[rules-users] infinite loop rules problem

[Wolfgang Laun]

Collecting stuff from several matches into a single Collector fact is best
done
by letting matches occur with rules at salience N. Then, put a single rule
matching the Collector, without any constraints, at salience < N.
This matches any Collector fact, and, in the consequence you should
remove this fact, which has done its duty. To distinguish (as in your case)
the successful case (one match) from others, you might just use an if
statement in the consequence. (Well, yes, this isn't quite comme-il-faut,
but it'll get the job done.) So, don't bother with updates on the Collector
fact.

As for the frequently used && to connect the constraints, it is preferred
to use individual constraint groups, separated by a comma, for matches
with different fact attributes. Constraint groups can be shared among
rules (in the Rete node network) which is the essence of Rete being
fast enough to cope with the many-many pattern matching effort.

-W


2009/9/28 Costigliola Joel (EXT) <joel.costigliola-ext at natixis.com>

>   Hello,
>
>
>
> Me again and no it is not spamming, and I’m still drools newbie ;-)
>
>
>
> I was facing a problem of infinite loop with one of my rule, I have solved
> it but I’m wondering if my solution is not too costful on a performance
> point of view.
>
> So my question is really on the most efficient way of solving the infinite
> loop problem I’m gonna expose you right now.
>
>
>
> First of all, a few words the problem I want to solve with Drools :
>
> My company is a bank where traders are making deals on markets, these deals
> must be classified in book, this is what we call “booking process”.
>
> Booking is done according to booking criteria : which trader has made the
> deal ? on which product ? etc …
>
> A booking rule defines a set of criteria and the target book where the deal
> will classified.
>
>
>
> The guilty rule’s job was to fill DealMatchingBookingRules with the
> booking rules applicable on a deal, (DealMatchingBookingRules references a
> unique deal).
>
> I have put below a corrected version by commenting the update(
> $dealMatchingBookingRules) instruction of the RHS.
>
>
>
> With update uncommented, the problem occurred when 2 booking rule were
> matching the same deal in here’s my understanding of the problem
>
> Facts inserted in the session :
>
> -         dmbr1 (instance of DealMatchingBookingRule) referencing a deal
>
> -         br1 and br2 matching the deal referenced in dmr1
>
> Results :
>
>    1. rule is activated with (dmbr1, br1), dmbr1 is updated
>    2. rule is activated with (dmbr1, br2), dmbr1 is updated - (dmbr1, br1)
>    does not activate the rule because of no-loop rule attribute
>    3. rule is activated AGAIN with (dmbr1, br1), dmbr1 is updated : back
>    to step 1
>    4. rule is activated AGAIN with (dmbr1, br2), dmbr1 is updated : back
>    to step 2
>    5. infinite loop on step1 & step 2
>
>
>
> I have fixed the problem by removing the call to update, but for the next
> steps of my process (not shown here) Drools need to aware of the modified DealMatchingBookingRules.
> I thus have written a rule which only update all DealMatchingBookingRules.
>
>
>
> Is there a better way to solve this infinite loop ?
>
> Feel free to make comments, I’m really open to any suggestion/enhancement.
>
>
>
>
> Regards,
>
>
>
> Joël Costigliola
>
>
>
>
>
> *rule* "Find matching level 1 booking rules by deal"
>
>   *salience* 10
>
>   *no-loop*
>
>   *ruleflow-group* "Find level 1 matching booking rules by deal group"
>
>
>
>   *when*
>
>     $dealMatchingBookingRules : DealMatchingBookingRules($dealModel : deal,
> $dealProductRelatedIndexes : dealProductRelatedIndexes)
>
>     $bookingRule : BTExecutionBookingRuleModel (
>
>       priority == 1
>
>       // when a criterion is not set, it is considered as satisfied.
>
>       && (traderCriterion == *null* || $dealModel.trader ==
> traderCriterion)
>
>       && (portfolioCriterion == *null* || $dealModel.portfolio ==
> portfolioCriterion)
>
>       // when a product type criterion is set to unknown, it is considered
> as satisfied whatever deal product type is.
>
>       && (productTypeStringCriterion == *null* || productTypeCriterion ==
> ProductType.Unknown
>
>           || $dealModel.product.productType == productTypeCriterion)
>
>       && (listedIndexCriterion == *null* ||
> $dealProductRelatedIndexes.relatedIndexes *contains* listedIndexCriterion)
>
>     )
>
>   *then*
>
>     $dealMatchingBookingRules.addMatchingBookingRule($bookingRule);
>
>     // update($dealMatchingBookingRules) : COMMENTED BECAUSE WAS CAUSING
> INFINITE LOOP !
>
> *end*
>
>
>
> // Does the job of update($dealMatchingBookingRules) but without INFINITE
> LOOP.
>
> *rule* "Refresh facts in level 1 booking rule process"
>
>   *salience* 5
>
>   *no-loop*
>
>   *ruleflow-group* "Refresh facts in level 1 booking rule process group"
>
>
>
>   *when*
>
>     $dealMatchingBookingRules : DealMatchingBookingRules()
>
>   *then*
>
>     *update*($dealMatchingBookingRules);
>
> *end*
>
>
>
>
>
>
>    ------------------------------
>
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