Set a ListMoveChange filter when using OptaPlanner Spring Boot starter

Question

We are using the OptaPlanner Spring Boot starter to create a vehicle routing problem solver based on the example in the OptaPlanner quickstarts:

https://github.com/kiegroup/optaplanner-quickstarts/tree/stable/use-cases/vehicle-routing

So we do not have an solveConfig.xml file. We would like to define a filter for ListChangeMoves but it's not clear how we would register this without using an XML file. We have tried using a solverConfig.xml e.g.

<localSearch>
  <unionMoveSelector>
    <listChangeMoveSelector>
      <filterClass>my.filter.Class</filterClass>
    </listChangeMoveSelector>
  </unionMoveSelector>
</localSearch>

But this is not working. Is there an example of setting up a filter for list moves?

Answer 1

This is a XML solver config using a a swap move selector and a change move selector with move filtering:

  <constructionHeuristic/>
  <localSearch>
    <unionMoveSelector>
      <changeMoveSelector>
        <filterClass>org.acme.vehiclerouting.solver.ChangeMoveSelectorFilter</filterClass>
      </changeMoveSelector>
      <swapMoveSelector/>
    </unionMoveSelector>
  </localSearch>

If you don't want to use swap moves, then you don't need the union move selector and the configuration can be simplified to:

  <constructionHeuristic/>
  <localSearch>
    <changeMoveSelector>
      <filterClass>org.acme.vehiclerouting.solver.ChangeMoveSelectorFilter</filterClass>
    </changeMoveSelector>
  </localSearch>

A few comments:

• I'm including the CH phase because it is necessary in a typical case. See OptaPlanner terminates immediately if I add constructionHeuristic config for an explanation.
• The ChangeMoveSelector is automatically configured to produce ListChangeMoves if the planning entity has a @PlanningListVariable. There is no <listChangeMoveSelector> config element.
• More information including how to implement the move selection filter can be found in the documentation.

UPDATE: No XML configuration

It's possible to inject SolverConfig, modify it and then use it to create other objects, for example Solver, SolverManager, and ScoreManager.

The code would look something like this:

@Component
class MyService {

    // Don't inject these.
    private final SolverManager<VrpSolution, Long> solverManager;
    private final ScoreManager<VrpSolution, HardSoftScore> scoreManager;

    // But inject the SolverConfig.
    public MyService(SolverConfig solverConfig) {
        // And instantiate SolverManager and ScoreManager manually.
        this.solverManager = SolverManager.<VrpSolution, Long>create(
            solverConfig.withPhaseList(Arrays.asList(
                new ConstructionHeuristicPhaseConfig(),
                new LocalSearchPhaseConfig().withMoveSelectorConfig(
                        new ChangeMoveSelectorConfig()
                                .withFilterClass(MyFilter.class)))));
        this.scoreManager = ScoreManager.create(SolverFactory.create(solverConfig));
    }
}

Pros:

• SolverConfig will be initialized by OptaPlannerAutoConfiguration (from optaplanner-spring-boot-starter) before it's injected into your component. That means:
• The solution and entity classes will be auto-discovered and you don't have to specify them (which you have to in solverConfig.xml).
• You can use application.properties to do minor solver config tweaks, for example set time-spent termination.

Cons:

• You have to create Solver,SolverManager, and ScoreManager instances manually. Specifically, you can't have a @Bean method producing an instance of one of the types above because that would deactivate OptaPlannerAutoConfiguration, which creates the SolverConfig bean.