<div><br></div> It looks like a bug, as it should not raise a NPE no matter what.... which version of Drools are you using?<div><br></div><div> Edson<br><br><div class="gmail_quote">2011/9/8 Bruno Freudensprung <span dir="ltr"><<a href="mailto:bruno.freudensprung@temis.com">bruno.freudensprung@temis.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><u></u>
<div bgcolor="#ffffff" text="#000000">
<br>
Hi Edson, hi all,<br>
<br>
To stick to the subject, I have a strange problem (stack trace in
PS) with a rule containing two accumulate calls, the result of the
first one is re-injected as the input of the second one. Those
accumulate functions are "home made". <br>
The first one (tokenize) returns an ArrayList of Token objects built
by tokenizing the "text" of the Sentence objects.<br>
The second one (build10windows) returns an ArrayList of Window
objects, each one them containing 10 consecutive tokens.<br>
Here is the rule<br>
<br>
<tt> when<br>
$budget : ManualAnnotation(text == "something")<br>
<b>$tokens</b> : java.util.ArrayList() <b>from
accumulate </b>($s : Sentence(), <b>tokenize</b>($s))<br>
$windows : java.util.ArrayList() <b>from accumulate </b>($t
: Token() <b>from $tokens</b>, <b>build10windows</b>($t))<br>
# removed a part here but the problem occurs even without
this part<br>
then<br>
retract($budget);<br>
</tt><br>
Is there anything else one should be aware of when implementing
their own accumulate function? I mean things related to the fact
that "classical" accumulate functions (sum, average) return an
immutable object that does not share anything with the context
object.<br>
Although accumulate, reverse, and getResult methods of my functions
are unit tested, I suspect something that could be related to
stateless/stateful considerations.<br>
What do you think?<br>
<br>
Many thanks,<br>
<br>
Bruno.<br>
<br>
PS :<br>
<br>
The stack trace is:<br>
at
org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)<br>
at
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:927)<br>
at
org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:856)<br>
at
org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1071)<br>
at
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:785)<br>
at
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:751)<br>
at
org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:218)<br>
at
org.drools.command.runtime.rule.FireAllRulesCommand.execute(FireAllRulesCommand.java:99)<br>
at
org.drools.command.runtime.rule.FireAllRulesCommand.execute(FireAllRulesCommand.java:33)<br>
at
org.drools.command.runtime.BatchExecutionCommandImpl.execute(BatchExecutionCommandImpl.java:159)<br>
at
org.drools.command.runtime.BatchExecutionCommandImpl.execute(BatchExecutionCommandImpl.java:81)<br>
at
org.drools.impl.StatelessKnowledgeSessionImpl.execute(StatelessKnowledgeSessionImpl.java:262)<br>
... 5 more<br>
Caused by: java.lang.NullPointerException<br>
at
org.drools.reteoo.AccumulateNode.getFirstMatch(AccumulateNode.java:967)<br>
at
org.drools.reteoo.AccumulateNode.splitList(AccumulateNode.java:920)<br>
at
org.drools.reteoo.AccumulateNode.removePreviousMatchesForLeftTuple(AccumulateNode.java:874)<br>
at
org.drools.reteoo.AccumulateNode.retractLeftTuple(AccumulateNode.java:205)<br>
at
org.drools.reteoo.CompositeLeftTupleSinkAdapter.doPropagateRetractLeftTuple(CompositeLeftTupleSinkAdapter.java:238)<br>
at
org.drools.reteoo.CompositeLeftTupleSinkAdapter.propagateRetractLeftTupleDestroyRightTuple(CompositeLeftTupleSinkAdapter.java:138)<br>
at
org.drools.reteoo.AccumulateNode.retractLeftTuple(AccumulateNode.java:212)<br>
at
org.drools.reteoo.ObjectTypeNode.retractObject(ObjectTypeNode.java:240)<br>
at
org.drools.reteoo.EntryPointNode.retractObject(EntryPointNode.java:231)<br>
at
org.drools.common.AbstractWorkingMemory.retract(AbstractWorkingMemory.java:1288)<br>
at
org.drools.base.DefaultKnowledgeHelper.retract(DefaultKnowledgeHelper.java:201)<br>
at
org.drools.base.DefaultKnowledgeHelper.retract(DefaultKnowledgeHelper.java:214)<br>
at
defaultpkg.Rule_Display_windows_0.defaultConsequence(Rule_Display_windows_0.java:21)<br>
at
defaultpkg.Rule_Display_windows_0DefaultConsequenceInvoker.evaluate(Rule_Display_windows_0DefaultConsequenceInvoker.java:29)<br>
at
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:917)<br>
... 15 more<div class="im"><br>
<br>
<br>
Bruno.<br>
<br>
Le 24/08/2011 16:21, Edson Tirelli a écrit :
</div><blockquote type="cite">
<div><br>
</div><div><div></div><div class="h5">
Yes, evaluation is incremental, so for every new fact, it will
call accumulate() and getResult().
<div><br>
</div>
<div> We do want to reduce the calls to getResult(), improving
performance, but it is not easy to figure out a way, as from an
engine perspective, it never knows when the application is done
inserting facts and it is time to calculate the final result.</div>
<div><br>
</div>
<div> Edson<br>
<br>
<div class="gmail_quote">2011/8/24 Bruno Freudensprung <span dir="ltr"><<a href="mailto:bruno.freudensprung@temis.com" target="_blank">bruno.freudensprung@temis.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex">
Hi,<br>
<br>
While testing my custom accumulation function I noticed an
unexpected<br>
behavior (th'ats of course a personal point of view).<br>
It seems that Drools 5.1 calls accumulate(...) and
getResult(...) as<br>
many times as the number of accumulated facts (accumulate,
getResult,<br>
accumulate, getResult, etc...).<br>
Is it supposed to work like this?<br>
<br>
Best regards,<br>
<br>
Bruno.<br>
<br>
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</div>
<br>
<br clear="all">
<div><br>
</div>
-- <br>
Edson Tirelli<br>
JBoss Drools Core Development<br>
JBoss by Red Hat @ <a href="http://www.jboss.com" target="_blank">www.jboss.com</a><br>
</div>
<pre><fieldset></fieldset>
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<br>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br> Edson Tirelli<br> JBoss Drools Core Development<br> JBoss by Red Hat @ <a href="http://www.jboss.com">www.jboss.com</a><br>
</div>