/*
* Copyright 2010 Red Hat, Inc. and/or its affiliates.
*
* 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.optaplanner.core.impl.solver.termination;
import org.optaplanner.core.impl.phase.scope.AbstractPhaseScope;
import org.optaplanner.core.impl.solver.ChildThreadType;
import org.optaplanner.core.impl.solver.scope.DefaultSolverScope;
public class UnimprovedStepCountTermination extends AbstractTermination {
private final int unimprovedStepCountLimit;
public UnimprovedStepCountTermination(int unimprovedStepCountLimit) {
this.unimprovedStepCountLimit = unimprovedStepCountLimit;
if (unimprovedStepCountLimit < 0) {
throw new IllegalArgumentException("The unimprovedStepCountLimit (" + unimprovedStepCountLimit
+ ") cannot be negative.");
}
}
public int getUnimprovedStepCountLimit() {
return unimprovedStepCountLimit;
}
// ************************************************************************
// Terminated methods
// ************************************************************************
@Override
public boolean isSolverTerminated(DefaultSolverScope solverScope) {
throw new UnsupportedOperationException(
getClass().getSimpleName() + " can only be used for phase termination.");
}
@Override
public boolean isPhaseTerminated(AbstractPhaseScope phaseScope) {
int unimprovedStepCount = calculateUnimprovedStepCount(phaseScope);
return unimprovedStepCount >= unimprovedStepCountLimit;
}
protected int calculateUnimprovedStepCount(AbstractPhaseScope phaseScope) {
int bestStepIndex = phaseScope.getBestSolutionStepIndex();
int lastStepIndex = phaseScope.getLastCompletedStepScope().getStepIndex();
return lastStepIndex - bestStepIndex;
}
// ************************************************************************
// Time gradient methods
// ************************************************************************
@Override
public double calculateSolverTimeGradient(DefaultSolverScope solverScope) {
throw new UnsupportedOperationException(
getClass().getSimpleName() + " can only be used for phase termination.");
}
@Override
public double calculatePhaseTimeGradient(AbstractPhaseScope phaseScope) {
int unimprovedStepCount = calculateUnimprovedStepCount(phaseScope);
double timeGradient = ((double) unimprovedStepCount) / ((double) unimprovedStepCountLimit);
return Math.min(timeGradient, 1.0);
}
// ************************************************************************
// Other methods
// ************************************************************************
@Override
public UnimprovedStepCountTermination createChildThreadTermination(
DefaultSolverScope solverScope, ChildThreadType childThreadType) {
return new UnimprovedStepCountTermination(unimprovedStepCountLimit);
}
@Override
public String toString() {
return "UnimprovedStepCount(" + unimprovedStepCountLimit + ")";
}
}