Nginx interpretation built-in non-default module ngx_http_stub_status_module

1 Background

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

The Ngx_http_stub_status_module is an nginx built-in HTTP module that provides status information for Nginx. This module is not compiled by default, so it is necessary to specify the module to be loaded when compiling Nginx:

--with-http_stub_status_module

Why do you take it as an example? Because it is also a short enough module, is a typical handler module. Then we will explain the module process, are:

1. A Brief introduction
2. Examples of Use
3. Instruction Introduction
4. SOURCE Analysis

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;}

We assume that you are experimenting on this machine and that you are opening port 80, then enter it in the browser:

http://localhost/nginx_status

You will see a message like this:

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

Its meaning is easy to understand:

• First line

  • Current number of active connections: 291

• Second line

  • Number of connections accepted by the server: 16630948 (accepted connection #)
  • Number of connections that the server has processed: 16630948 (handled connection #)
  • Requests processed by the server: 31070465 (can be calculated, average 1.8 requests per connection) (Handled connection #)

• Third line

  • The number of Reading–nginx read Requests is 6;
  • The number of times the Writting–nginx reads the request body, processes the request and sends a response to the client is 179;
  • waiting– the number of long connections currently active: 106.

Nginx official explanation is as follows:

• active connections–number of all open connections
• server accepts handled requests–nginx accepted 16630948 connections, handled 16630948 connections (no one is 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

The only instruction in this module is:

stub_status

• Grammar:stub_status on
• Scope: Location
• Function: Statistics The location of the information.

4 Source Analysis

Look at the full code first:

/* Copyright (c) Igor Sysoev * Copyright (c) Nginx, Inc. */#include <ngx_config.h> #include <ngx_core.h> #incl                                 Ude <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|n Gx_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 */NUL L,/* init main configuration */NULL,/* Create Serv                          ER configuration */null,/* Merge server configuration */null,        /* Create location Configuration */NULL/* Merge location configuration */}; ngx_module_t Ngx_http_stub_status_module = {NGX_MODULE_V1, &AMP;NGX_HTTP_STUB_STATUS_MODULE_CTX,/* Module CO ntext */ngx_http_status_commands,/* Module directives */Ngx_http_module,/* mo  Dule type */NULL,/* INIT master */NULL,/* init module */NULL,/* INIT process */NULL,/* init Thread */NULL,/* EXIT thread */NULL,/* Exit PR Ocess */NULL,/* Exit Master */ngx_module_v1_padding};static ngx_int_t ngx_http_s    Tatus_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 requests\ N ")-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 requests\n", sizeof ("server accepts ha    ndled requests\n ")-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-(R    D + 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;}

Pretty short, huh? The key is that Nginx provides a good way to extend the module, so you can write less code (NDK can let you write less, this is something).

4.1 Module Definition 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};

There is no essential difference from the Ngx_http_hello_world_module described earlier.

4.2 Command Set definition 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};

command set definition as above, get the following information:

• Name:stub_status
• Type:server conf, location conf, Conf flag, one of the last relatively unfamiliar, similar values are:

  • #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

Here are some explanations of types:

4.2.1 Ngx_conf_xxx

The following macro definitions are from Ngx_conf_file.h:

#define NGX_CONF_NOARGS 0x00000001//command does not accept parameter # define NGX_CONF_TAKE1 0x00000002//Command carries 1 parameters # define Ngx_conf_take 2 0x00000004//Command carries 2 parameters # define NGX_CONF_TAKE3 0x00000008//Command carries 3 parameters # define NGX_CONF_TAKE4 0x00000010/ /Command carry 4 parameters # define NGX_CONF_TAKE5 0x00000020//Command carry 5 Parameters # define NGX_CONF_TAKE6 0x00000040//Command carry 6 parameters # define NG X_conf_take7 0x00000080//Command carries 7 parameter # define NGX_CONF_TAKE12 (ngx_conf_take1| NGX_CONF_TAKE2)//command carries 1 or 2 parameter # define NGX_CONF_TAKE13 (ngx_conf_take1| NGX_CONF_TAKE3)//command carries 1 or 3 parameter # define NGX_CONF_TAKE23 (ngx_conf_take2| NGX_CONF_TAKE3)//command carries 2 or 3 parameter # define NGX_CONF_TAKE123 (ngx_conf_take1| ngx_conf_take2| NGX_CONF_TAKE3)//command carries 1, 2 or 3 parameter # define NGX_CONF_TAKE1234 (ngx_conf_take1| ngx_conf_take2| ngx_conf_take3| NGX_CONF_TAKE4)//Command carry 1, 2, 3 or 4 parameter # define Ngx_conf_args_number 0x000000ff//Command # define Ngx_conf_block 0x00000100/ /block field, followed by {...}, such as server {...} #define NGX_CONF_FLAG 0x00000200//Command accepts "on|off "parameter # define Ngx_conf_any 0x00000400#define ngx_conf_1more 0x00000800//Command carry at least 1 parameters # define Ngx_conf_2more 0x00001000//Command carries at least 2 parameters # define NGX_CONF_MULTI 0x00002000//Command carry multiple parameters

4.3 Context definition 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 */};

This is all NULL, simple enough, speechless??

4.4 Command Set function 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;}

In contrast to the Ngx_http_hello_world_module:

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;}

The only difference is that ngx_http_hello_world_module a more ngx_conf_set_str_slot. This is left to do a question, the following will be introduced, for the time being irrelevant to the key topic.

4.5 Command handling function 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;

This module requires the accepted request class to be, and other types of requests to be rejected.

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

Discard the request body, because this module is not used.

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

If the request is of the head type, the Content_Type, status field of the response header is set directly, and the response header is sent.

    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;        }    }

Create a buffer and write to the buffer what we see above in the browser.

    size = sizeof ("Active connections: \ n") + Ngx_atomic_t_len + sizeof ("server accepts handled requests\n")-    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;    Encapsulated sprintf b->last = ngx_sprintf (b->last, "Active connections:%ua \ n", AC); Encapsulates the memcpy b->last = Ngx_cpymem (b->last, "server accepts handled requests\n", sizeof ("    Server accepts handled requests\n ")-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)); 

The buffer is finished. Then set the status of the response header, Content_length_n (remember?) The B->last-b->pos is just the second area of the buffer, which is the part of the data that has been written. ）

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

Sends a response header.

    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);}

5 Reference

1. Http://wiki.nginx.org/HttpStubStatusModule
2. http://blog.csdn.net/lengzijian/article/details/7356064
3. Http://www.codinglabs.org/html/intro-of-nginx-module-development.html

Nginx interpretation built-in non-default module ngx_http_stub_status_module