org.graphstream.stream.sync.SinkTime Maven / Gradle / Ivy

/*
 * This file is part of GraphStream .
 * 
 * GraphStream is a library whose purpose is to handle static or dynamic
 * graph, create them from scratch, file or any source and display them.
 * 
 * This program is free software distributed under the terms of two licenses, the
 * CeCILL-C license that fits European law, and the GNU Lesser General Public
 * License. You can  use, modify and/ or redistribute the software under the terms
 * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
 * URL  or under the terms of the GNU LGPL as published by
 * the Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see .
 * 
 * The fact that you are presently reading this means that you have had
 * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms.
 */

/**
 * @since 2009-12-07
 * 
 * @author Yoann Pigné 
 * @author Antoine Dutot 
 * @author Guilhelm Savin 
 * @author Hicham Brahimi 
 */
package org.graphstream.stream.sync;

import java.security.AccessControlException;
import java.util.HashMap;

public class SinkTime {
	/**
	 * Key used to disable synchro. Just run : java -DSYNC_DISABLE_KEY ...
	 */
	public static final String SYNC_DISABLE_KEY = "org.graphstream.stream.sync.disable";
	/**
	 * Flag used to disable sync.
	 */
	protected static final boolean disableSync;

	/*
	 * The following code is used to prevent AccessControlException to be thrown
	 * when trying to get the value of the property (in applets for example).
	 */
	static {
		boolean off;

		try {
			off = System.getProperty(SYNC_DISABLE_KEY) != null;
		} catch (AccessControlException ex) {
			off = false;
		}

		disableSync = off;
	}

	/**
	 * Map storing times of sources.
	 */
	protected HashMap times = new HashMap();

	/**
	 * Update timeId for a source.
	 * 
	 * @param sourceId
	 * @param timeId
	 * @return true if time has been updated
	 */
	protected boolean setTimeFor(String sourceId, long timeId) {
		Long knownTimeId = times.get(sourceId);

		if (knownTimeId == null) {
			times.put(sourceId, timeId);
			return true;
		} else if (timeId > knownTimeId) {
			times.put(sourceId, timeId);
			return true;
		}

		return false;
	}

	/**
	 * Allow to know if event is new for this source. This updates the timeId mapped
	 * to the source.
	 * 
	 * @param sourceId
	 * @param timeId
	 * @return true if event is new for the source
	 */
	public boolean isNewEvent(String sourceId, long timeId) {
		return disableSync || setTimeFor(sourceId, timeId);
	}
}