113 lines
3.0 KiB
Python
113 lines
3.0 KiB
Python
from __future__ import absolute_import
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from kafka.vendor import six
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from .base import Partitioner
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class Murmur2Partitioner(Partitioner):
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"""
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Implements a partitioner which selects the target partition based on
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the hash of the key. Attempts to apply the same hashing
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function as mainline java client.
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"""
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def partition(self, key, partitions=None):
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if not partitions:
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partitions = self.partitions
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# https://github.com/apache/kafka/blob/0.8.2/clients/src/main/java/org/apache/kafka/clients/producer/internals/Partitioner.java#L69
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idx = (murmur2(key) & 0x7fffffff) % len(partitions)
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return partitions[idx]
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class LegacyPartitioner(Partitioner):
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"""DEPRECATED -- See Issue 374
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Implements a partitioner which selects the target partition based on
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the hash of the key
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"""
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def partition(self, key, partitions=None):
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if not partitions:
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partitions = self.partitions
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size = len(partitions)
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idx = hash(key) % size
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return partitions[idx]
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# Default will change to Murmur2 in 0.10 release
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HashedPartitioner = LegacyPartitioner
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# https://github.com/apache/kafka/blob/0.8.2/clients/src/main/java/org/apache/kafka/common/utils/Utils.java#L244
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def murmur2(key):
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"""Pure-python Murmur2 implementation.
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Based on java client, see org.apache.kafka.common.utils.Utils.murmur2
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Args:
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key: if not a bytes type, encoded using default encoding
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Returns: MurmurHash2 of key bytearray
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"""
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# Convert key to bytes or bytearray
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if isinstance(key, bytearray) or (six.PY3 and isinstance(key, bytes)):
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data = key
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else:
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data = bytearray(str(key).encode())
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length = len(data)
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seed = 0x9747b28c
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# 'm' and 'r' are mixing constants generated offline.
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# They're not really 'magic', they just happen to work well.
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m = 0x5bd1e995
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r = 24
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# Initialize the hash to a random value
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h = seed ^ length
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length4 = length // 4
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for i in range(length4):
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i4 = i * 4
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k = ((data[i4 + 0] & 0xff) +
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((data[i4 + 1] & 0xff) << 8) +
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((data[i4 + 2] & 0xff) << 16) +
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((data[i4 + 3] & 0xff) << 24))
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k &= 0xffffffff
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k *= m
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k &= 0xffffffff
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k ^= (k % 0x100000000) >> r # k ^= k >>> r
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k &= 0xffffffff
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k *= m
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k &= 0xffffffff
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h *= m
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h &= 0xffffffff
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h ^= k
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h &= 0xffffffff
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# Handle the last few bytes of the input array
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extra_bytes = length % 4
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if extra_bytes >= 3:
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h ^= (data[(length & ~3) + 2] & 0xff) << 16
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h &= 0xffffffff
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if extra_bytes >= 2:
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h ^= (data[(length & ~3) + 1] & 0xff) << 8
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h &= 0xffffffff
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if extra_bytes >= 1:
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h ^= (data[length & ~3] & 0xff)
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h &= 0xffffffff
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h *= m
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h &= 0xffffffff
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h ^= (h % 0x100000000) >> 13 # h >>> 13;
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h &= 0xffffffff
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h *= m
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h &= 0xffffffff
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h ^= (h % 0x100000000) >> 15 # h >>> 15;
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h &= 0xffffffff
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return h
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