/usr/lib/python2.7/dist-packages/fasteners/tests/test_process_lock.py is in python-fasteners 0.12.0-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# Copyright 2011 OpenStack Foundation.
# Copyright 2011 Justin Santa Barbara
#
# 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.
import errno
import fcntl
import multiprocessing
import os
import shutil
import signal
import tempfile
import threading
import time
from fasteners import process_lock as pl
from fasteners import test
class BrokenLock(pl.InterProcessLock):
def __init__(self, name, errno_code):
super(BrokenLock, self).__init__(name)
self.errno_code = errno_code
def unlock(self):
pass
def trylock(self):
err = IOError()
err.errno = self.errno_code
raise err
class ProcessLockTest(test.TestCase):
def setUp(self):
super(ProcessLockTest, self).setUp()
self.lock_dir = tempfile.mkdtemp()
self.tmp_dirs = [self.lock_dir]
def tearDown(self):
super(ProcessLockTest, self).tearDown()
for a_dir in reversed(self.tmp_dirs):
if os.path.exists(a_dir):
shutil.rmtree(a_dir, ignore_errors=True)
def test_lock_acquire_release_file_lock(self):
lock_file = os.path.join(self.lock_dir, 'lock')
lock = pl.InterProcessLock(lock_file)
def try_lock():
try:
my_lock = pl.InterProcessLock(lock_file)
my_lock.lockfile = open(lock_file, 'w')
my_lock.trylock()
my_lock.unlock()
os._exit(1)
except IOError:
os._exit(0)
def attempt_acquire(count):
children = []
for i in range(count):
child = multiprocessing.Process(target=try_lock)
child.start()
children.append(child)
exit_codes = []
for child in children:
child.join()
exit_codes.append(child.exitcode)
return sum(exit_codes)
self.assertTrue(lock.acquire())
try:
acquired_children = attempt_acquire(10)
self.assertEqual(0, acquired_children)
finally:
lock.release()
acquired_children = attempt_acquire(5)
self.assertNotEqual(0, acquired_children)
def test_nested_synchronized_external_works(self):
sentinel = object()
@pl.interprocess_locked(os.path.join(self.lock_dir, 'test-lock-1'))
def outer_lock():
@pl.interprocess_locked(os.path.join(self.lock_dir, 'test-lock-2'))
def inner_lock():
return sentinel
return inner_lock()
self.assertEqual(sentinel, outer_lock())
def _do_test_lock_externally(self, lock_dir):
lock_path = os.path.join(lock_dir, "lock")
def lock_files(handles_dir):
with pl.InterProcessLock(lock_path):
# Open some files we can use for locking
handles = []
for n in range(50):
path = os.path.join(handles_dir, ('file-%s' % n))
handles.append(open(path, 'w'))
# Loop over all the handles and try locking the file
# without blocking, keep a count of how many files we
# were able to lock and then unlock. If the lock fails
# we get an IOError and bail out with bad exit code
count = 0
for handle in handles:
try:
fcntl.flock(handle, fcntl.LOCK_EX | fcntl.LOCK_NB)
count += 1
fcntl.flock(handle, fcntl.LOCK_UN)
except IOError:
os._exit(2)
finally:
handle.close()
# Check if we were able to open all files
self.assertEqual(50, count)
handles_dir = tempfile.mkdtemp()
self.tmp_dirs.append(handles_dir)
children = []
for n in range(50):
pid = os.fork()
if pid:
children.append(pid)
else:
try:
lock_files(handles_dir)
finally:
os._exit(0)
for child in children:
(pid, status) = os.waitpid(child, 0)
if pid:
self.assertEqual(0, status)
def test_lock_externally(self):
self._do_test_lock_externally(self.lock_dir)
def test_lock_externally_lock_dir_not_exist(self):
os.rmdir(self.lock_dir)
self._do_test_lock_externally(self.lock_dir)
def test_lock_file_exists(self):
lock_file = os.path.join(self.lock_dir, 'lock')
@pl.interprocess_locked(lock_file)
def foo():
self.assertTrue(os.path.exists(lock_file))
foo()
def test_bad_acquire(self):
lock_file = os.path.join(self.lock_dir, 'lock')
lock = BrokenLock(lock_file, errno.EBUSY)
self.assertRaises(threading.ThreadError, lock.acquire)
def test_bad_release(self):
lock_file = os.path.join(self.lock_dir, 'lock')
lock = pl.InterProcessLock(lock_file)
self.assertRaises(threading.ThreadError, lock.release)
def test_interprocess_lock(self):
lock_file = os.path.join(self.lock_dir, 'lock')
pid = os.fork()
if pid:
# Make sure the child grabs the lock first
start = time.time()
while not os.path.exists(lock_file):
if time.time() - start > 5:
self.fail('Timed out waiting for child to grab lock')
time.sleep(0)
lock1 = pl.InterProcessLock('foo')
lock1.lockfile = open(lock_file, 'w')
# NOTE(bnemec): There is a brief window between when the lock file
# is created and when it actually becomes locked. If we happen to
# context switch in that window we may succeed in locking the
# file. Keep retrying until we either get the expected exception
# or timeout waiting.
while time.time() - start < 5:
try:
lock1.trylock()
lock1.unlock()
time.sleep(0)
except IOError:
# This is what we expect to happen
break
else:
self.fail('Never caught expected lock exception')
# We don't need to wait for the full sleep in the child here
os.kill(pid, signal.SIGKILL)
else:
try:
lock2 = pl.InterProcessLock('foo')
lock2.lockfile = open(lock_file, 'w')
have_lock = False
while not have_lock:
try:
lock2.trylock()
have_lock = True
except IOError:
pass
finally:
# NOTE(bnemec): This is racy, but I don't want to add any
# synchronization primitives that might mask a problem
# with the one we're trying to test here.
time.sleep(.5)
os._exit(0)
def test_non_destructive(self):
lock_file = os.path.join(self.lock_dir, 'not-destroyed')
with open(lock_file, 'w') as f:
f.write('test')
with pl.InterProcessLock(lock_file):
with open(lock_file) as f:
self.assertEqual(f.read(), 'test')
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