33 lines
1021 B
Python
33 lines
1021 B
Python
from __future__ import absolute_import
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import random
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from .hashed import murmur2
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class DefaultPartitioner(object):
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"""Default partitioner.
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Hashes key to partition using murmur2 hashing (from java client)
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If key is None, selects partition randomly from available,
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or from all partitions if none are currently available
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"""
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@classmethod
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def __call__(cls, key, all_partitions, available):
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"""
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Get the partition corresponding to key
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:param key: partitioning key
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:param all_partitions: list of all partitions sorted by partition ID
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:param available: list of available partitions in no particular order
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:return: one of the values from all_partitions or available
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"""
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if key is None:
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if available:
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return random.choice(available)
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return random.choice(all_partitions)
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idx = murmur2(key)
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idx &= 0x7fffffff
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idx %= len(all_partitions)
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return all_partitions[idx]
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