3613587536
memcached's ASCII protocol supports unicode keys, so lets support them as well. Since using unicode keys for memcache is uncommon and to preserve the previous behavior disable support by default.
47 lines
1.3 KiB
Python
47 lines
1.3 KiB
Python
from pymemcache.client.murmur3 import murmur3_32
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class RendezvousHash(object):
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"""
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Implements the Highest Random Weight (HRW) hashing algorithm most
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commonly referred to as rendezvous hashing.
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Originally developed as part of python-clandestined.
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Copyright (c) 2014 Ernest W. Durbin III
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"""
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def __init__(self, nodes=None, seed=0, hash_function=murmur3_32):
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"""
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Constructor.
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"""
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self.nodes = []
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self.seed = seed
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if nodes is not None:
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self.nodes = nodes
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self.hash_function = lambda x: hash_function(x, seed)
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def add_node(self, node):
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if node not in self.nodes:
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self.nodes.append(node)
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def remove_node(self, node):
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if node in self.nodes:
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self.nodes.remove(node)
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else:
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raise ValueError("No such node %s to remove" % (node))
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def get_node(self, key):
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high_score = -1
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winner = None
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for node in self.nodes:
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score = self.hash_function(
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"%s-%s" % (node, key))
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if score > high_score:
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(high_score, winner) = (score, node)
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elif score == high_score:
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(high_score, winner) = (score, max(str(node), str(winner)))
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return winner
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