Re: [rules-users] Question about custom accumulation functions

Hi Edson, hi all, 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 :