Module_Session::__construct

public function __construct($vars = null)
{
    // This part only needs to be run once
    if (null===Session::$instance)
    {
        // Load config
        Session::$config = Core::config('session');

        if (!isset(Session::$config['check_string']) || !Session::$config['check_string'])
        {
            Session::$config['check_string'] = '&$@de23#$%@.d3l-3=!#1';
        }

        if (!isset(Session::$config['name']) || !preg_match('#^(?=.*[a-z])[a-z0-9_]++$#iD', Session::$config['name']))
        {
            // Name the session, this will also be the name of the cookie
            Session::$config['name'] = 'PHPSESSINID';
        }

        if (IS_DEBUG)
        {
            $time = microtime(1);
            $is_debug = (bool)Core::debug()->profiler()->is_open();
            if ($is_debug)
            {
                Core::debug()->profiler()->start('Core', 'Session StartTime');
            }
        }

        if (isset(Session::$config['driver']) && class_exists('Session_Driver_' . Session::$config['driver'], true))
        {
            $driver_name = 'Session_Driver_' . Session::$config['driver'];

            if (isset(Session::$config['driver_config']))
            {
                $this->driver = new $driver_name(Session::$config['driver_config']);
            }
            else
            {
                $this->driver = new $driver_name();
            }
        }
        else
        {
            $this->driver = new Session_Driver_Default();
        }

        if (IS_DEBUG)
        {
            if ($is_debug)
            {
                Core::debug()->profiler()->stop();
            }

            # 输出Session启动使用时间
            Core::debug()->info(microtime(1)-$time, 'Session start use time');
        }

        if ($vars)
        {
            $this->set($vars);
        }

        if (!isset($_SESSION['_flash_session_']))
        {
            $_SESSION['_flash_session_'] = array();
        }
        Session::$flash = & $_SESSION['_flash_session_'];

        # 清理Flash Session
        $this->expire_flash();

        $_SESSION['SID'] = $this->driver->session_id();

        # 确保关闭前执行保存
        Core::register_shutdown_function(array('Session', 'write_close'));

        Session::$instance = $this;

        # 加载用户数据
        Session::load_member_data();
    }
}