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45 lines
1.3 KiB
45 lines
1.3 KiB
#
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# This file is part of pysnmp software.
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#
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# Copyright (c) 2005-2016, Ilya Etingof <ilya@glas.net>
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# License: http://pysnmp.sf.net/license.html
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#
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# Limited-size dictionary-like class to use for caches
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#
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class Cache:
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def __init__(self, maxSize=256):
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self.__maxSize = maxSize
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self.__size = 0
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self.__chopSize = maxSize//10
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self.__chopSize = self.__chopSize and self.__chopSize or 1
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self.__cache = {}
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self.__usage = {}
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def __contains__(self, k):
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return k in self.__cache
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def __getitem__(self, k):
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self.__usage[k] += 1
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return self.__cache[k]
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def __len__(self):
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return self.__size
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def __setitem__(self, k, v):
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if self.__size >= self.__maxSize:
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keys = list(self.__usage.keys())
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keys.sort(key=lambda x, d=self.__usage: d[x])
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for _k in keys[:self.__chopSize]:
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del self.__cache[_k]
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del self.__usage[_k]
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self.__size = self.__size - self.__chopSize
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if k not in self.__cache:
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self.__size += 1
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self.__usage[k] = 0
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self.__cache[k] = v
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def __delitem__(self, k):
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del self.__cache[k]
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del self.__usage[k]
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self.__size = self.__size - 1
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