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    1. 站長(zhǎng)資訊網(wǎng)
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      Nginx解讀內(nèi)置非默認(rèn)模塊 ngx_http_stub_status_module

      1 Background

      http://nginx.org/en/docs/http/ngx_http_stub_status_module.html

      ngx_http_stub_status_module 是一個(gè) Nginx 的內(nèi)置 HTTP 模塊,該模塊可以提供 Nginx 的狀態(tài)信息。默認(rèn)情況下這個(gè)模塊是不被編譯進(jìn)來(lái)的,所以在編譯 Nginx 時(shí)要指定加載該模塊:

      --with-http_stub_status_module

      為什么拿它做例子?因?yàn)樗彩莻€(gè)足夠短小精悍的模塊,是一個(gè)典型 handler 模塊。那么以后我們講解模塊的過(guò)程,都是:

      1. 簡(jiǎn)要的介紹
      2. 使用的實(shí)例
      3. 指令介紹
      4. 源碼分析

      2 Simple example

      location /nginx_status {    stub_status on;    access_log   off;
      access_log /usr/local/nginx/logs/status.log;    #日志 allow SOME.IP.ADD.RESS; deny all; }

      我們假設(shè)你是在本機(jī)上實(shí)驗(yàn),并且開(kāi)啟的是 80 端口,那么在瀏覽器中輸入:

      http://localhost/nginx_status  

      會(huì)看到這樣的信息:

      Active connections: 291  server accepts handled requests    16630948 16630948 31070465  Reading: 6 Writing: 179 Waiting: 106  

      其含義很容易理解:

      • 第一行
        • 當(dāng)前的活躍連接數(shù):291
      • 第二行
        • 服務(wù)器已接受的連接數(shù):16630948(accepted connection #)
        • 服務(wù)器已處理的連接數(shù):16630948(handled connection #)
        • 服務(wù)器已處理的請(qǐng)求:31070465(可以算出,平均每個(gè)連接有 1.8 個(gè)請(qǐng)求)(handled connection #)
      • 第三行
        • Reading – Nginx 讀取的請(qǐng)求頭次數(shù)為 6;
        • Writting – Nginx 讀取請(qǐng)求體、處理請(qǐng)求并發(fā)送響應(yīng)給客戶端的次數(shù)為 179;
        • Waiting – 當(dāng)前活動(dòng)的長(zhǎng)連接數(shù):106。

      Nginx 官方的解釋如下:

      • active connections – number of all open connections
      • server accepts handled requests – nginx accepted 16630948 connections, handled 16630948 connections (no one was closed just it was accepted), and handles 31070465 requests (1.8 requests per connection)
      • reading – nginx reads request header
      • writing – nginx reads request body, processes request, or writes response to a client
      • waiting – keep-alive connections, actually it is active – (reading + writing)

      3 Directives

      這個(gè)模塊中的唯一一個(gè)指令,是:

      stub_status  
      • 語(yǔ)法:stub_status on
      • 作用域:location
      • 功能:統(tǒng)計(jì)這個(gè) location 的信息。

      4 Source analysis

      先看完整代碼:

      /*   * Copyright (C) Igor Sysoev   * Copyright (C) Nginx, Inc.   */      #include <ngx_config.h>  #include <ngx_core.h>  #include <ngx_http.h>      static char *ngx_http_set_status(ngx_conf_t *cf, ngx_command_t *cmd,                                   void *conf);    static ngx_command_t  ngx_http_status_commands[] = {        { ngx_string("stub_status"),        NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,        ngx_http_set_status,        0,        0,        NULL },          ngx_null_command  };        static ngx_http_module_t  ngx_http_stub_status_module_ctx = {      NULL,                                  /* preconfiguration */      NULL,                                  /* postconfiguration */        NULL,                                  /* create main configuration */      NULL,                                  /* init main configuration */        NULL,                                  /* create server configuration */      NULL,                                  /* merge server configuration */        NULL,                                  /* create location configuration */      NULL                                   /* merge location configuration */  };      ngx_module_t  ngx_http_stub_status_module = {      NGX_MODULE_V1,      &ngx_http_stub_status_module_ctx,      /* module context */      ngx_http_status_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_status_handler(ngx_http_request_t *r)  {      size_t             size;      ngx_int_t          rc;      ngx_buf_t         *b;      ngx_chain_t        out;      ngx_atomic_int_t   ap, hn, ac, rq, rd, wr;        if (r->method != NGX_HTTP_GET && r->method != NGX_HTTP_HEAD) {          return NGX_HTTP_NOT_ALLOWED;      }        rc = ngx_http_discard_request_body(r);        if (rc != NGX_OK) {          return rc;      }        ngx_str_set(&r->headers_out.content_type, "text/plain");        if (r->method == NGX_HTTP_HEAD) {          r->headers_out.status = NGX_HTTP_OK;            rc = ngx_http_send_header(r);            if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) {              return rc;          }      }        size = sizeof("Active connections:  n") + NGX_ATOMIC_T_LEN             + sizeof("server accepts handled requestsn") - 1             + 6 + 3 * NGX_ATOMIC_T_LEN             + sizeof("Reading:  Writing:  Waiting:  n") + 3 * NGX_ATOMIC_T_LEN;        b = ngx_create_temp_buf(r->pool, size);      if (b == NULL) {          return NGX_HTTP_INTERNAL_SERVER_ERROR;      }        out.buf = b;      out.next = NULL;        ap = *ngx_stat_accepted;      hn = *ngx_stat_handled;      ac = *ngx_stat_active;      rq = *ngx_stat_requests;      rd = *ngx_stat_reading;      wr = *ngx_stat_writing;        b->last = ngx_sprintf(b->last, "Active connections: %uA n", ac);        b->last = ngx_cpymem(b->last, "server accepts handled requestsn",                           sizeof("server accepts handled requestsn") - 1);        b->last = ngx_sprintf(b->last, " %uA %uA %uA n", ap, hn, rq);        b->last = ngx_sprintf(b->last, "Reading: %uA Writing: %uA Waiting: %uA n",                            rd, wr, ac - (rd + wr));        r->headers_out.status = NGX_HTTP_OK;      r->headers_out.content_length_n = b->last - b->pos;        b->last_buf = 1;        rc = ngx_http_send_header(r);        if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) {          return rc;      }        return ngx_http_output_filter(r, &out);  }      static char *ngx_http_set_status(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)  {      ngx_http_core_loc_conf_t  *clcf;        clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);      clcf->handler = ngx_http_status_handler;        return NGX_CONF_OK;  }  

      的確夠短小精悍吧?關(guān)鍵在于 Nginx 提供的模塊擴(kuò)展方式比較好,讓你可以少寫(xiě)一些代碼(NDK 可以讓你寫(xiě)的更少,這是后話)。

      4.1 模塊定義 ngx_http_stub_status_module

      ngx_module_t  ngx_http_stub_status_module = {      NGX_MODULE_V1,      &ngx_http_stub_status_module_ctx,      /* module context */      ngx_http_status_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  };  

      與此前介紹的 ngx_http_hello_world_module 并無(wú)本質(zhì)區(qū)別。

      4.2 命令集定義 ngx_http_status_commands

      static ngx_command_t  ngx_http_status_commands[] = {        { ngx_string("stub_status"),        NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,        ngx_http_set_status,        0,        0,        NULL },          ngx_null_command  };  

      命令集定義如上,得到如下信息:

      • name:stub_status
      • type:server conf、location conf、conf flag,其中最后一個(gè)比較陌生,相似的取值有:
        • #define NGX_CONF_ARGS_NUMBER 0x000000ff
        • #define NGX_CONF_BLOCK 0x00000100
        • #define NGX_CONF_FLAG 0x00000200
        • #define NGX_CONF_ANY 0x00000400
        • #define NGX_CONF_1MORE 0x00000800
        • #define NGX_CONF_2MORE 0x00001000
        • #define NGX_CONF_MULTI 0x00002000
      • set:ngx_http_set_status

      下面解釋下一些 types:

      4.2.1 NGX_CONF_XXX

      以下宏定義來(lái)自 ngx_conf_file.h:

      #define NGX_CONF_NOARGS      0x00000001 // 命令不接受參數(shù)  #define NGX_CONF_TAKE1       0x00000002 // 命令攜帶1個(gè)參數(shù)  #define NGX_CONF_TAKE2       0x00000004 // 命令攜帶2個(gè)參數(shù)  #define NGX_CONF_TAKE3       0x00000008 // 命令攜帶3個(gè)參數(shù)  #define NGX_CONF_TAKE4       0x00000010 // 命令攜帶4個(gè)參數(shù)  #define NGX_CONF_TAKE5       0x00000020 // 命令攜帶5個(gè)參數(shù)  #define NGX_CONF_TAKE6       0x00000040 // 命令攜帶6個(gè)參數(shù)  #define NGX_CONF_TAKE7       0x00000080 // 命令攜帶7個(gè)參數(shù)    #define NGX_CONF_TAKE12      (NGX_CONF_TAKE1|NGX_CONF_TAKE2) // 命令攜帶1個(gè)或2個(gè)參數(shù)  #define NGX_CONF_TAKE13      (NGX_CONF_TAKE1|NGX_CONF_TAKE3) // 命令攜帶1個(gè)或3個(gè)參數(shù)  #define NGX_CONF_TAKE23      (NGX_CONF_TAKE2|NGX_CONF_TAKE3) // 命令攜帶2個(gè)或3個(gè)參數(shù)  #define NGX_CONF_TAKE123     (NGX_CONF_TAKE1|NGX_CONF_TAKE2|NGX_CONF_TAKE3) // 命令攜帶1個(gè)、2個(gè)或3個(gè)參數(shù)  #define NGX_CONF_TAKE1234    (NGX_CONF_TAKE1|NGX_CONF_TAKE2|NGX_CONF_TAKE3|NGX_CONF_TAKE4) // 命令攜帶1個(gè)、2個(gè)、3個(gè)或4個(gè)參數(shù)    #define NGX_CONF_ARGS_NUMBER 0x000000ff // 命令  #define NGX_CONF_BLOCK       0x00000100 // 塊域,后面跟 {…},比如 server {...}  #define NGX_CONF_FLAG        0x00000200 // 命令接受“on|off”參數(shù)  #define NGX_CONF_ANY         0x00000400  #define NGX_CONF_1MORE       0x00000800 // 命令攜帶至少1個(gè)參數(shù)  #define NGX_CONF_2MORE       0x00001000 // 命令攜帶至少2個(gè)參數(shù)  #define NGX_CONF_MULTI       0x00002000 // 命令攜帶多個(gè)參數(shù)  

      4.3 上下文定義 ngx_http_stub_status_module_ctx

      static ngx_http_module_t  ngx_http_stub_status_module_ctx = {      NULL,                                  /* preconfiguration */      NULL,                                  /* postconfiguration */        NULL,                                  /* create main configuration */      NULL,                                  /* init main configuration */        NULL,                                  /* create server configuration */      NULL,                                  /* merge server configuration */        NULL,                                  /* create location configuration */      NULL                                   /* merge location configuration */  };  

      這個(gè)都是 NULL,夠簡(jiǎn)單,無(wú)話可說(shuō)了??

      4.4 命令設(shè)置函數(shù) ngx_http_set_status

      static char *ngx_http_set_status(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) {        ngx_http_core_loc_conf_t  *clcf;        clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);      clcf->handler = ngx_http_status_handler;        return NGX_CONF_OK;  }  

      和 ngx_http_hello_world_module 對(duì)比下:

      static char* ngx_http_hello_world(ngx_conf_t* cf, ngx_command_t* cmd, void* conf) {        ngx_http_core_loc_conf_t* clcf;        clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);      clcf->handler = ngx_http_hello_world_handler;        ngx_conf_set_str_slot(cf, cmd, conf);        return NGX_CONF_OK;  }  

      唯一的區(qū)別,就是 ngx_http_hello_world_module 多了一句 ngx_conf_set_str_slot。這個(gè)先留做一個(gè)問(wèn)題,后面會(huì)介紹,暫時(shí)與關(guān)鍵主題無(wú)關(guān)。

      4.5 命令處理函數(shù) ngx_http_status_handler

      static ngx_int_t ngx_http_status_handler(ngx_http_request_t *r)  {      size_t             size;      ngx_int_t          rc;      ngx_buf_t         *b;      ngx_chain_t        out;      ngx_atomic_int_t   ap, hn, ac, rq, rd, wr;  

      這個(gè)模塊要求接受的請(qǐng)求類是 GET、HEAD,其他類型的請(qǐng)求會(huì)被拒絕。

          if (r->method != NGX_HTTP_GET && r->method != NGX_HTTP_HEAD) {          return NGX_HTTP_NOT_ALLOWED;      }  

      放棄請(qǐng)求體,因?yàn)檫@個(gè)模塊用不上。

          rc = ngx_http_discard_request_body(r);        if (rc != NGX_OK) {          return rc;      }  

      如果請(qǐng)求是 HEAD 類型的,則直接設(shè)置響應(yīng)頭的 content_type、status 字段,并發(fā)送響應(yīng)頭。

          ngx_str_set(&r->headers_out.content_type, "text/plain");        if (r->method == NGX_HTTP_HEAD) {          r->headers_out.status = NGX_HTTP_OK;            rc = ngx_http_send_header(r);            if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) {              return rc;          }      }  

      創(chuàng)建一個(gè)緩沖區(qū),向緩沖區(qū)寫(xiě)入我們上面在瀏覽器中看到的東西。

          size = sizeof("Active connections:  n") + NGX_ATOMIC_T_LEN             + sizeof("server accepts handled requestsn") - 1             + 6 + 3 * NGX_ATOMIC_T_LEN             + sizeof("Reading:  Writing:  Waiting:  n") + 3 * NGX_ATOMIC_T_LEN;        b = ngx_create_temp_buf(r->pool, size);      if (b == NULL) {          return NGX_HTTP_INTERNAL_SERVER_ERROR;      }        out.buf = b;      out.next = NULL;        ap = *ngx_stat_accepted;      hn = *ngx_stat_handled;      ac = *ngx_stat_active;      rq = *ngx_stat_requests;      rd = *ngx_stat_reading;      wr = *ngx_stat_writing;        // 封裝了 sprintf      b->last = ngx_sprintf(b->last, "Active connections: %uA n", ac);        // 封裝了 memcpy      b->last = ngx_cpymem(b->last, "server accepts handled requestsn",                           sizeof("server accepts handled requestsn") - 1);        b->last = ngx_sprintf(b->last, " %uA %uA %uA n", ap, hn, rq);        b->last = ngx_sprintf(b->last, "Reading: %uA Writing: %uA Waiting: %uA n",                            rd, wr, ac - (rd + wr));  

      緩沖區(qū)寫(xiě)完了。然后設(shè)置下響應(yīng)頭的 status、content_length_n(還記得嗎?b->last – b->pos 剛好是緩沖區(qū)的第二個(gè)區(qū)域,是已寫(xiě)入數(shù)據(jù)部分。)

          r->headers_out.status = NGX_HTTP_OK;      r->headers_out.content_length_n = b->last - b->pos;        b->last_buf = 1;  

      發(fā)送響應(yīng)頭。

          rc = ngx_http_send_header(r);        if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) {          return rc;      }  

      filter。

          return ngx_http_output_filter(r, &out);  }  
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