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# Copyright 2012 Bouvet ASA
#
# Author: Endre Karlson <endre.karlson@bouvet.no>
#
# 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 abc
from oslo_config import cfg
from oslo_log import log as logging
from stevedore import driver
from stevedore import enabled
LOG = logging.getLogger(__name__)
CONF = cfg.CONF
class Plugin(object, metaclass=abc.ABCMeta):
__plugin_ns__ = None
__plugin_name__ = None
__plugin_type__ = None
def __init__(self):
self.name = self.get_canonical_name()
LOG.debug("Loaded plugin %s", self.name)
@classmethod
def get_canonical_name(cls):
"""
Return the plugin name
"""
type_ = cls.get_plugin_type()
name = cls.get_plugin_name()
return "%s:%s" % (type_, name)
@classmethod
def get_plugin_name(cls):
return cls.__plugin_name__
@classmethod
def get_plugin_type(cls):
return cls.__plugin_type__
class DriverPlugin(Plugin):
"""
A Driver plugin is a singleton, where only a single driver will loaded
at a time.
For example: Storage implementations (SQLAlchemy)
"""
@classmethod
def get_driver(cls, name):
"""Load a single driver"""
LOG.debug('Looking for driver %s in %s', name, cls.__plugin_ns__)
mgr = driver.DriverManager(cls.__plugin_ns__, name)
return mgr.driver
class ExtensionPlugin(Plugin):
"""
Extension plugins are loaded as a group, where multiple extensions will
be loaded and used at the same time.
For example: Designate Sink handlers
"""
@classmethod
def get_extensions(cls, enabled_extensions=None):
"""Load a series of extensions"""
LOG.debug('Looking for extensions in %s' % cls.__plugin_ns__)
def _check_func(ext):
if enabled_extensions is None:
# All extensions are enabled by default, if no specific list
# is specified
return True
return ext.plugin.get_plugin_name() in enabled_extensions
mgr = enabled.EnabledExtensionManager(
cls.__plugin_ns__, check_func=_check_func,
propagate_map_exceptions=True)
return [e.plugin for e in mgr]
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