Add a module for dynamically loading plugins

Change-Id: I662b5989941b467c78a392098db0cd19ff86201c
Signed-off-by: Zane Bitter <zbitter@redhat.com>
changes/84/17084/1
Zane Bitter 10 years ago
parent a0cf5dfa5c
commit faca9953c0

@ -0,0 +1,64 @@
# vim: tabstop=4 shiftwidth=4 softtabstop=4
#
# 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 pkgutil
import sys
import types
from heat.openstack.common import log as logging
logger = logging.getLogger(__name__)
def _module_name(*components):
return '.'.join(components)
def create_subpackage(path, parent_package_name, subpackage_name="plugins"):
package_name = _module_name(parent_package_name, subpackage_name)
package = types.ModuleType(package_name)
package.__path__ = [path] if isinstance(path, basestring) else list(path)
sys.modules[package_name] = package
return package
def _import_module(importer, module_name, package):
fullname = _module_name(package.__name__, module_name)
if fullname in sys.modules:
return sys.modules[fullname]
loader = importer.find_module(fullname)
if loader is None:
return None
module = loader.load_module(fullname)
setattr(package, module_name, module)
return module
def load_modules(package, ignore_error=False):
path = package.__path__
for importer, module_name, is_package in pkgutil.walk_packages(path):
try:
module = _import_module(importer, module_name, package)
except ImportError as ex:
logger.error(_('Failed to import module %s') % module_name)
if not ignore_error:
raise
else:
if module is not None:
yield module

@ -0,0 +1,70 @@
# vim: tabstop=4 shiftwidth=4 softtabstop=4
# 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 nose
import pkgutil
import sys
import unittest
from nose.plugins.attrib import attr
import heat.engine
from heat.common import plugin_loader
@attr(tag=['unit', 'plugin_loader'])
@attr(speed='fast')
class PluginLoaderTest(unittest.TestCase):
def test_module_name(self):
self.assertEqual(plugin_loader._module_name('foo.bar', 'blarg.wibble'),
'foo.bar.blarg.wibble')
def test_create_subpackage_single_path(self):
pkg_name = 'heat.engine.test_single_path'
self.assertFalse(pkg_name in sys.modules)
pkg = plugin_loader.create_subpackage('/tmp',
'heat.engine',
'test_single_path')
self.assertTrue(pkg_name in sys.modules)
self.assertEqual(sys.modules[pkg_name], pkg)
self.assertEqual(pkg.__path__, ['/tmp'])
self.assertEqual(pkg.__name__, pkg_name)
def test_create_subpackage_path_list(self):
path_list = ['/tmp']
pkg_name = 'heat.engine.test_path_list'
self.assertFalse(pkg_name in sys.modules)
pkg = plugin_loader.create_subpackage('/tmp',
'heat.engine',
'test_path_list')
self.assertTrue(pkg_name in sys.modules)
self.assertEqual(sys.modules[pkg_name], pkg)
self.assertEqual(pkg.__path__, path_list)
self.assertFalse(pkg.__path__ is path_list)
self.assertEqual(pkg.__name__, pkg_name)
def test_import_module_existing(self):
import heat.engine.service
importer = pkgutil.ImpImporter(heat.engine.__path__[0])
loaded = plugin_loader._import_module(importer,
'service',
heat.engine)
self.assertTrue(loaded is heat.engine.service)
def test_import_module_garbage(self):
importer = pkgutil.ImpImporter(heat.engine.__path__[0])
self.assertEqual(plugin_loader._import_module(importer,
'wibble',
heat.engine),
None)
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