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分类: C/C++

2014-07-17 15:52:13

原文地址:consistent hash代码 作者:bjpiao


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  1. #include <iostream>
  2. #include "util/tc_common.h"
  3. #include "wbl_comm.h"
  4. #include "wbl/string_utility.h"

  5. #define MMC_CONSISTENT_POINTS 160
  6. #define MMC_CONSISTENT_BUCKETS 1024

  7. #define HASH_DATA_LENGTH 28

  8. using namespace std;
  9. using namespace wbl;

  10. uint32_t crc32_table256[] = {
  11.     0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
  12.     0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
  13.     0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
  14.     0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
  15.     0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
  16.     0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
  17.     0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
  18.     0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
  19.     0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
  20.     0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
  21.     0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
  22.     0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
  23.     0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
  24.     0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
  25.     0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
  26.     0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
  27.     0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
  28.     0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
  29.     0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
  30.     0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
  31.     0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
  32.     0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
  33.     0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
  34.     0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
  35.     0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
  36.     0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
  37.     0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
  38.     0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
  39.     0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
  40.     0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
  41.     0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
  42.     0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
  43.     0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
  44.     0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
  45.     0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
  46.     0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
  47.     0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
  48.     0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
  49.     0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
  50.     0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
  51.     0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
  52.     0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
  53.     0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
  54.     0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
  55.     0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
  56.     0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
  57.     0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
  58.     0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
  59.     0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
  60.     0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
  61.     0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
  62.     0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
  63.     0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
  64.     0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
  65.     0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
  66.     0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
  67.     0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
  68.     0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
  69.     0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
  70.     0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
  71.     0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
  72.     0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
  73.     0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
  74.     0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
  75. };

  76. typedef struct {
  77.     unsigned int point;
  78.     string ip;
  79. }consistent_hash_node;

  80. typedef struct {
  81.     int numpoints;
  82.     unsigned int nnodes;
  83.     consistent_hash_node *nodes;
  84. }consistent_hash_continuum;

  85. typedef struct{
  86.     string serverip;
  87.     float weight;
  88. } serveraddr;

  89. class ConsistentHash
  90. {
  91.     consistent_hash_node *buckets[MMC_CONSISTENT_BUCKETS];
  92.     consistent_hash_continuum *continuum;
  93.     serveraddr *server;

  94. public :
  95.     ConsistentHash(){};
  96.     ~ConsistentHash()
  97.     {
  98.         delete [] continuum->nodes;
  99.         delete [] continuum;
  100.         delete [] server;
  101.     }
  102.     
  103.     int init_consistent_hash(const string &serverip);
  104.     string get_consistent_hash_peer(const string &strInput);
  105.     
  106. private:
  107. //    int consistent_hash_compare_continuum_nodes(const consistent_hash_node *node1, const consistent_hash_node *node2);
  108. //    int consistent_hash_compare_continuum_nodes(const void *node1, const void *node2);
  109.     consistent_hash_node *consistent_hash_find(unsigned int point);
  110.     unsigned int crc32(u_char *p, size_t len);
  111. };

  112. int consistent_hash_compare_continuum_nodes(const void *n1, const void *n2)
  113. {
  114.     consistent_hash_node *node1 = (consistent_hash_node *)n1;
  115.     consistent_hash_node *node2 = (consistent_hash_node *)n2;
  116.     
  117.     if (node1->point < node2->point) {
  118.         return -1;
  119.     }
  120.     else if (node1->point > node2->point) {
  121.         return 1;
  122.     }

  123.     return 0;
  124. }

  125. int ConsistentHash::init_consistent_hash(const string &serverip)
  126. {
  127.     u_char hash_data[HASH_DATA_LENGTH];
  128.     uint32_t step;
  129.     unsigned int i, k, points = 0;
  130.  
  131.     vector<string> vServerIps;
  132.     wbl::Split(serverip, ";", vServerIps);
  133.     if(vServerIps.size()<=0)
  134.     {
  135.         cout << "the input server ip is empty" << endl;
  136.         return -1;
  137.     }

  138.     unsigned int servernum = vServerIps.size();
  139.     
  140.     server = new serveraddr[servernum];
  141.     float sum=0;

  142.     for(i=0; i<servernum; i )
  143.     {
  144.         vector<string> temp;
  145.         temp.clear();
  146.         wbl::Split(vServerIps[i], ",", temp);
  147.         if(temp.size()!=2)
  148.         {
  149.             cout << "the server address's format is wrong" << endl;
  150.             return -1;
  151.         }
  152.         server[i].serverip = temp[0];
  153.         server[i].weight = (float)wbl::s2i(temp[1]);
  154.         sum =server[i].weight;
  155.     }
  156.     
  157.     for(i=0; i<servernum; i )
  158.     {
  159.         server[i].weight = server[i].weight / sum;
  160.     }

  161.     
  162.     for (i=0;i<HASH_DATA_LENGTH;i )
  163.         hash_data[i] = 0;

  164.     step = (uint32_t) (0xffffffff / MMC_CONSISTENT_BUCKETS);
  165.     
  166.     
  167.     for (i = 0; i < servernum; i ) {
  168.         points = (unsigned int)(server[i].weight * MMC_CONSISTENT_POINTS);
  169.     }
  170.     
  171.     continuum = new consistent_hash_continuum;
  172.     continuum->nodes = new consistent_hash_node[points];
  173.     continuum->nnodes = 0;

  174.     for (i = 0; i < servernum; i ) {
  175.         unsigned int j = (unsigned int)(MMC_CONSISTENT_POINTS * server[i].weight);
  176.         for (k = 0; k < j; k ) {
  177.                 snprintf((char *)hash_data, 28, "%s-%ui", server[i].serverip.c_str(), k);
  178.                 continuum->nodes[continuum->nnodes].ip = server[i].serverip;
  179.                 continuum->nodes[continuum->nnodes].point = crc32(hash_data, strlen((char *)hash_data));
  180.                 continuum->nnodes ;
  181.         }
  182.     }
  183.     
  184.     
  185.     qsort(continuum->nodes, continuum->nnodes, sizeof(consistent_hash_node), consistent_hash_compare_continuum_nodes);

  186.     for (i = 0; i < MMC_CONSISTENT_BUCKETS; i ) {
  187.         buckets[i] = consistent_hash_find(step * i);
  188.     }
  189.     return 0;
  190. }

  191. string ConsistentHash::get_consistent_hash_peer(const string &strInput)
  192. {
  193.     unsigned int point = crc32((unsigned char *)strInput.c_str(), strInput.size());
  194.     string ip = buckets[point % MMC_CONSISTENT_BUCKETS]->ip;
  195.     return ip;
  196. }

  197. consistent_hash_node* ConsistentHash::consistent_hash_find(unsigned int point)
  198. {
  199.     int mid = 0, lo = 0, hi = continuum->nnodes - 1;

  200.     while (1)
  201.     {
  202.         if (point <= continuum->nodes[lo].point ||
  203.                 point > continuum->nodes[hi].point) {
  204.             return &continuum->nodes[lo];
  205.         }

  206.         /* test middle point */
  207.         mid = lo (hi - lo) / 2;

  208.         /* perfect match */
  209.         if (point <= continuum->nodes[mid].point &&
  210.                 point > (mid ? continuum->nodes[mid-1].point : 0)) {
  211.             return &continuum->nodes[mid];
  212.         }

  213.         /* too low, go up */
  214.         if (continuum->nodes[mid].point < point) {
  215.             lo = mid 1;
  216.         }
  217.         else {
  218.             hi = mid - 1;
  219.         }
  220.     }
  221. }

  222. unsigned int ConsistentHash::crc32(u_char *p, size_t len)
  223. {
  224.     uint32_t crc;

  225.     crc = 0xffffffff;

  226.     while (len--) {
  227.         crc = crc32_table256[(crc ^ *p ) & 0xff] ^ (crc >> 8);
  228.     }

  229.     return crc ^ 0xffffffff;
  230. }

  231. int main()
  232. {
  233.     ConsistentHash ch;
  234.     string strip = "120.204.201.16,25;120.204.201.17,25;117.135.129.180,25;120.196.211.49,25;";
  235.     ch.init_consistent_hash(strip);
  236.     
  237.     string musicid = "123456";
  238.     cout << ch.get_consistent_hash_peer(musicid);
  239.     return 0;
  240. }

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