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/*
* Copyright (C) Maxim Dounin
* Copyright (C) Nginx, Inc.
*/
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>
typedef struct {
ngx_uint_t *conns;
} ngx_http_upstream_least_conn_conf_t;
typedef struct {
/* the round robin data must be first */
ngx_http_upstream_rr_peer_data_t rrp;
ngx_uint_t *conns;
ngx_event_get_peer_pt get_rr_peer;
ngx_event_free_peer_pt free_rr_peer;
} ngx_http_upstream_lc_peer_data_t;
static ngx_int_t ngx_http_upstream_init_least_conn_peer(ngx_http_request_t *r,
ngx_http_upstream_srv_conf_t *us);
static ngx_int_t ngx_http_upstream_get_least_conn_peer(
ngx_peer_connection_t *pc, void *data);
static void ngx_http_upstream_free_least_conn_peer(ngx_peer_connection_t *pc,
void *data, ngx_uint_t state);
static void *ngx_http_upstream_least_conn_create_conf(ngx_conf_t *cf);
static char *ngx_http_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd,
void *conf);
static ngx_command_t ngx_http_upstream_least_conn_commands[] = {
{ ngx_string("least_conn"),
NGX_HTTP_UPS_CONF|NGX_CONF_NOARGS,
ngx_http_upstream_least_conn,
0,
0,
NULL },
ngx_null_command
};
static ngx_http_module_t ngx_http_upstream_least_conn_module_ctx = {
NULL, /* preconfiguration */
NULL, /* postconfiguration */
NULL, /* create main configuration */
NULL, /* init main configuration */
ngx_http_upstream_least_conn_create_conf, /* create server configuration */
NULL, /* merge server configuration */
NULL, /* create location configuration */
NULL /* merge location configuration */
};
ngx_module_t ngx_http_upstream_least_conn_module = {
NGX_MODULE_V1,
&ngx_http_upstream_least_conn_module_ctx, /* module context */
ngx_http_upstream_least_conn_commands, /* module directives */
NGX_HTTP_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_http_upstream_init_least_conn(ngx_conf_t *cf,
ngx_http_upstream_srv_conf_t *us)
{
ngx_uint_t n;
ngx_http_upstream_rr_peers_t *peers;
ngx_http_upstream_least_conn_conf_t *lcf;
ngx_log_debug0(NGX_LOG_DEBUG_HTTP, cf->log, 0,
"init least conn");
if (ngx_http_upstream_init_round_robin(cf, us) != NGX_OK) {
return NGX_ERROR;
}
peers = us->peer.data;
n = peers->number;
if (peers->next) {
n += peers->next->number;
}
lcf = ngx_http_conf_upstream_srv_conf(us,
ngx_http_upstream_least_conn_module);
lcf->conns = ngx_pcalloc(cf->pool, sizeof(ngx_uint_t) * n);
if (lcf->conns == NULL) {
return NGX_ERROR;
}
us->peer.init = ngx_http_upstream_init_least_conn_peer;
return NGX_OK;
}
static ngx_int_t
ngx_http_upstream_init_least_conn_peer(ngx_http_request_t *r,
ngx_http_upstream_srv_conf_t *us)
{
ngx_http_upstream_lc_peer_data_t *lcp;
ngx_http_upstream_least_conn_conf_t *lcf;
ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
"init least conn peer");
lcf = ngx_http_conf_upstream_srv_conf(us,
ngx_http_upstream_least_conn_module);
lcp = ngx_palloc(r->pool, sizeof(ngx_http_upstream_lc_peer_data_t));
if (lcp == NULL) {
return NGX_ERROR;
}
lcp->conns = lcf->conns;
r->upstream->peer.data = &lcp->rrp;
if (ngx_http_upstream_init_round_robin_peer(r, us) != NGX_OK) {
return NGX_ERROR;
}
r->upstream->peer.get = ngx_http_upstream_get_least_conn_peer;
r->upstream->peer.free = ngx_http_upstream_free_least_conn_peer;
lcp->get_rr_peer = ngx_http_upstream_get_round_robin_peer;
lcp->free_rr_peer = ngx_http_upstream_free_round_robin_peer;
return NGX_OK;
}
static ngx_int_t
ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
{
ngx_http_upstream_lc_peer_data_t *lcp = data;
time_t now;
uintptr_t m;
ngx_int_t rc, total;
ngx_uint_t i, n, p, many;
ngx_http_upstream_rr_peer_t *peer, *best;
ngx_http_upstream_rr_peers_t *peers;
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
"get least conn peer, try: %ui", pc->tries);
if (lcp->rrp.peers->single) {
return lcp->get_rr_peer(pc, &lcp->rrp);
}
pc->cached = 0;
pc->connection = NULL;
now = ngx_time();
peers = lcp->rrp.peers;
best = NULL;
total = 0;
#if (NGX_SUPPRESS_WARN)
many = 0;
p = 0;
#endif
for (i = 0; i < peers->number; i++) {
n = i / (8 * sizeof(uintptr_t));
m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t));
if (lcp->rrp.tried[n] & m) {
continue;
}
peer = &peers->peer[i];
if (peer->down) {
continue;
}
if (peer->max_fails
&& peer->fails >= peer->max_fails
&& now - peer->checked <= peer->fail_timeout)
{
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
|| lcp->conns[i] * best->weight < lcp->conns[p] * peer->weight)
{
best = peer;
many = 0;
p = i;
} else if (lcp->conns[i] * best->weight
== lcp->conns[p] * peer->weight)
{
many = 1;
}
}
if (best == NULL) {
ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0,
"get least conn peer, no peer found");
goto failed;
}
if (many) {
ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0,
"get least conn peer, many");
for (i = p; i < peers->number; i++) {
n = i / (8 * sizeof(uintptr_t));
m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t));
if (lcp->rrp.tried[n] & m) {
continue;
}
peer = &peers->peer[i];
if (peer->down) {
continue;
}
if (lcp->conns[i] * best->weight != lcp->conns[p] * peer->weight) {
continue;
}
if (peer->max_fails
&& peer->fails >= peer->max_fails
&& now - peer->checked <= peer->fail_timeout)
{
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;
best->checked = now;
pc->sockaddr = best->sockaddr;
pc->socklen = best->socklen;
pc->name = &best->name;
lcp->rrp.current = p;
n = p / (8 * sizeof(uintptr_t));
m = (uintptr_t) 1 << p % (8 * sizeof(uintptr_t));
lcp->rrp.tried[n] |= m;
lcp->conns[p]++;
if (pc->tries == 1 && peers->next) {
pc->tries += peers->next->number;
}
return NGX_OK;
failed:
if (peers->next) {
ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0,
"get least conn peer, backup servers");
lcp->conns += peers->number;
lcp->rrp.peers = peers->next;
pc->tries = lcp->rrp.peers->number;
n = lcp->rrp.peers->number / (8 * sizeof(uintptr_t)) + 1;
for (i = 0; i < n; i++) {
lcp->rrp.tried[i] = 0;
}
rc = ngx_http_upstream_get_least_conn_peer(pc, lcp);
if (rc != NGX_BUSY) {
return rc;
}
}
/* all peers failed, mark them as live for quick recovery */
for (i = 0; i < peers->number; i++) {
peers->peer[i].fails = 0;
}
pc->name = peers->name;
return NGX_BUSY;
}
static void
ngx_http_upstream_free_least_conn_peer(ngx_peer_connection_t *pc,
void *data, ngx_uint_t state)
{
ngx_http_upstream_lc_peer_data_t *lcp = data;
ngx_log_debug2(NGX_LOG_DEBUG_HTTP, pc->log, 0,
"free least conn peer %ui %ui", pc->tries, state);
if (lcp->rrp.peers->single) {
lcp->free_rr_peer(pc, &lcp->rrp, state);
return;
}
if (state == 0 && pc->tries == 0) {
return;
}
lcp->conns[lcp->rrp.current]--;
lcp->free_rr_peer(pc, &lcp->rrp, state);
}
static void *
ngx_http_upstream_least_conn_create_conf(ngx_conf_t *cf)
{
ngx_http_upstream_least_conn_conf_t *conf;
conf = ngx_pcalloc(cf->pool,
sizeof(ngx_http_upstream_least_conn_conf_t));
if (conf == NULL) {
return NULL;
}
/*
* set by ngx_pcalloc():
*
* conf->conns = NULL;
*/
return conf;
}
static char *
ngx_http_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
ngx_http_upstream_srv_conf_t *uscf;
uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module);
uscf->peer.init_upstream = ngx_http_upstream_init_least_conn;
uscf->flags = NGX_HTTP_UPSTREAM_CREATE
|NGX_HTTP_UPSTREAM_WEIGHT
|NGX_HTTP_UPSTREAM_MAX_FAILS
|NGX_HTTP_UPSTREAM_FAIL_TIMEOUT
|NGX_HTTP_UPSTREAM_DOWN
|NGX_HTTP_UPSTREAM_BACKUP;
return NGX_CONF_OK;
}