$sessionHandler = new SessionHandler(connection::getConn());
$setHandler = session_set_save_handler(
    array($sessionHandler, 'open'),
    array($sessionHandler, 'close'),
    array($sessionHandler, 'read'),
    array($sessionHandler, 'write'),
    array($sessionHandler, 'destroy'),
    array($sessionHandler, 'gc')
);
register_shutdown_function('session_write_close');
session_start();