001package org.cpsolver.ifs.termination;
002
003import org.cpsolver.ifs.model.Value;
004import org.cpsolver.ifs.model.Variable;
005import org.cpsolver.ifs.solution.Solution;
006import org.cpsolver.ifs.util.DataProperties;
007
008/**
009 * General implementation of termination condition. <br>
010 * <br>
011 * Solver stops when the solution is complete (all varaibles are assigned) or
012 * when a timeout is reached (expressed either by the number of iterations or by
013 * a time). <br>
014 * <br>
015 * Parameters: <br>
016 * <table border='1'><caption>Related Solver Parameters</caption>
017 * <tr>
018 * <th>Parameter</th>
019 * <th>Type</th>
020 * <th>Comment</th>
021 * </tr>
022 * <tr>
023 * <td>Termination.StopWhenComplete</td>
024 * <td>{@link Double}</td>
025 * <td>if true, solver stops when a complete solution is found</td>
026 * </tr>
027 * <tr>
028 * <td>Termination.MaxIters</td>
029 * <td>{@link Integer}</td>
030 * <td>if zero or positive, solver stops when the given number of iteration is
031 * reached</td>
032 * </tr>
033 * <tr>
034 * <td>Termination.TimeOut</td>
035 * <td>{@link Double}</td>
036 * <td>if zero or positive, solver stops when the given timeout (given in
037 * seconds) is reached</td>
038 * </tr>
039 * </table>
040 * 
041 * @see org.cpsolver.ifs.solver.Solver
042 * 
043 * @author  Tomáš Müller
044 * @version IFS 1.3 (Iterative Forward Search)<br>
045 *          Copyright (C) 2006 - 2014 Tomáš Müller<br>
046 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
047 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
048 * <br>
049 *          This library is free software; you can redistribute it and/or modify
050 *          it under the terms of the GNU Lesser General Public License as
051 *          published by the Free Software Foundation; either version 3 of the
052 *          License, or (at your option) any later version. <br>
053 * <br>
054 *          This library is distributed in the hope that it will be useful, but
055 *          WITHOUT ANY WARRANTY; without even the implied warranty of
056 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
057 *          Lesser General Public License for more details. <br>
058 * <br>
059 *          You should have received a copy of the GNU Lesser General Public
060 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
061 *
062 * @param <V> Variable
063 * @param <T> Value
064 **/
065public class GeneralTerminationCondition<V extends Variable<V, T>, T extends Value<V, T>> implements
066        TerminationCondition<V, T> {
067    protected static org.apache.logging.log4j.Logger sLogger = org.apache.logging.log4j.LogManager.getLogger(GeneralTerminationCondition.class);
068    private int iMaxIter;
069    private double iTimeOut;
070    private boolean iStopWhenComplete;
071
072    public GeneralTerminationCondition(DataProperties properties) {
073        iMaxIter = properties.getPropertyInt("Termination.MaxIters", -1);
074        iTimeOut = properties.getPropertyDouble("Termination.TimeOut", -1.0);
075        iStopWhenComplete = properties.getPropertyBoolean("Termination.StopWhenComplete", false);
076    }
077
078    @Override
079    public boolean canContinue(Solution<V, T> currentSolution) {
080        if (iMaxIter >= 0 && currentSolution.getIteration() >= iMaxIter) {
081            sLogger.info("Maximum number of iteration reached.");
082            return false;
083        }
084        if (iTimeOut >= 0 && currentSolution.getTime() > iTimeOut) {
085            sLogger.info("Timeout reached.");
086            return false;
087        }
088        if (iStopWhenComplete || (iMaxIter < 0 && iTimeOut < 0)) {
089            boolean ret = (currentSolution.getAssignment().nrUnassignedVariables(currentSolution.getModel()) != 0);
090            if (!ret)
091                sLogger.info("Complete solution found.");
092            return ret;
093        }
094        return true;
095    }
096}