org.btrplace.scheduler.choco.ObjectiveAlterer Maven / Gradle / Ivy

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/*
 * Copyright (c) 2016 University Nice Sophia Antipolis
 *
 * This file is part of btrplace.
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This library 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 .
 */

package org.btrplace.scheduler.choco;


/**
 * A class to provide a method to customize the optimisation process of the solver.
 * Instead of trying all the possible values, you will be able to choose the value to try
 * for the objective variable. This may speed up the improvement phase.
 * 
 * As the solver will not longer try all the possible values, the completeness of
 * the resolution process is no longer guarantee and may remove some (possibly good) solutions.
 *
 * @author Fabien Hermenier
 */
@FunctionalInterface
public interface ObjectiveAlterer {

    /**
     * compute the new bound to apply to the best value computed so far
     * The new bound to try will be the last computed value plus the newBound.
     *
     * @param rp           the associated problem
     * @param currentValue the current value of the objective
     * @return the computed newBound should be aligned with the resolution policy: a greater value for a variable to maximize,
     * a smaller value for a variable to minimize
     */
    int newBound(ReconfigurationProblem rp, int currentValue);

}