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src/http/modules/ngx_http_upstream_least_conn_module.c - nginx source code

Global variables defined

Functions defined

Source code


  2. /*
  3. * Copyright (C) Maxim Dounin
  4. * Copyright (C) Nginx, Inc.
  5. */


  8. #include <ngx_config.h>
  9. #include <ngx_core.h>
  10. #include <ngx_http.h>


  13. static ngx_int_t ngx_http_upstream_init_least_conn_peer(ngx_http_request_t *r,
  14.     ngx_http_upstream_srv_conf_t *us);
  15. static ngx_int_t ngx_http_upstream_get_least_conn_peer(
  16.     ngx_peer_connection_t *pc, void *data);
  17. static char *ngx_http_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd,
  18.     void *conf);


  21. ‌static ngx_command_t  ngx_http_upstream_least_conn_commands[] = {

  23.     { ngx_string("least_conn"),
  24.       NGX_HTTP_UPS_CONF|NGX_CONF_NOARGS,
  25.       ngx_http_upstream_least_conn,
  26.       0,
  27.       0,
  28.       NULL },

  30.       ngx_null_command
  31. };


  34. ‌static ngx_http_module_t  ngx_http_upstream_least_conn_module_ctx = {
  35.     NULL,                                  /* preconfiguration */
  36.     NULL,                                  /* postconfiguration */

  38.     NULL,                                  /* create main configuration */
  39.     NULL,                                  /* init main configuration */

  41.     NULL,                                  /* create server configuration */
  42.     NULL,                                  /* merge server configuration */

  44.     NULL,                                  /* create location configuration */
  45.     NULL                                   /* merge location configuration */
  46. };


  49. ‌ngx_module_t  ngx_http_upstream_least_conn_module = {
  50.     NGX_MODULE_V1,
  51.     &ngx_http_upstream_least_conn_module_ctx, /* module context */
  52.     ngx_http_upstream_least_conn_commands, /* module directives */
  53.     NGX_HTTP_MODULE,                       /* module type */
  54.     NULL,                                  /* init master */
  55.     NULL,                                  /* init module */
  56.     NULL,                                  /* init process */
  57.     NULL,                                  /* init thread */
  58.     NULL,                                  /* exit thread */
  59.     NULL,                                  /* exit process */
  60.     NULL,                                  /* exit master */
  61.     NGX_MODULE_V1_PADDING
  62. };


  65. static ngx_int_t
  66. ‌ngx_http_upstream_init_least_conn(ngx_conf_t *cf,
  67.     ngx_http_upstream_srv_conf_t *us)
  68. {
  69.     ngx_log_debug0(NGX_LOG_DEBUG_HTTP, cf->log, 0,
  70.                    "init least conn");

  72.     if (ngx_http_upstream_init_round_robin(cf, us) != NGX_OK) {
  73.         return NGX_ERROR;
  74.     }

  76.     us->peer.init = ngx_http_upstream_init_least_conn_peer;

  78.     return NGX_OK;
  79. }


  82. static ngx_int_t
  83. ‌ngx_http_upstream_init_least_conn_peer(ngx_http_request_t *r,
  84.     ngx_http_upstream_srv_conf_t *us)
  85. {
  86.     ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
  87.                    "init least conn peer");

  89.     if (ngx_http_upstream_init_round_robin_peer(r, us) != NGX_OK) {
  90.         return NGX_ERROR;
  91.     }

  93.     r->upstream->peer.get = ngx_http_upstream_get_least_conn_peer;

  95.     return NGX_OK;
  96. }


  99. static ngx_int_t
  100. ‌ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
  101. {
  102.     ngx_http_upstream_rr_peer_data_t  *rrp = data;

  104.     time_t                         now;
  105.     uintptr_t                      m;
  106.     ngx_int_t                      rc, total;
  107.     ngx_uint_t                     i, n, p, many;
  108.     ngx_http_upstream_rr_peer_t   *peer, *best;
  109.     ngx_http_upstream_rr_peers_t  *peers;

  111.     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
  112.                    "get least conn peer, try: %ui", pc->tries);

  114.     if (rrp->peers->single) {
  115.         return ngx_http_upstream_get_round_robin_peer(pc, rrp);
  116.     }

  118.     pc->cached = 0;
  119.     pc->connection = NULL;

  121.     now = ngx_time();

  123.     peers = rrp->peers;

  125.     ngx_http_upstream_rr_peers_wlock(peers);

  127. #if (NGX_HTTP_UPSTREAM_ZONE)
  128.     if (peers->config && rrp->config != *peers->config) {
  129.         goto busy;
  130.     }
  131. #endif

  133.     best = NULL;
  134.     total = 0;

  136. #if (NGX_SUPPRESS_WARN)
  137.     many = 0;
  138.     p = 0;
  139. #endif

  141.     for (peer = peers->peer, i = 0;
  142.          peer;
  143.          peer = peer->next, i++)
  144.     {
  145.         n = i / (8 * sizeof(uintptr_t));
  146.         m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t));

  148.         if (rrp->tried[n] & m) {
  149.             continue;
  150.         }

  152.         if (peer->down) {
  153.             continue;
  154.         }

  156.         if (peer->max_fails
  157.             && peer->fails >= peer->max_fails
  158.             && now - peer->checked <= peer->fail_timeout)
  159.         {
  160.             continue;
  161.         }

  163.         if (peer->max_conns && peer->conns >= peer->max_conns) {
  164.             continue;
  165.         }

  167.         /*
  168.          * select peer with least number of connections; if there are
  169.          * multiple peers with the same number of connections, select
  170.          * based on round-robin
  171.          */

  173.         if (best == NULL
  174.             || peer->conns * best->weight < best->conns * peer->weight)
  175.         {
  176.             best = peer;
  177.             many = 0;
  178.             p = i;

  180.         } else if (peer->conns * best->weight == best->conns * peer->weight) {
  181.             many = 1;
  182.         }
  183.     }

  185.     if (best == NULL) {
  186.         ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0,
  187.                        "get least conn peer, no peer found");

  189.         goto failed;
  190.     }

  192.     if (many) {
  193.         ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0,
  194.                        "get least conn peer, many");

  196.         for (peer = best, i = p;
  197.              peer;
  198.              peer = peer->next, i++)
  199.         {
  200.             n = i / (8 * sizeof(uintptr_t));
  201.             m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t));

  203.             if (rrp->tried[n] & m) {
  204.                 continue;
  205.             }

  207.             if (peer->down) {
  208.                 continue;
  209.             }

  211.             if (peer->conns * best->weight != best->conns * peer->weight) {
  212.                 continue;
  213.             }

  215.             if (peer->max_fails
  216.                 && peer->fails >= peer->max_fails
  217.                 && now - peer->checked <= peer->fail_timeout)
  218.             {
  219.                 continue;
  220.             }

  222.             if (peer->max_conns && peer->conns >= peer->max_conns) {
  223.                 continue;
  224.             }

  226.             peer->current_weight += peer->effective_weight;
  227.             total += peer->effective_weight;

  229.             if (peer->effective_weight < peer->weight) {
  230.                 peer->effective_weight++;
  231.             }

  233.             if (peer->current_weight > best->current_weight) {
  234.                 best = peer;
  235.                 p = i;
  236.             }
  237.         }
  238.     }

  240.     best->current_weight -= total;

  242.     if (now - best->checked > best->fail_timeout) {
  243.         best->checked = now;
  244.     }

  246.     pc->sockaddr = best->sockaddr;
  247.     pc->socklen = best->socklen;
  248.     pc->name = &best->name;

  250.     best->conns++;

  252.     rrp->current = best;
  253.     ngx_http_upstream_rr_peer_ref(peers, best);

  255.     n = p / (8 * sizeof(uintptr_t));
  256.     m = (uintptr_t) 1 << p % (8 * sizeof(uintptr_t));

  258.     rrp->tried[n] |= m;

  260.     ngx_http_upstream_rr_peers_unlock(peers);

  262.     return NGX_OK;

  264. failed:

  266.     if (peers->next) {
  267.         ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0,
  268.                        "get least conn peer, backup servers");

  270.         rrp->peers = peers->next;

  272.         n = (rrp->peers->number + (8 * sizeof(uintptr_t) - 1))
  273.                 / (8 * sizeof(uintptr_t));

  275.         for (i = 0; i < n; i++) {
  276.             rrp->tried[i] = 0;
  277.         }

  279.         ngx_http_upstream_rr_peers_unlock(peers);

  281.         rc = ngx_http_upstream_get_least_conn_peer(pc, rrp);

  283.         if (rc != NGX_BUSY) {
  284.             return rc;
  285.         }

  287.         ngx_http_upstream_rr_peers_wlock(peers);
  288.     }

  290. #if (NGX_HTTP_UPSTREAM_ZONE)
  291. busy:
  292. #endif

  294.     ngx_http_upstream_rr_peers_unlock(peers);

  296.     pc->name = peers->name;

  298.     return NGX_BUSY;
  299. }


  302. static char *
  303. ‌ngx_http_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
  304. {
  305.     ngx_http_upstream_srv_conf_t  *uscf;

  307.     uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module);

  309.     if (uscf->peer.init_upstream) {
  310.         ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
  311.                            "load balancing method redefined");
  312.     }

  314.     uscf->peer.init_upstream = ngx_http_upstream_init_least_conn;

  316.     uscf->flags = NGX_HTTP_UPSTREAM_CREATE
  317.                   |NGX_HTTP_UPSTREAM_MODIFY
  318.                   |NGX_HTTP_UPSTREAM_WEIGHT
  319.                   |NGX_HTTP_UPSTREAM_MAX_CONNS
  320.                   |NGX_HTTP_UPSTREAM_MAX_FAILS
  321.                   |NGX_HTTP_UPSTREAM_FAIL_TIMEOUT
  322.                   |NGX_HTTP_UPSTREAM_DOWN
  323.                   |NGX_HTTP_UPSTREAM_BACKUP;

  325.     return NGX_CONF_OK;
  326. }

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