/*
* Copyright 2012 JBoss Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.drools.planner.core.localsearch.decider.acceptor.lateacceptance;
import org.drools.planner.core.localsearch.scope.LocalSearchMoveScope;
import org.drools.planner.core.localsearch.scope.LocalSearchSolverPhaseScope;
import org.drools.planner.core.localsearch.scope.LocalSearchStepScope;
import org.drools.planner.core.localsearch.decider.acceptor.AbstractAcceptor;
import org.drools.planner.core.score.Score;
public class LateAcceptanceAcceptor extends AbstractAcceptor {
protected int lateAcceptanceSize = -1;
protected Score[] previousScores;
protected int lateScoreIndex = -1;
public void setLateAcceptanceSize(int lateAcceptanceSize) {
this.lateAcceptanceSize = lateAcceptanceSize;
}
// ************************************************************************
// Worker methods
// ************************************************************************
@Override
public void phaseStarted(LocalSearchSolverPhaseScope phaseScope) {
super.phaseStarted(phaseScope);
validate();
previousScores = new Score[lateAcceptanceSize];
Score initialScore = phaseScope.getBestScore();
for (int i = 0; i < previousScores.length; i++) {
previousScores[i] = initialScore;
}
lateScoreIndex = 0;
}
private void validate() {
if (lateAcceptanceSize <= 0) {
throw new IllegalArgumentException("The lateAcceptanceSize (" + lateAcceptanceSize
+ ") cannot be negative or zero.");
}
}
@Override
public void phaseEnded(LocalSearchSolverPhaseScope phaseScope) {
super.phaseEnded(phaseScope);
previousScores = null;
lateScoreIndex = -1;
}
public boolean isAccepted(LocalSearchMoveScope moveScope) {
moveScope.getStepScope().getStepIndex();
Score score = moveScope.getScore();
Score lateScore = previousScores[lateScoreIndex];
return score.compareTo(lateScore) >= 0;
}
@Override
public void stepEnded(LocalSearchStepScope stepScope) {
super.stepEnded(stepScope);
previousScores[lateScoreIndex] = stepScope.getScore();
lateScoreIndex = (lateScoreIndex + 1) % lateAcceptanceSize;
}
}