if(log.isInfoEnabled()) log.info("flushing took " + (stop-start) + " msecs");
if(log.isDebugEnabled()) log.debug("flushing took " + (stop-start) + " msecs");
    public void flushEvents() {        long start, stop;        ack_promise.reset();        start=System.currentTimeMillis();        down(new Event(Event.ACK));        ack_promise.getResult(0);        stop=System.currentTimeMillis();        if(log.isInfoEnabled()) log.info("flushing took " + (stop-start) + " msecs");    }