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zepfredzepfred
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feat: new stuck criterion
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3 files changed

+170
-2
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3 files changed

+170
-2
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‎core/src/main/java/ai/timefold/solver/core/impl/localsearch/decider/acceptor/AcceptorFactory.java‎

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@@ -17,8 +17,8 @@
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import ai.timefold.solver.core.impl.localsearch.decider.acceptor.lateacceptance.LateAcceptanceAcceptor;
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import ai.timefold.solver.core.impl.localsearch.decider.acceptor.simulatedannealing.SimulatedAnnealingAcceptor;
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import ai.timefold.solver.core.impl.localsearch.decider.acceptor.stepcountinghillclimbing.StepCountingHillClimbingAcceptor;
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import ai.timefold.solver.core.impl.localsearch.decider.acceptor.stuckcriterion.DiminishedReturnsStuckCriterion;
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import ai.timefold.solver.core.impl.localsearch.decider.acceptor.stuckcriterion.StuckCriterion;
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import ai.timefold.solver.core.impl.localsearch.decider.acceptor.stuckcriterion.UnimprovedTimeStuckCriterion;
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import ai.timefold.solver.core.impl.localsearch.decider.acceptor.tabu.EntityTabuAcceptor;
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import ai.timefold.solver.core.impl.localsearch.decider.acceptor.tabu.MoveTabuAcceptor;
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import ai.timefold.solver.core.impl.localsearch.decider.acceptor.tabu.ValueTabuAcceptor;
@@ -222,7 +222,7 @@ private Optional<MoveTabuAcceptor<Solution_>> buildMoveTabuAcceptor(HeuristicCon
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if (acceptorTypeListsContainsAcceptorType(AcceptorType.LATE_ACCEPTANCE)
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|| (!acceptorTypeListsContainsAcceptorType(AcceptorType.DIVERSIFIED_LATE_ACCEPTANCE)
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&& acceptorConfig.getLateAcceptanceSize() != null)) {
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StuckCriterion<Solution_> strategy = new DiminishedReturnsStuckCriterion<>();
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StuckCriterion<Solution_> strategy = new UnimprovedTimeStuckCriterion<>();
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var acceptor = new LateAcceptanceAcceptor<>(strategy);
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acceptor.setLateAcceptanceSize(Objects.requireNonNullElse(acceptorConfig.getLateAcceptanceSize(), 400));
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return Optional.of(acceptor);

‎core/src/main/java/ai/timefold/solver/core/impl/localsearch/decider/acceptor/stuckcriterion/UnimprovedTimeStuckCriterion.java‎

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package ai.timefold.solver.core.impl.localsearch.decider.acceptor.stuckcriterion;
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import ai.timefold.solver.core.api.score.Score;
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import ai.timefold.solver.core.impl.localsearch.scope.LocalSearchMoveScope;
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import ai.timefold.solver.core.impl.localsearch.scope.LocalSearchPhaseScope;
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import ai.timefold.solver.core.impl.localsearch.scope.LocalSearchStepScope;
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import ai.timefold.solver.core.impl.solver.scope.SolverScope;
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import ai.timefold.solver.core.impl.solver.termination.UnimprovedTimeMillisSpentTermination;
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public class UnimprovedTimeStuckCriterion<Solution_, Score_ extends Score<Score_>>
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extends AbstractGeometricStuckCriterion<Solution_> {
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protected static final long START_TIME_WINDOW_MILLIS = 30_000;
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protected static final long REGULAR_TIME_WINDOW_MILLIS = 300_000;
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private UnimprovedTimeMillisSpentTermination<Solution_> unimprovedTimeStuckCriterion;
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private boolean triggered;
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private Score_ currentBestScore;
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public UnimprovedTimeStuckCriterion() {
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this(new UnimprovedTimeMillisSpentTermination<>(START_TIME_WINDOW_MILLIS));
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}
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protected UnimprovedTimeStuckCriterion(UnimprovedTimeMillisSpentTermination<Solution_> unimprovedTimeStuckCriterion) {
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super(START_TIME_WINDOW_MILLIS);
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this.unimprovedTimeStuckCriterion = unimprovedTimeStuckCriterion;
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}
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@Override
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boolean evaluateCriterion(LocalSearchMoveScope<Solution_> moveScope) {
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triggered = unimprovedTimeStuckCriterion.isPhaseTerminated(moveScope.getStepScope().getPhaseScope());
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return triggered;
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}
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@Override
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public void stepStarted(LocalSearchStepScope<Solution_> stepScope) {
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currentBestScore = stepScope.getPhaseScope().getBestScore();
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if (triggered) {
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// We need to recreate the termination criterion as the time window has changed
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// After the first restart we use a higher time window
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setScalingFactor(REGULAR_TIME_WINDOW_MILLIS);
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unimprovedTimeStuckCriterion = new UnimprovedTimeMillisSpentTermination<>(nextRestart);
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// The criterion must be initialized; otherwise, no restart will occur
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unimprovedTimeStuckCriterion.phaseStarted(stepScope.getPhaseScope());
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triggered = false;
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}
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}
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@Override
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public void stepEnded(LocalSearchStepScope<Solution_> stepScope) {
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unimprovedTimeStuckCriterion.stepEnded(stepScope);
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if (currentBestScore.compareTo(stepScope.getPhaseScope().getBestScore()) < 0
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&& nextRestart > START_TIME_WINDOW_MILLIS) {
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// If the solution has been improved after a restart,
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// we reset the criterion and restart the evaluation of the metric
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setScalingFactor(START_TIME_WINDOW_MILLIS);
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super.solvingStarted(stepScope.getPhaseScope().getSolverScope());
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unimprovedTimeStuckCriterion = new UnimprovedTimeMillisSpentTermination<>(nextRestart);
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// The criterion must be initialized; otherwise, no restart will occur
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unimprovedTimeStuckCriterion.phaseStarted(stepScope.getPhaseScope());
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logger.info("Stuck criterion reset, next restart ({}), previous best score({}), new best score ({})", nextRestart,
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currentBestScore, stepScope.getPhaseScope().getBestScore());
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}
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}
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@Override
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public void phaseStarted(LocalSearchPhaseScope<Solution_> phaseScope) {
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super.phaseStarted(phaseScope);
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unimprovedTimeStuckCriterion.phaseStarted(phaseScope);
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triggered = false;
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}
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@Override
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public void phaseEnded(LocalSearchPhaseScope<Solution_> phaseScope) {
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super.phaseEnded(phaseScope);
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unimprovedTimeStuckCriterion.phaseEnded(phaseScope);
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}
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@Override
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public void solvingStarted(SolverScope<Solution_> solverScope) {
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super.solvingStarted(solverScope);
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unimprovedTimeStuckCriterion.solvingStarted(solverScope);
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}
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@Override
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public void solvingEnded(SolverScope<Solution_> solverScope) {
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super.solvingEnded(solverScope);
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unimprovedTimeStuckCriterion.solvingEnded(solverScope);
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}
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}

‎core/src/test/java/ai/timefold/solver/core/impl/localsearch/decider/acceptor/stuckcriterion/UnimprovedTimeStuckCriterionTest.java‎

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package ai.timefold.solver.core.impl.localsearch.decider.acceptor.stuckcriterion;
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import static ai.timefold.solver.core.impl.localsearch.decider.acceptor.stuckcriterion.DiminishedReturnsStuckCriterion.START_TIME_WINDOW_MILLIS;
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import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
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import static org.mockito.ArgumentMatchers.any;
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import static org.mockito.Mockito.mock;
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import static org.mockito.Mockito.when;
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import ai.timefold.solver.core.api.score.buildin.simple.SimpleScore;
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import ai.timefold.solver.core.impl.localsearch.scope.LocalSearchMoveScope;
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import ai.timefold.solver.core.impl.localsearch.scope.LocalSearchPhaseScope;
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import ai.timefold.solver.core.impl.localsearch.scope.LocalSearchStepScope;
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import ai.timefold.solver.core.impl.solver.scope.SolverScope;
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import ai.timefold.solver.core.impl.solver.termination.UnimprovedTimeMillisSpentTermination;
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import org.junit.jupiter.api.Test;
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class UnimprovedTimeStuckCriterionTest {
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@Test
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void isSolverStuck() {
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var solverScope = mock(SolverScope.class);
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var phaseScope = mock(LocalSearchPhaseScope.class);
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var stepScope = mock(LocalSearchStepScope.class);
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var moveScope = mock(LocalSearchMoveScope.class);
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var termination = mock(UnimprovedTimeMillisSpentTermination.class);
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when(moveScope.getStepScope()).thenReturn(stepScope);
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when(stepScope.getPhaseScope()).thenReturn(phaseScope);
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when(phaseScope.getSolverScope()).thenReturn(solverScope);
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when(moveScope.getScore()).thenReturn(SimpleScore.of(1));
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when(phaseScope.getBestScore()).thenReturn(SimpleScore.of(1));
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when(termination.isPhaseTerminated(any())).thenReturn(false, true);
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// No restart
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var strategy = new UnimprovedTimeStuckCriterion<>(termination);
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strategy.solvingStarted(null);
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strategy.phaseStarted(phaseScope);
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assertThat(strategy.isSolverStuck(moveScope)).isFalse();
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// First restart
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assertThat(strategy.isSolverStuck(moveScope)).isTrue();
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assertThat(strategy.nextRestart).isEqualTo(2L * START_TIME_WINDOW_MILLIS);
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// Second restart
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assertThat(strategy.isSolverStuck(moveScope)).isTrue();
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assertThat(strategy.nextRestart).isEqualTo(3L * START_TIME_WINDOW_MILLIS);
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}
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@Test
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void reset() {
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var solverScope = mock(SolverScope.class);
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var phaseScope = mock(LocalSearchPhaseScope.class);
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var stepScope = mock(LocalSearchStepScope.class);
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var moveScope = mock(LocalSearchMoveScope.class);
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var termination = mock(UnimprovedTimeMillisSpentTermination.class);
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when(moveScope.getStepScope()).thenReturn(stepScope);
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when(stepScope.getPhaseScope()).thenReturn(phaseScope);
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when(phaseScope.getSolverScope()).thenReturn(solverScope);
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when(moveScope.getScore()).thenReturn(SimpleScore.of(1));
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when(phaseScope.getBestScore()).thenReturn(SimpleScore.of(1));
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when(termination.isPhaseTerminated(any())).thenReturn(true);
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// Restart
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var strategy = new UnimprovedTimeStuckCriterion<>(termination);
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strategy.solvingStarted(null);
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strategy.phaseStarted(phaseScope);
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assertThat(strategy.isSolverStuck(moveScope)).isTrue();
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assertThat(strategy.nextRestart).isEqualTo(2L * START_TIME_WINDOW_MILLIS);
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// Reset
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strategy.stepStarted(stepScope);
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when(phaseScope.getBestScore()).thenReturn(SimpleScore.of(2));
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strategy.stepEnded(stepScope);
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assertThat(strategy.nextRestart).isEqualTo(START_TIME_WINDOW_MILLIS);
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}
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}

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