[rules-users] lock-on-active clarification needed

[Esteban Aliverti]

I've put together my ideas and findings in this topic in my blog:
http://ilesteban.wordpress.com/2012/11/16/about-drools-and-infinite-execution-loops/
Feel free to read it and provide feedback if desired.

Best Regards,


XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Esteban Aliverti
- Blog @ http://ilesteban.wordpress.com


On Thu, Nov 15, 2012 at 2:14 PM, Esteban Aliverti <
esteban.aliverti at gmail.com> wrote:

> Thanks for your clarifications and thoughts.
> My misunderstanding was because I always thought that lock-on-active meant
> lock-on-RULE-active. Something like lock after the first activation and do
> not unlock until the agenda group is changed.
> The real meaning is lock-on-AGENDA_GROUP-active. Meaning: do not create
> activations of this rule (no matter if using update(), modify(), insert()
> or retract()) if the agenda group where it belongs is active.
>
> Best Regards!
>
>
> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>
> Esteban Aliverti
> - Blog @ http://ilesteban.wordpress.com
>
>
> On Thu, Nov 15, 2012 at 7:54 AM, Mattias Nilsson Grip <
> mattias.nilsson.grip at redpill-linpro.com> wrote:
>
>> Armand/Esteban,
>>
>> I had a look at source code (
>> org.drools.common.DefaultAgenda.createActivation(...) ) and as far as I can
>> tell it should not matter if the rules match on the same facts or not. I
>> interpret the source code like this:
>>
>> "While an agenda group or rule flow group is active, any rules within
>> that group with lock-on-active set to true are prevented from creating new
>> activations"
>>
>> I.e. the rule "Rule 1" cannot create an activation since its agenda group
>> MAIN is already active when its conditions are fulfilled.
>>
>> Regards,
>> Mattias
>>
>> ----- Original Message -----
>> From: "Armand Welsh" <AWelsh at statestreet.com>
>> To: "Rules Users List" <rules-users at lists.jboss.org>
>> Sent: Wednesday, 14 November, 2012 11:04:36 PM
>> Subject: Re: [rules-users] lock-on-active clarification needed
>>
>> Esteban,
>>
>> I too have been confused by lock-on-active. Only after reading the
>> definition many times, have I come to the following conclusion:
>>
>> Looking at the documentation, and other examples, I think I can how
>> lock-on-active behaves. From what I gather, it looks like when “init “ rule
>> fires, the activations for that rule consist of the DataSample() facts (all
>> of them). You then modify the fact, but at the same time, the
>> lock-on-active blocks any further activations from occur as a result of
>> modifying the DataSample() fact.
>>
>> Since “Rule 1” depends on DataSample, and it is in the same agenda group
>> as init, “Rule 1” cannot fire until the agenda group is changed, or the
>> ruleflow-group is changed.
>>
>> What is being blocked by lock-on-active is not the reactivation of the
>> rule. What is being blocked is the resultant activations as a result of
>> modify the DataSample fact.
>>
>> This block only holds true on the current focus (agenda-group or
>> ruleflow-group). Think of it as a way of temporarily removing the facts
>> from the knowledge tree.
>>
>> From: rules-users-bounces at lists.jboss.org [mailto:
>> rules-users-bounces at lists.jboss.org] On Behalf Of Esteban Aliverti
>> Sent: Wednesday, November 14, 2012 3:41 AM
>> To: Rules Users List
>> Subject: [rules-users] lock-on-active clarification needed
>>
>> Hi all,
>>
>> I'm dealing with a set of rules having the lock-on-active attribute and
>> I'm not getting the (at least what I understand as) expected results.
>>
>> I've created an isolated JUnit test. I'm attaching it to this email.
>>
>> Basically, I have 2 rules:
>>
>> rule "init"
>>
>> lock-on-active true
>>
>> when
>> $d: DataSample()
>> then
>> System.out.println("Setting predefined value");
>> modify($d){
>> addValue(Parameter.PARAM_A, 10.0)
>> }
>> end
>>
>> rule "Rule 1"
>> lock-on-active true
>> when
>> DataSample($v: values[Parameter.PARAM_A] < 20)
>> then
>> System.out.println("Rule 1: "+$v);
>> end
>>
>> DataSample is a Java class containing a Map<Parameter, Double> where
>> Parameter is an enum.
>>
>> In the test I'm creating a ksession and inserting an empty DataSample
>> object.
>>
>> I understand that as soon as the object is inserted, both rules are
>> evaluated and the result is going to be an activation of rule "init"; and
>> this is what is actually happening. So far so good.
>>
>> Now, after I call fireAllRules() I expect that 'Rule 1' becomes active
>> because of the modification of the fact in "init". Well, this is not the
>> case. I don't see any activation for "Rule 1".
>>
>> My understanding about lock-on-active is that a rule that WAS ACTIVATED
>> is not going to be re-activated until the current agenda group is switched.
>> The odd thing here is that I never had an activation for "Rule 1" so I
>> don't see why it activation after "init" is executed should be prevented.
>>
>> So my question is: Is my understanding wrong? What is the expected
>> behavior of lock-on-active in this situation? I read the documentation but
>> I couldn't get any hint:
>>
>> "
>> Whenever a ruleflow-group becomes active or an agenda-group receives the
>> focus, any rule within that group that has lock-on-active set to true will
>> not be activated any more ; irrespective of the origin of the update, the
>> activation of a matching rule is discarded. This is a stronger version of
>> no-loop, because the change could now be caused not only by the rule
>> itself. It's ideal for calculation rules where you have a number of rules
>> that modify a fact and you don't want any rule re-matching and firing
>> again. Only when the ruleflow-group is no longer active or the agenda-group
>> loses the focus those rules with lock-on-active set to true become eligible
>> again for their activations to be placed onto the agenda."
>>
>> Best Regards,
>>
>> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>>
>> Esteban Aliverti
>> - Blog @ http://ilesteban.wordpress.com
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>> rules-users at lists.jboss.org
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>>
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>
>
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