorkerStore):
room_id: str,
servers: Collection[str],
device_lists_stream_id: int,
joined_via: str,
) -> None:
"""Mark the given room as containing events with partial state.
@ -1842,6 +1869,7 @@ class RoomStore(RoomBackgroundUpdateStore, RoomWorkerStore):
servers: other servers known to be in the room
device_lists_stream_id: the device_lists stream ID at the time when we first
joined the room.
joined_via: the server name we requested a partial join from.
"""
await self.db_pool.runInteraction(
"store_partial_state_room",
@ -1849,6 +1877,7 @@ class RoomStore(RoomBackgroundUpdateStore, RoomWorkerStore):
room_id,
servers,
device_lists_stream_id,
joined_via,
)
def _store_partial_state_room_txn(
@ -1857,6 +1886,7 @@ class RoomStore(RoomBackgroundUpdateStore, RoomWorkerStore):
room_id: str,
servers: Collection[str],
device_lists_stream_id: int,
joined_via: str,
) -> None:
DatabasePool.simple_insert_txn(
txn,
@ -1866,6 +1896,7 @@ class RoomStore(RoomBackgroundUpdateStore, RoomWorkerStore):
"device_lists_stream_id": device_lists_stream_id,
# To be updated later once the join event is persisted.
"join_event_id": None,
"joined_via": joined_via,
},
)
DatabasePool.simple_insert_many_txn(

View File

@ -0,0 +1,18 @@
/* Copyright 2022 The Matrix.org Foundation C.I.C
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
-- When we resync partial state, we prioritise doing so using the server we
-- partial-joined from. To do this we need to record which server that was!
ALTER TABLE partial_state_rooms ADD COLUMN joined_via TEXT;