111 lines
3.6 KiB
Python
111 lines
3.6 KiB
Python
"""ExtensionManager
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"""
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import pkg_resources
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import logging
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LOG = logging.getLogger(__name__)
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class Extension(object):
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"""Book-keeping object for tracking extensions.
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:param name: The entry point name.
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:type name: str
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:param entry_point: The EntryPoint instance returned by :mod:`pkg_resources`.
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:type entry_point: EntryPoint
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:param plugin: The value returned by entry_point.load()
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:param obj: The object returned by plugin(*args, **kwds) if the
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manager invoked the extension on load.
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"""
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def __init__(self, name, entry_point, plugin, obj):
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self.name = name
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self.entry_point = entry_point
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self.plugin = plugin
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self.obj = obj
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class ExtensionManager(object):
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"""Base class for all of the other managers.
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:param namespace: The namespace for the entry points.
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:type namespace: str
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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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:type invoke_on_load: bool
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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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:type invoke_args: tuple
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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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:type invoke_kwds: dict
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"""
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def __init__(self, namespace, invoke_on_load=False, invoke_args=(), invoke_kwds={}):
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self.namespace = namespace
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self.extensions = []
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for ep in pkg_resources.iter_entry_points(self.namespace):
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LOG.debug('found extension %r', ep)
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try:
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ext = self._load_one_plugin(ep,
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invoke_on_load,
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invoke_args,
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invoke_kwds,
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)
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if ext:
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self.extensions.append(ext)
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except KeyboardInterrupt:
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raise
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except Exception as err:
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LOG.error('Could not load %r: %s', ep.name, err)
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return
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def _load_one_plugin(self, ep, invoke_on_load, invoke_args, invoke_kwds):
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plugin = ep.load()
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if invoke_on_load:
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obj = plugin(ep.name, *invoke_args, **invoke_kwds)
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else:
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obj = None
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return Extension(ep.name, ep, plugin, obj)
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def names(self):
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"Returns the names of the discovered extensions"
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return [e.name for e in self.extensions]
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def map(self, func, *args, **kwds):
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"""Iterate over the extensions invoking func() for each.
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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 :class:`Extension`
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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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if not self.extensions:
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raise RuntimeError('No %s extensions found' % self.namespace)
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response = []
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for e in self.extensions:
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try:
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response.append(func(e, *args, **kwds))
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except Exception as err:
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LOG.error('error calling %r: %s', e.name, err)
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LOG.exception(err)
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return response
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def __iter__(self):
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return iter(self.extensions)
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