Skip to content

Revert "Send a SSS response immediately if the config has changed and there are new results to sync (#19714)" #19784

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
reivilibre merged 2 commits into from
May 15, 2026
+29 −155
Merged

Revert "Send a SSS response immediately if the config has changed and there are new results to sync (#19714)" #19784

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
63b9cb3
Revert "Send a SSS response immediately if the config has changed and…
reivilibre May 14, 2026
9269074
Newsfile
reivilibre May 14, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions changelog.d/19784.bugfix
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Revert 'Have [MSC4186: Simplified Sliding Sync](https://github.com/matrix-org/matrix-spec-proposals/pull/4186) return a new response immediately if a room subscription has changed and produced a new response. ([\#19714](https://github.com/element-hq/synapse/issues/19714))' due to performance problems.
52 changes: 24 additions & 28 deletions synapse/handlers/sliding_sync/__init__.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -167,38 +167,34 @@ async def wait_for_sync_for_user(
timeout_ms -= after_wait_ts - before_wait_ts
timeout_ms = max(timeout_ms, 0)

# Compute a response immediately. We always need to do this before
# waiting for new data (unlike in /v3/sync), as the request config might
# have changed (e.g. new room subscriptions, etc).
now_token = self.event_sources.get_current_token()
result = await self.current_sync_for_user(
sync_config,
from_token=from_token,
to_token=now_token,
)

# Return immediately if we have a result, the timeout is 0, or this is
# an initial sync.
if result or timeout_ms == 0 or from_token is None:
return result, did_wait

# Otherwise, we wait for something to happen and report it to the user.
async def current_sync_callback(
before_token: StreamToken, after_token: StreamToken
) -> SlidingSyncResult:
return await self.current_sync_for_user(
# We're going to respond immediately if the timeout is 0 or if this is an
# initial sync (without a `from_token`) so we can avoid calling
# `notifier.wait_for_events()`.
if timeout_ms == 0 or from_token is None:
now_token = self.event_sources.get_current_token()
result = await self.current_sync_for_user(
sync_config,
from_token=from_token,
to_token=after_token,
to_token=now_token,
)
else:
# Otherwise, we wait for something to happen and report it to the user.
async def current_sync_callback(
before_token: StreamToken, after_token: StreamToken
) -> SlidingSyncResult:
return await self.current_sync_for_user(
sync_config,
from_token=from_token,
to_token=after_token,
)

result = await self.notifier.wait_for_events(
sync_config.user.to_string(),
timeout_ms,
current_sync_callback,
from_token=now_token,
)
did_wait = True
result = await self.notifier.wait_for_events(
sync_config.user.to_string(),
timeout_ms,
current_sync_callback,
from_token=from_token.stream_token,
)
did_wait = True

return result, did_wait

Expand Down
12 changes: 4 additions & 8 deletions synapse/handlers/sliding_sync/room_lists.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -852,15 +852,11 @@ async def _filter_relevant_rooms_to_send(
previous_connection_state.room_configs.get(room_id)
)
if prev_room_sync_config is not None:
# Always include rooms whose effective config has
# expanded. This covers timeline-limit increases and
# required-state additions introduced by room
# subscriptions overriding list-derived params.
# Always include rooms whose timeline limit has increased.
# (see the "XXX: Odd behavior" described below)
if (
prev_room_sync_config.combine_room_sync_config(
room_config
)
!= prev_room_sync_config
prev_room_sync_config.timeline_limit
< room_config.timeline_limit
):
rooms_should_send.add(room_id)
continue
Expand Down
119 changes: 0 additions & 119 deletions tests/rest/client/sliding_sync/test_room_subscriptions.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,6 @@
from synapse.api.constants import EventTypes, HistoryVisibility
from synapse.rest.client import login, room, sync
from synapse.server import HomeServer
from synapse.types import JsonDict
from synapse.util.clock import Clock

from tests.rest.client.sliding_sync.test_sliding_sync import SlidingSyncBase
Expand Down Expand Up @@ -127,124 +126,6 @@ def test_room_subscriptions_with_join_membership(self) -> None:
response_body["rooms"][room_id1],
)

def test_room_subscription_required_state_expansion_returns_immediately(
self,
) -> None:
"""
Test that adding a room subscription with stronger params than the list causes an
incremental long-poll to return immediately, even without new stream activity.
"""
user1_id = self.register_user("user1", "pass")
user1_tok = self.login(user1_id, "pass")

room_id1 = self.helper.create_room_as(user1_id, tok=user1_tok)

sync_body: JsonDict = {
"lists": {
"foo-list": {
"ranges": [[0, 0]],
"required_state": [],
"timeline_limit": 0,
}
},
"conn_id": "conn_id",
}
_, from_token = self.do_sync(sync_body, tok=user1_tok)

sync_body["room_subscriptions"] = {
room_id1: {
"required_state": [
[EventTypes.Create, ""],
],
"timeline_limit": 0,
}
}

channel = self.make_request(
"POST",
self.sync_endpoint + f"?timeout=10000&pos={from_token}",
content=sync_body,
access_token=user1_tok,
await_result=False,
)
channel.await_result(timeout_ms=3000)
self.assertEqual(channel.code, 200, channel.json_body)

state_map = self.get_success(
self.storage_controllers.state.get_current_state(room_id1)
)

room_response = channel.json_body["rooms"][room_id1]
self.assertNotIn("initial", room_response)
self._assertRequiredStateIncludes(
room_response["required_state"],
{
state_map[(EventTypes.Create, "")],
},
exact=True,
)

def test_room_subscription_required_state_change_returns_immediately(self) -> None:
"""
Test that expanding an existing room subscription's required state causes an
incremental long-poll to return immediately, even without new stream activity.
"""
user1_id = self.register_user("user1", "pass")
user1_tok = self.login(user1_id, "pass")

room_id1 = self.helper.create_room_as(
user1_id, tok=user1_tok, extra_content={"name": "Foo"}
)

sync_body: JsonDict = {
"room_subscriptions": {
room_id1: {
"required_state": [
[EventTypes.Create, ""],
],
"timeline_limit": 0,
}
},
"conn_id": "conn_id",
}
response_body, from_token = self.do_sync(sync_body, tok=user1_tok)

state_map = self.get_success(
self.storage_controllers.state.get_current_state(room_id1)
)
self._assertRequiredStateIncludes(
response_body["rooms"][room_id1]["required_state"],
{
state_map[(EventTypes.Create, "")],
},
exact=True,
)

sync_body["room_subscriptions"][room_id1]["required_state"] = [
[EventTypes.Create, ""],
[EventTypes.Name, ""],
]

channel = self.make_request(
"POST",
self.sync_endpoint + f"?timeout=10000&pos={from_token}",
content=sync_body,
access_token=user1_tok,
await_result=False,
)
channel.await_result(timeout_ms=3000)
self.assertEqual(channel.code, 200, channel.json_body)

room_response = channel.json_body["rooms"][room_id1]
self.assertNotIn("initial", room_response)
self._assertRequiredStateIncludes(
room_response["required_state"],
{
state_map[(EventTypes.Name, "")],
},
exact=True,
)

def test_room_subscriptions_with_leave_membership(self) -> None:
"""
Test `room_subscriptions` with a leave room should give us timeline and state
Expand Down
Loading