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PLANNER-1254 UnimprovedTimeMillisSpentScoreDifferenceThresholdTermina…
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162
...impl/solver/termination/UnimprovedTimeMillisSpentScoreDifferenceThresholdTermination.java
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| /* | ||
| * Copyright 2018 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. | ||
| */ | ||
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| package org.optaplanner.core.impl.solver.termination; | ||
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| import java.util.ArrayDeque; | ||
| import java.util.Iterator; | ||
| import java.util.Queue; | ||
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| import org.apache.commons.lang3.tuple.Pair; | ||
| import org.optaplanner.core.api.score.Score; | ||
| import org.optaplanner.core.impl.phase.scope.AbstractPhaseScope; | ||
| import org.optaplanner.core.impl.phase.scope.AbstractStepScope; | ||
| import org.optaplanner.core.impl.solver.ChildThreadType; | ||
| import org.optaplanner.core.impl.solver.scope.DefaultSolverScope; | ||
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| public class UnimprovedTimeMillisSpentScoreDifferenceThresholdTermination extends AbstractTermination { | ||
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| private final long unimprovedTimeMillisSpentLimit; | ||
| private final Score unimprovedScoreDifferenceThreshold; | ||
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| private Queue<Pair<Long, Score>> bestScoreImprovementHistoryQueue; | ||
| // safeTimeMillis is until when we're safe from termination | ||
| private long solverSafeTimeMillis = -1L; | ||
| private long phaseSafeTimeMillis = -1L; | ||
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| public UnimprovedTimeMillisSpentScoreDifferenceThresholdTermination(long unimprovedTimeMillisSpentLimit, | ||
| Score unimprovedScoreDifferenceThreshold) { | ||
| this.unimprovedTimeMillisSpentLimit = unimprovedTimeMillisSpentLimit; | ||
| this.unimprovedScoreDifferenceThreshold = unimprovedScoreDifferenceThreshold; | ||
| if (unimprovedTimeMillisSpentLimit <= 0L) { | ||
| throw new IllegalArgumentException("The unimprovedTimeMillisSpentLimit (" + unimprovedTimeMillisSpentLimit | ||
| + ") cannot be negative."); | ||
| } | ||
| } | ||
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| public long getUnimprovedTimeMillisSpentLimit() { | ||
| return unimprovedTimeMillisSpentLimit; | ||
| } | ||
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| public Score getUnimprovedScoreDifferenceThreshold() { | ||
| return unimprovedScoreDifferenceThreshold; | ||
| } | ||
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| @Override | ||
| public void solvingStarted(DefaultSolverScope solverScope) { | ||
| bestScoreImprovementHistoryQueue = new ArrayDeque<>(); | ||
| solverSafeTimeMillis = solverScope.getBestSolutionTimeMillis() + unimprovedTimeMillisSpentLimit; | ||
| } | ||
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| @Override | ||
| public void solvingEnded(DefaultSolverScope solverScope) { | ||
| bestScoreImprovementHistoryQueue = null; | ||
| solverSafeTimeMillis = -1L; | ||
| } | ||
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| @Override | ||
| public void phaseStarted(AbstractPhaseScope phaseScope) { | ||
| phaseSafeTimeMillis = phaseScope.getStartingSystemTimeMillis() + unimprovedTimeMillisSpentLimit; | ||
| } | ||
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| @Override | ||
| public void phaseEnded(AbstractPhaseScope phaseScope) { | ||
| phaseSafeTimeMillis = -1L; | ||
| } | ||
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| @Override | ||
| public void stepEnded(AbstractStepScope stepScope) { | ||
| if (stepScope.getBestScoreImproved()) { | ||
| DefaultSolverScope solverScope = stepScope.getPhaseScope().getSolverScope(); | ||
| long bestSolutionTimeMillis = solverScope.getBestSolutionTimeMillis(); | ||
| Score bestScore = solverScope.getBestScore(); | ||
| for (Iterator<Pair<Long, Score>> it = bestScoreImprovementHistoryQueue.iterator(); it.hasNext(); ) { | ||
| Pair<Long, Score> bestScoreImprovement = it.next(); | ||
| Score scoreDifference = bestScore.subtract(bestScoreImprovement.getValue()); | ||
| if (scoreDifference.compareTo(unimprovedScoreDifferenceThreshold) >= 0) { | ||
| it.remove(); | ||
| long safeTimeMillis = bestScoreImprovement.getKey() + unimprovedTimeMillisSpentLimit; | ||
| solverSafeTimeMillis = safeTimeMillis; | ||
| phaseSafeTimeMillis = safeTimeMillis; | ||
| } else { | ||
| break; | ||
| } | ||
| } | ||
| bestScoreImprovementHistoryQueue.add(Pair.of(bestSolutionTimeMillis, bestScore)); | ||
| } | ||
| } | ||
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| // ************************************************************************ | ||
| // Terminated methods | ||
| // ************************************************************************ | ||
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| @Override | ||
| public boolean isSolverTerminated(DefaultSolverScope solverScope) { | ||
| return isTerminated(solverSafeTimeMillis); | ||
| } | ||
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| @Override | ||
| public boolean isPhaseTerminated(AbstractPhaseScope phaseScope) { | ||
| return isTerminated(phaseSafeTimeMillis); | ||
| } | ||
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| protected boolean isTerminated(long safeTimeMillis) { | ||
| // It's possible that there is already an improving move in the forager | ||
| // that will end up pushing the safeTimeMillis further | ||
| // but that doesn't change the fact that the best score didn't improve enough in the specified time interval. | ||
| // It just looks weird because it terminates even though the final step is a high enough score improvement. | ||
| long now = System.currentTimeMillis(); | ||
| return now > safeTimeMillis; | ||
| } | ||
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| // ************************************************************************ | ||
| // Time gradient methods | ||
| // ************************************************************************ | ||
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| @Override | ||
| public double calculateSolverTimeGradient(DefaultSolverScope solverScope) { | ||
| return calculateTimeGradient(solverSafeTimeMillis); | ||
| } | ||
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| @Override | ||
| public double calculatePhaseTimeGradient(AbstractPhaseScope phaseScope) { | ||
| return calculateTimeGradient(phaseSafeTimeMillis); | ||
| } | ||
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| protected double calculateTimeGradient(long safeTimeMillis) { | ||
| long now = System.currentTimeMillis(); | ||
| long unimprovedTimeMillisSpent = now - (safeTimeMillis - unimprovedTimeMillisSpentLimit); | ||
| double timeGradient = ((double) unimprovedTimeMillisSpent) / ((double) unimprovedTimeMillisSpentLimit); | ||
| return Math.min(timeGradient, 1.0); | ||
| } | ||
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| // ************************************************************************ | ||
| // Other methods | ||
| // ************************************************************************ | ||
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| @Override | ||
| public UnimprovedTimeMillisSpentScoreDifferenceThresholdTermination createChildThreadTermination( | ||
| DefaultSolverScope solverScope, ChildThreadType childThreadType) { | ||
| return new UnimprovedTimeMillisSpentScoreDifferenceThresholdTermination( | ||
| unimprovedTimeMillisSpentLimit, unimprovedScoreDifferenceThreshold); | ||
| } | ||
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| @Override | ||
| public String toString() { | ||
| return "UnimprovedTimeMillisSpent(" + unimprovedTimeMillisSpentLimit + ")"; | ||
| } | ||
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| } |