consistent hash代码

#include <iostream>
#include "util/tc_common.h"
#include "wbl_comm.h"
#include "wbl/string_utility.h"

#define MMC_CONSISTENT_POINTS 160
#define MMC_CONSISTENT_BUCKETS 1024

#define HASH_DATA_LENGTH 28

using namespace std;
using namespace wbl;

uint32_t  crc32_table256[] = {
    0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
    0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
    0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
    0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
    0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
    0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
    0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
    0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
    0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
    0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
    0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
    0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
    0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
    0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
    0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
    0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
    0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
    0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
    0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
    0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
    0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
    0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
    0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
    0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
    0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
    0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
    0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
    0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
    0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
    0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
    0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
    0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
    0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
    0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
    0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
    0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
    0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
    0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
    0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
    0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
    0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
    0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
    0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
    0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
    0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
    0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
    0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
    0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
    0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
    0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
    0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
    0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
    0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
    0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
    0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
    0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
    0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
    0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
    0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
    0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
    0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
    0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
    0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
    0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
};

typedef struct {
    unsigned int                     point;
    string                    ip;
}consistent_hash_node;

typedef struct {
    int                  numpoints;
    unsigned int         nnodes;
    consistent_hash_node       *nodes;
}consistent_hash_continuum;

typedef struct{
    string serverip;
    float  weight;
} serveraddr;

class ConsistentHash
{
    consistent_hash_node       *buckets[MMC_CONSISTENT_BUCKETS];
    consistent_hash_continuum  *continuum;
    serveraddr *server;

public :
    ConsistentHash(){};
    ~ConsistentHash()
    {
        delete [] continuum->nodes;
        delete [] continuum;
        delete [] server;
    }

    int init_consistent_hash(const string &serverip);
    string get_consistent_hash_peer(const string &strInput);

private:
//    int consistent_hash_compare_continuum_nodes(const consistent_hash_node *node1, const consistent_hash_node *node2);
//    int consistent_hash_compare_continuum_nodes(const void *node1, const void *node2);
    consistent_hash_node *consistent_hash_find(unsigned int point);
    unsigned int crc32(u_char *p, size_t len);
};

int consistent_hash_compare_continuum_nodes(const void *n1, const void *n2)
{
    consistent_hash_node *node1 = (consistent_hash_node *)n1;
    consistent_hash_node *node2 = (consistent_hash_node *)n2;

    if (node1->point < node2->point) {
        return -1;
    }
    else if (node1->point > node2->point) {
        return 1;
    }

    return 0;
}

int ConsistentHash::init_consistent_hash(const string &serverip)
{
    u_char                                        hash_data[HASH_DATA_LENGTH];
    uint32_t                                      step;
    unsigned int                                  i, k, points = 0;

    vector<string> vServerIps;
    wbl::Split(serverip, ";", vServerIps);
    if(vServerIps.size()<=0)
    {
        cout << "the input server ip is empty" << endl;
        return -1;
    }

    unsigned int servernum = vServerIps.size();

    server = new serveraddr[servernum];
    float sum=0;

    for(i=0; i<servernum; i  )
    {
        vector<string> temp;
        temp.clear();
        wbl::Split(vServerIps[i], ",", temp);
        if(temp.size()!=2)
        {
            cout << "the server address's format is wrong" << endl;
            return -1;
        }
        server[i].serverip = temp[0];
        server[i].weight = (float)wbl::s2i(temp[1]);
        sum =server[i].weight;
    }

    for(i=0; i<servernum; i  )
    {
        server[i].weight = server[i].weight / sum;
    }


    for (i=0;i<HASH_DATA_LENGTH;i  )
        hash_data[i] = 0;

    step = (uint32_t) (0xffffffff / MMC_CONSISTENT_BUCKETS);


    for (i = 0; i < servernum; i  ) {
        points  = (unsigned int)(server[i].weight * MMC_CONSISTENT_POINTS);
    }

    continuum = new consistent_hash_continuum;
    continuum->nodes = new consistent_hash_node[points];
    continuum->nnodes = 0;

    for (i = 0; i < servernum; i  ) {
        unsigned int j = (unsigned int)(MMC_CONSISTENT_POINTS * server[i].weight);
        for (k = 0; k < j; k  ) {
                snprintf((char *)hash_data, 28, "%s-%ui", server[i].serverip.c_str(), k);
                continuum->nodes[continuum->nnodes].ip = server[i].serverip;
                continuum->nodes[continuum->nnodes].point = crc32(hash_data, strlen((char *)hash_data));
                continuum->nnodes  ;
        }
    }


    qsort(continuum->nodes, continuum->nnodes, sizeof(consistent_hash_node), consistent_hash_compare_continuum_nodes);

    for (i = 0; i < MMC_CONSISTENT_BUCKETS; i  ) {
        buckets[i] = consistent_hash_find(step * i);
    }
    return 0;
}

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

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

    while (1)
    {
        if (point <= continuum->nodes[lo].point ||
                point > continuum->nodes[hi].point) {
            return &continuum->nodes[lo];
        }

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

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

        /* too low, go up */
        if (continuum->nodes[mid].point < point) {
            lo = mid   1;
        }
        else {
            hi = mid - 1;
        }
    }
}

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

    crc = 0xffffffff;

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

    return crc ^ 0xffffffff;
}

int main()
{
    ConsistentHash ch;
    string strip = "120.204.201.16,25;120.204.201.17,25;117.135.129.180,25;120.196.211.49,25;";
    ch.init_consistent_hash(strip);

    string musicid = "123456";
    cout << ch.get_consistent_hash_peer(musicid);
    return 0;
}