memcache存储session 简单版本 实现功能了 空了来修改~

include('cls_session.php');
$m =new Memcache;
$m->connect('localhost',11211);    
$sess = new cls_session($m);

session_name       = $session_name;

        $this->db  = &$db;
        $this->_ip = '127.0.0.1';

        if ($session_id == '' && !empty($_COOKIE[$this->session_name]))
        {
            $this->session_id = $_COOKIE[$this->session_name];
        }
        else
        {
            $this->session_id = $session_id;
        }

        if ($this->session_id)
        {
            $tmp_session_id = substr($this->session_id, 0, 32);
            if ($this->gen_session_key($tmp_session_id) == substr($this->session_id, 32))
            {
                $this->session_id = $tmp_session_id;
            }
            else
            {
                $this->session_id = '';
            }
        }

        $this->_time = time();

        if ($this->session_id)
        {

            $this->load_session();
        }
        else
        {

            $this->gen_session_id();

            setcookie($this->session_name, $this->session_id . $this->gen_session_key($this->session_id), 0);
        }

        register_shutdown_function(array(&$this, 'close_session'));
    }

    function gen_session_id()
    {
        $this->session_id = md5(uniqid(mt_rand(), true));

        return $this->insert_session();
    }

    function gen_session_key($session_id)
    {
        static $ip = '';

        if ($ip == '')
        {
            $ip = substr($this->_ip, 0, strrpos($this->_ip, '.'));
        }

        return sprintf('%08x', crc32(!empty($_SERVER['HTTP_USER_AGENT']) ? $_SERVER['HTTP_USER_AGENT'] . ROOT_PATH . $ip . $session_id : ROOT_PATH . $ip . $session_id));
    }

    function insert_session()
    {
    	$this->db->set(
    		$this->session_id,
    		array(
    			'ip'   => $this->_ip,
    			'time' => $this->_time, 
    		),
    		false,
    		$this->max_life_time
    	);
    	
    }

    function load_session()
    {
		$GLOBALS['_SESSION'] = $this->db->get($this->session_id);
    }

    function update_session()
    {
		$this->db->replace($this->session_id,$GLOBALS['_SESSION'],$this->max_life_time);
    }

    function close_session()
    {
    	$this->update_session();
    }

    function get_session_id()
    {
        return $this->session_id;
    }
    function destroy_session()
    {    
    	setcookie($this->session_name,'', 0);
    	$this->db->delete($this->session_id);
    }
}