43 lines
1.2 KiB
Python
43 lines
1.2 KiB
Python
#
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# This file is part of pysnmp software.
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#
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# Copyright (c) 2005-2018, Ilya Etingof <etingof@gmail.com>
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# License: http://snmplabs.com/pysnmp/license.html
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#
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import random
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random.seed()
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class Integer(object):
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"""Return a next value in a reasonably MT-safe manner"""
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def __init__(self, maximum, increment=256):
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self.__maximum = maximum
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if increment >= maximum:
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increment = maximum
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self.__increment = increment
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self.__threshold = increment // 2
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e = random.randrange(self.__maximum - self.__increment)
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self.__bank = list(range(e, e + self.__increment))
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def __repr__(self):
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return '%s(%d, %d)' % (
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self.__class__.__name__,
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self.__maximum,
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self.__increment
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)
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def __call__(self):
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v = self.__bank.pop(0)
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if v % self.__threshold:
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return v
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else:
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# this is MT-safe unless too many (~ increment/2) threads
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# bump into this code simultaneously
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e = self.__bank[-1] + 1
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if e > self.__maximum:
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e = 0
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self.__bank.extend(range(e, e + self.__threshold))
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return v
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