[jboss-jira] [JBoss JIRA] Commented: (JBRULES-1315) Rule that uses a 'collect' and 'from' clause together causes problem

[Pavlin Zahariev (JIRA)]

    [ http://jira.jboss.com/jira/browse/JBRULES-1315?page=comments#action_12398505 ] 
            
Pavlin Zahariev commented on JBRULES-1315:
------------------------------------------

Hi,
the evil is the sharedCounter which is not used properly. It is increased when a node is found to be equal to an existing node, but on node TupleSource.remove is decreased when a tupleSink calls its tupleSource to detach it from its sink. IMHO there is no clear relation on how many times a node was shared and how many nodes it has in the sink. 

The problem happens because sharedCounter is used to check if a node isInUse. This is wrong. Node is in use, if a tupleSink has a reference to its tupleSource - nothing to do with sharedCounter. I also couldn't find any other use of the sharedCounter.

Therefore override the imp[ementation of isInUse() in class TupleSource like this.
	public boolean isInUse() {
		if (null!=sink) {
			Sink[] sinks = sink.getSinks();
			return ((null!=sinks) && (0<sinks.length));
		}
		
		return false;
	}

Now it works fine.

Probably more general solution could be offered from drools team. 

Cheers,

Pavlin


> Rule that uses a 'collect' and 'from' clause together causes problem
> --------------------------------------------------------------------
>
>                 Key: JBRULES-1315
>                 URL: http://jira.jboss.com/jira/browse/JBRULES-1315
>             Project: JBoss Drools
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>          Components: Reteoo
>    Affects Versions: 4.0.3
>            Reporter: Igor Bolic
>         Assigned To: Edson Tirelli
>         Attachments: testRemovePackage.rar
>
>
> Test case:
> Write a Rule that uses a 'collect' and 'from' clause together, example:
> package com.sample.mypackage
> rule "Apply discount"
>         when
>                 $order: Order();
>                 $items : ArrayList() from collect (OrderItem() from $order.items)
>         then
>                 #apply discount
> end
> first i add the package to RuleBase object, everthing works fine. When i try to 'refresh' my rules, i.e. first remove the package and again 
> add the same (modified) package to the RuleBase object, following error occurs: 
> java.lang.IllegalArgumentException: Cannot remove a sink, when the list of sinks is null
>         at org.drools.reteoo.ObjectSource.removeObjectSink(ObjectSource.java:116)
>         at org.drools.reteoo.AlphaNode.remove(AlphaNode.java:181)
>         at org.drools.reteoo.LeftInputAdapterNode.remove(LeftInputAdapterNode.java:204)
>         at org.drools.reteoo.FromNode.remove(FromNode.java:153)
>         at org.drools.reteoo.RightInputAdapterNode.remove(RightInputAdapterNode.java:167)
>         at org.drools.reteoo.BetaNode.remove(BetaNode.java:186)
>         at org.drools.reteoo.RuleTerminalNode.remove(RuleTerminalNode.java:461)
>         at org.drools.reteoo.ReteooBuilder.removeRule(ReteooBuilder.java:224)
>         at org.drools.reteoo.ReteooRuleBase.removeRule(ReteooRuleBase.java:272)
>         at org.drools.common.AbstractRuleBase.removePackage(AbstractRuleBase.java:460)
>         ... 
> I've found a workaround for this error by writing my .drl code as following:
> package com.sample.mypackage
> rule "Explode Cart"  
>         salience 11
>         dialect "java"
>         when
>                 $order: Order()
>                 $item : OrderItem() from $order.items
>         then
>                 insert( $item );
> end
> rule "Apply discount"
>         no-loop true
>         when
>                 $order : Order();
>                 $items : ArrayList() from collect (OrderItem())
>         then
>                 #apply discount
> end 
> Now, my rules are 'refreshed' without any error.

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