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".
The first one (tokenize) returns an ArrayList of Token objects built
by tokenizing the "text" of the Sentence objects.
The second one (build10windows) returns an ArrayList of Window
objects, each one them containing 10 consecutive tokens.
Here is the rule
when
$budget : ManualAnnotation(text == "something") $tokens : java.util.ArrayList() from
accumulate ($s : Sentence(), tokenize($s))
$windows : java.util.ArrayList() from accumulate ($t
: Token() from $tokens, build10windows($t))
# removed a part here but the problem occurs even without
this part
then
retract($budget);
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.
Although accumulate, reverse, and getResult methods of my functions
are unit tested, I suspect something that could be related to
stateless/stateful considerations.
What do you think?
Many thanks,
Bruno.
PS :
The stack trace is:
at
org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)
at
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:927)
at
org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:856)
at
org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1071)
at
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:785)
at
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:751)
at
org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:218)
at
org.drools.command.runtime.rule.FireAllRulesCommand.execute(FireAllRulesCommand.java:99)
at
org.drools.command.runtime.rule.FireAllRulesCommand.execute(FireAllRulesCommand.java:33)
at
org.drools.command.runtime.BatchExecutionCommandImpl.execute(BatchExecutionCommandImpl.java:159)
at
org.drools.command.runtime.BatchExecutionCommandImpl.execute(BatchExecutionCommandImpl.java:81)
at
org.drools.impl.StatelessKnowledgeSessionImpl.execute(StatelessKnowledgeSessionImpl.java:262)
... 5 more
Caused by: java.lang.NullPointerException
at
org.drools.reteoo.AccumulateNode.getFirstMatch(AccumulateNode.java:967)
at
org.drools.reteoo.AccumulateNode.splitList(AccumulateNode.java:920)
at
org.drools.reteoo.AccumulateNode.removePreviousMatchesForLeftTuple(AccumulateNode.java:874)
at
org.drools.reteoo.AccumulateNode.retractLeftTuple(AccumulateNode.java:205)
at
org.drools.reteoo.CompositeLeftTupleSinkAdapter.doPropagateRetractLeftTuple(CompositeLeftTupleSinkAdapter.java:238)
at
org.drools.reteoo.CompositeLeftTupleSinkAdapter.propagateRetractLeftTupleDestroyRightTuple(CompositeLeftTupleSinkAdapter.java:138)
at
org.drools.reteoo.AccumulateNode.retractLeftTuple(AccumulateNode.java:212)
at
org.drools.reteoo.ObjectTypeNode.retractObject(ObjectTypeNode.java:240)
at
org.drools.reteoo.EntryPointNode.retractObject(EntryPointNode.java:231)
at
org.drools.common.AbstractWorkingMemory.retract(AbstractWorkingMemory.java:1288)
at
org.drools.base.DefaultKnowledgeHelper.retract(DefaultKnowledgeHelper.java:201)
at
org.drools.base.DefaultKnowledgeHelper.retract(DefaultKnowledgeHelper.java:214)
at
defaultpkg.Rule_Display_windows_0.defaultConsequence(Rule_Display_windows_0.java:21)
at
defaultpkg.Rule_Display_windows_0DefaultConsequenceInvoker.evaluate(Rule_Display_windows_0DefaultConsequenceInvoker.java:29)
at
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:917)
... 15 more
Bruno.
Le 24/08/2011 16:21, Edson Tirelli a écrit :
Yes, evaluation is incremental, so for every new fact, it will
call accumulate() and getResult().
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.
While testing my custom accumulation function I noticed an
unexpected
behavior (th'ats of course a personal point of view).
It seems that Drools 5.1 calls accumulate(...) and
getResult(...) as
many times as the number of accumulated facts (accumulate,
getResult,
accumulate, getResult, etc...).
Is it supposed to work like this?