def setUp(self):
self.lock_dir = tempfile.mkdtemp()
self.lock_path = os.path.join(self.lock_dir, "lock")
self.lock = OwnerPrintingInterProcessFileLock(self.lock_path)
self.manager = Manager()
self.lock_held = self.manager.Event()
self.terminate = self.manager.Event()
self.lock_process = Process(target=hold_lock_until_terminate,
args=(self.lock_path, self.lock_held,
self.terminate))
def lifecycle_lock(self):
"""An identity-keyed inter-process lock for safeguarding lifecycle and other operations."""
safe_mkdir(self._metadata_base_dir)
return OwnerPrintingInterProcessFileLock(
# N.B. This lock can't key into the actual named metadata dir (e.g. `.pids/pantsd/lock`
# via `ProcessMetadataManager._get_metadata_dir_by_name()`) because of a need to purge
# the named metadata dir on startup to avoid stale metadata reads.
os.path.join(self._metadata_base_dir,
".lock.{}".format(self._name)))
def hold_lock_until_terminate(path, lock_held, terminate):
lock = OwnerPrintingInterProcessFileLock(path)
lock.acquire()
lock_held.set()
# NOTE: We shouldn't ever wait this long, this is just to ensure
# we don't somehow leak child processes.
terminate.wait(60)
lock.release()
lock_held.clear()
class TestOwnerPrintingInterProcessFileLock(unittest.TestCase):
def setUp(self):
self.lock_dir = tempfile.mkdtemp()
self.lock_path = os.path.join(self.lock_dir, "lock")
self.lock = OwnerPrintingInterProcessFileLock(self.lock_path)
self.manager = Manager()
self.lock_held = self.manager.Event()
self.terminate = self.manager.Event()
self.lock_process = Process(target=hold_lock_until_terminate,
args=(self.lock_path, self.lock_held,
self.terminate))
def tearDown(self):
self.terminate.set()
try:
shutil.rmtree(self.lock_dir)
except OSError:
pass
def test_non_blocking_attempt(self):
self.lock_process.start()
self.lock_held.wait()
self.assertFalse(self.lock.acquire(blocking=False))
def test_message(self):
self.lock_process.start()
self.lock_held.wait()
self.assertTrue(os.path.exists(self.lock.message_path))
with open(self.lock.message_path, "r") as f:
message_content = f.read()
self.assertIn(str(self.lock_process.pid), message_content)
os.unlink(self.lock.message_path)
def message_fn(message):
self.assertIn(self.lock.missing_message_output, message)
self.lock.acquire(blocking=False, message_fn=message_fn)
def test_blocking(self):
self.lock_process.start()
self.lock_held.wait()
self.assertFalse(self.lock.acquire(timeout=0.1))
acquire_is_blocking = self.manager.Event()
def terminate_subproc(terminate, acquire_is_blocking):
acquire_is_blocking.wait()
terminate.set()
Thread(target=terminate_subproc,
args=(self.terminate, acquire_is_blocking)).start()
def message_fn(message):
self.assertIn(str(self.lock_process.pid), message)
acquire_is_blocking.set()
# NOTE: We shouldn't ever wait this long (locally this runs in ~milliseconds)
# but sometimes CI containers are extremely slow, so we choose a very large
# value just in case.
self.assertTrue(self.lock.acquire(timeout=30, message_fn=message_fn))
def test_reentrant(self):
self.assertTrue(self.lock.acquire())
self.assertTrue(self.lock.acquire())
def test_release(self):
self.assertTrue(self.lock.acquire())
self.assertTrue(self.lock.acquired)
self.lock.release()
self.assertFalse(self.lock.acquired)