/*
* Copyright 2012 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.heuristic.selector.move.decorator;
import java.util.Iterator;
import java.util.Map;
import java.util.NavigableMap;
import java.util.TreeMap;
import org.optaplanner.core.config.heuristic.selector.common.SelectionCacheType;
import org.optaplanner.core.impl.heuristic.move.Move;
import org.optaplanner.core.impl.heuristic.selector.common.SelectionCacheLifecycleBridge;
import org.optaplanner.core.impl.heuristic.selector.common.SelectionCacheLifecycleListener;
import org.optaplanner.core.impl.heuristic.selector.common.decorator.SelectionProbabilityWeightFactory;
import org.optaplanner.core.impl.heuristic.selector.move.AbstractMoveSelector;
import org.optaplanner.core.impl.heuristic.selector.move.MoveSelector;
import org.optaplanner.core.impl.score.director.ScoreDirector;
import org.optaplanner.core.impl.solver.random.RandomUtils;
import org.optaplanner.core.impl.solver.scope.DefaultSolverScope;
public class ProbabilityMoveSelector extends AbstractMoveSelector implements SelectionCacheLifecycleListener {
protected final MoveSelector childMoveSelector;
protected final SelectionCacheType cacheType;
protected final SelectionProbabilityWeightFactory probabilityWeightFactory;
protected NavigableMap<Double, Move> cachedMoveMap = null;
protected double probabilityWeightTotal = -1.0;
public ProbabilityMoveSelector(MoveSelector childMoveSelector, SelectionCacheType cacheType,
SelectionProbabilityWeightFactory probabilityWeightFactory) {
this.childMoveSelector = childMoveSelector;
this.cacheType = cacheType;
this.probabilityWeightFactory = probabilityWeightFactory;
if (childMoveSelector.isNeverEnding()) {
throw new IllegalStateException("The selector (" + this
+ ") has a childMoveSelector (" + childMoveSelector
+ ") with neverEnding (" + childMoveSelector.isNeverEnding() + ").");
}
phaseLifecycleSupport.addEventListener(childMoveSelector);
if (cacheType.isNotCached()) {
throw new IllegalArgumentException("The selector (" + this
+ ") does not support the cacheType (" + cacheType + ").");
}
phaseLifecycleSupport.addEventListener(new SelectionCacheLifecycleBridge(cacheType, this));
}
@Override
public SelectionCacheType getCacheType() {
return cacheType;
}
// ************************************************************************
// Worker methods
// ************************************************************************
@Override
public void constructCache(DefaultSolverScope solverScope) {
cachedMoveMap = new TreeMap<>();
ScoreDirector scoreDirector = solverScope.getScoreDirector();
double probabilityWeightOffset = 0L;
for (Move entity : childMoveSelector) {
double probabilityWeight = probabilityWeightFactory.createProbabilityWeight(
scoreDirector, entity);
cachedMoveMap.put(probabilityWeightOffset, entity);
probabilityWeightOffset += probabilityWeight;
}
probabilityWeightTotal = probabilityWeightOffset;
}
@Override
public void disposeCache(DefaultSolverScope solverScope) {
probabilityWeightTotal = -1.0;
}
@Override
public boolean isCountable() {
return true;
}
@Override
public boolean isNeverEnding() {
return true;
}
@Override
public long getSize() {
return cachedMoveMap.size();
}
@Override
public Iterator<Move> iterator() {
return new Iterator<Move>() {
@Override
public boolean hasNext() {
return true;
}
@Override
public Move next() {
double randomOffset = RandomUtils.nextDouble(workingRandom, probabilityWeightTotal);
Map.Entry<Double, Move> entry = cachedMoveMap.floorEntry(randomOffset);
// entry is never null because randomOffset < probabilityWeightTotal
return entry.getValue();
}
@Override
public void remove() {
throw new UnsupportedOperationException("The optional operation remove() is not supported.");
}
};
}
@Override
public String toString() {
return "Probability(" + childMoveSelector + ")";
}
}