[rules-users] npe in LogicalRetractCallback when using jpa persistence

[Chris Raschl]

Hi Edson,
thanks für your response. I'll try to provide a testcase... if you don't 
get a jira ticket, the test revealed it was user error. :-)

- chris

Am 10.08.2010 16:16, schrieb Edson Tirelli:
>      Chris,
>
>      I will look into this problem, but I am not sure how to reproduce
> it. Maybe you can provide me a test case? If so, please open a JIRA,
> attached your test case and ping me.
>
>      Thanks,
>          Edson
>
>
> 2010/8/10 Chris Raschl <c.raschl at dyless.com <mailto:c.raschl at dyless.com>>
>
>     Hi,
>     Just in case someone faces the same problem, comments inline:
>
>     Am 05.08.2010 13:53, schrieb Chris Raschl:
>      > I'm using the latest drools and drools flow snapshot with jpa
>     persistence.
>      >
>      > When I'm retracting a fact from the knowledge session (which causes
>      > logical retraction), the session can't be persisted any more.
>      >
>      > During retraction a LogicalRetractCallback is instantiated using this
>      > constructor:
>      >
>      > public LogicalRetractCallback(final TruthMaintenanceSystem tms,
>      >                                 final LogicalDependency node,
>      >                                 final Set set,
>      >                                 final InternalFactHandle handle,
>      >                                 final PropagationContext context,
>      >                                 final Activation activation) {
>      >       this.tms = tms;
>      >       this.node = node;
>      >       this.set = set;
>      >       this.handle = handle;
>      >       this.context = context;
>      > }
>      >
>      > As you can see an activation object can be passed (and actually is
>      > passed) to the constructor, but is never used. Retraction works
>     though.
>      >
>      > The problem occurs when the knowledge session is persisted, because
>      > LogicalRetractCallback.write assumes that activation is not null,
>     which
>      > leads to this npe:
>      >
>      > Caused by: java.lang.NullPointerException
>      >
>     org.drools.common.TruthMaintenanceSystem$LogicalRetractCallback.write(TruthMaintenanceSystem.java:251)
>      >
>     org.drools.marshalling.impl.OutputMarshaller.writeActionQueue(OutputMarshaller.java:201)
>
>     Adding this.activation = activation to the constructor does not help,
>     beause the npe in the write method remains. I tried it, then the whole
>     expression "context.terminalTupleMap.get( this.activation.getTuple() )"
>     in the write method evaluates to null...
>
>     I found out persistence was triggered by an unneccessary flush in my
>     code. I removed that, everything works now.
>
>     That seems to be the case because the action queue is empty then and
>     there's no need to persist it, thus the write method is never called. I
>     guess the problem remains if someone tries to persist a session with an
>     action queue containing a LogicalRetractCallback object.
>
>     - chris
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>
>
>
>
> --
>    Edson Tirelli
>    JBoss Drools Core Development
>    JBoss by Red Hat @ www.jboss.com <http://www.jboss.com>
>
>
>
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