if(log.isInfoEnabled()) log.info("changed role to " + new_impl.getClass().getName());
if(log.isDebugEnabled()) log.debug("changed role to " + new_impl.getClass().getName());
    public void setImpl(GmsImpl new_impl) {        synchronized(impl_mutex) {            impl=new_impl;             if(log.isInfoEnabled()) log.info("changed role to " + new_impl.getClass().getName());        }    }