499 lines
17 KiB
Python
499 lines
17 KiB
Python
# Copyright 2019 New Vector Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import traceback
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from parameterized import parameterized_class
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from twisted.internet import defer
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from twisted.internet.defer import CancelledError, Deferred, ensureDeferred
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from twisted.internet.task import Clock
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from twisted.python.failure import Failure
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from synapse.logging.context import (
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SENTINEL_CONTEXT,
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LoggingContext,
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PreserveLoggingContext,
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current_context,
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make_deferred_yieldable,
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)
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from synapse.util.async_helpers import (
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ObservableDeferred,
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concurrently_execute,
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delay_cancellation,
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stop_cancellation,
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timeout_deferred,
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)
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from tests.unittest import TestCase
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class ObservableDeferredTest(TestCase):
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def test_succeed(self):
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origin_d = Deferred()
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observable = ObservableDeferred(origin_d)
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observer1 = observable.observe()
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observer2 = observable.observe()
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self.assertFalse(observer1.called)
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self.assertFalse(observer2.called)
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# check the first observer is called first
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def check_called_first(res):
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self.assertFalse(observer2.called)
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return res
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observer1.addBoth(check_called_first)
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# store the results
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results = [None, None]
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def check_val(res, idx):
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results[idx] = res
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return res
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observer1.addCallback(check_val, 0)
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observer2.addCallback(check_val, 1)
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origin_d.callback(123)
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self.assertEqual(results[0], 123, "observer 1 callback result")
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self.assertEqual(results[1], 123, "observer 2 callback result")
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def test_failure(self):
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origin_d = Deferred()
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observable = ObservableDeferred(origin_d, consumeErrors=True)
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observer1 = observable.observe()
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observer2 = observable.observe()
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self.assertFalse(observer1.called)
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self.assertFalse(observer2.called)
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# check the first observer is called first
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def check_called_first(res):
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self.assertFalse(observer2.called)
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return res
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observer1.addBoth(check_called_first)
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# store the results
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results = [None, None]
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def check_val(res, idx):
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results[idx] = res
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return None
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observer1.addErrback(check_val, 0)
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observer2.addErrback(check_val, 1)
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try:
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raise Exception("gah!")
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except Exception as e:
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origin_d.errback(e)
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self.assertEqual(str(results[0].value), "gah!", "observer 1 errback result")
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self.assertEqual(str(results[1].value), "gah!", "observer 2 errback result")
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def test_cancellation(self):
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"""Test that cancelling an observer does not affect other observers."""
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origin_d: "Deferred[int]" = Deferred()
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observable = ObservableDeferred(origin_d, consumeErrors=True)
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observer1 = observable.observe()
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observer2 = observable.observe()
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observer3 = observable.observe()
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self.assertFalse(observer1.called)
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self.assertFalse(observer2.called)
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self.assertFalse(observer3.called)
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# cancel the second observer
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observer2.cancel()
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self.assertFalse(observer1.called)
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self.failureResultOf(observer2, CancelledError)
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self.assertFalse(observer3.called)
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# other observers resolve as normal
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origin_d.callback(123)
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self.assertEqual(observer1.result, 123, "observer 1 callback result")
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self.assertEqual(observer3.result, 123, "observer 3 callback result")
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# additional observers resolve as normal
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observer4 = observable.observe()
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self.assertEqual(observer4.result, 123, "observer 4 callback result")
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class TimeoutDeferredTest(TestCase):
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def setUp(self):
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self.clock = Clock()
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def test_times_out(self):
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"""Basic test case that checks that the original deferred is cancelled and that
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the timing-out deferred is errbacked
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"""
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cancelled = [False]
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def canceller(_d):
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cancelled[0] = True
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non_completing_d = Deferred(canceller)
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timing_out_d = timeout_deferred(non_completing_d, 1.0, self.clock)
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self.assertNoResult(timing_out_d)
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self.assertFalse(cancelled[0], "deferred was cancelled prematurely")
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self.clock.pump((1.0,))
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self.assertTrue(cancelled[0], "deferred was not cancelled by timeout")
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self.failureResultOf(timing_out_d, defer.TimeoutError)
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def test_times_out_when_canceller_throws(self):
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"""Test that we have successfully worked around
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https://twistedmatrix.com/trac/ticket/9534"""
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def canceller(_d):
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raise Exception("can't cancel this deferred")
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non_completing_d = Deferred(canceller)
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timing_out_d = timeout_deferred(non_completing_d, 1.0, self.clock)
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self.assertNoResult(timing_out_d)
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self.clock.pump((1.0,))
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self.failureResultOf(timing_out_d, defer.TimeoutError)
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def test_logcontext_is_preserved_on_cancellation(self):
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blocking_was_cancelled = [False]
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@defer.inlineCallbacks
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def blocking():
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non_completing_d = Deferred()
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with PreserveLoggingContext():
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try:
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yield non_completing_d
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except CancelledError:
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blocking_was_cancelled[0] = True
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raise
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with LoggingContext("one") as context_one:
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# the errbacks should be run in the test logcontext
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def errback(res, deferred_name):
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self.assertIs(
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current_context(),
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context_one,
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"errback %s run in unexpected logcontext %s"
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% (deferred_name, current_context()),
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)
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return res
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original_deferred = blocking()
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original_deferred.addErrback(errback, "orig")
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timing_out_d = timeout_deferred(original_deferred, 1.0, self.clock)
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self.assertNoResult(timing_out_d)
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self.assertIs(current_context(), SENTINEL_CONTEXT)
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timing_out_d.addErrback(errback, "timingout")
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self.clock.pump((1.0,))
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self.assertTrue(
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blocking_was_cancelled[0], "non-completing deferred was not cancelled"
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)
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self.failureResultOf(timing_out_d, defer.TimeoutError)
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self.assertIs(current_context(), context_one)
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class _TestException(Exception):
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pass
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class ConcurrentlyExecuteTest(TestCase):
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def test_limits_runners(self):
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"""If we have more tasks than runners, we should get the limit of runners"""
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started = 0
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waiters = []
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processed = []
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async def callback(v):
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# when we first enter, bump the start count
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nonlocal started
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started += 1
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# record the fact we got an item
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processed.append(v)
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# wait for the goahead before returning
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d2 = Deferred()
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waiters.append(d2)
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await d2
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# set it going
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d2 = ensureDeferred(concurrently_execute(callback, [1, 2, 3, 4, 5], 3))
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# check we got exactly 3 processes
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self.assertEqual(started, 3)
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self.assertEqual(len(waiters), 3)
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# let one finish
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waiters.pop().callback(0)
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# ... which should start another
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self.assertEqual(started, 4)
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self.assertEqual(len(waiters), 3)
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# we still shouldn't be done
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self.assertNoResult(d2)
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# finish the job
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while waiters:
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waiters.pop().callback(0)
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# check everything got done
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self.assertEqual(started, 5)
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self.assertCountEqual(processed, [1, 2, 3, 4, 5])
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self.successResultOf(d2)
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def test_preserves_stacktraces(self):
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"""Test that the stacktrace from an exception thrown in the callback is preserved"""
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d1 = Deferred()
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async def callback(v):
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# alas, this doesn't work at all without an await here
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await d1
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raise _TestException("bah")
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async def caller():
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try:
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await concurrently_execute(callback, [1], 2)
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except _TestException as e:
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tb = traceback.extract_tb(e.__traceback__)
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# we expect to see "caller", "concurrently_execute" and "callback".
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self.assertEqual(tb[0].name, "caller")
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self.assertEqual(tb[1].name, "concurrently_execute")
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self.assertEqual(tb[-1].name, "callback")
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else:
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self.fail("No exception thrown")
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d2 = ensureDeferred(caller())
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d1.callback(0)
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self.successResultOf(d2)
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def test_preserves_stacktraces_on_preformed_failure(self):
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"""Test that the stacktrace on a Failure returned by the callback is preserved"""
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d1 = Deferred()
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f = Failure(_TestException("bah"))
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async def callback(v):
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# alas, this doesn't work at all without an await here
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await d1
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await defer.fail(f)
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async def caller():
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try:
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await concurrently_execute(callback, [1], 2)
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except _TestException as e:
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tb = traceback.extract_tb(e.__traceback__)
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# we expect to see "caller", "concurrently_execute", "callback",
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# and some magic from inside ensureDeferred that happens when .fail
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# is called.
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self.assertEqual(tb[0].name, "caller")
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self.assertEqual(tb[1].name, "concurrently_execute")
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self.assertEqual(tb[-2].name, "callback")
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else:
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self.fail("No exception thrown")
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d2 = ensureDeferred(caller())
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d1.callback(0)
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self.successResultOf(d2)
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@parameterized_class(
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("wrapper",),
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[("stop_cancellation",), ("delay_cancellation",)],
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)
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class CancellationWrapperTests(TestCase):
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"""Common tests for the `stop_cancellation` and `delay_cancellation` functions."""
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wrapper: str
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def wrap_deferred(self, deferred: "Deferred[str]") -> "Deferred[str]":
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if self.wrapper == "stop_cancellation":
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return stop_cancellation(deferred)
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elif self.wrapper == "delay_cancellation":
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return delay_cancellation(deferred)
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else:
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raise ValueError(f"Unsupported wrapper type: {self.wrapper}")
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def test_succeed(self):
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"""Test that the new `Deferred` receives the result."""
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deferred: "Deferred[str]" = Deferred()
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wrapper_deferred = self.wrap_deferred(deferred)
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# Success should propagate through.
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deferred.callback("success")
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self.assertTrue(wrapper_deferred.called)
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self.assertEqual("success", self.successResultOf(wrapper_deferred))
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def test_failure(self):
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"""Test that the new `Deferred` receives the `Failure`."""
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deferred: "Deferred[str]" = Deferred()
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wrapper_deferred = self.wrap_deferred(deferred)
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# Failure should propagate through.
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deferred.errback(ValueError("abc"))
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self.assertTrue(wrapper_deferred.called)
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self.failureResultOf(wrapper_deferred, ValueError)
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self.assertIsNone(deferred.result, "`Failure` was not consumed")
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class StopCancellationTests(TestCase):
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"""Tests for the `stop_cancellation` function."""
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def test_cancellation(self):
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"""Test that cancellation of the new `Deferred` leaves the original running."""
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deferred: "Deferred[str]" = Deferred()
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wrapper_deferred = stop_cancellation(deferred)
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# Cancel the new `Deferred`.
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wrapper_deferred.cancel()
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self.assertTrue(wrapper_deferred.called)
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self.failureResultOf(wrapper_deferred, CancelledError)
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self.assertFalse(
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deferred.called, "Original `Deferred` was unexpectedly cancelled"
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)
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# Now make the original `Deferred` fail.
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# The `Failure` must be consumed, otherwise unwanted tracebacks will be printed
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# in logs.
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deferred.errback(ValueError("abc"))
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self.assertIsNone(deferred.result, "`Failure` was not consumed")
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class DelayCancellationTests(TestCase):
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"""Tests for the `delay_cancellation` function."""
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def test_deferred_cancellation(self):
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"""Test that cancellation of the new `Deferred` waits for the original."""
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deferred: "Deferred[str]" = Deferred()
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wrapper_deferred = delay_cancellation(deferred)
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# Cancel the new `Deferred`.
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wrapper_deferred.cancel()
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self.assertNoResult(wrapper_deferred)
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self.assertFalse(
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deferred.called, "Original `Deferred` was unexpectedly cancelled"
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)
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# Now make the original `Deferred` fail.
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# The `Failure` must be consumed, otherwise unwanted tracebacks will be printed
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# in logs.
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deferred.errback(ValueError("abc"))
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self.assertIsNone(deferred.result, "`Failure` was not consumed")
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# Now that the original `Deferred` has failed, we should get a `CancelledError`.
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self.failureResultOf(wrapper_deferred, CancelledError)
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def test_coroutine_cancellation(self):
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"""Test that cancellation of the new `Deferred` waits for the original."""
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blocking_deferred: "Deferred[None]" = Deferred()
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completion_deferred: "Deferred[None]" = Deferred()
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async def task():
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await blocking_deferred
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completion_deferred.callback(None)
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# Raise an exception. Twisted should consume it, otherwise unwanted
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# tracebacks will be printed in logs.
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raise ValueError("abc")
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wrapper_deferred = delay_cancellation(task())
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# Cancel the new `Deferred`.
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wrapper_deferred.cancel()
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self.assertNoResult(wrapper_deferred)
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self.assertFalse(
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blocking_deferred.called, "Cancellation was propagated too deep"
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)
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self.assertFalse(completion_deferred.called)
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# Unblock the task.
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blocking_deferred.callback(None)
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self.assertTrue(completion_deferred.called)
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# Now that the original coroutine has failed, we should get a `CancelledError`.
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self.failureResultOf(wrapper_deferred, CancelledError)
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def test_suppresses_second_cancellation(self):
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"""Test that a second cancellation is suppressed.
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Identical to `test_cancellation` except the new `Deferred` is cancelled twice.
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"""
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deferred: "Deferred[str]" = Deferred()
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wrapper_deferred = delay_cancellation(deferred)
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# Cancel the new `Deferred`, twice.
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wrapper_deferred.cancel()
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wrapper_deferred.cancel()
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self.assertNoResult(wrapper_deferred)
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self.assertFalse(
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deferred.called, "Original `Deferred` was unexpectedly cancelled"
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)
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# Now make the original `Deferred` fail.
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# The `Failure` must be consumed, otherwise unwanted tracebacks will be printed
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# in logs.
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deferred.errback(ValueError("abc"))
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self.assertIsNone(deferred.result, "`Failure` was not consumed")
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# Now that the original `Deferred` has failed, we should get a `CancelledError`.
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self.failureResultOf(wrapper_deferred, CancelledError)
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def test_propagates_cancelled_error(self):
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"""Test that a `CancelledError` from the original `Deferred` gets propagated."""
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deferred: "Deferred[str]" = Deferred()
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wrapper_deferred = delay_cancellation(deferred)
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# Fail the original `Deferred` with a `CancelledError`.
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cancelled_error = CancelledError()
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deferred.errback(cancelled_error)
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# The new `Deferred` should fail with exactly the same `CancelledError`.
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self.assertTrue(wrapper_deferred.called)
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self.assertIs(cancelled_error, self.failureResultOf(wrapper_deferred).value)
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def test_preserves_logcontext(self):
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"""Test that logging contexts are preserved."""
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blocking_d: "Deferred[None]" = Deferred()
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async def inner():
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await make_deferred_yieldable(blocking_d)
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async def outer():
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with LoggingContext("c") as c:
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try:
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await delay_cancellation(inner())
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self.fail("`CancelledError` was not raised")
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except CancelledError:
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self.assertEqual(c, current_context())
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# Succeed with no error, unless the logging context is wrong.
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# Run and block inside `inner()`.
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d = defer.ensureDeferred(outer())
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self.assertEqual(SENTINEL_CONTEXT, current_context())
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d.cancel()
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# Now unblock. `outer()` will consume the `CancelledError` and check the
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# logging context.
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blocking_d.callback(None)
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self.successResultOf(d)
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