mirror of https://github.com/python/cpython
100 lines
3.7 KiB
Python
100 lines
3.7 KiB
Python
"""Convenient client for all PyPI APIs.
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This module provides a ClientWrapper class which will use the "simple"
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or XML-RPC API to request information or files from an index.
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"""
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from packaging.pypi import simple, xmlrpc
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_WRAPPER_MAPPINGS = {'get_release': 'simple',
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'get_releases': 'simple',
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'search_projects': 'simple',
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'get_metadata': 'xmlrpc',
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'get_distributions': 'simple'}
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_WRAPPER_INDEXES = {'xmlrpc': xmlrpc.Client,
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'simple': simple.Crawler}
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def switch_index_if_fails(func, wrapper):
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"""Decorator that switch of index (for instance from xmlrpc to simple)
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if the first mirror return an empty list or raises an exception.
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"""
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def decorator(*args, **kwargs):
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retry = True
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exception = None
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methods = [func]
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for f in wrapper._indexes.values():
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if f != func.__self__ and hasattr(f, func.__name__):
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methods.append(getattr(f, func.__name__))
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for method in methods:
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try:
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response = method(*args, **kwargs)
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retry = False
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except Exception as e:
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exception = e
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if not retry:
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break
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if retry and exception:
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raise exception
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else:
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return response
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return decorator
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class ClientWrapper:
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"""Wrapper around simple and xmlrpc clients,
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Choose the best implementation to use depending the needs, using the given
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mappings.
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If one of the indexes returns an error, tries to use others indexes.
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:param index: tell which index to rely on by default.
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:param index_classes: a dict of name:class to use as indexes.
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:param indexes: a dict of name:index already instantiated
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:param mappings: the mappings to use for this wrapper
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"""
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def __init__(self, default_index='simple', index_classes=_WRAPPER_INDEXES,
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indexes={}, mappings=_WRAPPER_MAPPINGS):
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self._projects = {}
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self._mappings = mappings
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self._indexes = indexes
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self._default_index = default_index
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# instantiate the classes and set their _project attribute to the one
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# of the wrapper.
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for name, cls in index_classes.items():
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obj = self._indexes.setdefault(name, cls())
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obj._projects = self._projects
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obj._index = self
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def __getattr__(self, method_name):
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"""When asking for methods of the wrapper, return the implementation of
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the wrapped classes, depending the mapping.
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Decorate the methods to switch of implementation if an error occurs
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"""
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real_method = None
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if method_name in _WRAPPER_MAPPINGS:
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obj = self._indexes[_WRAPPER_MAPPINGS[method_name]]
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real_method = getattr(obj, method_name)
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else:
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# the method is not defined in the mappings, so we try first to get
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# it via the default index, and rely on others if needed.
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try:
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real_method = getattr(self._indexes[self._default_index],
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method_name)
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except AttributeError:
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other_indexes = [i for i in self._indexes
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if i != self._default_index]
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for index in other_indexes:
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real_method = getattr(self._indexes[index], method_name,
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None)
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if real_method:
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break
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if real_method:
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return switch_index_if_fails(real_method, self)
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else:
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raise AttributeError("No index have attribute '%s'" % method_name)
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