42 lines
1.3 KiB
C++
42 lines
1.3 KiB
C++
/*=============================================================================
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# Filename: BloomFilter.h
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# Author: Bookug Lobert
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# Mail: 1181955272@qq.com
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# Last Modified: 2015-10-20 13:18
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# Description: http://blog.csdn.net/hguisu/article/details/7866173
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TODO:this strategy can be used in Join and KVstore-search/modify/remove, or the uppest level!
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really better? appropiate if key num small but search too many!
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=============================================================================*/
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#ifndef _UTIL_BLOOMFILTER_H
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#define _UTIL_BLOOMFILTER_H
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#include "Util.h"
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#define SETBIT(ch, n) ch[n/8] |= 1 << (7-n%8)
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#define GETBIT(ch, n) (ch[n/8] & (1<<(7-n%8))) >> (7-n%8)
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class BloomFilter
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{
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public:
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BloomFilter();
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BloomFilter(unsigned _num); //num of all keys
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void addRecord(int _record);
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//NOTICE:we hope a Bstr-like struct here, for the length maybe very large
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void addRecord(const char* _record, unsigned _len);
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bool checkRecord(int _record) const;
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bool checkRecord(const char* _record, unsigned _len) const;
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~BloomFilter();
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private:
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unsigned length; //length of total bits, mod 8 == 0
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char *filter; //the bit space
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unsigned hfnum; //num of hash functions
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double rate; //false positive
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HashFunction* hfptr; //hash functions pointer array
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void init();
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};
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#endif //_UTIL_BLOOMFILTER_H
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