release/src/router/nginx/src/http/modules/ngx_http_degradation_module.c

   1
   2 /*
   3  * Copyright (C) Igor Sysoev
   4  * Copyright (C) Nginx, Inc.
   5  */
   6
   7
   8 #include <ngx_config.h>
   9 #include <ngx_core.h>
  10 #include <ngx_http.h>
  11
  12
  13 typedef struct {
  14     size_t      sbrk_size;
  15 } ngx_http_degradation_main_conf_t;
  16
  17
  18 typedef struct {
  19     ngx_uint_t  degrade;
  20 } ngx_http_degradation_loc_conf_t;
  21
  22
  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 };
  28
  29
  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);
  37
  38
  39 static ngx_command_t  ngx_http_degradation_commands[] = {
  40
  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 },
  47
  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 },
  54
  55       ngx_null_command
  56 };
  57
  58
  59 static ngx_http_module_t  ngx_http_degradation_module_ctx = {
  60     NULL,                                  /* preconfiguration */
  61     ngx_http_degradation_init,             /* postconfiguration */
  62
  63     ngx_http_degradation_create_main_conf, /* create main configuration */
  64     NULL,                                  /* init main configuration */
  65
  66     NULL,                                  /* create server configuration */
  67     NULL,                                  /* merge server configuration */
  68
  69     ngx_http_degradation_create_loc_conf,  /* create location configuration */
  70     ngx_http_degradation_merge_loc_conf    /* merge location configuration */
  71 };
  72
  73
  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 };
  88
  89
  90 static ngx_int_t
  91 ngx_http_degradation_handler(ngx_http_request_t *r)
  92 {
  93     ngx_http_degradation_loc_conf_t  *dlcf;
  94
  95     dlcf = ngx_http_get_module_loc_conf(r, ngx_http_degradation_module);
  96
  97     if (dlcf->degrade && ngx_http_degraded(r)) {
  98         return dlcf->degrade;
  99     }
 100
 101     return NGX_DECLINED;
 102 }
 103
 104
 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;
 113
 114     dmcf = ngx_http_get_module_main_conf(r, ngx_http_degradation_module);
 115
 116     if (dmcf->sbrk_size) {
 117
 118         log = 0;
 119         now = ngx_time();
 120
 121         /* lock mutex */
 122
 123         if (now != sbrk_time) {
 124
 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              */
 131
 132             sbrk_size = (size_t) sbrk(0) - ((uintptr_t) ngx_palloc & ~0x3FFFFF);
 133             sbrk_time = now;
 134             log = 1;
 135         }
 136
 137         /* unlock mutex */
 138
 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             }
 145
 146             return 1;
 147         }
 148     }
 149
 150     return 0;
 151 }
 152
 153
 154 static void *
 155 ngx_http_degradation_create_main_conf(ngx_conf_t *cf)
 156 {
 157     ngx_http_degradation_main_conf_t  *dmcf;
 158
 159     dmcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_degradation_main_conf_t));
 160     if (dmcf == NULL) {
 161         return NULL;
 162     }
 163
 164     return dmcf;
 165 }
 166
 167
 168 static void *
 169 ngx_http_degradation_create_loc_conf(ngx_conf_t *cf)
 170 {
 171     ngx_http_degradation_loc_conf_t  *conf;
 172
 173     conf = ngx_palloc(cf->pool, sizeof(ngx_http_degradation_loc_conf_t));
 174     if (conf == NULL) {
 175         return NULL;
 176     }
 177
 178     conf->degrade = NGX_CONF_UNSET_UINT;
 179
 180     return conf;
 181 }
 182
 183
 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;
 189
 190     ngx_conf_merge_uint_value(conf->degrade, prev->degrade, 0);
 191
 192     return NGX_CONF_OK;
 193 }
 194
 195
 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;
 200
 201     ngx_str_t  *value, s;
 202
 203     value = cf->args->elts;
 204
 205     if (ngx_strncmp(value[1].data, "sbrk=", 5) == 0) {
 206
 207         s.len = value[1].len - 5;
 208         s.data = value[1].data + 5;
 209
 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         }
 216
 217         return NGX_CONF_OK;
 218     }
 219
 220     ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
 221                        "invalid parameter \"%V\"", &value[1]);
 222
 223     return NGX_CONF_ERROR;
 224 }
 225
 226
 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;
 232
 233     cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);
 234
 235     h = ngx_array_push(&cmcf->phases[NGX_HTTP_PREACCESS_PHASE].handlers);
 236     if (h == NULL) {
 237         return NGX_ERROR;
 238     }
 239
 240     *h = ngx_http_degradation_handler;
 241
 242     return NGX_OK;
 243 }