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src/http/modules/ngx_http_degradation_module.c - nginx-1.7.10

Global variables defined

Data types defined

Functions defined

Source code


  2. /*
  3. * Copyright (C) Igor Sysoev
  4. * Copyright (C) Nginx, Inc.
  5. */


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


  13. typedef struct {
  14.     size_t      sbrk_size;
  15. ‌} ngx_http_degradation_main_conf_t;


  18. typedef struct {
  19.     ngx_uint_t  degrade;
  20. ‌} ngx_http_degradation_loc_conf_t;


  23. ‌static ngx_conf_enum_t  ngx_http_degrade[] = {
  24.     { ngx_string("204"), 204 },
  25.     { ngx_string("444"), 444 },
  26.     { ngx_null_string, 0 }
  27. };


  30. static void *ngx_http_degradation_create_main_conf(ngx_conf_t *cf);
  31. static void *ngx_http_degradation_create_loc_conf(ngx_conf_t *cf);
  32. static char *ngx_http_degradation_merge_loc_conf(ngx_conf_t *cf, void *parent,
  33.     void *child);
  34. static char *ngx_http_degradation(ngx_conf_t *cf, ngx_command_t *cmd,
  35.     void *conf);
  36. static ngx_int_t ngx_http_degradation_init(ngx_conf_t *cf);


  39. ‌static ngx_command_t  ngx_http_degradation_commands[] = {

  41.     { ngx_string("degradation"),
  42.       NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE1,
  43.       ngx_http_degradation,
  44.       NGX_HTTP_MAIN_CONF_OFFSET,
  45.       0,
  46.       NULL },

  48.     { ngx_string("degrade"),
  49.       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
  50.       ngx_conf_set_enum_slot,
  51.       NGX_HTTP_LOC_CONF_OFFSET,
  52.       offsetof(ngx_http_degradation_loc_conf_t, degrade),
  53.       &ngx_http_degrade },

  55.       ngx_null_command
  56. };


  59. ‌static ngx_http_module_t  ngx_http_degradation_module_ctx = {
  60.     NULL,                                  /* preconfiguration */
  61.     ngx_http_degradation_init,             /* postconfiguration */

  63.     ngx_http_degradation_create_main_conf, /* create main configuration */
  64.     NULL,                                  /* init main configuration */

  66.     NULL,                                  /* create server configuration */
  67.     NULL,                                  /* merge server configuration */

  69.     ngx_http_degradation_create_loc_conf,  /* create location configuration */
  70.     ngx_http_degradation_merge_loc_conf    /* merge location configuration */
  71. };


  74. ‌ngx_module_t  ngx_http_degradation_module = {
  75.     NGX_MODULE_V1,
  76.     &ngx_http_degradation_module_ctx,      /* module context */
  77.     ngx_http_degradation_commands,         /* module directives */
  78.     NGX_HTTP_MODULE,                       /* module type */
  79.     NULL,                                  /* init master */
  80.     NULL,                                  /* init module */
  81.     NULL,                                  /* init process */
  82.     NULL,                                  /* init thread */
  83.     NULL,                                  /* exit thread */
  84.     NULL,                                  /* exit process */
  85.     NULL,                                  /* exit master */
  86.     NGX_MODULE_V1_PADDING
  87. };


  90. static ngx_int_t
  91. ‌ngx_http_degradation_handler(ngx_http_request_t *r)
  92. {
  93.     ngx_http_degradation_loc_conf_t  *dlcf;

  95.     dlcf = ngx_http_get_module_loc_conf(r, ngx_http_degradation_module);

  97.     if (dlcf->degrade && ngx_http_degraded(r)) {
  98.         return dlcf->degrade;
  99.     }

  101.     return NGX_DECLINED;
  102. }


  105. ngx_uint_t
  106. ‌ngx_http_degraded(ngx_http_request_t *r)
  107. {
  108.     time_t                             now;
  109.     ngx_uint_t                         log;
  110.     static size_t                      sbrk_size;
  111.     static time_t                      sbrk_time;
  112.     ngx_http_degradation_main_conf_t  *dmcf;

  114.     dmcf = ngx_http_get_module_main_conf(r, ngx_http_degradation_module);

  116.     if (dmcf->sbrk_size) {

  118.         log = 0;
  119.         now = ngx_time();

  121.         /* lock mutex */

  123.         if (now != sbrk_time) {

  125.             /*
  126.              * ELF/i386 is loaded at 0x08000000, 128M
  127.              * ELF/amd64 is loaded at 0x00400000, 4M
  128.              *
  129.              * use a function address to subtract the loading address
  130.              */

  132.             sbrk_size = (size_t) sbrk(0) - ((uintptr_t) ngx_palloc & ~0x3FFFFF);
  133.             sbrk_time = now;
  134.             log = 1;
  135.         }

  137.         /* unlock mutex */

  139.         if (sbrk_size >= dmcf->sbrk_size) {
  140.             if (log) {
  141.                 ngx_log_error(NGX_LOG_NOTICE, r->connection->log, 0,
  142.                               "degradation sbrk:%uzM",
  143.                               sbrk_size / (1024 * 1024));
  144.             }

  146.             return 1;
  147.         }
  148.     }

  150.     return 0;
  151. }


  154. static void *
  155. ‌ngx_http_degradation_create_main_conf(ngx_conf_t *cf)
  156. {
  157.     ngx_http_degradation_main_conf_t  *dmcf;

  159.     dmcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_degradation_main_conf_t));
  160.     if (dmcf == NULL) {
  161.         return NULL;
  162.     }

  164.     return dmcf;
  165. }


  168. static void *
  169. ‌ngx_http_degradation_create_loc_conf(ngx_conf_t *cf)
  170. {
  171.     ngx_http_degradation_loc_conf_t  *conf;

  173.     conf = ngx_palloc(cf->pool, sizeof(ngx_http_degradation_loc_conf_t));
  174.     if (conf == NULL) {
  175.         return NULL;
  176.     }

  178.     conf->degrade = NGX_CONF_UNSET_UINT;

  180.     return conf;
  181. }


  184. static char *
  185. ‌ngx_http_degradation_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
  186. {
  187.     ngx_http_degradation_loc_conf_t  *prev = parent;
  188.     ngx_http_degradation_loc_conf_t  *conf = child;

  190.     ngx_conf_merge_uint_value(conf->degrade, prev->degrade, 0);

  192.     return NGX_CONF_OK;
  193. }


  196. static char *
  197. ‌ngx_http_degradation(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
  198. {
  199.     ngx_http_degradation_main_conf_t  *dmcf = conf;

  201.     ngx_str_t  *value, s;

  203.     value = cf->args->elts;

  205.     if (ngx_strncmp(value[1].data, "sbrk=", 5) == 0) {

  207.         s.len = value[1].len - 5;
  208.         s.data = value[1].data + 5;

  210.         dmcf->sbrk_size = ngx_parse_size(&s);
  211.         if (dmcf->sbrk_size == (size_t) NGX_ERROR) {
  212.             ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
  213.                                "invalid sbrk size \"%V\"", &value[1]);
  214.             return NGX_CONF_ERROR;
  215.         }

  217.         return NGX_CONF_OK;
  218.     }

  220.     ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
  221.                        "invalid parameter \"%V\"", &value[1]);

  223.     return NGX_CONF_ERROR;
  224. }


  227. static ngx_int_t
  228. ‌ngx_http_degradation_init(ngx_conf_t *cf)
  229. {
  230.     ngx_http_handler_pt        *h;
  231.     ngx_http_core_main_conf_t  *cmcf;

  233.     cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);

  235.     h = ngx_array_push(&cmcf->phases[NGX_HTTP_PREACCESS_PHASE].handlers);
  236.     if (h == NULL) {
  237.         return NGX_ERROR;
  238.     }

  240.     *h = ngx_http_degradation_handler;

  242.     return NGX_OK;
  243. }

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