/* 
 * Copyright (c) 2006 Stiftung Deutsches Elektronen-Synchroton, 
 * Member of the Helmholtz Association, (DESY), HAMBURG, GERMANY.
 *
 * THIS SOFTWARE IS PROVIDED UNDER THIS LICENSE ON AN "../AS IS" BASIS. 
 * WITHOUT WARRANTY OF ANY KIND, EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED 
 * TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR PARTICULAR PURPOSE AND 
 * NON-INFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE 
 * FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR 
 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. SHOULD THE SOFTWARE PROVE DEFECTIVE 
 * IN ANY RESPECT, THE USER ASSUMES THE COST OF ANY NECESSARY SERVICING, REPAIR OR 
 * CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL PART OF THIS LICENSE. 
 * NO USE OF ANY SOFTWARE IS AUTHORIZED HEREUNDER EXCEPT UNDER THIS DISCLAIMER.
 * DESY HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, 
 * OR MODIFICATIONS.
 * THE FULL LICENSE SPECIFYING FOR THE SOFTWARE THE REDISTRIBUTION, MODIFICATION, 
 * USAGE AND OTHER RIGHTS AND OBLIGATIONS IS INCLUDED WITH THE DISTRIBUTION OF THIS 
 * PROJECT IN THE FILE LICENSE.HTML. IF THE LICENSE IS NOT INCLUDED YOU MAY FIND A COPY 
 * AT HTTP://WWW.DESY.DE/LEGAL/LICENSE.HTM
 */
package org.csstudio.platform.internal.simpledal.local;

import java.util.Date;

/**
 * Thread that encapsulates a <code>java.lang.Runnable</code> and repeatedly
 * runs it in a defined interval.
 * 
 * @author Alexander Will, Sven Wende
 * @version $Revision$
 */
public final class IntervalThread extends Thread {

	/**
	 * The encapsulated <code>java.lang.Runnable</code>.
	 */
	private Runnable _runnable;

	/**
	 * Flag that indicates if the thread should continue its execution.
	 */
	private boolean _running;

	/**
	 * The time periode that lies between two executions of the encapsulated
	 * <code>java.lang.Runnable</code>.
	 */
	private int _refreshRate;

	/**
	 * Standard constructor.
	 * 
	 * @param runnable
	 *            the encapsulated <code>java.lang.Runnable</code>.
	 * @param refreshRate
	 *            the time periode that lies between two executions of the
	 *            encapsulated <code>java.lang.Runnable</code>.
	 */
	public IntervalThread(final Runnable runnable, final int refreshRate) {
		_runnable = runnable;
		_refreshRate = refreshRate;
		_running = true;
	}

	/**
	 * {@inheritDoc}.
	 */
	@Override
	public void run() {
		while (_running) {
			if (_runnable != null) {
				_runnable.run();
			}

			long targetMs = new Date().getTime() + _refreshRate;

			while (System.currentTimeMillis() < targetMs) {
				yield();
			}
		}
	}

	/**
	 * Tell this thread that it should stop its execution.
	 */
	public void stopRunning() {
		_runnable = null;

		_running = false;

	}
}