001/*
002 * Copyright 2006 - 2013
003 *     Stefan Balev     <stefan.balev@graphstream-project.org>
004 *     Julien Baudry    <julien.baudry@graphstream-project.org>
005 *     Antoine Dutot    <antoine.dutot@graphstream-project.org>
006 *     Yoann Pigné      <yoann.pigne@graphstream-project.org>
007 *     Guilhelm Savin   <guilhelm.savin@graphstream-project.org>
008 * 
009 * This file is part of GraphStream <http://graphstream-project.org>.
010 * 
011 * GraphStream is a library whose purpose is to handle static or dynamic
012 * graph, create them from scratch, file or any source and display them.
013 * 
014 * This program is free software distributed under the terms of two licenses, the
015 * CeCILL-C license that fits European law, and the GNU Lesser General Public
016 * License. You can  use, modify and/ or redistribute the software under the terms
017 * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
018 * URL <http://www.cecill.info> or under the terms of the GNU LGPL as published by
019 * the Free Software Foundation, either version 3 of the License, or (at your
020 * option) any later version.
021 * 
022 * This program is distributed in the hope that it will be useful, but WITHOUT ANY
023 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
024 * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
025 * 
026 * You should have received a copy of the GNU Lesser General Public License
027 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
028 * 
029 * The fact that you are presently reading this means that you have had
030 * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms.
031 */
032package org.graphstream.stream.sync;
033
034import java.security.AccessControlException;
035import java.util.HashMap;
036
037public class SinkTime {
038        /**
039         * Key used to disable synchro. Just run : java -DSYNC_DISABLE_KEY ...
040         */
041        public static final String SYNC_DISABLE_KEY = "org.graphstream.stream.sync.disable";
042        /**
043         * Flag used to disable sync.
044         */
045        protected static final boolean disableSync;
046
047        /*
048         * The following code is used to prevent AccessControlException to be thrown
049         * when trying to get the value of the property (in applets for example).
050         */
051        static {
052                boolean off;
053
054                try {
055                        off = System.getProperty(SYNC_DISABLE_KEY) != null;
056                } catch (AccessControlException ex) {
057                        off = false;
058                }
059
060                disableSync = off;
061        }
062
063        /**
064         * Map storing times of sources.
065         */
066        protected HashMap<String, Long> times = new HashMap<String, Long>();
067
068        /**
069         * Update timeId for a source.
070         * 
071         * @param sourceId
072         * @param timeId
073         * @return true if time has been updated
074         */
075        protected boolean setTimeFor(String sourceId, long timeId) {
076                Long knownTimeId = times.get(sourceId);
077
078                if (knownTimeId == null) {
079                        times.put(sourceId, timeId);
080                        return true;
081                } else if (timeId > knownTimeId) {
082                        times.put(sourceId, timeId);
083                        return true;
084                }
085
086                return false;
087        }
088
089        /**
090         * Allow to know if event is new for this source. This updates the timeId
091         * mapped to the source.
092         * 
093         * @param sourceId
094         * @param timeId
095         * @return true if event is new for the source
096         */
097        public boolean isNewEvent(String sourceId, long timeId) {
098                return disableSync || setTimeFor(sourceId, timeId);
099        }
100}