/usr/share/pyshared/txzookeeper/tests/test_lock.py is in python-txzookeeper 0.9.5-0ubuntu1.
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# Copyright (C) 2010-2011 Canonical Ltd. All Rights Reserved
#
# This file is part of txzookeeper.
#
# Authors:
# Kapil Thangavelu
#
# txzookeeper is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# txzookeeper is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with txzookeeper. If not, see <http://www.gnu.org/licenses/>.
#
from twisted.internet.defer import (
inlineCallbacks, returnValue, Deferred, succeed)
from zookeeper import NoNodeException
from txzookeeper import ZookeeperClient
from txzookeeper.lock import Lock, LockError
from mocker import ANY
from txzookeeper.tests import ZookeeperTestCase, utils
class LockTests(ZookeeperTestCase):
def setUp(self):
super(LockTests, self).setUp()
self.clients = []
def tearDown(self):
cleanup = False
for client in self.clients:
if not cleanup and client.connected:
utils.deleteTree(handle=client.handle)
cleanup = True
client.close()
@inlineCallbacks
def open_client(self, credentials=None):
"""
Open a zookeeper client, optionally authenticating with the
credentials if given.
"""
client = ZookeeperClient("127.0.0.1:2181")
self.clients.append(client)
yield client.connect()
if credentials:
d = client.add_auth("digest", credentials)
# hack to keep auth fast
yield client.exists("/")
yield d
returnValue(client)
@inlineCallbacks
def test_acquire_release(self):
"""
A lock can be acquired and released.
"""
client = yield self.open_client()
path = yield client.create("/lock-test")
lock = Lock(path, client)
yield lock.acquire()
self.assertEqual(lock.acquired, True)
released = yield lock.release()
self.assertEqual(released, True)
@inlineCallbacks
def test_lock_reuse(self):
"""
A lock instance may be reused after an acquire/release cycle.
"""
client = yield self.open_client()
path = yield client.create("/lock-test")
lock = Lock(path, client)
yield lock.acquire()
self.assertTrue(lock.acquired)
yield lock.release()
self.assertFalse(lock.acquired)
yield lock.acquire()
self.assertTrue(lock.acquired)
yield lock.release()
self.assertFalse(lock.acquired)
@inlineCallbacks
def test_error_on_double_acquire(self):
"""
Attempting to acquire an already held lock, raises a Value Error.
"""
client = yield self.open_client()
path = yield client.create("/lock-test")
lock = Lock(path, client)
yield lock.acquire()
self.assertEqual(lock.acquired, True)
yield self.failUnlessFailure(lock.acquire(), LockError)
@inlineCallbacks
def test_acquire_after_error(self):
"""
Any instance state associated with a failed acquired should be cleared
on error, allowing subsequent to succeed.
"""
client = yield self.open_client()
path = "/lock-test-acquire-after-error"
lock = Lock(path, client)
d = lock.acquire()
self.failUnlessFailure(d, NoNodeException)
yield d
yield client.create(path)
yield lock.acquire()
self.assertEqual(lock.acquired, True)
@inlineCallbacks
def test_error_on_acquire_acquiring(self):
"""
Attempting to acquire the lock while an attempt is already in progress,
raises a LockError.
"""
client = yield self.open_client()
path = yield client.create("/lock-test")
lock = Lock(path, client)
# setup the client to create the intended environment
mock_client = self.mocker.patch(client)
mock_client.create(ANY, flags=ANY)
self.mocker.result(succeed("%s/%s" % (path, "lock-3")))
mock_client.get_children("/lock-test")
self.mocker.result(succeed(["lock-2", "lock-3"]))
mock_client.exists_and_watch("%s/%s" % (path, "lock-2"))
watch = Deferred()
self.mocker.result((succeed(True), watch))
self.mocker.replay()
# now we attempt to acquire the lock, rigged above to not succeed
d = lock.acquire()
test_deferred = Deferred()
# and next we schedule a lock attempt, which should fail as we're
# still attempting to acquire the lock.
def attempt_acquire():
# make sure lock was previously attempted acquired without
# error (disregarding that it was rigged to *fail*)
from twisted.python.failure import Failure
self.assertFalse(isinstance(d.result, Failure))
# acquire lock and expect to fail
self.failUnlessFailure(lock.acquire(), LockError)
# after we've verified the error handling, end the test
test_deferred.callback(None)
from twisted.internet import reactor
reactor.callLater(0.1, attempt_acquire)
yield test_deferred
@inlineCallbacks
def test_no_previous_owner_bypasses_watch(self):
"""
Coverage test. Internally the lock algorithm checks and sets a
watch on the nearest candidate node. If the node has been removed
between the time between the get_children and exists call, the we
immediately reattempt to get the lock without waiting on the watch.
"""
client = yield self.open_client()
path = yield client.create("/lock-no-previous")
# setup the client to create the intended environment
mock_client = self.mocker.patch(client)
mock_client.create(ANY, flags=ANY)
self.mocker.result(succeed("%s/%s" % (path, "lock-3")))
mock_client.get_children(path)
self.mocker.result(succeed(["lock-2", "lock-3"]))
mock_client.exists_and_watch("%s/%s" % (path, "lock-2"))
watch = Deferred()
self.mocker.result((succeed(False), watch))
mock_client.get_children(path)
self.mocker.result(succeed(["lock-3"]))
self.mocker.replay()
lock = Lock(path, mock_client)
yield lock.acquire()
self.assertTrue(lock.acquired)
@inlineCallbacks
def test_error_when_releasing_unacquired(self):
"""
If an attempt is made to release a lock, that not currently being held,
than a C{LockError} exception is raised.
"""
client = yield self.open_client()
lock_dir = yield client.create("/lock-multi-test")
lock = Lock(lock_dir, client)
self.failUnlessFailure(lock.release(), LockError)
@inlineCallbacks
def test_multiple_acquiring_clients(self):
"""
Multiple clients can compete for the lock, only one client's Lock
instance may hold the lock at any given moment.
"""
client = yield self.open_client()
client2 = yield self.open_client()
lock_dir = yield client.create("/lock-multi-test")
lock = Lock(lock_dir, client)
lock2 = Lock(lock_dir, client2)
yield lock.acquire()
self.assertTrue(lock.acquired)
lock2_acquire = lock2.acquire()
yield lock.release()
yield lock2_acquire
self.assertTrue(lock2.acquired)
self.assertFalse(lock.acquired)
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