[rules-users] drools-planner move question - move generation by DRL

[Geoffrey De Smet]

Op 23-08-12 21:52, Ricardo schreef:
> How to do a move generation by DRL? is this available in which version?
>
>
I haven't done it yet at this time (no examples, no docs), but it should 
be relatively easy to do in the new selector architecture (5.5.0.Beta1+),
by implementing a MoveIteratorFactory, a stronger alternative to a 
simple MoveListFactory:

public class ... extends MoveIteratorFactory {

     public Iterator<Move> createOriginalMoveIterator(ScoreDirector 
scoreDirector) {
          ((DroolsScoreDirector) 
scoreDirector).getWorkingMemory().getQueryResults(...)
          ...
     }

     ... // implement other 2 methods correct too

}

There's a big pitfall however:
That WorkingMemory is used for to do and undo every step that is 
evaluated (to enable the huge speed bonus of incremental score calculation).
So when you add a (forward chained) rule for move generation in that 
WM's RuleBase,
it can (and will) slow down every score calculation...
However, if you add (backward chained) queries instead, that should have 
no performance impact.
I haven't experimented with this yet and I welcome any feedback if 
you're doing experiments with this.

Long term solution:
When I implement multi-threaded solvers (depending on how much time I 
get for Planner this will be sooner or later - it is a massive change), 
there will be a WM that is used for move selection only. So, we 'll be 
able to add (forward chained) rules on that, without slowing down the 
score calculation.
After the feature "multi-threaded solvers", I 'll add official support 
for "move generation by DRL".

>
> -----
> with kind regards,
>
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