Function ch_ring_create_ring

example/cacheCluster/consistentHash.c:41–90

}

ring_t *ch_ring_create_ring(int n_server, double *weight) {
  vnode_t *vnodes =
      (vnode_t *)malloc(sizeof(vnode_t) * n_server * N_VNODE_PER_SERVER);

  ring_t *ring = (ring_t *)malloc(sizeof(ring_t));
  ring->n_server = n_server;
  ring->n_point = n_server * N_VNODE_PER_SERVER;
  ring->vnodes = vnodes;

  int i;
  unsigned int k, cnt = 0;

  for (i = 0; i < n_server; i++) {
    // default all servers have the same weight
    unsigned int ks = N_VNODE_PER_SERVER / 4;
    if (weight != NULL)
      ks = (unsigned int)floorf(weight[i] * (float)n_server *
                                (N_VNODE_PER_SERVER / 4));

    for (k = 0; k < ks; k++) {
      /* 40 hashes, 4 numbers per hash = 160 points per server */
      char ss[30];
      unsigned char digest[16];

      sprintf(ss, "%u-%u", i, k);
      md5_digest(ss, digest);

      /* Use successive 4-bytes from hash as numbers for the points on the
       * circle: */
      int h;
      for (h = 0; h < 4; h++) {
        // printf("%d i %d k %d h %d %d %d\n", cnt, i, k, h, ring->n_server,
        // ring->n_point);
        vnodes[cnt].point = (digest[3 + h * 4] << 24) |
                            (digest[2 + h * 4] << 16) |
                            (digest[1 + h * 4] << 8) | digest[h * 4];

        vnodes[cnt].server_id = i;
        cnt++;
      }
    }
  }

  /* Sorts in ascending order of "point" */
  qsort((void *)vnodes, cnt, sizeof(vnode_t), ch_ring_compare);

  //  for (i=0; i< 200; i++)
  //    printf("%u %u\n", vnodes[i].point, vnodes[i].server_id);
  return ring;
}

int ch_ring_get_vnode_idx(const char *const key, const ring_t *const ring) {
  unsigned int h = ketama_hash(key);