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bazarr/libs/stevedore/named.py

160 lines
7.1 KiB

# 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 logging
from .extension import ExtensionManager
LOG = logging.getLogger(__name__)
class NamedExtensionManager(ExtensionManager):
"""Loads only the named extensions.
This is useful for explicitly enabling extensions in a
configuration file, for example.
:param namespace: The namespace for the entry points.
:type namespace: str
:param names: The names of the extensions to load.
:type names: list(str)
:param invoke_on_load: Boolean controlling whether to invoke the
object returned by the entry point after the driver is loaded.
:type invoke_on_load: bool
:param invoke_args: Positional arguments to pass when invoking
the object returned by the entry point. Only used if invoke_on_load
is True.
:type invoke_args: tuple
:param invoke_kwds: Named arguments to pass when invoking
the object returned by the entry point. Only used if invoke_on_load
is True.
:type invoke_kwds: dict
:param name_order: If true, sort the loaded extensions to match the
order used in ``names``.
:type name_order: bool
:param propagate_map_exceptions: Boolean controlling whether exceptions
are propagated up through the map call or whether they are logged and
then ignored
:type propagate_map_exceptions: bool
:param on_load_failure_callback: Callback function that will be called when
a entrypoint can not be loaded. The arguments that will be provided
when this is called (when an entrypoint fails to load) are
(manager, entrypoint, exception)
:type on_load_failure_callback: function
:param on_missing_entrypoints_callback: Callback function that will be
called when one or more names cannot be found. The provided argument
will be a subset of the 'names' parameter.
:type on_missing_entrypoints_callback: function
:param verify_requirements: Use setuptools to enforce the
dependencies of the plugin(s) being loaded. Defaults to False.
:type verify_requirements: bool
:param warn_on_missing_entrypoint: Flag to control whether failing
to load a plugin is reported via a log mess. Only applies if
on_missing_entrypoints_callback is None.
:type warn_on_missing_entrypoint: bool
"""
def __init__(self, namespace, names,
invoke_on_load=False, invoke_args=(), invoke_kwds={},
name_order=False, propagate_map_exceptions=False,
on_load_failure_callback=None,
on_missing_entrypoints_callback=None,
verify_requirements=False,
warn_on_missing_entrypoint=True):
self._init_attributes(
namespace, names, name_order=name_order,
propagate_map_exceptions=propagate_map_exceptions,
on_load_failure_callback=on_load_failure_callback)
extensions = self._load_plugins(invoke_on_load,
invoke_args,
invoke_kwds,
verify_requirements)
self._missing_names = set(names) - set([e.name for e in extensions])
if self._missing_names:
if on_missing_entrypoints_callback:
on_missing_entrypoints_callback(self._missing_names)
elif warn_on_missing_entrypoint:
LOG.warning('Could not load %s' %
', '.join(self._missing_names))
self._init_plugins(extensions)
@classmethod
def make_test_instance(cls, extensions, namespace='TESTING',
propagate_map_exceptions=False,
on_load_failure_callback=None,
verify_requirements=False):
"""Construct a test NamedExtensionManager
Test instances are passed a list of extensions to use rather than
loading them from entry points.
:param extensions: Pre-configured Extension instances
:type extensions: list of :class:`~stevedore.extension.Extension`
:param namespace: The namespace for the manager; used only for
identification since the extensions are passed in.
:type namespace: str
:param propagate_map_exceptions: Boolean controlling whether exceptions
are propagated up through the map call or whether they are logged
and then ignored
:type propagate_map_exceptions: bool
:param on_load_failure_callback: Callback function that will
be called when a entrypoint can not be loaded. The
arguments that will be provided when this is called (when
an entrypoint fails to load) are (manager, entrypoint,
exception)
:type on_load_failure_callback: function
:param verify_requirements: Use setuptools to enforce the
dependencies of the plugin(s) being loaded. Defaults to False.
:type verify_requirements: bool
:return: The manager instance, initialized for testing
"""
o = cls.__new__(cls)
names = [e.name for e in extensions]
o._init_attributes(namespace, names,
propagate_map_exceptions=propagate_map_exceptions,
on_load_failure_callback=on_load_failure_callback)
o._init_plugins(extensions)
return o
def _init_attributes(self, namespace, names, name_order=False,
propagate_map_exceptions=False,
on_load_failure_callback=None):
super(NamedExtensionManager, self)._init_attributes(
namespace, propagate_map_exceptions=propagate_map_exceptions,
on_load_failure_callback=on_load_failure_callback)
self._names = names
self._missing_names = set()
self._name_order = name_order
def _init_plugins(self, extensions):
super(NamedExtensionManager, self)._init_plugins(extensions)
if self._name_order:
self.extensions = [self[n] for n in self._names
if n not in self._missing_names]
def _load_one_plugin(self, ep, invoke_on_load, invoke_args, invoke_kwds,
verify_requirements):
# Check the name before going any further to prevent
# undesirable code from being loaded at all if we are not
# going to use it.
if ep.name not in self._names:
return None
return super(NamedExtensionManager, self)._load_one_plugin(
ep, invoke_on_load, invoke_args, invoke_kwds,
verify_requirements,
)