/*
* Copyright (C) Maxim Dounin
* Copyright (C) Nginx, Inc.
*/
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_stream.h>
static ngx_int_t ngx_stream_upstream_init_least_conn_peer(
ngx_stream_session_t *s, ngx_stream_upstream_srv_conf_t *us);
static ngx_int_t ngx_stream_upstream_get_least_conn_peer(
ngx_peer_connection_t *pc, void *data);
static char *ngx_stream_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd,
void *conf);
static ngx_command_t ngx_stream_upstream_least_conn_commands[] = {
{ ngx_string("least_conn"),
NGX_STREAM_UPS_CONF|NGX_CONF_NOARGS,
ngx_stream_upstream_least_conn,
0,
0,
NULL },
ngx_null_command
};
static ngx_stream_module_t ngx_stream_upstream_least_conn_module_ctx = {
NULL, /* preconfiguration */
NULL, /* postconfiguration */
NULL, /* create main configuration */
NULL, /* init main configuration */
NULL, /* create server configuration */
NULL /* merge server configuration */
};
ngx_module_t ngx_stream_upstream_least_conn_module = {
NGX_MODULE_V1,
&ngx_stream_upstream_least_conn_module_ctx, /* module context */
ngx_stream_upstream_least_conn_commands, /* module directives */
NGX_STREAM_MODULE, /* module type */
NULL, /* init master */
NULL, /* init module */
NULL, /* init process */
NULL, /* init thread */
NULL, /* exit thread */
NULL, /* exit process */
NULL, /* exit master */
NGX_MODULE_V1_PADDING
};
static ngx_int_t
ngx_stream_upstream_init_least_conn(ngx_conf_t *cf,
ngx_stream_upstream_srv_conf_t *us)
{
ngx_log_debug0(NGX_LOG_DEBUG_STREAM, cf->log, 0,
"init least conn");
if (ngx_stream_upstream_init_round_robin(cf, us) != NGX_OK) {
return NGX_ERROR;
}
us->peer.init = ngx_stream_upstream_init_least_conn_peer;
return NGX_OK;
}
static ngx_int_t
ngx_stream_upstream_init_least_conn_peer(ngx_stream_session_t *s,
ngx_stream_upstream_srv_conf_t *us)
{
ngx_log_debug0(NGX_LOG_DEBUG_STREAM, s->connection->log, 0,
"init least conn peer");
if (ngx_stream_upstream_init_round_robin_peer(s, us) != NGX_OK) {
return NGX_ERROR;
}
s->upstream->peer.get = ngx_stream_upstream_get_least_conn_peer;
return NGX_OK;
}
static ngx_int_t
ngx_stream_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
{
ngx_stream_upstream_rr_peer_data_t *rrp = data;
time_t now;
uintptr_t m;
ngx_int_t rc, total;
ngx_uint_t i, n, p, many;
ngx_stream_upstream_rr_peer_t *peer, *best;
ngx_stream_upstream_rr_peers_t *peers;
ngx_log_debug1(NGX_LOG_DEBUG_STREAM, pc->log, 0,
"get least conn peer, try: %ui", pc->tries);
if (rrp->peers->single) {
return ngx_stream_upstream_get_round_robin_peer(pc, rrp);
}
pc->connection = NULL;
now = ngx_time();
peers = rrp->peers;
ngx_stream_upstream_rr_peers_wlock(peers);
best = NULL;
total = 0;
#if (NGX_SUPPRESS_WARN)
many = 0;
p = 0;
#endif
for (peer = peers->peer, i = 0;
peer;
peer = peer->next, i++)
{
n = i / (8 * sizeof(uintptr_t));
m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t));
if (rrp->tried[n] & m) {
continue;
}
if (peer->down) {
continue;
}
if (peer->max_fails
&& peer->fails >= peer->max_fails
&& now - peer->checked <= peer->fail_timeout)
{
continue;
}
if (peer->max_conns && peer->conns >= peer->max_conns) {
continue;
}
/*
* select peer with least number of connections; if there are
* multiple peers with the same number of connections, select
* based on round-robin
*/
if (best == NULL
|| peer->conns * best->weight < best->conns * peer->weight)
{
best = peer;
many = 0;
p = i;
} else if (peer->conns * best->weight == best->conns * peer->weight) {
many = 1;
}
}
if (best == NULL) {
ngx_log_debug0(NGX_LOG_DEBUG_STREAM, pc->log, 0,
"get least conn peer, no peer found");
goto failed;
}
if (many) {
ngx_log_debug0(NGX_LOG_DEBUG_STREAM, pc->log, 0,
"get least conn peer, many");
for (peer = best, i = p;
peer;
peer = peer->next, i++)
{
n = i / (8 * sizeof(uintptr_t));
m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t));
if (rrp->tried[n] & m) {
continue;
}
if (peer->down) {
continue;
}
if (peer->conns * best->weight != best->conns * peer->weight) {
continue;
}
if (peer->max_fails
&& peer->fails >= peer->max_fails
&& now - peer->checked <= peer->fail_timeout)
{
continue;
}
if (peer->max_conns && peer->conns >= peer->max_conns) {
continue;
}
peer->current_weight += peer->effective_weight;
total += peer->effective_weight;
if (peer->effective_weight < peer->weight) {
peer->effective_weight++;
}
if (peer->current_weight > best->current_weight) {
best = peer;
p = i;
}
}
}
best->current_weight -= total;
if (now - best->checked > best->fail_timeout) {
best->checked = now;
}
pc->sockaddr = best->sockaddr;
pc->socklen = best->socklen;
pc->name = &best->name;
best->conns++;
rrp->current = best;
n = p / (8 * sizeof(uintptr_t));
m = (uintptr_t) 1 << p % (8 * sizeof(uintptr_t));
rrp->tried[n] |= m;
ngx_stream_upstream_rr_peers_unlock(peers);
return NGX_OK;
failed:
if (peers->next) {
ngx_log_debug0(NGX_LOG_DEBUG_STREAM, pc->log, 0,
"get least conn peer, backup servers");
rrp->peers = peers->next;
n = (rrp->peers->number + (8 * sizeof(uintptr_t) - 1))
/ (8 * sizeof(uintptr_t));
for (i = 0; i < n; i++) {
rrp->tried[i] = 0;
}
ngx_stream_upstream_rr_peers_unlock(peers);
rc = ngx_stream_upstream_get_least_conn_peer(pc, rrp);
if (rc != NGX_BUSY) {
return rc;
}
ngx_stream_upstream_rr_peers_wlock(peers);
}
ngx_stream_upstream_rr_peers_unlock(peers);
pc->name = peers->name;
return NGX_BUSY;
}
static char *
ngx_stream_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
ngx_stream_upstream_srv_conf_t *uscf;
uscf = ngx_stream_conf_get_module_srv_conf(cf, ngx_stream_upstream_module);
if (uscf->peer.init_upstream) {
ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
"load balancing method redefined");
}
uscf->peer.init_upstream = ngx_stream_upstream_init_least_conn;
uscf->flags = NGX_STREAM_UPSTREAM_CREATE
|NGX_STREAM_UPSTREAM_WEIGHT
|NGX_STREAM_UPSTREAM_MAX_CONNS
|NGX_STREAM_UPSTREAM_MAX_FAILS
|NGX_STREAM_UPSTREAM_FAIL_TIMEOUT
|NGX_STREAM_UPSTREAM_DOWN
|NGX_STREAM_UPSTREAM_BACKUP;
return NGX_CONF_OK;
}
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