if(log.isInfoEnabled()) log.info("multicast socket closed");
if(log.isDebugEnabled()) log.debug("multicast socket closed");
    void closeMulticastSocket() {        if(mcast_sock != null) {            try {                if(mcast_addr != null) {                    // by sending a dummy packet the thread will be awakened                    sendDummyPacket(mcast_addr.getIpAddress(), mcast_addr.getPort());                    Util.sleep(300);                    mcast_sock.leaveGroup(mcast_addr.getIpAddress());                }                mcast_sock.close(); // this will cause the mcast receiver thread to break out of its loop                mcast_sock=null;                 if(log.isInfoEnabled()) log.info("multicast socket closed");            }            catch(IOException ex) {            }            mcast_addr=null;        }    }