haproxy ip-hash

　　整型的Hash算法使用的是Thomas Wang's 32 Bit / 64 Bit Mix Function ，这是一种基于位移运算的散列方法。基于移位的散列是使用Key值进行移位操作。通常是结合左移和右移。每个移位过程的结果进行累加，最后移位的结果作为最终结果。这种方法的好处是避免了乘法运算，从而提高Hash函数本身的性能。

/* Full-avalanche integer hashing function from Thomas Wang, suitable for use
 * with a modulo. See below, worth a read !
 * http://www.concentric.net/~Ttwang/tech/inthash.htm
 *
 * See also tests performed by Bob Jenkins (says it's faster than his) :
 * http://burtleburtle.net/bob/hash/integer.html
 *
 * This function is small and fast. It does not seem as smooth as bj6 though.
 * About 0x40 bytes, 6 shifts.
 */
int counts_tw1[NSERV][NSERV];
uint32_t hash_tw1(uint32_t a)
{
    a += ~(a<<15);
    a ^=  (a>>10);
    a +=  (a<<3);
    a ^=  (a>>6);
    a += ~(a<<11);
    a ^=  (a>>16);
    return a;
}

　　字符串使用的MurmurHash算法，MurmurHash算法具有高运算性能，低碰撞率的特点，由Austin Appleby创建于2008年，现已应用到Hadoop、libstdc++、nginx、libmemcached等开源系统。2011年Appleby被Google雇佣，随后Google推出其变种的CityHash算法。

djb hash

djb 哈希算法很简单，只有几行代码，其功能与 MurmurHash 类似，都是将字符串转换为 hash 值，下面是它的代码：

/* And a caseinsensitive hash function (based on djb hash) */
unsigned int dictGenCaseHashFunction(constunsigned char *buf, int len) {
    unsigned int hash = (unsignedint)dict_hash_function_seed;
 
    while (len--)
        hash = ((hash << 5) + hash) +(tolower(*buf++)); /* hash * 33 + c */
    return hash;
}

/**  
* Hash算法大全<br>  
* 推荐使用FNV1算法  
* @algorithm None  
* @author Goodzzp 2006-11-20  
* @lastEdit Goodzzp 2006-11-20   
* @editDetail Create  
*/  
public class HashAlgorithms   
{   
/**  
* 加法hash  
* @param key 字符串  
* @param prime 一个质数  
* @return hash结果  
*/  
public static int additiveHash(String key, int prime)   
{   
   int hash, i;   
   for (hash = key.length(), i = 0; i < key.length(); i++)   
    hash += key.charAt(i);   
   return (hash % prime);   
}   
  
/**  
* 旋转hash  
* @param key 输入字符串  
* @param prime 质数  
* @return hash值  
*/  
public static int rotatingHash(String key, int prime)   
{   
   int hash, i;   
   for (hash=key.length(), i=0; i<key.length(); ++i)   
     hash = (hash<<4)^(hash>>28)^key.charAt(i);   
   return (hash % prime);   
//   return (hash ^ (hash>>10) ^ (hash>>20));   
}   
  
// 替代：   
// 使用：hash = (hash ^ (hash>>10) ^ (hash>>20)) & mask;   
// 替代：hash %= prime;   
  
  
/**  
* MASK值，随便找一个值，最好是质数  
*/  
static int M_MASK = 0x8765fed1;   
/**  
* 一次一个hash  
* @param key 输入字符串  
* @return 输出hash值  
*/  
public static int oneByOneHash(String key)   
{   
   int   hash, i;   
   for (hash=0, i=0; i<key.length(); ++i)   
   {   
     hash += key.charAt(i);   
     hash += (hash << 10);   
     hash ^= (hash >> 6);   
   }   
   hash += (hash << 3);   
   hash ^= (hash >> 11);   
   hash += (hash << 15);   
//   return (hash & M_MASK);   
   return hash;   
}   
  
/**  
* Bernstein's hash  
* @param key 输入字节数组  
* @param level 初始hash常量  
* @return 结果hash  
*/  
public static int bernstein(String key)   
{   
   int hash = 0;   
   int i;   
   for (i=0; i<key.length(); ++i) hash = 33*hash + key.charAt(i);   
   return hash;   
}   
  
//   
//// Pearson's Hash   
// char pearson(char[]key, ub4 len, char tab[256])   
// {   
//   char hash;   
//   ub4 i;   
//   for (hash=len, i=0; i<len; ++i)    
//     hash=tab[hash^key[i]];   
//   return (hash);   
// }   
  
//// CRC Hashing，计算crc,具体代码见其他   
// ub4 crc(char *key, ub4 len, ub4 mask, ub4 tab[256])   
// {   
//   ub4 hash, i;   
//   for (hash=len, i=0; i<len; ++i)   
//     hash = (hash >> 8) ^ tab[(hash & 0xff) ^ key[i]];   
//   return (hash & mask);   
// }   
  
/**  
* Universal Hashing  
*/  
public static int universal(char[]key, int mask, int[] tab)   
{   
   int hash = key.length, i, len = key.length;   
   for (i=0; i<(len<<3); i+=8)   
   {   
     char k = key[i>>3];   
     if ((k&0x01) == 0) hash ^= tab[i+0];   
     if ((k&0x02) == 0) hash ^= tab[i+1];   
     if ((k&0x04) == 0) hash ^= tab[i+2];   
     if ((k&0x08) == 0) hash ^= tab[i+3];   
     if ((k&0x10) == 0) hash ^= tab[i+4];   
     if ((k&0x20) == 0) hash ^= tab[i+5];   
     if ((k&0x40) == 0) hash ^= tab[i+6];   
     if ((k&0x80) == 0) hash ^= tab[i+7];   
   }   
   return (hash & mask);   
}   
  
/**  
* Zobrist Hashing  
*/    
public static int zobrist( char[] key,int mask, int[][] tab)   
{   
   int hash, i;   
   for (hash=key.length, i=0; i<key.length; ++i)   
     hash ^= tab[i][key[i]];   
   return (hash & mask);   
}   
  
// LOOKUP3    
// 见Bob Jenkins(3).c文件   
  
// 32位FNV算法   
static int M_SHIFT = 0;   
/**  
* 32位的FNV算法  
* @param data 数组  
* @return int值  
*/  
    public static int FNVHash(byte[] data)   
    {   
        int hash = (int)2166136261L;   
        for(byte b : data)   
            hash = (hash * 16777619) ^ b;   
        if (M_SHIFT == 0)   
            return hash;   
        return (hash ^ (hash >> M_SHIFT)) & M_MASK;   
    }   
    /**  
     * 改进的32位FNV算法1  
     * @param data 数组  
     * @return int值  
     */  
    public static int FNVHash1(byte[] data)   
    {   
        final int p = 16777619;   
        int hash = (int)2166136261L;   
        for(byte b:data)   
            hash = (hash ^ b) * p;   
        hash += hash << 13;   
        hash ^= hash >> 7;   
        hash += hash << 3;   
        hash ^= hash >> 17;   
        hash += hash << 5;   
        return hash;   
    }   
    /**  
     * 改进的32位FNV算法1  
     * @param data 字符串  
     * @return int值  
     */  
    public static int FNVHash1(String data)   
    {   
        final int p = 16777619;   
        int hash = (int)2166136261L;   
        for(int i=0;i<data.length();i++)   
            hash = (hash ^ data.charAt(i)) * p;   
        hash += hash << 13;   
        hash ^= hash >> 7;   
        hash += hash << 3;   
        hash ^= hash >> 17;   
        hash += hash << 5;   
        return hash;   
    }   
  
    /**  
     * Thomas Wang的算法，整数hash  
     */    
    public static int intHash(int key)   
    {   
      key += ~(key << 15);   
      key ^= (key >>> 10);   
      key += (key << 3);   
      key ^= (key >>> 6);   
      key += ~(key << 11);   
      key ^= (key >>> 16);   
      return key;   
    }   
    /**  
     * RS算法hash  
     * @param str 字符串  
     */  
    public static int RSHash(String str)   
    {   
        int b    = 378551;   
        int a    = 63689;   
        int hash = 0;   
  
       for(int i = 0; i < str.length(); i++)   
       {   
          hash = hash * a + str.charAt(i);   
          a    = a * b;   
       }   
  
       return (hash & 0x7FFFFFFF);   
    }   
    /* End Of RS Hash Function */  
  
    /**  
     * JS算法  
     */  
    public static int JSHash(String str)   
    {   
       int hash = 1315423911;   
  
       for(int i = 0; i < str.length(); i++)   
       {   
          hash ^= ((hash << 5) + str.charAt(i) + (hash >> 2));   
       }   
  
       return (hash & 0x7FFFFFFF);   
    }   
    /* End Of JS Hash Function */  
  
    /**  
     * PJW算法  
     */  
    public static int PJWHash(String str)   
    {   
        int BitsInUnsignedInt = 32;   
        int ThreeQuarters     = (BitsInUnsignedInt * 3) / 4;   
        int OneEighth         = BitsInUnsignedInt / 8;   
        int HighBits          = 0xFFFFFFFF << (BitsInUnsignedInt - OneEighth);   
        int hash              = 0;   
        int test              = 0;   
  
       for(int i = 0; i < str.length();i++)   
       {   
          hash = (hash << OneEighth) + str.charAt(i);   
  
          if((test = hash & HighBits) != 0)   
          {   
             hash = (( hash ^ (test >> ThreeQuarters)) & (~HighBits));   
          }   
       }   
  
       return (hash & 0x7FFFFFFF);   
    }   
    /* End Of P. J. Weinberger Hash Function */  
  
    /**  
     * ELF算法  
     */  
    public static int ELFHash(String str)   
    {   
        int hash = 0;   
        int x    = 0;   
  
       for(int i = 0; i < str.length(); i++)   
       {   
          hash = (hash << 4) + str.charAt(i);   
          if((x = (int)(hash & 0xF0000000L)) != 0)   
          {   
             hash ^= (x >> 24);   
             hash &= ~x;   
          }   
       }   
  
       return (hash & 0x7FFFFFFF);   
    }   
    /* End Of ELF Hash Function */  
  
    /**  
     * BKDR算法  
     */  
    public static int BKDRHash(String str)   
    {   
        int seed = 131; // 31 131 1313 13131 131313 etc..   
        int hash = 0;   
  
       for(int i = 0; i < str.length(); i++)   
       {   
          hash = (hash * seed) + str.charAt(i);   
       }   
  
       return (hash & 0x7FFFFFFF);   
    }   
    /* End Of BKDR Hash Function */  
  
    /**  
     * SDBM算法  
     */  
    public static int SDBMHash(String str)   
    {   
        int hash = 0;   
  
       for(int i = 0; i < str.length(); i++)   
       {   
          hash = str.charAt(i) + (hash << 6) + (hash << 16) - hash;   
       }   
  
       return (hash & 0x7FFFFFFF);   
    }   
    /* End Of SDBM Hash Function */  
  
    /**  
     * DJB算法  
     */  
    public static int DJBHash(String str)   
    {   
       int hash = 5381;   
  
       for(int i = 0; i < str.length(); i++)   
       {   
          hash = ((hash << 5) + hash) + str.charAt(i);   
       }   
  
       return (hash & 0x7FFFFFFF);   
    }   
    /* End Of DJB Hash Function */  
  
    /**  
     * DEK算法  
     */  
    public static int DEKHash(String str)   
    {   
        int hash = str.length();   
  
       for(int i = 0; i < str.length(); i++)   
       {   
          hash = ((hash << 5) ^ (hash >> 27)) ^ str.charAt(i);   
       }   
  
       return (hash & 0x7FFFFFFF);   
    }   
    /* End Of DEK Hash Function */  
  
    /**  
     * AP算法  
     */  
    public static int APHash(String str)   
    {   
        int hash = 0;   
  
       for(int i = 0; i < str.length(); i++)   
       {   
          hash ^= ((i & 1) == 0) ? ( (hash << 7) ^ str.charAt(i) ^ (hash >> 3)) :   
                                   (~((hash << 11) ^ str.charAt(i) ^ (hash >> 5)));   
       }   
  
//       return (hash & 0x7FFFFFFF);   
       return hash;   
    }   
    /* End Of AP Hash Function */  
       
    /**  
     * JAVA自己带的算法  
     */  
    public static int java(String str)   
{   
   int h = 0;   
   int off = 0;   
   int len = str.length();   
   for (int i = 0; i < len; i++)   
   {   
    h = 31 * h + str.charAt(off++);   
   }   
   return h;   
}   
       
/**  
 * 混合hash算法，输出64位的值  
 */  
public static long mixHash(String str)   
{   
    long hash = str.hashCode();   
    hash <<= 32;   
    hash |= FNVHash1(str);   
    return hash;   
}

posted @ 2022-09-21 22:15 codestacklinuxer 阅读(56) 评论(0) 收藏举报

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djb hash

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haproxy ip-hash

djb hash

乘风好去，长空万里，直下看山河!!! 研究过httpserver、nginx、内核tcpip协议栈源码，内存管理、摄像头-iic-spi等驱动!! 目前搞搞准入看看内核看看身份逻辑看看管控写写go