oslo.concurrency/oslo_concurrency/tests/unit/test_lockutils.py

#    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 collections
import errno
import fcntl
import multiprocessing
import os
import signal
import subprocess
import sys
import tempfile
import threading
import time
from unittest import mock

from oslotest import base as test_base

from oslo_concurrency.fixture import lockutils as fixtures
from oslo_concurrency import lockutils
from oslo_config import fixture as config


def lock_files(handles_dir, out_queue):
    with lockutils.lock('external', 'test-', external=True):
        # 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 OSError:
                os._exit(2)
            finally:
                handle.close()
        return out_queue.put(count)


class LockTestCase(test_base.BaseTestCase):

    def setUp(self):
        super().setUp()
        self.config = self.useFixture(config.Config(lockutils.CONF)).config

    def test_synchronized_wrapped_function_metadata(self):
        @lockutils.synchronized('whatever', 'test-')
        def foo():
            """Bar."""
            pass

        self.assertEqual('Bar.', foo.__doc__, "Wrapped function's docstring "
                                              "got lost")
        self.assertEqual('foo', foo.__name__, "Wrapped function's name "
                                              "got mangled")

    def test_lock_internally_different_collections(self):
        s1 = lockutils.Semaphores()
        s2 = lockutils.Semaphores()
        trigger = threading.Event()
        who_ran = collections.deque()

        def f(name, semaphores, pull_trigger):
            with lockutils.internal_lock('testing', semaphores=semaphores):
                if pull_trigger:
                    trigger.set()
                else:
                    trigger.wait()
                who_ran.append(name)

        threads = [
            threading.Thread(target=f, args=(1, s1, True)),
            threading.Thread(target=f, args=(2, s2, False)),
        ]
        for thread in threads:
            thread.start()
        for thread in threads:
            thread.join()
        self.assertEqual([1, 2], sorted(who_ran))

    def test_lock_internally(self):
        """We can lock across multiple threads."""
        saved_sem_num = len(lockutils._semaphores)
        seen_threads = list()

        def f(_id):
            with lockutils.lock('testlock2', 'test-', external=False):
                for x in range(10):
                    seen_threads.append(_id)

        threads = []
        for i in range(10):
            thread = threading.Thread(target=f, args=(i,))
            threads.append(thread)
            thread.start()

        for thread in threads:
            thread.join()

        self.assertEqual(100, len(seen_threads))
        # Looking at the seen threads, split it into chunks of 10, and verify
        # that the last 9 match the first in each chunk.
        for i in range(10):
            for j in range(9):
                self.assertEqual(seen_threads[i * 10],
                                 seen_threads[i * 10 + 1 + j])

        self.assertEqual(saved_sem_num, len(lockutils._semaphores),
                         "Semaphore leak detected")

    def test_lock_internal_fair(self):
        """Check that we're actually fair."""

        def f(_id):
            with lockutils.lock('testlock', 'test-',
                                external=False, fair=True):
                lock_holder.append(_id)

        lock_holder = []
        threads = []
        # While holding the fair lock, spawn a bunch of threads that all try
        # to acquire the lock.  They will all block.  Then release the lock
        # and see what happens.
        with lockutils.lock('testlock', 'test-', external=False, fair=True):
            for i in range(10):
                thread = threading.Thread(target=f, args=(i,))
                threads.append(thread)
                thread.start()
                # Allow some time for the new thread to get queued onto the
                # list of pending writers before continuing.  This is gross
                # but there's no way around it without using knowledge of
                # fasteners internals.
                time.sleep(0.5)
        # Wait for all threads.
        for thread in threads:
            thread.join()

        self.assertEqual(10, len(lock_holder))
        # Check that the threads each got the lock in fair order.
        for i in range(10):
            self.assertEqual(i, lock_holder[i])

    def test_fair_lock_with_semaphore(self):
        def do_test():
            s = lockutils.Semaphores()
            with lockutils.lock('testlock', 'test-', semaphores=s, fair=True):
                pass
        self.assertRaises(NotImplementedError, do_test)

    def test_fair_lock_with_nonblocking(self):
        def do_test():
            with lockutils.lock('testlock', 'test-', fair=True,
                                blocking=False):
                pass
        self.assertRaises(NotImplementedError, do_test)

    def test_nested_synchronized_external_works(self):
        """We can nest external syncs."""
        self.config(lock_path=tempfile.mkdtemp(), group='oslo_concurrency')
        sentinel = object()

        @lockutils.synchronized('testlock1', 'test-', external=True)
        def outer_lock():

            @lockutils.synchronized('testlock2', 'test-', external=True)
            def inner_lock():
                return sentinel
            return inner_lock()

        self.assertEqual(sentinel, outer_lock())

    def _do_test_lock_externally(self):
        """We can lock across multiple processes."""
        children = []
        for n in range(50):
            queue = multiprocessing.Queue()
            proc = multiprocessing.Process(
                target=lock_files,
                args=(tempfile.mkdtemp(), queue))
            proc.start()
            children.append((proc, queue))
        for child, queue in children:
            child.join()
            count = queue.get(block=False)
            self.assertEqual(50, count)

    def test_lock_externally(self):
        self.config(lock_path=tempfile.mkdtemp(), group='oslo_concurrency')

        self._do_test_lock_externally()

    def test_lock_externally_lock_dir_not_exist(self):
        lock_dir = tempfile.mkdtemp()
        os.rmdir(lock_dir)
        self.config(lock_path=lock_dir, group='oslo_concurrency')

        self._do_test_lock_externally()

    def test_lock_with_prefix(self):
        # TODO(efried): Embetter this test
        self.config(lock_path=tempfile.mkdtemp(), group='oslo_concurrency')
        foo = lockutils.lock_with_prefix('mypfix-')

        with foo('mylock', external=True):
            # We can't check much
            pass

    def test_synchronized_with_prefix(self):
        lock_name = 'mylock'
        lock_pfix = 'mypfix-'

        foo = lockutils.synchronized_with_prefix(lock_pfix)

        @foo(lock_name, external=True)
        def bar(dirpath, pfix, name):
            return True

        lock_dir = tempfile.mkdtemp()
        self.config(lock_path=lock_dir, group='oslo_concurrency')

        self.assertTrue(bar(lock_dir, lock_pfix, lock_name))

    def test_synchronized_without_prefix(self):
        self.config(lock_path=tempfile.mkdtemp(), group='oslo_concurrency')

        @lockutils.synchronized('lock', external=True)
        def test_without_prefix():
            # We can't check much
            pass

        test_without_prefix()

    def test_synchronized_prefix_without_hypen(self):
        self.config(lock_path=tempfile.mkdtemp(), group='oslo_concurrency')

        @lockutils.synchronized('lock', 'hypen', True)
        def test_without_hypen():
            # We can't check much
            pass

        test_without_hypen()

    def test_contextlock(self):
        self.config(lock_path=tempfile.mkdtemp(), group='oslo_concurrency')

        # Note(flaper87): Lock is not external, which means
        # a semaphore will be yielded
        with lockutils.lock("test") as sem:
            self.assertIsInstance(sem, threading.Semaphore)

            # NOTE(flaper87): Lock is external so an InterProcessLock
            # will be yielded.
            with lockutils.lock("test2", external=True) as lock:
                self.assertTrue(lock.exists())

            with lockutils.lock("test1", external=True) as lock1:
                self.assertIsInstance(lock1, lockutils.InterProcessLock)

    def test_contextlock_unlocks(self):
        self.config(lock_path=tempfile.mkdtemp(), group='oslo_concurrency')

        with lockutils.lock("test") as sem:
            self.assertIsInstance(sem, threading.Semaphore)

            with lockutils.lock("test2", external=True) as lock:
                self.assertTrue(lock.exists())

            # NOTE(flaper87): Lock should be free
            with lockutils.lock("test2", external=True) as lock:
                self.assertTrue(lock.exists())

        # NOTE(flaper87): Lock should be free
        # but semaphore should already exist.
        with lockutils.lock("test") as sem2:
            self.assertEqual(sem, sem2)

    @mock.patch('logging.Logger.info')
    @mock.patch('os.remove')
    @mock.patch('oslo_concurrency.lockutils._get_lock_path')
    def test_remove_lock_external_file_exists(self, path_mock, remove_mock,
                                              log_mock):
        lockutils.remove_external_lock_file(mock.sentinel.name,
                                            mock.sentinel.prefix,
                                            mock.sentinel.lock_path)

        path_mock.assert_called_once_with(mock.sentinel.name,
                                          mock.sentinel.prefix,
                                          mock.sentinel.lock_path)
        remove_mock.assert_called_once_with(path_mock.return_value)
        log_mock.assert_not_called()

    @mock.patch('logging.Logger.warning')
    @mock.patch('os.remove', side_effect=OSError(errno.ENOENT, None))
    @mock.patch('oslo_concurrency.lockutils._get_lock_path')
    def test_remove_lock_external_file_doesnt_exists(self, path_mock,
                                                     remove_mock, log_mock):
        lockutils.remove_external_lock_file(mock.sentinel.name,
                                            mock.sentinel.prefix,
                                            mock.sentinel.lock_path)
        path_mock.assert_called_once_with(mock.sentinel.name,
                                          mock.sentinel.prefix,
                                          mock.sentinel.lock_path)
        remove_mock.assert_called_once_with(path_mock.return_value)
        log_mock.assert_not_called()

    @mock.patch('logging.Logger.warning')
    @mock.patch('os.remove', side_effect=OSError(errno.EPERM, None))
    @mock.patch('oslo_concurrency.lockutils._get_lock_path')
    def test_remove_lock_external_file_permission_error(
            self, path_mock, remove_mock, log_mock):
        lockutils.remove_external_lock_file(mock.sentinel.name,
                                            mock.sentinel.prefix,
                                            mock.sentinel.lock_path)
        path_mock.assert_called_once_with(mock.sentinel.name,
                                          mock.sentinel.prefix,
                                          mock.sentinel.lock_path)
        remove_mock.assert_called_once_with(path_mock.return_value)
        log_mock.assert_called()

    def test_no_slash_in_b64(self):
        # base64(sha1(foobar)) has a slash in it
        with lockutils.lock("foobar"):
            pass


class FileBasedLockingTestCase(test_base.BaseTestCase):
    def setUp(self):
        super().setUp()
        self.lock_dir = tempfile.mkdtemp()

    def test_lock_file_exists(self):
        lock_file = os.path.join(self.lock_dir, 'lock-file')

        @lockutils.synchronized('lock-file', external=True,
                                lock_path=self.lock_dir)
        def foo():
            self.assertTrue(os.path.exists(lock_file))

        foo()

    def test_interprocess_lock(self):
        lock_file = os.path.join(self.lock_dir, 'processlock')

        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 = lockutils.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 OSError:
                    # 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 = lockutils.InterProcessLock('foo')
                lock2.lockfile = open(lock_file, 'w')
                have_lock = False
                while not have_lock:
                    try:
                        lock2.trylock()
                        have_lock = True
                    except OSError:
                        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_interprocess_nonblocking_external_lock(self):
        """Check that we're not actually blocking between processes."""

        nb_calls = multiprocessing.Value('i', 0)

        @lockutils.synchronized('foo', blocking=False, external=True,
                                lock_path=self.lock_dir)
        def foo(param):
            """Simulate a long-running operation in a process."""
            param.value += 1
            time.sleep(.5)

        def other(param):
            foo(param)

        process = multiprocessing.Process(target=other, args=(nb_calls, ))
        process.start()
        # Make sure the other process grabs the lock
        start = time.time()
        while not os.path.exists(os.path.join(self.lock_dir, 'foo')):
            if time.time() - start > 5:
                self.fail('Timed out waiting for process to grab lock')
            time.sleep(0)
        process1 = multiprocessing.Process(target=other, args=(nb_calls, ))
        process1.start()
        process1.join()
        process.join()
        self.assertEqual(1, nb_calls.value)

    def test_interthread_external_lock(self):
        call_list = []

        @lockutils.synchronized('foo', external=True, lock_path=self.lock_dir)
        def foo(param):
            """Simulate a long-running threaded operation."""
            call_list.append(param)
            # 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)
            call_list.append(param)

        def other(param):
            foo(param)

        thread = threading.Thread(target=other, args=('other',))
        thread.start()
        # Make sure the other thread grabs the lock
        # NOTE(bnemec): File locks do not actually work between threads, so
        # this test is verifying that the local semaphore is still enforcing
        # external locks in that case.  This means this test does not have
        # the same race problem as the process test above because when the
        # file is created the semaphore has already been grabbed.
        start = time.time()
        while not os.path.exists(os.path.join(self.lock_dir, 'foo')):
            if time.time() - start > 5:
                self.fail('Timed out waiting for thread to grab lock')
            time.sleep(0)
        thread1 = threading.Thread(target=other, args=('main',))
        thread1.start()
        thread1.join()
        thread.join()
        self.assertEqual(['other', 'other', 'main', 'main'], call_list)

    def test_interthread_nonblocking_external_lock(self):
        call_list = []

        @lockutils.synchronized('foo', external=True, blocking=False,
                                lock_path=self.lock_dir)
        def foo(param):
            """Simulate a long-running threaded operation."""
            call_list.append(param)
            time.sleep(.5)
            call_list.append(param)

        def other(param):
            foo(param)

        thread = threading.Thread(target=other, args=('other',))
        thread.start()
        # Make sure the other thread grabs the lock
        start = time.time()
        while not os.path.exists(os.path.join(self.lock_dir, 'foo')):
            if time.time() - start > 5:
                self.fail('Timed out waiting for thread to grab lock')
            time.sleep(0)
        thread1 = threading.Thread(target=other, args=('main',))
        thread1.start()
        thread1.join()
        thread.join()
        self.assertEqual(['other', 'other'], call_list)

    def test_interthread_nonblocking_internal_lock(self):
        call_list = []

        @lockutils.synchronized('foo', blocking=False,
                                lock_path=self.lock_dir)
        def foo(param):
            # Simulate a long-running threaded operation.
            call_list.append(param)
            time.sleep(.5)
            call_list.append(param)

        def other(param):
            foo(param)

        thread = threading.Thread(target=other, args=('other',))
        thread.start()
        # Make sure the other thread grabs the lock
        start = time.time()
        while not call_list:
            if time.time() - start > 5:
                self.fail('Timed out waiting for thread to grab lock')
            time.sleep(0)
        thread1 = threading.Thread(target=other, args=('main',))
        thread1.start()
        thread1.join()
        thread.join()
        self.assertEqual(['other', 'other'], call_list)

    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 lockutils.lock('not-destroyed', external=True,
                            lock_path=self.lock_dir):
            with open(lock_file) as f:
                self.assertEqual('test', f.read())


class LockutilsModuleTestCase(test_base.BaseTestCase):

    def setUp(self):
        super().setUp()
        self.old_env = os.environ.get('OSLO_LOCK_PATH')
        if self.old_env is not None:
            del os.environ['OSLO_LOCK_PATH']

    def tearDown(self):
        if self.old_env is not None:
            os.environ['OSLO_LOCK_PATH'] = self.old_env
        super().tearDown()

    def test_main(self):
        script = '\n'.join([
            'import os',
            'lock_path = os.environ.get("OSLO_LOCK_PATH")',
            'assert lock_path is not None',
            'assert os.path.isdir(lock_path)',
        ])
        argv = ['', sys.executable, '-c', script]
        retval = lockutils._lock_wrapper(argv)
        self.assertEqual(0, retval, "Bad OSLO_LOCK_PATH has been set")

    def test_return_value_maintained(self):
        script = '\n'.join([
            'import sys',
            'sys.exit(1)',
        ])
        argv = ['', sys.executable, '-c', script]
        retval = lockutils._lock_wrapper(argv)
        self.assertEqual(1, retval)

    def test_direct_call_explodes(self):
        cmd = [sys.executable, '-m', 'oslo_concurrency.lockutils']
        with open(os.devnull, 'w') as devnull:
            retval = subprocess.call(cmd, stderr=devnull)
            self.assertEqual(1, retval)


class TestLockFixture(test_base.BaseTestCase):

    def setUp(self):
        super().setUp()
        self.config = self.useFixture(config.Config(lockutils.CONF)).config
        self.tempdir = tempfile.mkdtemp()

    def _check_in_lock(self):
        self.assertTrue(self.lock.exists())

    def tearDown(self):
        self._check_in_lock()
        super().tearDown()

    def test_lock_fixture(self):
        # Setup lock fixture to test that teardown is inside the lock
        self.config(lock_path=self.tempdir, group='oslo_concurrency')
        fixture = fixtures.LockFixture('test-lock')
        self.useFixture(fixture)
        self.lock = fixture.lock


class TestGetLockPath(test_base.BaseTestCase):

    def setUp(self):
        super().setUp()
        self.conf = self.useFixture(config.Config(lockutils.CONF)).conf

    def test_get_default(self):
        lockutils.set_defaults(lock_path='/the/path')
        self.assertEqual('/the/path', lockutils.get_lock_path(self.conf))

    def test_get_override(self):
        lockutils._register_opts(self.conf)
        self.conf.set_override('lock_path', '/alternate/path',
                               group='oslo_concurrency')
        self.assertEqual('/alternate/path', lockutils.get_lock_path(self.conf))