94 lines
2.8 KiB
Python
94 lines
2.8 KiB
Python
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# Copyright 2016 The TensorFlow Authors. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# ==============================================================================
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"""Caching utilities."""
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import inspect
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import weakref
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# TODO(mdan): Add a garbage collection hook for cleaning up modules.
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class _TransformedFnCache(object):
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"""Generic hierarchical cache for transformed functions.
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The keys are soft references (i.e. they are discarded when the key is
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destroyed) created from the source function by `_get_key`. The subkeys are
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strong references and can be any value. Typically they identify different
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kinds of transformation.
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"""
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__slots__ = ('_cache',)
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def __init__(self):
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self._cache = weakref.WeakKeyDictionary()
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def _get_key(self, entity):
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raise NotImplementedError('subclasses must override')
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def has(self, entity, subkey):
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key = self._get_key(entity)
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parent = self._cache.get(key, None)
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if parent is None:
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return False
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return subkey in parent
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def __getitem__(self, entity):
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key = self._get_key(entity)
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parent = self._cache.get(key, None)
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if parent is None:
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# The bucket is initialized to support this usage:
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# cache[key][subkey] = value
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self._cache[key] = parent = {}
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return parent
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def __len__(self):
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return len(self._cache)
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class CodeObjectCache(_TransformedFnCache):
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"""A function cache based on code objects.
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Code objects are good proxies for the source code of a function.
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This cache efficiently handles functions that share code objects, such as
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functions defined in a loop, bound methods, etc.
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The cache falls back to the function object, if it doesn't have a code object.
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"""
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def _get_key(self, entity):
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if hasattr(entity, '__code__'):
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return entity.__code__
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else:
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return entity
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class UnboundInstanceCache(_TransformedFnCache):
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"""A function cache based on unbound function objects.
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Using the function for the cache key allows efficient handling of object
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methods.
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Unlike the _CodeObjectCache, this discriminates between different functions
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even if they have the same code. This is needed for decorators that may
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masquerade as another function.
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"""
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def _get_key(self, entity):
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if inspect.ismethod(entity):
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return entity.__func__
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return entity
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