OptaPlanner，影子变量的损坏值更改为未损坏值

Question

optaplanner-bom 版本 7.45.0.Final.

@PlanningEntity
public class Task {
    
@PlanningVariable(valueRangeProviderRefs = "timeGrainRange")
private TimeGrain startingTimeGrain;

@CustomShadowVariable(variableListenerClass = DurationUpdatingVariableListener.class,
        sources = { @PlanningVariableReference(variableName = "startingTimeGrain") })
private Long durationInGrains;
......

在 DurationUpdatingVariableListener 类中：

public void afterVariableChanged(ScoreDirector scoreDirector, Task e) { 
    if (null == e.getStartingTimeGrain()) {
        return;
    }
    Schedule s = (Schedule)scoreDirector.getWorkingSolution();
    List<Task> tasksToBeUpdated = s.getTasksToBeUpdated(e);  // calculate all updates
    for (Task t: tasksToBeUpdated) {
        scoreDirector.beforeVariableChanged(t, NAME_DURATION);
        t.setDurationInGrains(convertToGrain(t.getDurationInSecs()));
        scoreDirector.afterVariableChanged(t, NAME_DURATION);
    }
}

逻辑是，当一个任务的startingTimeGrain改变时，会影响一些任务的时长。问题是，当变量“tasksToBeUpdated”只包含一个任务时，没有错误。当它包含多个任务时，出现以下错误：

ERROR 30844 --- [pool-1-thread-1] o.o.c.impl.solver.DefaultSolverManager   : Solving failed for problemId (1).

java.lang.IllegalStateException: The move thread with moveThreadIndex (3) has thrown an exception. Relayed here in the parent thread.
    at org.optaplanner.core.impl.heuristic.thread.OrderByMoveIndexBlockingQueue.take(OrderByMoveIndexBlockingQueue.java:147) ~[optaplanner-core-7.45.0.Final.jar:7.45.0.Final]
    at org.optaplanner.core.impl.constructionheuristic.decider.MultiThreadedConstructionHeuristicDecider.forageResult(MultiThreadedConstructionHeuristicDecider.java:186) ~[optaplanner-core-7.45.0.Final.jar:7.45.0.Final]
    ......
Caused by: java.lang.IllegalStateException: VariableListener corruption after completedAction (Undo(id=1, ...., startingTimeGrain=null {null -> {"grainIndex":1,"id":1}})):
    The entity (id=2, ..., startingTimeGrain=1)'s shadow variable (Task.durationInGrains)'s corrupted value (4) changed to uncorrupted value (3) after all VariableListeners were triggered without changes to the genuine variables.
      Maybe the VariableListener class (DurationUpdatingVariableListener) for that shadow variable (Task.durationInGrains) forgot to update it when one of its sources changed.

    at org.optaplanner.core.impl.score.director.AbstractScoreDirector.assertShadowVariablesAreNotStale(AbstractScoreDirector.java:545) ~[optaplanner-core-7.45.0.Final.jar:7.45.0.Final]
    ......

可以肯定的是，Task.setDurationInGrains() 只在 afterVariableChanged() 中被调用。为什么会发生错误？ Here 是Schedule.getTasksToBeUpdated(Task task)的代码。

Answer 1

确保您的持续时间更新侦听器能够正确“清理”受撤消移动影响的所有任务的影子变量。因此，例如，如果您有：

Task(id=1, startingTimeGrain=null, durationInGrains=null)
Task(id=2, startingTimeGrain={"grainIndex":2,"id":1}, durationInGrains=3)

你会的

Move(id=1, ...., startingTimeGrain=null {null -> {"grainIndex":1,"id":1}})

您的持续时间更新侦听器可能会导致如下结果：

Task(id=1, startingTimeGrain={"grainIndex":1,"id":1}, durationInGrains=1)
Task(id=2, startingTimeGrain={"grainIndex":2,"id":1}, durationInGrains=4)

请注意，任务 2 受到更改任务 1 的移动的影响，并且其持续时间由侦听器更新。

如果这是真的，那么在上面的移动被撤消之后：

Undo(id=1, ...., startingTimeGrain=null {null -> {"grainIndex":1,"id":1}})

为了避免监听器损坏，这是绝对必须发生的：

Task(id=1, startingTimeGrain=null, durationInGrains=null)
Task(id=2, startingTimeGrain={"grainIndex":2,"id":1}, durationInGrains=3)

注意持续时间更新监听器负责：

1. 在撤消后将任务 1 上的 durationInGrains 设置为 null，将其从 Grain 1 中取消分配。
2. 重新计算受任务 1 移动影响的任务 2 的持续时间，并将其持续时间设置为与任务 1 移动完成之前相同的值 (3)。