ngx_add_inherited_sockets函数分析

野性酷女 2022-09-14 00:10 166阅读 0赞

ngx\_add\_inherited\_sockets开始通过getenv获取"NGINX"环境变量，如果是NULL，直接return，通过增加log发现，正常这个值确实是NULL。

NGINX\_VAR环境变量的设置是在平滑升级的时候才设置，nginx所采用的平滑升级能够保证在不中止服务的状况下更新nginx版本，具体需要看下ngx\_exec\_new\_binary函数的实现。

所以ngx\_add\_inherited\_sockets一般情况下用处不大，除非是需要升级nginx。

static ngx_int_t
    ngx_add_inherited_sockets(ngx_cycle_t *cycle) {
        
        u_char *p, *v, *inherited;
        ngx_int_t s;
        ngx_listening_t *ls;
    
        inherited = (u_char *)getenv(NGINX_VAR);
    
        if (inherited == NULL) {
        
            return NGX_OK;
        }
    
        ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0,
                      "using inherited sockets from \"%s\"", inherited);
        if (ngx_array_init(&cycle->listening, cycle->pool, 10,
                           sizeof(ngx_listening_t)) != NGX_OK) {
        
            return NGX_ERROR;
        }
    
        for (p = inherited, v = p; *p; p++) {
        
            if (*p == ':' || *p == ';') {
        
                s = ngx_atoi(v, p - v);
                if (s == NGX_ERROR) {
        
                    ngx_log_error(NGX_LOG_EMERG, cycle->log, 0,
                                  "invalid socket number \"%s\" in " NGINX_VAR
                                  " environment variable, ignoring the rest"
                                  " of the variable",
                                  v);
                    break;
                }
    
                v = p + 1;
    
                ls = ngx_array_push(&cycle->listening);
                if (ls == NULL) {
        
                    return NGX_ERROR;
                }
    
                ngx_memzero(ls, sizeof(ngx_listening_t));
    
                ls->fd = (ngx_socket_t)s;
            }
        }
    
        if (v != p) {
        
            ngx_log_error(NGX_LOG_EMERG, cycle->log, 0,
                          "invalid socket number \"%s\" in " NGINX_VAR
                          " environment variable, ignoring",
                          v);
        }
    
        ngx_inherited = 1;
    
        return ngx_set_inherited_sockets(cycle);
    }

ps找到nginx的进程，然后看nginx的environ也没有什么信息

$ ps -ef | grep nginx
    root      4993  2764  0 12:01 ?        00:00:00 nginx: master process ./sbin/nginx
    hui       5007  4993  0 12:01 ?        00:00:00 nginx: worker process
    
    $ sudo cat /proc/4993/environ 
     process ./sbin/nginx
    
    $ cat /proc/5007/environ 
     process

### 附：nginx中输出log的办法 ###

在nginx的main函数中，每个函数调用前增加log后，在logs/error.log文件中，只能输出到ngx\_log\_redirect\_stderr，因为在这之后的log都被redirect了。

$ sudo cat logs/error.log 
    2021/09/28 11:23:27 [notice] 24632#0: ungx_save_argv
    2021/09/28 11:23:27 [notice] 24632#0: ngx_process_options
    2021/09/28 11:23:27 [notice] 24632#0: ngx_os_init
    2021/09/28 11:23:27 [notice] 24632#0: ngx_crc32_table_init
    2021/09/28 11:23:27 [notice] 24632#0: ngx_slab_sizes_init
    2021/09/28 11:23:27 [notice] 24632#0: ngx_add_inherited_sockets
    2021/09/28 11:23:27 [notice] 24632#0: ngx_preinit_modules
    2021/09/28 11:23:27 [notice] 24632#0: ngx_init_cycle
    2021/09/28 11:23:27 [notice] 24633#0: ngx_log_redirect_stderr

所以要输出全部log，需要在nginx.conf文件中配置log输出路径到`/home/hui/disk4t/media-test/samples/log.txt`，后面的debug是对应的log level。

worker_processes  1;
    error_log /home/hui/disk4t/media-test/samples/log.txt debug;

nginx中的log level有8级

#define NGX_LOG_STDERR            0
    #define NGX_LOG_EMERG             1
    #define NGX_LOG_ALERT             2
    #define NGX_LOG_CRIT              3
    #define NGX_LOG_ERR               4
    #define NGX_LOG_WARN              5
    #define NGX_LOG_NOTICE            6
    #define NGX_LOG_INFO              7
    #define NGX_LOG_DEBUG             8

如果没有在configure的时候带上debug选项，输出的log是很少的，比如启动nginx，就只有下面这几行log

2021/09/28 11:28:32 [notice] 29022#0: using the "epoll" event method
    2021/09/28 11:28:32 [notice] 29022#0: nginx/1.18.0
    2021/09/28 11:28:32 [notice] 29022#0: built by gcc 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)
    2021/09/28 11:28:32 [notice] 29022#0: OS: Linux 5.4.0-81-generic
    2021/09/28 11:28:32 [notice] 29022#0: getrlimit(RLIMIT_NOFILE): 1024:4096
    2021/09/28 11:28:32 [notice] 29023#0: start worker processes
    2021/09/28 11:28:32 [notice] 29023#0: start worker process 29024

加上`--with-debug`选项后，输出log就很多了：

./configure --prefix=/usr/local/nginx  --with-debug --with-http_ssl_module  --add-module=../nginx-rtmp-module  --with-http_flv_module --with-http_mp4_module

$ tail /home/hui/disk4t/media-test/samples/log.txt
    2021/09/28 12:38:53 [debug] 5007#0: *4 free: 000056092AC69560, unused: 0
    2021/09/28 12:38:53 [debug] 5007#0: *4 free: 000056092ACADD60, unused: 2772
    2021/09/28 12:38:53 [debug] 5007#0: *4 free: 000056092AC3B320
    2021/09/28 12:38:53 [debug] 5007#0: *4 hc free: 0000000000000000
    2021/09/28 12:38:53 [debug] 5007#0: *4 hc busy: 0000000000000000 0
    2021/09/28 12:38:53 [debug] 5007#0: *4 reusable connection: 1
    2021/09/28 12:38:53 [debug] 5007#0: *4 event timer add: 3: 65000:962096260
    2021/09/28 12:38:53 [debug] 5007#0: timer delta: 15016
    2021/09/28 12:38:53 [debug] 5007#0: worker cycle
    2021/09/28 12:38:53 [debug] 5007#0: epoll timer: 65000

--------------------

参考

\-[Nginx启动流程之ngx\_add\_inherited\_sockets][Nginx_ngx_add_inherited_sockets]

[Nginx_ngx_add_inherited_sockets]: https://blog.csdn.net/oyw5201314ck/article/details/78394321