from binascii import crc_hqx
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from redis.typing import EncodedT
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# Redis Cluster's key space is divided into 16384 slots.
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# For more information see: https://github.com/redis/redis/issues/2576
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REDIS_CLUSTER_HASH_SLOTS = 16384
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__all__ = ["key_slot", "REDIS_CLUSTER_HASH_SLOTS"]
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def key_slot(key: EncodedT, bucket: int = REDIS_CLUSTER_HASH_SLOTS) -> int:
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"""Calculate key slot for a given key.
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See Keys distribution model in https://redis.io/topics/cluster-spec
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:param key - bytes
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:param bucket - int
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"""
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start = key.find(b"{")
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if start > -1:
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end = key.find(b"}", start + 1)
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if end > -1 and end != start + 1:
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key = key[start + 1 : end]
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return crc_hqx(key, 0) % bucket
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