uint32_t
server_pool_idx(struct server_pool *pool, uint8_t *key, uint32_t keylen)
{
uint32_t hash, idx;
ASSERT(array_n(&pool->server) != 0);
ASSERT(key != NULL);
/*
* If hash_tag: is configured for this server pool, we use the part of
* the key within the hash tag as an input to the distributor. Otherwise
* we use the full key
*/
if (!string_empty(&pool->hash_tag)) {
struct string *tag = &pool->hash_tag;
uint8_t *tag_start, *tag_end;
tag_start = nc_strchr(key, key + keylen, tag->data[0]);
if (tag_start != NULL) {
tag_end = nc_strchr(tag_start + 1, key + keylen, tag->data[1]);
if ((tag_end != NULL) && (tag_end - tag_start > 1)) {
key = tag_start + 1;
keylen = (uint32_t)(tag_end - key);
}
}
}
switch (pool->dist_type) {
case DIST_KETAMA:
hash = server_pool_hash(pool, key, keylen);
idx = ketama_dispatch(pool->continuum, pool->ncontinuum, hash);
break;
case DIST_MODULA:
hash = server_pool_hash(pool, key, keylen);
idx = modula_dispatch(pool->continuum, pool->ncontinuum, hash);
break;
case DIST_RANDOM:
idx = random_dispatch(pool->continuum, pool->ncontinuum, 0);
break;
default:
NOT_REACHED();
return 0;
}
ASSERT(idx < array_n(&pool->server));
return idx;
}
static struct server *
server_pool_server(struct server_pool *pool, uint8_t *key, uint32_t keylen)
{
struct server *server;
uint32_t hash, idx;
ASSERT(array_n(&pool->server) != 0);
ASSERT(key != NULL && keylen != 0);
switch (pool->dist_type) {
case DIST_KETAMA:
hash = server_pool_hash(pool, key, keylen);
idx = ketama_dispatch(pool->continuum, pool->ncontinuum, hash);
break;
case DIST_MODULA:
hash = server_pool_hash(pool, key, keylen);
idx = modula_dispatch(pool->continuum, pool->ncontinuum, hash);
break;
case DIST_RANDOM:
idx = random_dispatch(pool->continuum, pool->ncontinuum, 0);
break;
default:
NOT_REACHED();
return NULL;
}
ASSERT(idx < array_n(&pool->server));
server = array_get(&pool->server, idx);
log_debug(LOG_VERB, "key '%.*s' on dist %d maps to server '%.*s'", keylen,
key, pool->dist_type, server->pname.len, server->pname.data);
return server;
}
