37 lines
982 B
Python
37 lines
982 B
Python
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from __future__ import absolute_import
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import random
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from .cache import Cache
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# random.choice cannot be pickled in Python 2.7
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def _choice(seq):
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return random.choice(seq)
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class RRCache(Cache):
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"""Random Replacement (RR) cache implementation."""
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def __init__(self, maxsize, choice=random.choice, getsizeof=None):
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Cache.__init__(self, maxsize, getsizeof)
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# TODO: use None as default, assing to self.choice directly?
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if choice is random.choice:
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self.__choice = _choice
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else:
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self.__choice = choice
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@property
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def choice(self):
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"""The `choice` function used by the cache."""
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return self.__choice
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def popitem(self):
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"""Remove and return a random `(key, value)` pair."""
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try:
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key = self.__choice(list(self))
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except IndexError:
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raise KeyError('%s is empty' % self.__class__.__name__)
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else:
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return (key, self.pop(key))
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