msgs.notify();
msgs.notifyAll();
    public void ack(long seqno, Address sender) {	Entry   entry;	Boolean received;	synchronized(msgs) {	    entry = (Entry)msgs.get(new Long(seqno));	    if (entry == null) return;		    	    synchronized(entry) {		received = (Boolean)entry.senders.get(sender);		if (received == null || received.booleanValue()) return;					// If not yet received		entry.senders.put(sender, Boolean.TRUE);		entry.num_received++;		if (!entry.allReceived()) return;	    }		    	    synchronized(stable_msgs) {		entry.cancel();		msgs.remove(new Long(seqno));		stable_msgs.add(new Long(seqno));	    }	    // wake up waitUntilAllAcksReceived() method	    msgs.notify();	}    }