ngx_int_t
ngx_http_upstream_init_consistent_hash(ngx_conf_t *cf,
ngx_http_upstream_srv_conf_t *us)
{
/* ip max 15, :port max 6, maxweight is highest number of uchar */
u_char *last, hash_data[28];
uint32_t step;
ngx_uint_t i, j, k, n;
ngx_uint_t real_nodes, points_per_node;
ngx_http_upstream_server_t *server;
ngx_http_upstream_rr_peer_t *rr_peer;
ngx_http_upstream_rr_peers_t *prr_peers;
ngx_http_upstream_consistent_hash_buckets *buckets;
ngx_http_upstream_consistent_hash_continuum *continuum;
ngx_http_upstream_consistent_hash_srv_conf_t *uchscf;
uchscf = ngx_http_conf_upstream_srv_conf(us,
ngx_http_upstream_consistent_hash_module);
if (uchscf == NULL) {
return NGX_ERROR;
}
if (ngx_http_upstream_init_round_robin(cf, us) != NGX_OK) {
return NGX_ERROR;
}
prr_peers = us->peer.data;
us->peer.init = ngx_http_upstream_init_consistent_hash_peer;
buckets = ngx_pcalloc(cf->pool,
sizeof(ngx_http_upstream_consistent_hash_buckets));
if (!us->servers) {
return NGX_ERROR;
}
server = us->servers->elts;
n = real_nodes = 0;
for (i = 0; i < us->servers->nelts; i++) {
n += server[i].naddrs;
real_nodes += server[i].weight * server[i].naddrs;
}
/*
* The optimal points number is Q/S
* See the section 6.2 from the paper 'Dynamo: Amazon's Highly Available
* Key-value Store'
*/
points_per_node = (ngx_uint_t) MMC_CONSISTENT_BUCKETS / real_nodes;
if (points_per_node == 0) {
points_per_node = 1;
}
continuum = ngx_pcalloc(cf->pool,
sizeof(ngx_http_upstream_consistent_hash_continuum));
continuum->nodes = ngx_palloc(cf->pool,
sizeof(ngx_http_upstream_consistent_hash_node) * MMC_CONSISTENT_BUCKETS);
for (i = 0; i < us->servers->nelts; i++) {
for (j = 0; j < server[i].naddrs; j++) {
rr_peer = ngx_http_upstream_consistent_hash_find_rr_peer(prr_peers,
server[i].addrs[j].sockaddr);
if (rr_peer == NULL) {
return NGX_ERROR;
}
for (k = 0; k < (points_per_node * server[i].weight); k++) {
last = ngx_snprintf(hash_data, 28, "%V-%ui",
&server[i].addrs[j].name, k);
continuum->nodes[continuum->nnodes].point =
ngx_http_upstream_consistent_hash_node_point(hash_data,
(last - hash_data));
continuum->nodes[continuum->nnodes].rr_peer = rr_peer;
continuum->nnodes++;
}
}
}
ngx_qsort(continuum->nodes, continuum->nnodes,
sizeof(ngx_http_upstream_consistent_hash_node),
(const void*) ngx_http_upstream_consistent_hash_compare_continuum_nodes);
step = (uint32_t) (0xffffffff / MMC_CONSISTENT_BUCKETS);
for (i = 0; i < MMC_CONSISTENT_BUCKETS; i++) {
buckets->bucket[i] =
ngx_http_upstream_consistent_hash_find(continuum, step * i);
}
#if (CONSISTENT_DEBUG)
ngx_http_upstream_consistent_hash_print_continuum(cf, continuum);
ngx_http_upstream_consistent_hash_print_buckets(cf, buckets);
#endif
buckets->continuum = continuum;
uchscf->data = buckets;
return NGX_OK;
}
ngx_int_t
ngx_http_upstream_init_consistent_hash(ngx_conf_t *cf,
ngx_http_upstream_srv_conf_t *us)
{
/* ip max 15, :port max 6, maxweight is highest number of uchar */
u_char hash_data[HASH_DATA_LENGTH];
uint32_t step;
ngx_uint_t i, j, k, n, points = 0;
ngx_http_upstream_server_t *server;
ngx_http_upstream_consistent_hash_buckets *buckets;
ngx_http_upstream_consistent_hash_continuum *continuum;
for (i=0;i<HASH_DATA_LENGTH;i++) hash_data[i] = 0;
step = (uint32_t) (0xffffffff / MMC_CONSISTENT_BUCKETS);
buckets = ngx_pcalloc(cf->pool,
sizeof(ngx_http_upstream_consistent_hash_buckets));
us->peer.init = ngx_http_upstream_init_consistent_hash_peer;
if (!us->servers) {
return NGX_ERROR;
}
server = us->servers->elts;
for (n = 0, i = 0; i < us->servers->nelts; i++) {
n += server[i].naddrs;
points += server[i].weight * server[i].naddrs * MMC_CONSISTENT_POINTS;
}
continuum = ngx_pcalloc(cf->pool,
sizeof(ngx_http_upstream_consistent_hash_continuum));
continuum->nodes = ngx_pcalloc(cf->pool,
sizeof(ngx_http_upstream_consistent_hash_node) * points);
for (i = 0; i < us->servers->nelts; i++) {
for (j = 0; j < server[i].naddrs; j++) {
for (k = 0; k < ((MMC_CONSISTENT_POINTS * server[i].weight) / server[i].naddrs); k++) {
ngx_snprintf(hash_data, 28, "%V-%ui", &server[i].addrs[j].name, k);
continuum->nodes[continuum->nnodes].sockaddr = server[i].addrs[j].sockaddr;
continuum->nodes[continuum->nnodes].socklen = server[i].addrs[j].socklen;
continuum->nodes[continuum->nnodes].name = server[i].addrs[j].name;
continuum->nodes[continuum->nnodes].name.data[server[i].addrs[j].name.len] = 0;
continuum->nodes[continuum->nnodes].point = ngx_crc32_long(hash_data, ngx_strlen(hash_data));
continuum->nnodes++;
}
}
}
qsort(continuum->nodes, continuum->nnodes,
sizeof(ngx_http_upstream_consistent_hash_node),
(const void*) ngx_http_upstream_consistent_hash_compare_continuum_nodes);
for (i = 0; i < MMC_CONSISTENT_BUCKETS; i++) {
buckets->buckets[i] =
ngx_http_upstream_consistent_hash_find(continuum, step * i);
}
#if (CONSISTENT_DEBUG)
ngx_http_upstream_consistent_hash_print_continuum(cf, continuum);
ngx_http_upstream_consistent_hash_print_buckets(cf, buckets);
#endif
buckets->continuum = continuum;
us->peer.data = buckets;
return NGX_OK;
}
