diff --git a/nova/api/openstack/wsgi_app.py b/nova/api/openstack/wsgi_app.py index fd807a8e56db..947958a9e484 100644 --- a/nova/api/openstack/wsgi_app.py +++ b/nova/api/openstack/wsgi_app.py @@ -30,6 +30,8 @@ CONF = cfg.CONF CONFIG_FILES = ['api-paste.ini', 'nova.conf'] +LOG = logging.getLogger(__name__) + objects.register_all() @@ -75,8 +77,13 @@ def error_application(exc, name): return application -def init_application(name): - conf_files = _get_config_files() +@utils.run_once('Global data already initialized, not re-initializing.', + LOG.info) +def init_global_data(conf_files): + # NOTE(melwitt): parse_args initializes logging and calls global rpc.init() + # and db_api.configure(). The db_api.configure() call does not initiate any + # connection to the database. + # NOTE(gibi): sys.argv is set by the wsgi runner e.g. uwsgi sets it based # on the --pyargv parameter of the uwsgi binary config.parse_args(sys.argv, default_config_files=conf_files) @@ -93,11 +100,25 @@ def init_application(name): logging.getLogger(__name__), logging.DEBUG) + +def init_application(name): + conf_files = _get_config_files() + + # NOTE(melwitt): The init_application method can be called multiple times + # within a single python interpreter instance if any exception is raised + # during it (example: DBConnectionError while setting up the service) and + # apache/mod_wsgi reloads the init_application script. So, we initialize + # global data separately and decorate the method to run only once in a + # python interpreter instance. + init_global_data(conf_files) + try: _setup_service(CONF.host, name) except exception.ServiceTooOld as exc: return error_application(exc, name) + # This global init is safe because if we got here, we already successfully + # set up the service and setting up the profile cannot fail. service.setup_profiler(name, CONF.host) conf = conf_files[0] diff --git a/nova/tests/unit/api/openstack/test_wsgi_app.py b/nova/tests/unit/api/openstack/test_wsgi_app.py new file mode 100644 index 000000000000..4cb7459c982d --- /dev/null +++ b/nova/tests/unit/api/openstack/test_wsgi_app.py @@ -0,0 +1,85 @@ +# 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 tempfile + +import fixtures +import mock +from oslo_config import fixture as config_fixture +from oslotest import base + +from nova.api.openstack import wsgi_app +from nova import test +from nova.tests import fixtures as nova_fixtures + + +class WSGIAppTest(base.BaseTestCase): + + _paste_config = """ +[app:nova-api] +use = egg:Paste#static +document_root = /tmp + """ + + def setUp(self): + # Ensure BaseTestCase's ConfigureLogging fixture is disabled since + # we're using our own (StandardLogging). + with fixtures.EnvironmentVariable('OS_LOG_CAPTURE', '0'): + super(WSGIAppTest, self).setUp() + self.stdlog = self.useFixture(nova_fixtures.StandardLogging()) + self.conf = tempfile.NamedTemporaryFile(mode='w+t') + self.conf.write(self._paste_config.lstrip()) + self.conf.seek(0) + self.conf.flush() + self.addCleanup(self.conf.close) + # Use of this fixture takes care of cleaning up config settings for + # subsequent tests. + self.useFixture(config_fixture.Config()) + + @mock.patch('sys.argv', return_value=mock.sentinel.argv) + @mock.patch('nova.db.sqlalchemy.api.configure') + @mock.patch('nova.api.openstack.wsgi_app._setup_service') + @mock.patch('nova.api.openstack.wsgi_app._get_config_files') + def test_init_application_called_twice(self, mock_get_files, mock_setup, + mock_db_configure, mock_argv): + """Test that init_application can tolerate being called twice in a + single python interpreter instance. + + When nova-api is run via mod_wsgi, if any exception is raised during + init_application, mod_wsgi will re-run the WSGI script without + restarting the daemon process even when configured for Daemon Mode. + + We access the database as part of init_application, so if nova-api + starts up before the database is up, we'll get, for example, a + DBConnectionError raised during init_application and our WSGI script + will get reloaded/re-run by mod_wsgi. + """ + mock_get_files.return_value = [self.conf.name] + mock_setup.side_effect = [test.TestingException, None] + # We need to mock the global database configure() method, else we will + # be affected by global database state altered by other tests that ran + # before this test, causing this test to fail with + # oslo_db.sqlalchemy.enginefacade.AlreadyStartedError. We can instead + # mock the method to raise an exception if it's called a second time in + # this test to simulate the fact that the database does not tolerate + # re-init [after a database query has been made]. + mock_db_configure.side_effect = [None, test.TestingException] + # Run init_application the first time, simulating an exception being + # raised during it. + self.assertRaises(test.TestingException, wsgi_app.init_application, + 'nova-api') + # Now run init_application a second time, it should succeed since no + # exception is being raised (the init of global data should not be + # re-attempted). + wsgi_app.init_application('nova-api') + self.assertIn('Global data already initialized, not re-initializing.', + self.stdlog.logger.output) diff --git a/nova/tests/unit/test_utils.py b/nova/tests/unit/test_utils.py index 639191fedf38..4786df0ce084 100644 --- a/nova/tests/unit/test_utils.py +++ b/nova/tests/unit/test_utils.py @@ -1293,3 +1293,101 @@ class TestOldComputeCheck(test.NoDBTestCase): 'not allowed to directly access the database. You should run this ' 'service without the [api_database]/connection config option. The ' 'service version check will only query the local cell.') + + +class RunOnceTests(test.NoDBTestCase): + + fake_logger = mock.MagicMock() + + @utils.run_once("already ran once", fake_logger) + def dummy_test_func(self, fail=False): + if fail: + raise ValueError() + return True + + def setUp(self): + super(RunOnceTests, self).setUp() + self.dummy_test_func.reset() + RunOnceTests.fake_logger.reset_mock() + + def test_wrapped_funtions_called_once(self): + self.assertFalse(self.dummy_test_func.called) + result = self.dummy_test_func() + self.assertTrue(result) + self.assertTrue(self.dummy_test_func.called) + + # assert that on second invocation no result + # is returned and that the logger is invoked. + result = self.dummy_test_func() + RunOnceTests.fake_logger.assert_called_once() + self.assertIsNone(result) + + def test_wrapped_funtions_called_once_raises(self): + self.assertFalse(self.dummy_test_func.called) + self.assertRaises(ValueError, self.dummy_test_func, fail=True) + self.assertTrue(self.dummy_test_func.called) + + # assert that on second invocation no result + # is returned and that the logger is invoked. + result = self.dummy_test_func() + RunOnceTests.fake_logger.assert_called_once() + self.assertIsNone(result) + + def test_wrapped_funtions_can_be_reset(self): + # assert we start with a clean state + self.assertFalse(self.dummy_test_func.called) + result = self.dummy_test_func() + self.assertTrue(result) + + self.dummy_test_func.reset() + # assert we restored a clean state + self.assertFalse(self.dummy_test_func.called) + result = self.dummy_test_func() + self.assertTrue(result) + + # assert that we never called the logger + RunOnceTests.fake_logger.assert_not_called() + + def test_reset_calls_cleanup(self): + mock_clean = mock.Mock() + + @utils.run_once("already ran once", self.fake_logger, + cleanup=mock_clean) + def f(): + pass + + f() + self.assertTrue(f.called) + + f.reset() + self.assertFalse(f.called) + mock_clean.assert_called_once_with() + + def test_clean_is_not_called_at_reset_if_wrapped_not_called(self): + mock_clean = mock.Mock() + + @utils.run_once("already ran once", self.fake_logger, + cleanup=mock_clean) + def f(): + pass + + self.assertFalse(f.called) + + f.reset() + self.assertFalse(f.called) + self.assertFalse(mock_clean.called) + + def test_reset_works_even_if_cleanup_raises(self): + mock_clean = mock.Mock(side_effect=ValueError()) + + @utils.run_once("already ran once", self.fake_logger, + cleanup=mock_clean) + def f(): + pass + + f() + self.assertTrue(f.called) + + self.assertRaises(ValueError, f.reset) + self.assertFalse(f.called) + mock_clean.assert_called_once_with() diff --git a/nova/utils.py b/nova/utils.py index a4a1abaaa17e..5239dd4ba8f9 100644 --- a/nova/utils.py +++ b/nova/utils.py @@ -1102,3 +1102,49 @@ def raise_if_old_compute(): scope=scope, min_service_level=current_service_version, oldest_supported_service=oldest_supported_service_level) + + +def run_once(message, logger, cleanup=None): + """This is a utility function decorator to ensure a function + is run once and only once in an interpreter instance. + + Note: this is copied from the placement repo (placement/util.py) + + The decorated function object can be reset by calling its + reset function. All exceptions raised by the wrapped function, + logger and cleanup function will be propagated to the caller. + """ + def outer_wrapper(func): + @functools.wraps(func) + def wrapper(*args, **kwargs): + if not wrapper.called: + # Note(sean-k-mooney): the called state is always + # updated even if the wrapped function completes + # by raising an exception. If the caller catches + # the exception it is their responsibility to call + # reset if they want to re-execute the wrapped function. + try: + return func(*args, **kwargs) + finally: + wrapper.called = True + else: + logger(message) + + wrapper.called = False + + def reset(wrapper, *args, **kwargs): + # Note(sean-k-mooney): we conditionally call the + # cleanup function if one is provided only when the + # wrapped function has been called previously. We catch + # and reraise any exception that may be raised and update + # the called state in a finally block to ensure its + # always updated if reset is called. + try: + if cleanup and wrapper.called: + return cleanup(*args, **kwargs) + finally: + wrapper.called = False + + wrapper.reset = functools.partial(reset, wrapper) + return wrapper + return outer_wrapper