Optaplanner, How to catch the current time at the beginning of the rule to use it in score?

Question

I have something like that:

   scoreHolder.addSoftConstraintMatch(kcontext, (System.currentTimeMillis()-$time.getTime()));

I want to use the current time at the beginning of firing the rule only, and not to be updated during running the rule. just to catch the current time at the first moment the rule is fired and does not change till the end of solving.

I'm using optaplanner 6.1.

thanks in advance.

Why would you want to do that? http://mywiki.wooledge.org/XyProblem — Ondrej Skopek, Mar 30 '16 at 21:34

score 0 · Answer 1 · answered Mar 30 '16 at 22:02

That would break OptaPlanner, as the Score of the same Solution would change over time (which also implies that comparing 2 different Solutions can not be done fairly - so if a new working score is compared to the best score (which was calculated x seconds ago) it breaks).

Instead, before the solver starts, set the current time millis in a singleton:

 myParametrization.setStartingMillis(System.currentMillis());
 ... = solver.solve(...);

and add that as a problem fact and use it in the score rules (see examination example's InstitutionParameterization).

Optaplanner, How to catch the current time at the beginning of the rule to use it in score?

1 Answers1