Nginx main()源码分析

int ngx_cdecl
main(int argc, char *const *argv)
{
    ngx_buf_t        *b;
    ngx_log_t        *log;
    ngx_uint_t        i;
    ngx_cycle_t      *cycle, init_cycle;
    ngx_conf_dump_t  *cd;
    ngx_core_conf_t  *ccf;

    ngx_debug_init();

    if (ngx_strerror_init() != NGX_OK) {
        return 1;
    }

    //解析命令行参数
    if (ngx_get_options(argc, argv) != NGX_OK) {
        return 1;
    }

    //版本？？？
    if (ngx_show_version) {
        ngx_show_version_info();

        if (!ngx_test_config) {
            return 0;
        }
    }

    /* TODO */ ngx_max_sockets = -1;

    //初始化并更新时间
    ngx_time_init();

#if (NGX_PCRE)
    //PCRE初始化
    ngx_regex_init();
#endif

    //获取进程pid
    ngx_pid = ngx_getpid();
    ngx_parent = ngx_getppid();
    
    //初始化log
    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()
     */

    //初始化init_cycle全局变量
    ngx_memzero(&init_cycle, sizeof(ngx_cycle_t));
    init_cycle.log = log;
    ngx_cycle = &init_cycle;

    //初始化内存池
    init_cycle.pool = ngx_create_pool(1024, log);
    if (init_cycle.pool == NULL) {
        return 1;
    }
    //存储命令行参数到内存池
    if (ngx_save_argv(&init_cycle, argc, argv) != NGX_OK) {
        return 1;
    }

    //存储程序、配置文件的路径以及conf参数
    if (ngx_process_options(&init_cycle) != NGX_OK) {
        return 1;
    }

    //初始化系统相关变量，内存页面大小ngx_pagesize,ngx_cacheline_size,最大连接数ngx_max_sockets等
    if (ngx_os_init(log) != NGX_OK) {
        return 1;
    }

    /*
     * ngx_crc32_table_init() requires ngx_cacheline_size set in ngx_os_init()
     */

    //初始化循环冗余校验表
    if (ngx_crc32_table_init() != NGX_OK) {
        return 1;
    }

    /*
     * ngx_slab_sizes_init() requires ngx_pagesize set in ngx_os_init()
     */

    // 初始化ngx_slab的一些参数
    ngx_slab_sizes_init();
    // ngx_slab_max_size = ngx_pagesize / 2;
    // ngx_slab_exact_size = ngx_pagesize / (8 * sizeof(uintptr_t));

    //热启动平滑过渡,继承原来的套接字
    if (ngx_add_inherited_sockets(&init_cycle) != NGX_OK) {
        return 1;
    }

    //初始化模块
    // 设置每个module的index和name
    if (ngx_preinit_modules() != NGX_OK) {
        return 1;
    }

    //初始化cycle
    cycle = ngx_init_cycle(&init_cycle);
    if (cycle == NULL) {
        // cycle->log 失效， 只能使用stderr
        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);
        }

        if (ngx_dump_config) {
            cd = cycle->config_dump.elts;

            for (i = 0; i < cycle->config_dump.nelts; i++) {

                ngx_write_stdout("# configuration file ");
                (void) ngx_write_fd(ngx_stdout, cd[i].name.data,
                                    cd[i].name.len);
                ngx_write_stdout(":" NGX_LINEFEED);

                b = cd[i].buffer;

                (void) ngx_write_fd(ngx_stdout, b->pos, b->last - b->pos);
                ngx_write_stdout(NGX_LINEFEED);
            }
        }

        return 0;
    }

    //处理信号
    if (ngx_signal) {
        return ngx_signal_process(cycle, ngx_signal);
    }

    
    ngx_os_status(cycle->log);

    ngx_cycle = cycle;

    //获取核心模块配置文件指针
    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

    //创建pid文件
    if (ngx_create_pidfile(&ccf->pid, cycle->log) != NGX_OK) {
        return 1;
    }

    if (ngx_log_redirect_stderr(cycle) != NGX_OK) {
        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;

    //创建子进程
    if (ngx_process == NGX_PROCESS_SINGLE) {
        ngx_single_process_cycle(cycle);

    } else {
        ngx_master_process_cycle(cycle);
    }

    return 0;
}