[rules-users] NPE on retract
Chris West
crayzfishr at gmail.com
Wed Apr 25 09:25:11 EDT 2007
I'll try to create a self contained test. It may be a difficult task. The
error seems to come and go depending on which other rules I leave in my rule
set. In particular, there is another rule that has many conditions and only
logs a message as the consequence that when it is included in the rule set,
this error occurs. That particular rule has nothing to do with the type of
object being retracted.
My misunderstanding was that Drools used object identity with an
IdentifyHashMap unless it was configured to use a regular HashMap. Is this
not the case?
Concerning not having equals/hashcode changing while the object is asserted
into working memory, is it ok for them to change as long as it is followed
by a "modify("? Is there different behavior between calling "modify" and
calling "retract and re-assert"?
Thanks for you help,
-Chris
On 4/24/07, Edson Tirelli <tirelli at post.com> wrote:
>
>
> Chris
>
> Can you provide a self contained test that shows the problem and open a
> JIRA with it?
> I will take a look in it.
>
> There is no requirement to define equals/hashcode, but if you do so,
> you need to make them time consistent, i.e., they cannot change during the
> time the object is asserted into the working memory or you may have problems
> (as hashcode and equals behaviors are defined as kind of "identity" of the
> object).
>
> []s
> Edson
>
> 2007/4/24, Chris West <crayzfishr at gmail.com>:
> >
> > Mark,
> >
> > The object being retracted currently has no hashcode and equals,
> > therefore defaulting to the ones on Object. The reason I'm even retracting
> > the object is so that I can assert it again to work around bug
> > http://jira.jboss.com/jira/browse/JBRULES-614. Therefore the reason I
> > am retracting the object is because it has changed.
> >
> > Is there a requirement to implement hashcode and equals? If so, does it
> > have to be based on all fields of the pojo? My intent was to implement
> > hashcode and equals, but only base them on the id fields of the class.
> >
> > -Chris
> >
> > On 4/24/07, Mark Proctor < mproctor at codehaus.org> wrote:
> > >
> > > Have you correctly implemented your equals and hashcode? Have you
> > > made sure that the objects fields haven't changed between the assert and the
> > > retract?
> > >
> > > Mark
> > > Chris West wrote:
> > >
> > > Hi,
> > >
> > > Using version 3.0.6 of jboss rules, while retracting an object, I get
> > > the following:
> > >
> > > java.lang.NullPointerException
> > > at org.drools.reteoo.beta.InstanceEqualConstrRightMemory.remove(Unknown
> > > Source)
> > > at org.drools.reteoo.BetaMemory.remove (Unknown Source)
> > > at org.drools.reteoo.NotNode.retractObject(Unknown Source)
> > > at org.drools.reteoo.ObjectSource.propagateRetractObject(Unknown
> > > Source)
> > > at org.drools.reteoo.RightInputAdapterNode.retractTuple (Unknown
> > > Source)
> > > at org.drools.reteoo.TupleSource.propagateRetractTuple(Unknown
> > > Source)
> > > at org.drools.reteoo.NotNode.retractTuple(Unknown Source)
> > > at org.drools.reteoo.TupleSource.propagateRetractTuple (Unknown
> > > Source)
> > > at org.drools.reteoo.JoinNode.retractObject(Unknown Source)
> > > at org.drools.reteoo.ObjectSource.propagateRetractObject(Unknown
> > > Source)
> > > at org.drools.reteoo.ObjectTypeNode.retractObject (Unknown Source)
> > >
> > > at org.drools.reteoo.Rete.retractObject(Unknown Source)
> > > at org.drools.reteoo.ReteooRuleBase.retractObject(Unknown Source)
> > > at org.drools.reteoo.ReteooWorkingMemory.doRetract(Unknown Source)
> > > at org.drools.common.AbstractWorkingMemory.retractObject(Unknown
> > > Source)
> > > at org.drools.common.AbstractWorkingMemory.retractObject(Unknown
> > > Source)
> > > at ascc.rules.AbstractRulesCoordinator.statusChanged(
> > > AbstractRulesCoordinator.java :354)
> > > at ascc.rules.AbstractRulesCoordinator$1.statusChanged(
> > > AbstractRulesCoordinator.java:111)
> > > at ascc.status.BaseStatusBoard.notifyChange(BaseStatusBoard.java
> > > :211)
> > > at ascc.status.BaseStatusBoard.notifyChange (BaseStatusBoard.java
> > > :191)
> > > at ascc.status.DefaultParkingStatusBoard.empty(
> > > DefaultParkingStatusBoard.java:318)
> > > at ascc.spotting.DefaultSpottingCoordinator.computeInitialSpot(
> > > DefaultSpottingCoordinator.java:578)
> > > at ascc.spotting.DefaultSpottingCoordinator.statusCreated(
> > > DefaultSpottingCoordinator.java:827)
> > > at ascc.status.BaseStatusBoard.notifyCreate(BaseStatusBoard.java
> > > :100)
> > > at ascc.status.BaseStatusBoard.notifyCreate (BaseStatusBoard.java
> > > :80)
> > > at ascc.status.DefaultAirPlanStatusBoard.missionAssignmentComplete
> > > (DefaultAirPlanStatusBoard.java:479)
> > > at
> > > ascc.missionassignment.Rule_6___Complete_mission_assignment_for_event_0.consequence(Rule_6___Complete_mission_assignment_for_event_0.java:36)
> > > at
> > > ascc.missionassignment.Rule_6___Complete_mission_assignment_for_event_0ConsequenceInvoker.evaluate(Rule_6___Complete_mission_assignment_for_event_0ConsequenceInvoker.java:24)
> > >
> > > ... 7 more
> > >
> > > Is there something I could be doing wrong? Is this a known bug?
> > >
> > > Thanks,
> > > -Chris
> > >
> > > ------------------------------
> > >
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> > >
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> > >
> > >
> > >
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>
>
> --
> Edson Tirelli
> Software Engineer - JBoss Rules Core Developer
> Office: +55 11 3529-6000
> Mobile: +55 11 9287-5646
> JBoss, a division of Red Hat @ www.jboss.com
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