209 lines
8.1 KiB
Python
209 lines
8.1 KiB
Python
# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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from collections.abc import Callable
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import importlib.metadata
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from typing import Any
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from typing import Concatenate
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from typing import ParamSpec
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from typing import TYPE_CHECKING
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from typing import TypeVar
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from .exception import MultipleMatches
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from .exception import NoMatches
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from .extension import ConflictResolverT
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from .extension import Extension
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from .extension import ExtensionManager
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from .extension import ignore_conflicts
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from .extension import OnLoadFailureCallbackT
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from .named import NamedExtensionManager
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from .named import OnMissingEntrypointsCallbackT
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from .named import warning_on_missing_entrypoint
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if TYPE_CHECKING:
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from typing_extensions import Self
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T = TypeVar('T')
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U = TypeVar('U')
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P = ParamSpec('P')
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class DriverManager(NamedExtensionManager[T]):
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"""Load a single plugin with a given name from the namespace.
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:param namespace: The namespace for the entry points.
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:param name: The name of the driver to load.
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:param invoke_on_load: Boolean controlling whether to invoke the
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object returned by the entry point after the driver is loaded.
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:param invoke_args: Positional arguments to pass when invoking
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the object returned by the entry point. Only used if invoke_on_load
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is True.
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:param invoke_kwds: Named arguments to pass when invoking
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the object returned by the entry point. Only used if invoke_on_load
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is True.
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:param on_load_failure_callback: Callback function that will be called when
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an entrypoint can not be loaded. The arguments that will be provided
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when this is called (when an entrypoint fails to load) are
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(manager, entrypoint, exception)
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:param on_missing_entrypoints_callback: Callback function that will be
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called when one or more names cannot be found. The provided argument
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will be a subset of the 'names' parameter.
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:param verify_requirements: **DEPRECATED** This is a no-op and will be
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removed in a future version.
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:param warn_on_missing_entrypoint: **DEPRECATED** Flag to control whether
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failing to load a plugin is reported via a log mess. Only applies if
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on_missing_entrypoints_callback is None. Users should instead set
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``on_missing_entrypoints_callback`` to ``None`` if they wish to disable
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logging.
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:param conflict_resolver: A callable that determines what to do in the
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event that there are multiple entrypoints in the same group with the
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same name. This is only used if retrieving entrypoint by name.
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"""
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def __init__(
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self,
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namespace: str,
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name: str,
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invoke_on_load: bool = False,
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invoke_args: tuple[Any, ...] | None = None,
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invoke_kwds: dict[str, Any] | None = None,
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on_load_failure_callback: 'OnLoadFailureCallbackT[T] | None' = None,
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on_missing_entrypoints_callback: (
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OnMissingEntrypointsCallbackT | None
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) = warning_on_missing_entrypoint,
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verify_requirements: bool | None = None,
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warn_on_missing_entrypoint: bool | None = None,
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*,
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conflict_resolver: 'ConflictResolverT[T]' = ignore_conflicts,
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) -> None:
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invoke_args = () if invoke_args is None else invoke_args
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invoke_kwds = {} if invoke_kwds is None else invoke_kwds
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on_load_failure_callback = (
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on_load_failure_callback or self._default_on_load_failure
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)
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super().__init__(
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namespace=namespace,
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names=[name],
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invoke_on_load=invoke_on_load,
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invoke_args=invoke_args,
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invoke_kwds=invoke_kwds,
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on_load_failure_callback=on_load_failure_callback,
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verify_requirements=verify_requirements,
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warn_on_missing_entrypoint=warn_on_missing_entrypoint,
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conflict_resolver=conflict_resolver,
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)
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@staticmethod
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def _default_on_load_failure(
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manager: 'ExtensionManager[T]',
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ep: importlib.metadata.EntryPoint,
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err: BaseException,
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) -> None:
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raise
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@classmethod
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def make_test_instance( # type: ignore[override]
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cls,
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extension: Extension[T],
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namespace: str = 'TESTING',
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propagate_map_exceptions: bool = False,
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on_load_failure_callback: 'OnLoadFailureCallbackT[T] | None' = None,
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verify_requirements: bool | None = None,
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*,
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conflict_resolver: 'ConflictResolverT[T]' = ignore_conflicts,
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) -> 'Self':
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"""Construct a test DriverManager
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Test instances are passed a list of extensions to work from rather
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than loading them from entry points.
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:param extension: Pre-configured Extension instance
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:param namespace: The namespace for the manager; used only for
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identification since the extensions are passed in.
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:param propagate_map_exceptions: Boolean controlling whether exceptions
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are propagated up through the map call or whether they are logged
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and then ignored
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:param on_load_failure_callback: Callback function that will
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be called when an entrypoint can not be loaded. The
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arguments that will be provided when this is called (when
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an entrypoint fails to load) are (manager, entrypoint,
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exception)
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:param verify_requirements: **DEPRECATED** This is a no-op and will be
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removed in a future version.
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:param conflict_resolver: A callable that determines what to do in the
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event that there are multiple entrypoints in the same group with
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the same name. This is only used if retrieving entrypoint by name.
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:return: The manager instance, initialized for testing
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"""
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o = super().make_test_instance(
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[extension],
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namespace=namespace,
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propagate_map_exceptions=propagate_map_exceptions,
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on_load_failure_callback=on_load_failure_callback,
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verify_requirements=verify_requirements,
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conflict_resolver=conflict_resolver,
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)
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return o
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def _init_plugins(self, extensions: list[Extension[T]]) -> None:
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super()._init_plugins(extensions)
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if not self.extensions:
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name = self._names[0]
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raise NoMatches(
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f'No {self.namespace!r} driver found, looking for {name!r}'
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)
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if len(self.extensions) > 1:
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discovered_drivers = ','.join(
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e.entry_point_target for e in self.extensions
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)
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raise MultipleMatches(
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f'Multiple {self.namespace!r} drivers found: '
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f'{discovered_drivers}'
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)
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def __call__(
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self,
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func: Callable[Concatenate[Extension[T], P], U],
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*args: Any,
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**kwds: Any,
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) -> U | None:
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"""Invokes func() for the single loaded extension.
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The signature for func() should be::
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def func(ext, *args, **kwds):
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pass
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The first argument to func(), 'ext', is the
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:class:`~stevedore.extension.Extension` instance.
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Exceptions raised from within func() are logged and ignored.
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:param func: Callable to invoke for each extension.
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:param args: Variable arguments to pass to func()
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:param kwds: Keyword arguments to pass to func()
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:returns: List of values returned from func()
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"""
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results = self.map(func, *args, **kwds)
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if results:
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return results[0]
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return None
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@property
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def driver(self) -> T | Callable[..., T]:
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"""Returns the driver being used by this manager."""
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ext = self.extensions[0]
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return ext.obj if ext.obj else ext.plugin
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