org.chocosolver.solver.search.restart.Restarter Maven / Gradle / Ivy
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/*
* This file is part of choco-solver, http://choco-solver.org/
*
* Copyright (c) 2023, IMT Atlantique. All rights reserved.
*
* Licensed under the BSD 4-clause license.
*
* See LICENSE file in the project root for full license information.
*/
package org.chocosolver.solver.search.restart;
import org.chocosolver.solver.Solver;
import org.chocosolver.util.criteria.LongCriterion;
/**
* This enables restarting a search on certain conditions
* (most of the time based on a counter).
*
* Created by cprudhom on 03/09/15.
* Project: choco.
*
* @author Charles Prud'homme
* @since 03/09/2015
*/
public final class Restarter extends AbstractRestart {
/**
* How often the restart should occur
*/
private final ICutoff restartStrategy;
/**
* How to trigger a restart
*/
private final LongCriterion criterion;
/**
* Count the number of restarts
*/
private int restartFromStrategyCount;
/**
* restrict the total number of restart
*/
private final int restartLimit;
/**
* When the next restart should be triggered
*/
private long limit;
/**
* Number of solutions found so far
*/
private long solutions;
private final boolean resetCutoffOnSolution;
/**
* @param restartStrategy defines when restarts happen
* @param criterion defines how to trigger a restart
* @param restartLimit restrict the total number of restart
* @param resetCutoffOnSolution reset cutoff sequence on solutions
*/
public Restarter(ICutoff restartStrategy,
LongCriterion criterion,
int restartLimit,
boolean resetCutoffOnSolution) {
this.restartStrategy = restartStrategy;
this.criterion = criterion;
this.restartLimit = restartLimit;
this.resetCutoffOnSolution = resetCutoffOnSolution;
}
@Override
public void init() {
restartFromStrategyCount = 0;
limit = restartStrategy.getNextCutoff();
this.next.init();
}
/**
* Check conditions for restarting
*
* @param solver the caller
* @return true if restarting is required
*/
@Override
public boolean mustRestart(Solver solver) {
if (resetCutoffOnSolution && solutions < solver.getSolutionCount()) {
solutions = solver.getSolutionCount();
restartStrategy.reset();
}
if (criterion.isMet(limit)) {
// update parameters for restarts
restartFromStrategyCount++;
if (restartFromStrategyCount >= restartLimit) {
limit = Long.MAX_VALUE;
} else if (criterion.isMet(limit)) {
limit += restartStrategy.getNextCutoff();
}
return true;
}
return next.mustRestart(solver);
}
}