/* * * Copyright (c) 1997-1999 Scott Oaks and Henry Wong. All Rights Reserved. * * Permission to use, copy, modify, and distribute this software * and its documentation for NON-COMMERCIAL purposes and * without fee is hereby granted. * * This sample source code is provided for example only, * on an unsupported, as-is basis.  * * AUTHOR MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. AUTHOR SHALL NOT BE LIABLE FOR * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. * * THIS SOFTWARE IS NOT DESIGNED OR INTENDED FOR USE OR RESALE AS ON-LINE * CONTROL EQUIPMENT IN HAZARDOUS ENVIRONMENTS REQUIRING FAIL-SAFE * PERFORMANCE, SUCH AS IN THE OPERATION OF NUCLEAR FACILITIES, AIRCRAFT * NAVIGATION OR COMMUNICATION SYSTEMS, AIR TRAFFIC CONTROL, DIRECT LIFE * SUPPORT MACHINES, OR WEAPONS SYSTEMS, IN WHICH THE FAILURE OF THE * SOFTWARE COULD LEAD DIRECTLY TO DEATH, PERSONAL INJURY, OR SEVERE * PHYSICAL OR ENVIRONMENTAL DAMAGE ("HIGH RISK ACTIVITIES").  AUTHOR * SPECIFICALLY DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR * HIGH RISK ACTIVITIES. */public class BusyFlag {	protected Thread busyflag = null;	protected int busycount = 0;	public void getBusyFlag() {		while (tryGetBusyFlag() == false) {			try {				Thread.sleep(100);			} catch (Exception e) {}		}	}	public synchronized boolean tryGetBusyFlag() {		if (busyflag == null) {			busyflag = Thread.currentThread();			busycount = 1;			return true;		}		if (busyflag == Thread.currentThread()) {			busycount++;			return true; 		}		return false;	}	public synchronized void freeBusyFlag () {		if (getBusyFlagOwner() == Thread.currentThread()) {			busycount--;			if (busycount == 0)				busyflag = null;		}	}	public synchronized Thread getBusyFlagOwner() {		return busyflag;	}}