126 lines
4.1 KiB
Python
126 lines
4.1 KiB
Python
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import importlib
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import importlib.machinery
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import importlib.util
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import inspect
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import logging
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import pkgutil
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import sys
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logger = logging.getLogger(__name__)
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def iter_namespace(ns_pkg):
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# Specifying the second argument (prefix) to iter_modules makes the
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# returned name an absolute name instead of a relative one. This allows
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# import_module to work without having to do additional modification to
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# the name.
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return pkgutil.iter_modules(ns_pkg.__path__, ns_pkg.__name__ + ".")
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def get_namespace_plugins(ns_pkg=None):
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if ns_pkg is None:
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import pelican.plugins as ns_pkg
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return {
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name: importlib.import_module(name)
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for finder, name, ispkg
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in iter_namespace(ns_pkg)
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if ispkg
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}
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def list_plugins(ns_pkg=None):
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from pelican.log import init as init_logging
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init_logging(logging.INFO)
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ns_plugins = get_namespace_plugins(ns_pkg)
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if ns_plugins:
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logger.info('Plugins found:\n' + '\n'.join(ns_plugins))
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else:
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logger.info('No plugins are installed')
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def load_legacy_plugin(plugin, plugin_paths):
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if '.' in plugin:
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# it is in a package, try to resolve package first
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package, _, _ = plugin.rpartition('.')
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load_legacy_plugin(package, plugin_paths)
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# Try to find plugin in PLUGIN_PATHS
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spec = importlib.machinery.PathFinder.find_spec(plugin, plugin_paths)
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if spec is None:
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# If failed, try to find it in normal importable locations
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spec = importlib.util.find_spec(plugin)
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if spec is None:
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raise ImportError('Cannot import plugin `{}`'.format(plugin))
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else:
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# Avoid loading the same plugin twice
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if spec.name in sys.modules:
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return sys.modules[spec.name]
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# create module object from spec
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mod = importlib.util.module_from_spec(spec)
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# place it into sys.modules cache
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# necessary if module imports itself at some point (e.g. packages)
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sys.modules[spec.name] = mod
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try:
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# try to execute it inside module object
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spec.loader.exec_module(mod)
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except Exception: # problem with import
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try:
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# remove module from sys.modules since it can't be loaded
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del sys.modules[spec.name]
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except KeyError:
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pass
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raise
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# if all went well, we have the plugin module
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return mod
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def load_plugins(settings):
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logger.debug('Finding namespace plugins')
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namespace_plugins = get_namespace_plugins()
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if namespace_plugins:
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logger.debug('Namespace plugins found:\n' +
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'\n'.join(namespace_plugins))
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plugins = []
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if settings.get('PLUGINS') is not None:
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for plugin in settings['PLUGINS']:
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if isinstance(plugin, str):
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logger.debug('Loading plugin `%s`', plugin)
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# try to find in namespace plugins
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if plugin in namespace_plugins:
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plugin = namespace_plugins[plugin]
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elif 'pelican.plugins.{}'.format(plugin) in namespace_plugins:
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plugin = namespace_plugins['pelican.plugins.{}'.format(
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plugin)]
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# try to import it
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else:
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try:
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plugin = load_legacy_plugin(
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plugin,
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settings.get('PLUGIN_PATHS', []))
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except ImportError as e:
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logger.error('Cannot load plugin `%s`\n%s', plugin, e)
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continue
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plugins.append(plugin)
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else:
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plugins = list(namespace_plugins.values())
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return plugins
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def get_plugin_name(plugin):
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"""
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Plugins can be passed as module objects, however this breaks caching as
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module objects cannot be pickled. To work around this, all plugins are
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stringified post-initialization.
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"""
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if inspect.isclass(plugin):
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return plugin.__qualname__
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if inspect.ismodule(plugin):
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return plugin.__name__
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return type(plugin).__qualname__
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