synapse/tests/util/test_async_helpers.py

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# Copyright 2019 New Vector Ltd
#
# 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.
from twisted.internet import defer
from twisted.internet.defer import CancelledError, Deferred
from twisted.internet.task import Clock
from synapse.logging.context import (
SENTINEL_CONTEXT,
LoggingContext,
PreserveLoggingContext,
current_context,
)
from synapse.util.async_helpers import ObservableDeferred, timeout_deferred
from tests.unittest import TestCase
class ObservableDeferredTest(TestCase):
def test_succeed(self):
origin_d = Deferred()
observable = ObservableDeferred(origin_d)
observer1 = observable.observe()
observer2 = observable.observe()
self.assertFalse(observer1.called)
self.assertFalse(observer2.called)
# check the first observer is called first
def check_called_first(res):
self.assertFalse(observer2.called)
return res
observer1.addBoth(check_called_first)
# store the results
results = [None, None]
def check_val(res, idx):
results[idx] = res
return res
observer1.addCallback(check_val, 0)
observer2.addCallback(check_val, 1)
origin_d.callback(123)
self.assertEqual(results[0], 123, "observer 1 callback result")
self.assertEqual(results[1], 123, "observer 2 callback result")
def test_failure(self):
origin_d = Deferred()
observable = ObservableDeferred(origin_d, consumeErrors=True)
observer1 = observable.observe()
observer2 = observable.observe()
self.assertFalse(observer1.called)
self.assertFalse(observer2.called)
# check the first observer is called first
def check_called_first(res):
self.assertFalse(observer2.called)
return res
observer1.addBoth(check_called_first)
# store the results
results = [None, None]
def check_val(res, idx):
results[idx] = res
return None
observer1.addErrback(check_val, 0)
observer2.addErrback(check_val, 1)
try:
raise Exception("gah!")
except Exception as e:
origin_d.errback(e)
self.assertEqual(str(results[0].value), "gah!", "observer 1 errback result")
self.assertEqual(str(results[1].value), "gah!", "observer 2 errback result")
class TimeoutDeferredTest(TestCase):
def setUp(self):
self.clock = Clock()
def test_times_out(self):
"""Basic test case that checks that the original deferred is cancelled and that
the timing-out deferred is errbacked
"""
cancelled = [False]
def canceller(_d):
cancelled[0] = True
non_completing_d = Deferred(canceller)
timing_out_d = timeout_deferred(non_completing_d, 1.0, self.clock)
self.assertNoResult(timing_out_d)
self.assertFalse(cancelled[0], "deferred was cancelled prematurely")
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self.clock.pump((1.0,))
self.assertTrue(cancelled[0], "deferred was not cancelled by timeout")
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self.failureResultOf(timing_out_d, defer.TimeoutError)
def test_times_out_when_canceller_throws(self):
"""Test that we have successfully worked around
https://twistedmatrix.com/trac/ticket/9534"""
def canceller(_d):
raise Exception("can't cancel this deferred")
non_completing_d = Deferred(canceller)
timing_out_d = timeout_deferred(non_completing_d, 1.0, self.clock)
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)
def test_logcontext_is_preserved_on_cancellation(self):
blocking_was_cancelled = [False]
@defer.inlineCallbacks
def blocking():
non_completing_d = Deferred()
with PreserveLoggingContext():
try:
yield non_completing_d
except CancelledError:
blocking_was_cancelled[0] = True
raise
with LoggingContext("one") as context_one:
# the errbacks should be run in the test logcontext
def errback(res, deferred_name):
self.assertIs(
current_context(),
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context_one,
"errback %s run in unexpected logcontext %s"
% (deferred_name, current_context()),
)
return res
original_deferred = blocking()
original_deferred.addErrback(errback, "orig")
timing_out_d = timeout_deferred(original_deferred, 1.0, self.clock)
self.assertNoResult(timing_out_d)
self.assertIs(current_context(), SENTINEL_CONTEXT)
timing_out_d.addErrback(errback, "timingout")
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self.clock.pump((1.0,))
self.assertTrue(
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blocking_was_cancelled[0], "non-completing deferred was not cancelled"
)
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self.failureResultOf(timing_out_d, defer.TimeoutError)
self.assertIs(current_context(), context_one)