from .defaults import BLOOMFILTER_BIT, BLOOMFILTER_HASH_NUMBERclass HashMap(object): def __init__(self, m, seed): self.m = m self.seed = seed def hash(self, value): """ Hash Algorithm :param value: Value :return: Hash Value """ ret = 0 for i in range(len(value)): ret += self.seed * ret + ord(value[i]) return (self.m - 1) & retclass BloomFilter(object): def __init__(self, server, key, bit=BLOOMFILTER_BIT, hash_number=BLOOMFILTER_HASH_NUMBER): """ Initialize BloomFilter :param server: Redis Server :param key: BloomFilter Key :param bit: m = 2 ^ bit :param hash_number: the number of hash function """ # default to 1 << 30 = 10,7374,1824 = 2^30 = 128MB, max filter 2^30/hash_number = 1,7895,6970 fingerprints self.m = 1 << bit self.seeds = range(hash_number) self.server = server self.key = key self.maps = [HashMap(self.m, seed) for seed in self.seeds] def exists(self, value): """ if value exists :param value: :return: """ if not value: return False exist = True for map in self.maps: offset = map.hash(value) exist = exist & self.server.getbit(self.key, offset) return exist def insert(self, value): """ add value to bloom :param value: :return: """ for f in self.maps: offset = f.hash(value) self.server.setbit(self.key, offset, 1)
来源：https://www.cnblogs.com/zhangjian0092/p/12012659.html