nginx初始化，main函数

前面的文章已经分析了nginx的模块化结构，下面开始进入nginx的初始化过程，首先应该从main函数开始：

源文件：Nginx.c

（1）调用ngx_get_options函数解析传进来的命令参数

（2）调用ngx_time_init初始化时间相关的数据

（3）调用ngx_log_init初始化日志相关

（4）初始化全局变量ngx_cycle，将其置0，并为其创建内存池

（5）调用ngx_save_argv保存命令参数至一些全局的变量

（6）调用ngx_process_options函数初始化全局变量ngx_cycle的conf_file，conf_param等参数

（7）调用ngx_os_init函数初始化与操作系统相关的一些信息，例如页大小，最大连接数等等。

（8）调用ngx_crc32_table_init初始化CRC表

（9）调用ngx_add_inherited_sockets继承socket，解析环境变量NGINX_VAR=“NGINX”中的socket，并将它们保存到ngx_cycle.listening数组中去，调用ngx_set_inherited_sockets函数逐一对ngx_cycle.listening中的元素进行设置，

（10）循环遍历全局变量ngx_modules，为其中的每一个模块的index域赋值

（11）调用ngx_init_cycle初始化ngx_cycle变量

（12）如果有信号，那么调用ngx_signal_process函数进行处理

（13）调用ngx_init_signals函数初始化与信号相关的东西

（14）调用ngx_daemon实现守护进程

（15）调用ngx_create_pidfile函数创建进程记录文件

（16）最后进入主循环，一般情况下都是调用ngx_master_process_cycle进入master以及worker方式

int ngx_cdeclmain(int argc, char *const *argv){    ngx_int_t         i;    ngx_log_t        *log;    ngx_cycle_t      *cycle, init_cycle;    ngx_core_conf_t  *ccf;    ngx_debug_init();    if (ngx_strerror_init() != NGX_OK) {        return 1;    }    if (ngx_get_options(argc, argv) != NGX_OK) {//解析传递进来的参数        return 1;    }    if (ngx_show_version) {        ngx_write_stderr("nginx version: " NGINX_VER NGX_LINEFEED);        if (ngx_show_help) {            ngx_write_stderr(                "Usage: nginx [-?hvVtq] [-s signal] [-c filename] "                             "[-p prefix] [-g directives]" NGX_LINEFEED                             NGX_LINEFEED                "Options:" NGX_LINEFEED                "  -?,-h         : this help" NGX_LINEFEED                "  -v            : show version and exit" NGX_LINEFEED                "  -V            : show version and configure options then exit"                                   NGX_LINEFEED                "  -t            : test configuration and exit" NGX_LINEFEED                "  -q            : suppress non-error messages "                                   "during configuration testing" NGX_LINEFEED                "  -s signal     : send signal to a master process: "                                   "stop, quit, reopen, reload" NGX_LINEFEED#ifdef NGX_PREFIX                "  -p prefix     : set prefix path (default: "                                   NGX_PREFIX ")" NGX_LINEFEED#else                "  -p prefix     : set prefix path (default: NONE)" NGX_LINEFEED#endif                "  -c filename   : set configuration file (default: "                                   NGX_CONF_PATH ")" NGX_LINEFEED                "  -g directives : set global directives out of configuration "                                   "file" NGX_LINEFEED NGX_LINEFEED                );        }        if (ngx_show_configure) {            ngx_write_stderr(#ifdef NGX_COMPILER                "built by " NGX_COMPILER NGX_LINEFEED#endif#if (NGX_SSL)#ifdef SSL_CTRL_SET_TLSEXT_HOSTNAME                "TLS SNI support enabled" NGX_LINEFEED#else                "TLS SNI support disabled" NGX_LINEFEED#endif#endif                "configure arguments:" NGX_CONFIGURE NGX_LINEFEED);        }        if (!ngx_test_config) {            return 0;        }    }    /* TODO */ ngx_max_sockets = -1;    ngx_time_init();#if (NGX_PCRE)    ngx_regex_init();#endif    ngx_pid = ngx_getpid();    log = ngx_log_init(ngx_prefix);    if (log == NULL) {        return 1;    }    /* STUB */#if (NGX_OPENSSL)    ngx_ssl_init(log);#endif    /*     * init_cycle->log is required for signal handlers and     * ngx_process_options()     */    ngx_memzero(&init_cycle, sizeof(ngx_cycle_t));    init_cycle.log = log;    ngx_cycle = &init_cycle;//初始化全局变量    init_cycle.pool = ngx_create_pool(1024, log);    if (init_cycle.pool == NULL) {        return 1;    }    if (ngx_save_argv(&init_cycle, argc, argv) != NGX_OK) {        return 1;    }    if (ngx_process_options(&init_cycle) != NGX_OK) {        return 1;    }    if (ngx_os_init(log) != NGX_OK) {        return 1;    }    /*     * ngx_crc32_table_init() requires ngx_cacheline_size set in ngx_os_init()     */    if (ngx_crc32_table_init() != NGX_OK) {        return 1;    }    if (ngx_add_inherited_sockets(&init_cycle) != NGX_OK) {        return 1;    }    ngx_max_module = 0;    for (i = 0; ngx_modules[i]; i++) {        ngx_modules[i]->index = ngx_max_module++;    }    cycle = ngx_init_cycle(&init_cycle);    if (cycle == NULL) {        if (ngx_test_config) {            ngx_log_stderr(0, "configuration file %s test failed",                           init_cycle.conf_file.data);        }        return 1;    }    if (ngx_test_config) {        if (!ngx_quiet_mode) {            ngx_log_stderr(0, "configuration file %s test is successful",                           cycle->conf_file.data);        }        return 0;    }    if (ngx_signal) {        return ngx_signal_process(cycle, ngx_signal);    }    ngx_os_status(cycle->log);    ngx_cycle = cycle;    ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);    if (ccf->master && ngx_process == NGX_PROCESS_SINGLE) {        ngx_process = NGX_PROCESS_MASTER;    }#if !(NGX_WIN32)    if (ngx_init_signals(cycle->log) != NGX_OK) {        return 1;    }    if (!ngx_inherited && ccf->daemon) {        if (ngx_daemon(cycle->log) != NGX_OK) {            return 1;        }        ngx_daemonized = 1;    }    if (ngx_inherited) {        ngx_daemonized = 1;    }#endif    if (ngx_create_pidfile(&ccf->pid, cycle->log) != NGX_OK) {        return 1;    }    if (cycle->log->file->fd != ngx_stderr) {        if (ngx_set_stderr(cycle->log->file->fd) == NGX_FILE_ERROR) {            ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,                          ngx_set_stderr_n " failed");            return 1;        }    }    if (log->file->fd != ngx_stderr) {        if (ngx_close_file(log->file->fd) == NGX_FILE_ERROR) {            ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,                          ngx_close_file_n " built-in log failed");        }    }    ngx_use_stderr = 0;    if (ngx_process == NGX_PROCESS_SINGLE) {        ngx_single_process_cycle(cycle);    } else {        ngx_master_process_cycle(cycle);//进入主循环    }    return 0;}