add lib for subliminal and set non-intrusive default ionice.

autoProcessMedia.cfg.spec

@@ -32,11 +32,11 @@
 [Posix]
     ### Process priority setting for External commands (Extractor and Transcoder) on Posix (Unix/Linux/OSX) systems.
     # Set the Niceness value for the nice command. These range from -20 (most favorable to the process) to 19 (least favorable to the process).
-    niceness = 10
+    niceness = 0
     # Set the ionice scheduling class. 0 for none, 1 for real time, 2 for best-effort, 3 for idle.
-    ionice_class = 2
+    ionice_class = 0
     # Set the ionice scheduling class data. This defines the class data, if the class accepts an argument. For real time and best-effort, 0-7 is valid data.
-    ionice_classdata = 4
+    ionice_classdata = 0
 
 [CouchPotato]
     #### autoProcessing for Movies

libs/stevedore/__init__.py

@@ -0,0 +1,36 @@
+# flake8: noqa
+
+__all__ = [
+    'ExtensionManager',
+    'EnabledExtensionManager',
+    'NamedExtensionManager',
+    'HookManager',
+    'DriverManager',
+]
+
+from .extension import ExtensionManager
+from .enabled import EnabledExtensionManager
+from .named import NamedExtensionManager
+from .hook import HookManager
+from .driver import DriverManager
+
+import logging
+
+# Configure a NullHandler for our log messages in case
+# the app we're used from does not set up logging.
+LOG = logging.getLogger('stevedore')
+
+if hasattr(logging, 'NullHandler'):
+    LOG.addHandler(logging.NullHandler())
+else:
+    class NullHandler(logging.Handler):
+        def handle(self, record):
+            pass
+
+        def emit(self, record):
+            pass
+
+        def createLock(self):
+            self.lock = None
+
+    LOG.addHandler(NullHandler())

libs/stevedore/dispatch.py

@@ -0,0 +1,216 @@
+import logging
+
+from .enabled import EnabledExtensionManager
+
+LOG = logging.getLogger(__name__)
+
+
+class DispatchExtensionManager(EnabledExtensionManager):
+    """Loads all plugins and filters on execution.
+
+    This is useful for long-running processes that need to pass
+    different inputs to different extensions.
+
+    :param namespace: The namespace for the entry points.
+    :type namespace: str
+    :param check_func: Function to determine which extensions to load.
+    :type check_func: callable
+    :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 propagate_map_exceptions: Boolean controlling whether exceptions
+        are propagated up through the map call or whether they are logged and
+        then ignored
+    :type invoke_on_load: bool
+    """
+
+    def map(self, filter_func, func, *args, **kwds):
+        """Iterate over the extensions invoking func() for any where
+        filter_func() returns True.
+
+        The signature of filter_func() should be::
+
+            def filter_func(ext, *args, **kwds):
+                pass
+
+        The first argument to filter_func(), 'ext', is the
+        :class:`~stevedore.extension.Extension`
+        instance. filter_func() should return True if the extension
+        should be invoked for the input arguments.
+
+        The signature for func() should be::
+
+            def func(ext, *args, **kwds):
+                pass
+
+        The first argument to func(), 'ext', is the
+        :class:`~stevedore.extension.Extension` instance.
+
+        Exceptions raised from within func() are propagated up and
+        processing stopped if self.propagate_map_exceptions is True,
+        otherwise they are logged and ignored.
+
+        :param filter_func: Callable to test each extension.
+        :param func: Callable to invoke for each extension.
+        :param args: Variable arguments to pass to func()
+        :param kwds: Keyword arguments to pass to func()
+        :returns: List of values returned from func()
+        """
+        if not self.extensions:
+            # FIXME: Use a more specific exception class here.
+            raise RuntimeError('No %s extensions found' % self.namespace)
+        response = []
+        for e in self.extensions:
+            if filter_func(e, *args, **kwds):
+                self._invoke_one_plugin(response.append, func, e, args, kwds)
+        return response
+
+    def map_method(self, filter_func, method_name, *args, **kwds):
+        """Iterate over the extensions invoking each one's object method called
+        `method_name` for any where filter_func() returns True.
+
+        This is equivalent of using :meth:`map` with func set to
+        `lambda x: x.obj.method_name()`
+        while being more convenient.
+
+        Exceptions raised from within the called method are propagated up
+        and processing stopped if self.propagate_map_exceptions is True,
+        otherwise they are logged and ignored.
+
+        .. versionadded:: 0.12
+
+        :param filter_func: Callable to test each extension.
+        :param method_name: The extension method name to call
+                            for each extension.
+        :param args: Variable arguments to pass to method
+        :param kwds: Keyword arguments to pass to method
+        :returns: List of values returned from methods
+        """
+        return self.map(filter_func, self._call_extension_method,
+                        method_name, *args, **kwds)
+
+
+class NameDispatchExtensionManager(DispatchExtensionManager):
+    """Loads all plugins and filters on execution.
+
+    This is useful for long-running processes that need to pass
+    different inputs to different extensions and can predict the name
+    of the extensions before calling them.
+
+    The check_func argument should return a boolean, with ``True``
+    indicating that the extension should be loaded and made available
+    and ``False`` indicating that the extension should be ignored.
+
+    :param namespace: The namespace for the entry points.
+    :type namespace: str
+    :param check_func: Function to determine which extensions to load.
+    :type check_func: callable
+    :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 propagate_map_exceptions: Boolean controlling whether exceptions
+        are propagated up through the map call or whether they are logged and
+        then ignored
+    :type invoke_on_load: 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
+
+    """
+
+    def __init__(self, namespace, check_func, invoke_on_load=False,
+                 invoke_args=(), invoke_kwds={},
+                 propagate_map_exceptions=False,
+                 on_load_failure_callback=None,
+                 verify_requirements=False):
+        super(NameDispatchExtensionManager, self).__init__(
+            namespace=namespace,
+            check_func=check_func,
+            invoke_on_load=invoke_on_load,
+            invoke_args=invoke_args,
+            invoke_kwds=invoke_kwds,
+            propagate_map_exceptions=propagate_map_exceptions,
+            on_load_failure_callback=on_load_failure_callback,
+            verify_requirements=verify_requirements,
+        )
+
+    def _init_plugins(self, extensions):
+        super(NameDispatchExtensionManager, self)._init_plugins(extensions)
+        self.by_name = dict((e.name, e) for e in self.extensions)
+
+    def map(self, names, func, *args, **kwds):
+        """Iterate over the extensions invoking func() for any where
+        the name is in the given list of names.
+
+        The signature for func() should be::
+
+            def func(ext, *args, **kwds):
+                pass
+
+        The first argument to func(), 'ext', is the
+        :class:`~stevedore.extension.Extension` instance.
+
+        Exceptions raised from within func() are propagated up and
+        processing stopped if self.propagate_map_exceptions is True,
+        otherwise they are logged and ignored.
+
+        :param names: List or set of name(s) of extension(s) to invoke.
+        :param func: Callable to invoke for each extension.
+        :param args: Variable arguments to pass to func()
+        :param kwds: Keyword arguments to pass to func()
+        :returns: List of values returned from func()
+        """
+        response = []
+        for name in names:
+            try:
+                e = self.by_name[name]
+            except KeyError:
+                LOG.debug('Missing extension %r being ignored', name)
+            else:
+                self._invoke_one_plugin(response.append, func, e, args, kwds)
+        return response
+
+    def map_method(self, names, method_name, *args, **kwds):
+        """Iterate over the extensions invoking each one's object method called
+        `method_name` for any where the name is in the given list of names.
+
+        This is equivalent of using :meth:`map` with func set to
+        `lambda x: x.obj.method_name()`
+        while being more convenient.
+
+        Exceptions raised from within the called method are propagated up
+        and processing stopped if self.propagate_map_exceptions is True,
+        otherwise they are logged and ignored.
+
+        .. versionadded:: 0.12
+
+        :param names: List or set of name(s) of extension(s) to invoke.
+        :param method_name: The extension method name
+                            to call for each extension.
+        :param args: Variable arguments to pass to method
+        :param kwds: Keyword arguments to pass to method
+        :returns: List of values returned from methods
+        """
+        return self.map(names, self._call_extension_method,
+                        method_name, *args, **kwds)

libs/stevedore/driver.py

@@ -0,0 +1,126 @@
+from .named import NamedExtensionManager
+
+
+class DriverManager(NamedExtensionManager):
+    """Load a single plugin with a given name from the namespace.
+
+    :param namespace: The namespace for the entry points.
+    :type namespace: str
+    :param name: The name of the driver to load.
+    :type name: 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 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
+    """
+
+    def __init__(self, namespace, name,
+                 invoke_on_load=False, invoke_args=(), invoke_kwds={},
+                 on_load_failure_callback=None,
+                 verify_requirements=False):
+        super(DriverManager, self).__init__(
+            namespace=namespace,
+            names=[name],
+            invoke_on_load=invoke_on_load,
+            invoke_args=invoke_args,
+            invoke_kwds=invoke_kwds,
+            on_load_failure_callback=on_load_failure_callback,
+            verify_requirements=verify_requirements,
+        )
+
+    @classmethod
+    def make_test_instance(cls, extension, namespace='TESTING',
+                           propagate_map_exceptions=False,
+                           on_load_failure_callback=None,
+                           verify_requirements=False):
+        """Construct a test DriverManager
+
+        Test instances are passed a list of extensions to work from rather
+        than loading them from entry points.
+
+        :param extension: Pre-configured Extension instance
+        :type extension: :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 = super(DriverManager, cls).make_test_instance(
+            [extension], namespace=namespace,
+            propagate_map_exceptions=propagate_map_exceptions,
+            on_load_failure_callback=on_load_failure_callback,
+            verify_requirements=verify_requirements)
+        return o
+
+    def _init_plugins(self, extensions):
+        super(DriverManager, self)._init_plugins(extensions)
+
+        if not self.extensions:
+            name = self._names[0]
+            raise RuntimeError('No %r driver found, looking for %r' %
+                               (self.namespace, name))
+        if len(self.extensions) > 1:
+            discovered_drivers = ','.join(e.entry_point_target
+                                          for e in self.extensions)
+
+            raise RuntimeError('Multiple %r drivers found: %s' %
+                               (self.namespace, discovered_drivers))
+
+    def __call__(self, func, *args, **kwds):
+        """Invokes func() for the single loaded extension.
+
+        The signature for func() should be::
+
+            def func(ext, *args, **kwds):
+                pass
+
+        The first argument to func(), 'ext', is the
+        :class:`~stevedore.extension.Extension` instance.
+
+        Exceptions raised from within func() are logged and ignored.
+
+        :param func: Callable to invoke for each extension.
+        :param args: Variable arguments to pass to func()
+        :param kwds: Keyword arguments to pass to func()
+        :returns: List of values returned from func()
+        """
+        results = self.map(func, *args, **kwds)
+        if results:
+            return results[0]
+
+    @property
+    def driver(self):
+        """Returns the driver being used by this manager.
+        """
+        ext = self.extensions[0]
+        return ext.obj if ext.obj else ext.plugin

libs/stevedore/enabled.py

@@ -0,0 +1,71 @@
+import logging
+
+from .extension import ExtensionManager
+
+
+LOG = logging.getLogger(__name__)
+
+
+class EnabledExtensionManager(ExtensionManager):
+    """Loads only plugins that pass a check function.
+
+    The check_func argument should return a boolean, with ``True``
+    indicating that the extension should be loaded and made available
+    and ``False`` indicating that the extension should be ignored.
+
+    :param namespace: The namespace for the entry points.
+    :type namespace: str
+    :param check_func: Function to determine which extensions to load.
+    :type check_func: callable
+    :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 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
+
+    """
+
+    def __init__(self, namespace, check_func, invoke_on_load=False,
+                 invoke_args=(), invoke_kwds={},
+                 propagate_map_exceptions=False,
+                 on_load_failure_callback=None,
+                 verify_requirements=False,):
+        self.check_func = check_func
+        super(EnabledExtensionManager, self).__init__(
+            namespace,
+            invoke_on_load=invoke_on_load,
+            invoke_args=invoke_args,
+            invoke_kwds=invoke_kwds,
+            propagate_map_exceptions=propagate_map_exceptions,
+            on_load_failure_callback=on_load_failure_callback,
+            verify_requirements=verify_requirements,
+        )
+
+    def _load_one_plugin(self, ep, invoke_on_load, invoke_args, invoke_kwds,
+                         verify_requirements):
+        ext = super(EnabledExtensionManager, self)._load_one_plugin(
+            ep, invoke_on_load, invoke_args, invoke_kwds,
+            verify_requirements,
+        )
+        if ext and not self.check_func(ext):
+            LOG.debug('ignoring extension %r', ep.name)
+            return None
+        return ext

libs/stevedore/extension.py

@@ -0,0 +1,275 @@
+"""ExtensionManager
+"""
+
+import pkg_resources
+
+import logging
+
+
+LOG = logging.getLogger(__name__)
+
+
+class Extension(object):
+    """Book-keeping object for tracking extensions.
+
+    The arguments passed to the constructor are saved as attributes of
+    the instance using the same names, and can be accessed by the
+    callables passed to :meth:`map` or when iterating over an
+    :class:`ExtensionManager` directly.
+
+    :param name: The entry point name.
+    :type name: str
+    :param entry_point: The EntryPoint instance returned by
+        :mod:`pkg_resources`.
+    :type entry_point: EntryPoint
+    :param plugin: The value returned by entry_point.load()
+    :param obj: The object returned by ``plugin(*args, **kwds)`` if the
+                manager invoked the extension on load.
+
+    """
+
+    def __init__(self, name, entry_point, plugin, obj):
+        self.name = name
+        self.entry_point = entry_point
+        self.plugin = plugin
+        self.obj = obj
+
+    @property
+    def entry_point_target(self):
+        """The module and attribute referenced by this extension's entry_point.
+
+        :return: A string representation of the target of the entry point in
+            'dotted.module:object' format.
+        """
+        return '%s:%s' % (self.entry_point.module_name,
+                          self.entry_point.attrs[0])
+
+
+class ExtensionManager(object):
+    """Base class for all of the other managers.
+
+    :param namespace: The namespace for the entry points.
+    :type namespace: 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 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
+    """
+
+    def __init__(self, namespace,
+                 invoke_on_load=False,
+                 invoke_args=(),
+                 invoke_kwds={},
+                 propagate_map_exceptions=False,
+                 on_load_failure_callback=None,
+                 verify_requirements=False):
+        self._init_attributes(
+            namespace,
+            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._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 ExtensionManager
+
+        Test instances are passed a list of extensions to work from rather
+        than loading them from entry points.
+
+        :param extensions: Pre-configured Extension instances to use
+        :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: When calling map, controls 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)
+        o._init_attributes(namespace,
+                           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, propagate_map_exceptions=False,
+                         on_load_failure_callback=None):
+        self.namespace = namespace
+        self.propagate_map_exceptions = propagate_map_exceptions
+        self._on_load_failure_callback = on_load_failure_callback
+
+    def _init_plugins(self, extensions):
+        self.extensions = extensions
+        self._extensions_by_name = None
+
+    ENTRY_POINT_CACHE = {}
+
+    def _find_entry_points(self, namespace):
+        if namespace not in self.ENTRY_POINT_CACHE:
+            eps = list(pkg_resources.iter_entry_points(namespace))
+            self.ENTRY_POINT_CACHE[namespace] = eps
+        return self.ENTRY_POINT_CACHE[namespace]
+
+    def _load_plugins(self, invoke_on_load, invoke_args, invoke_kwds,
+                      verify_requirements):
+        extensions = []
+        for ep in self._find_entry_points(self.namespace):
+            LOG.debug('found extension %r', ep)
+            try:
+                ext = self._load_one_plugin(ep,
+                                            invoke_on_load,
+                                            invoke_args,
+                                            invoke_kwds,
+                                            verify_requirements,
+                                            )
+                if ext:
+                    extensions.append(ext)
+            except (KeyboardInterrupt, AssertionError):
+                raise
+            except Exception as err:
+                LOG.error('Could not load %r: %s', ep.name, err)
+                LOG.exception(err)
+                if self._on_load_failure_callback is not None:
+                    self._on_load_failure_callback(self, ep, err)
+        return extensions
+
+    def _load_one_plugin(self, ep, invoke_on_load, invoke_args, invoke_kwds,
+                         verify_requirements):
+        plugin = ep.load(require=verify_requirements)
+        if invoke_on_load:
+            obj = plugin(*invoke_args, **invoke_kwds)
+        else:
+            obj = None
+        return Extension(ep.name, ep, plugin, obj)
+
+    def names(self):
+        "Returns the names of the discovered extensions"
+        # We want to return the names of the extensions in the order
+        # they would be used by map(), since some subclasses change
+        # that order.
+        return [e.name for e in self.extensions]
+
+    def map(self, func, *args, **kwds):
+        """Iterate over the extensions invoking func() for each.
+
+        The signature for func() should be::
+
+            def func(ext, *args, **kwds):
+                pass
+
+        The first argument to func(), 'ext', is the
+        :class:`~stevedore.extension.Extension` instance.
+
+        Exceptions raised from within func() are propagated up and
+        processing stopped if self.propagate_map_exceptions is True,
+        otherwise they are logged and ignored.
+
+        :param func: Callable to invoke for each extension.
+        :param args: Variable arguments to pass to func()
+        :param kwds: Keyword arguments to pass to func()
+        :returns: List of values returned from func()
+        """
+        if not self.extensions:
+            # FIXME: Use a more specific exception class here.
+            raise RuntimeError('No %s extensions found' % self.namespace)
+        response = []
+        for e in self.extensions:
+            self._invoke_one_plugin(response.append, func, e, args, kwds)
+        return response
+
+    @staticmethod
+    def _call_extension_method(extension, method_name, *args, **kwds):
+        return getattr(extension.obj, method_name)(*args, **kwds)
+
+    def map_method(self, method_name, *args, **kwds):
+        """Iterate over the extensions invoking a method by name.
+
+        This is equivalent of using :meth:`map` with func set to
+        `lambda x: x.obj.method_name()`
+        while being more convenient.
+
+        Exceptions raised from within the called method are propagated up
+        and processing stopped if self.propagate_map_exceptions is True,
+        otherwise they are logged and ignored.
+
+        .. versionadded:: 0.12
+
+        :param method_name: The extension method name
+                            to call for each extension.
+        :param args: Variable arguments to pass to method
+        :param kwds: Keyword arguments to pass to method
+        :returns: List of values returned from methods
+        """
+        return self.map(self._call_extension_method,
+                        method_name, *args, **kwds)
+
+    def _invoke_one_plugin(self, response_callback, func, e, args, kwds):
+        try:
+            response_callback(func(e, *args, **kwds))
+        except Exception as err:
+            if self.propagate_map_exceptions:
+                raise
+            else:
+                LOG.error('error calling %r: %s', e.name, err)
+                LOG.exception(err)
+
+    def __iter__(self):
+        """Produce iterator for the manager.
+
+        Iterating over an ExtensionManager produces the :class:`Extension`
+        instances in the order they would be invoked.
+        """
+        return iter(self.extensions)
+
+    def __getitem__(self, name):
+        """Return the named extension.
+
+        Accessing an ExtensionManager as a dictionary (``em['name']``)
+        produces the :class:`Extension` instance with the
+        specified name.
+        """
+        if self._extensions_by_name is None:
+            d = {}
+            for e in self.extensions:
+                d[e.name] = e
+            self._extensions_by_name = d
+        return self._extensions_by_name[name]

libs/stevedore/hook.py

@@ -0,0 +1,64 @@
+from .named import NamedExtensionManager
+
+
+class HookManager(NamedExtensionManager):
+    """Coordinate execution of multiple extensions using a common name.
+
+    :param namespace: The namespace for the entry points.
+    :type namespace: str
+    :param name: The name of the hooks to load.
+    :type name: 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 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
+    """
+
+    def __init__(self, namespace, name,
+                 invoke_on_load=False, invoke_args=(), invoke_kwds={},
+                 on_load_failure_callback=None,
+                 verify_requirements=False):
+        super(HookManager, self).__init__(
+            namespace,
+            [name],
+            invoke_on_load=invoke_on_load,
+            invoke_args=invoke_args,
+            invoke_kwds=invoke_kwds,
+            on_load_failure_callback=on_load_failure_callback,
+            verify_requirements=verify_requirements,
+        )
+
+    def _init_attributes(self, namespace, names, name_order=False,
+                         propagate_map_exceptions=False,
+                         on_load_failure_callback=None):
+        super(HookManager, self)._init_attributes(
+            namespace, names,
+            propagate_map_exceptions=propagate_map_exceptions,
+            on_load_failure_callback=on_load_failure_callback)
+        self._name = names[0]
+
+    def __getitem__(self, name):
+        """Return the named extensions.
+
+        Accessing a HookManager as a dictionary (``em['name']``)
+        produces a list of the :class:`Extension` instance(s) with the
+        specified name, in the order they would be invoked by map().
+        """
+        if name != self._name:
+            raise KeyError(name)
+        return self.extensions

libs/stevedore/named.py

@@ -0,0 +1,124 @@
+from .extension import ExtensionManager
+
+
+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 verify_requirements: Use setuptools to enforce the
+        dependencies of the plugin(s) being loaded. Defaults to False.
+    :type verify_requirements: 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,
+                 verify_requirements=False):
+        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._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._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]
+
+    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,
+        )