PHP 使用memcache保存session

<?php
class MySessionHandler implements SessionHandlerInterface
{
    private $savePath;

    public function open($savePath, $sessionName)
    {
        return true;
    }

    public function close()
    {
        return true;
    }

    public function read($sessionId)
    {
        $res = Libs_Cache_Memcache::getContent($sessionId);//从memcache中读取数据
        return $res;
    }

    public function write($sessionId, $data)
    {
        $res = Libs_Cache_Memcache::setContent($sessionId, $data, $lifetime);//将数据写入memcache
        return $res ? true : fasle;
    }

    public function destroy($sessionId)
    {
        $res = Libs_Cache_Memcache::delete($sessionId);
        return $res ? true : fasle;
    }

    public function gc($maxlifetime)
    {
        return true;
     }
}

$handler = new MySessionHandler();
session_set_save_handler($handler, true);
session_start();