Hi,

I'm not keen on spending time on a temp solution if I cannot estimate - at this time - how much time it will take me to build it correctly afterwards.
Budgets are limited... (as with anyone I guess :-)
Once again, it gives me a bad feeling that such a simple setup is giving me such a hard to solve issue.

I had thought that - given the project is only a very few classes - it would be peanuts for you or any other expert to pinpoint what I'm doing wrong.

Non the less...

I tried to have a look again to a number of examples and I changed my rules, with a positive result!
I seem to get the correct solution. But... I do not know if my changes are valid.
I mean, is it possible that I threw a number of possible solutions away?
Maybe this will not show right now but will have it's effect when numbers grow and possible solutions shrink.

So what I did is going from

rule "tasksInSameJobMustBeInSamePeriod"
    when
        $taskA : MaintenanceTask($id : id, $jobId : jobId, $periodId : periodId )
        MaintenanceTask(id != $id, jobId == $jobId, periodId != $periodId )     //  <============   a != $a
    then
        System.out.println("r3: " + $taskA );
        insertLogical(new IntConstraintOccurrence("tasksInSameJobMustBeInSamePeriod",  $taskA));
end

to

rule "tasksInSameJobMustBeInSamePeriod"
    when
        $taskA : MaintenanceTask($id : id, $jobId : jobId, $periodId : periodId )

        MaintenanceTask(id > $id,

jobId == $jobId, periodId > $periodId )    //  <================ a > $a

    then
        System.out.println("r3: " + $taskA );
        insertLogical(new IntConstraintOccurrence("tasksInSameJobMustBeInSamePeriod",  $taskA));

end 

Can you please tell me if this is THE solution or a dangerous move that works out now but will give issues when numbers grow?

Thanks a lot.

Michiel

 

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From: Geoffrey De Smet <ge0ffrey.spam@gmail.com>
To: Michiel Vermandel <mvermand@yahoo.com>; Rules Users List <rules-users@lists.jboss.org>
Sent: Monday, September 3, 2012 11:56 AM
Subject: Re: Best model for planning? technicians, airplanes and shifts => insertLogical problems

Op 03-09-12 11:30, Michiel Vermandel schreef:

I did not really start on one example. I have scrolled through several to try to figure out how to do it, then started from scratch for the POJO's and Rules.

The config file was copies from one of the examples because it contained too many things that were hard to get right in the beginning.

I know that is a risk but I needed to start somewhere.

I am thinking how to standardize the getting started with planner experience.
The cloud balance quick start is the example I pushing at the moment.
But for specific use case, it's better to start from an example that's similar to the user's use case.
The trouble is, it's often hard to see which example is similar and which is not.

3) What does "The workingMemory has 2 ConstraintOccurrence(s) in excess:" really mean?

    - Are the constraints there more than once?

No, it means that in a clean WorkingMemory, those 2 ConstraintOccurrences aren't there,
but in the incremental WorkingMemory, they are there.
So they are in excess: they should have been automatically retracted by the rule engine, but for some reason, they are not.

Read this section about incremental score calculation to understand why this complexity is needed:
  http://docs.jboss.org/drools/release/5.4.0.Final/drools-planner-docs/html_single/index.html#incrementalScoreCalculation

If you just want to prove that a Planner POC works for now (especially if you're close to giving up),
just take a few minutes to switch to a simple Java score calculator for now:
   http://docs.jboss.org/drools/release/5.4.0.Final/drools-planner-docs/html_single/index.html#d0e3336
It will be _much_ slower especially when it scales out (but it should still be faster than anything you can invent yourself within reasonable time).
Once that works fine and you get a good result on your toy problem and you can scale out to 100+ jobs,
then switch back to drools to scale out to 10000+ jobs and follow the rest of this mail.

    - has this something to do with the equals and hashcode (which I did implement (see below))?

Likely. The equals/hashcode methods are used of all objects in the causes parameter.
It's a design issue in Planner that the planner entity's equals/hashcode() needs to be used for the ConstraintOccurrence's causes.
Compensation action

    About the compensation action: is it already available on 5.4.0 final? Should I try that?

The plumbing is there in Drools Expert, but in Planner there are no decent examples, supporting code or even complex experiments yet.
It's a minefield, probably best to stay out until I get it done or you have more Planner experience :/

4) I have been looking to the equals and hashcode, though found many examples that implement solutionEquals and solutionHashcode instead.

    Currently I implemented them like this:

    @Override
    public int hashCode() {
        return id.hashCode(); //(*)
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (id == null || !(o instanceof MaintenanceTask)) {
            return false;
        } else {
            MaintenanceTask other = (MaintenanceTask) o;
            return id.equals(other.id);
        }
    }

Looks good

    (*) id is a String property which is passed into the entity object through the constructor and upon cloning it is passed from the clone source to the clone target:

        public MaintenanceTask clone() {
            System.out.println("Cloning task " + id);
            MaintenanceTask clone = new MaintenanceTask(job, id);
            clone.period = this.period;
            clone.technician = this.technician;
            return clone;
        }

Looks good.

   

    I am still confused about:

    - Which ones do I need to implement (equals or solutionEquals, ...)?

because of this code:
  https://github.com/droolsjbpm/drools-planner/blob/master/drools-planner-core/src/main/java/org/drools/planner/core/score/constraint/ConstraintOccurrence.java#L54
which is called by drools on insertLogical inserted objects (see drools expert manual on insertLogical)

    - Should an entity and a cloned entity have the same result for both equals and hashcode? (I guess so)

Yes, definitely.

    - Should only the entity objects have such implementations? (Planning variables are never cloned, right?)

It looks good. Only the entity's are cloned indeed during cloneSolution(): they are the only instances that change during planning.

  

 

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From: Geoffrey De Smet <ge0ffrey.spam@gmail.com>
To: Rules Users List <rules-users@lists.jboss.org>
Sent: Monday, September 3, 2012 10:44 AM
Subject: Re: [rules-users] Best model for planning? technicians, airplanes and shifts => insertLogical problems

Op 03-09-12 10:21, Michiel Vermandel schreef:
> Hi Geoffrey,
>
> Thanks for the support so far.
> I understand that you do not provide full support on this level.
> Though I have the feeling that this is really
> - a very basic solution setup
> - a beginners-mistake and since I'm looking into it now for about 3 days
> (since I started with planner) it seems to be not obvious to find for a
> beginner.
> So I was trying my luck in offering the code.
> It could be an opportunity to enrich the documentation ;-) ;-)

Good point, the score corruption problem is often a beginner problem and
it's a PITA. I 'll write some more docs about.

Do note that your 3 day implementation should be able to scale out to
10000 planes pretty easily, so hang in there :)
I fear you might have started copying from the wrong example nqueens (if
you did that) :/ Nurse rostering is a far more similar to this kind of
problem. I am not sure which example to promote in the docs: the nqueens
is simple enough to explain things on, but it's too simple to copy from
for real world stuff :/ Feedback welcome.

>
>
> Ok,
>
> 1) adding the $t2 results in the same sort of exception, only
> planningEntity seems different:
>
> with insertLogical(new
> UnweightedConstraintOccurrence("tasksInSameJobMustBeInSamePeriod", $t1,
> $t2));
>
> Exception in thread "main" java.lang.IllegalStateException: Score
> corruption: the workingScore (-2) is not the uncorruptedScore (0):
>    The workingMemory has 2 ConstraintOccurrence(s) in excess:
>      tasksInSameJobMustBeInSamePeriod/NEGATIVE_HARD:[Maintenance of
> Boeing 737 - PJ23.I#1 73111693, Maintenance of Boeing 737 - PJ23.I#2
> 427578167]
>      tasksInSameJobMustBeInSamePeriod/NEGATIVE_HARD:[Maintenance of
> Boeing 737 - PJ23.I#2 427578167, Maintenance of Boeing 737 - PJ23.I#1
> 73111693]
>    Check the score rules who created those ConstraintOccurrences. Verify
> that each ConstraintOccurrence's causes and weight is correct.
>      at
> org.drools.planner.core.score.director.AbstractScoreDirector.assertWorkingScore(AbstractScoreDirector.java:101)
>      at
> org.drools.planner.core.constructionheuristic.greedyFit.decider.DefaultGreedyDecider.doMove(DefaultGreedyDecider.java:110)
>      at
> org.drools.planner.core.constructionheuristic.greedyFit.decider.DefaultGreedyDecider.decideNextStep(DefaultGreedyDecider.java:78)
>      at
> org.drools.planner.core.constructionheuristic.greedyFit.DefaultGreedyFitSolverPhase.solve(DefaultGreedyFitSolverPhase.java:63)
>      at
> org.drools.planner.core.solver.DefaultSolver.runSolverPhases(DefaultSolver.java:183)
>      at
> org.drools.planner.core.solver.DefaultSolver.solve(DefaultSolver.java:151)
>      at
> be.axi.planner.domain.MaintenancePlanning.main(MaintenancePlanning.java:27)
>
> with insertLogical(new
> UnweightedConstraintOccurrence("tasksInSameJobMustBeInSamePeriod", $t1));
>
> Exception in thread "main" java.lang.IllegalStateException: Score
> corruption: the workingScore (-2) is not the uncorruptedScore (0):
>    The workingMemory has 2 ConstraintOccurrence(s) in excess:
>      tasksInSameJobMustBeInSamePeriod/NEGATIVE_HARD:[Maintenance of
> Airbus A350 - XJ34.I#2 778813475]
>      tasksInSameJobMustBeInSamePeriod/NEGATIVE_HARD:[Maintenance of
> Airbus A350 - XJ34.I#0 225744121]
>    Check the score rules who created those ConstraintOccurrences. Verify
> that each ConstraintOccurrence's causes and weight is correct.
>      at
> org.drools.planner.core.score.director.AbstractScoreDirector.assertWorkingScore(AbstractScoreDirector.java:101)
>      at
> org.drools.planner.core.constructionheuristic.greedyFit.decider.DefaultGreedyDecider.doMove(DefaultGreedyDecider.java:110)
>      at
> org.drools.planner.core.constructionheuristic.greedyFit.decider.DefaultGreedyDecider.decideNextStep(DefaultGreedyDecider.java:78)
>      at
> org.drools.planner.core.constructionheuristic.greedyFit.DefaultGreedyFitSolverPhase.solve(DefaultGreedyFitSolverPhase.java:63)
>      at
> org.drools.planner.core.solver.DefaultSolver.runSolverPhases(DefaultSolver.java:183)
>      at
> org.drools.planner.core.solver.DefaultSolver.solve(DefaultSolver.java:151)
>      at
> be.axi.planner.domain.MaintenancePlanning.main(MaintenancePlanning.java:27)
>
>
> 2) You suggested to replace UnweightedConstraintOccurrence with
> IntConstraintOccurrence. I will.
> UnweightedConstraintOccurrence is used in the very basic Queens example
> though...

Yep, my mistake.

>
> 3) Where is the best place to read about what insertLogical and
> IntConstraintOccurrence really do?
> What is the purpose of the Cause -objects, which should be passed?
> => where is the best place to find explanation about this?
> (http://docs.jboss.org/drools/release/5.4.0.Final/drools-planner-docs/html_single/
> doesn't really enlighten me on that part)

Look for "insertLogical" in the Drools Expert guide:

http://docs.jboss.org/drools/release/5.4.0.Final/drools-expert-docs/html_single/index.html

When rules do an insertLogical of an object A, it's discarded if another
object B in the WorkingMemory equals object A (through equals() and
through hashcode()). Because the ConstraintOccurrences need to be unique
so they aren't discarded, they ruleId, constraintType and causes are
used for equals()/hashcode().

Future work: "compensation action"
Recently, drools introduced something called "compensation action",
which can probably replace the use insertLogical(ConstraintOccurrence)
and make the causes parameter obsolete.
It's also faster.
My first experiments look very promising, but I haven't got time yet to
experiment with it on all examples and make it easy for users to use.

It would allow us to do something like this in the then part of a rule:
  hardAndSoftScoreHelper.addHardScore(-5);
or
  hardAndSoftScoreHelper.addSoftScore(- $sum);
or
  simpleScoreHelper.addScore(-7);

No need for causes, insertLogicals, no equals/hashcode() worries, much
more flexible, ...


4) Does your MaintenanceTask implement equals()/hashcode() other than
Object's original implementation?


>
> Thanks in advance.
>

yw

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