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# fixtures: Fixtures with cleanups for testing and convenience.
#
# Copyright (C) 2011, Martin Pool <mbp@sourcefrog.net>
#
# Licensed under either the Apache License, Version 2.0 or the BSD 3-clause
# license at the users choice. A copy of both licenses are available in the
# project source as Apache-2.0 and BSD. You may not use this file except in
# compliance with one of these two licences.
#
# Unless required by applicable law or agreed to in writing, software
# distributed under these licenses is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# license you chose for the specific language governing permissions and
# limitations under that license.
"""Timeout fixture."""
import signal
import fixtures
__all__ = [
'Timeout',
'TimeoutException',
]
class TimeoutException(Exception):
"""Timeout expired"""
class Timeout(fixtures.Fixture):
"""Fixture that aborts the contained code after a number of seconds.
The interrupt can be either gentle, in which case TimeoutException is
raised, or not gentle, in which case the process will typically be aborted
by SIGALRM.
Cautions:
* This has no effect on Windows.
* Only one Timeout can be used at any time per process.
"""
def __init__(self, timeout_secs, gentle):
self.timeout_secs = timeout_secs
self.alarm_fn = getattr(signal, 'alarm', None)
self.gentle = gentle
def signal_handler(self, signum, frame):
raise TimeoutException()
def setUp(self):
super(Timeout, self).setUp()
if self.alarm_fn is None:
return # Can't run on Windows
if self.gentle:
# Install a handler for SIGARLM so we can raise an exception rather
# than the default handler executing, which kills the process.
old_handler = signal.signal(signal.SIGALRM, self.signal_handler)
# We add the slarm cleanup before the cleanup for the signal handler,
# otherwise there is a race condition where the signal handler is
# cleaned up but the alarm still fires.
self.addCleanup(lambda: self.alarm_fn(0))
self.alarm_fn(self.timeout_secs)
if self.gentle:
self.addCleanup(lambda: signal.signal(signal.SIGALRM, old_handler))
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