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#
# This file is licensed under the Affero General Public License (AGPL) version 3.
#
# Copyright (C) 2025 Element Creations Ltd
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# See the GNU Affero General Public License for more details:
# <https://www.gnu.org/licenses/agpl-3.0.html>.
#
from unittest.mock import Mock
from twisted.internet.defer import Deferred
from twisted.internet.testing import MemoryReactor
from synapse.logging.context import PreserveLoggingContext, make_deferred_yieldable
from synapse.server import HomeServer
from synapse.util.background_queue import BackgroundQueue
from synapse.util.clock import Clock
from tests.unittest import HomeserverTestCase, logcontext_clean
class BackgroundQueueTests(HomeserverTestCase):
def prepare(
self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
) -> None:
self._process_item_mock = Mock(spec_set=[])
self.queue = BackgroundQueue[int](
hs=homeserver,
name="test_queue",
callback=self._process_item_mock,
timeout_ms=1000,
)
@logcontext_clean
def test_simple_call(self) -> None:
"""Test that items added to the queue are processed."""
# Register a deferred to be the return value of the callback.
callback_result_deferred: Deferred[None] = Deferred()
self._process_item_mock.side_effect = lambda _: make_deferred_yieldable(
callback_result_deferred
)
# Adding an item should cause the callback to be invoked.
self.queue.add(1)
self._process_item_mock.assert_called_once_with(1)
self._process_item_mock.reset_mock()
# Adding another item should not cause the callback to be invoked again
# until the previous one has completed.
self.queue.add(2)
self._process_item_mock.assert_not_called()
# Once the first callback completes, the second item should be
# processed.
with PreserveLoggingContext():
callback_result_deferred.callback(None)
self._process_item_mock.assert_called_once_with(2)
@logcontext_clean
def test_timeout(self) -> None:
"""Test that the background process wakes up if its idle, and that it
times out after being idle."""
# Register a deferred to be the return value of the callback.
callback_result_deferred: Deferred[None] = Deferred()
self._process_item_mock.side_effect = lambda _: make_deferred_yieldable(
callback_result_deferred
)
# Adding an item should cause the callback to be invoked.
self.queue.add(1)
self._process_item_mock.assert_called_once_with(1)
self._process_item_mock.reset_mock()
# Let the callback complete.
with PreserveLoggingContext():
callback_result_deferred.callback(None)
# Advance the clock by less than the timeout, and add another item.
self.reactor.advance(0.5)
self.assertIsNotNone(self.queue._wakeup_event)
self.queue.add(2)
# The callback should be invoked again.
callback_result_deferred = Deferred()
self._process_item_mock.side_effect = lambda _: make_deferred_yieldable(
callback_result_deferred
)
self._process_item_mock.assert_called_once_with(2)
self._process_item_mock.reset_mock()
# Let the callback complete.
with PreserveLoggingContext():
callback_result_deferred.callback(None)
# Advance the clock by more than the timeout.
self.reactor.advance(1.5)
# The background process should have exited, we check this by checking
# the internal wakeup event has been removed.
self.assertIsNone(self.queue._wakeup_event)
# Add another item. This should cause a new background process to be
# started.
self.queue.add(3)
self._process_item_mock.assert_called_once_with(3)
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