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Type: Bug
Resolution: Done
Priority: Minor
Fix Version/s: None
Affects Version/s: 7.16.0.Final
Component/s: None
Labels:
None

Sprint:
2019 Week 50-52 (from Dec 9)
Docs QE Status:
NEW
QE Status:
NEW

This rule file makes the engine stuck in an infinite loop.

Unable to find source-code formatter for language: drools. Available languages are: actionscript, ada, applescript, bash, c, c#, c++, cpp, css, erlang, go, groovy, haskell, html, java, javascript, js, json, lua, none, nyan, objc, perl, php, python, r, rainbow, ruby, scala, sh, sql, swift, visualbasic, xml, yaml

package com.example

declare Counter
    value: int
end

rule "Init" when
    not Counter()
then
    drools.insert(new Counter(0));
end

rule "Loop"
when
    c: Counter()
then
// removing this comment line removes the loop
    c.setValue(1);
    update(c);
end

But the loop is not an issue.
The issue is that if the commented line is removed the loop is gone.
This code doesn't cause the loop.

Unable to find source-code formatter for language: drools. Available languages are: actionscript, ada, applescript, bash, c, c#, c++, cpp, css, erlang, go, groovy, haskell, html, java, javascript, js, json, lua, none, nyan, objc, perl, php, python, r, rainbow, ruby, scala, sh, sql, swift, visualbasic, xml, yaml

package com.example

declare Counter
    value: int
end

rule "Init" when
    not Counter()
then
    drools.insert(new Counter(0));
end

rule "Loop"
when
    c: Counter()
then
    c.setValue(1);
    update(c);
end

Java code used to run the engine.

public class DroolsLoopingTest {
    public static class LoopError extends RuntimeException {
    }

    public static void main(String[] args) {
        System.setProperty("drools.dump.dir", ".");

        final KieServices ks = KieServices.Factory.get();
        final KieRepository kr = ks.getRepository();
        final KieFileSystem kfs = ks.newKieFileSystem();

        kfs.write("src/main/resources/loop.drl", new ClassPathResource("loop.drl"));

        final KieBuilder kb = ks.newKieBuilder(kfs);
        kb.buildAll();
        if (kb.getResults().hasMessages(Message.Level.ERROR))
            throw new RuntimeException(kb.getResults().toString());

        final KieContainer kContainer = ks.newKieContainer(kr.getDefaultReleaseId());
        KieSession kSession = kContainer.newKieSession();

        kSession.addEventListener(new DefaultAgendaEventListener() {
            private int i = 0;

            @Override
            public void afterMatchFired(AfterMatchFiredEvent event) {
                System.out.println(event);
                if (++i > 10) throw new LoopError();
            }
        });

        try {
            kSession.fireAllRules();
            throw new RuntimeException("Expected loop error");
        } catch (LoopError e) {
            System.out.println("Loop detected");
        }
    }
}

I noticed a difference in generated code.
The rule file with the comment line generates this code

public static void defaultConsequence(KnowledgeHelper drools,  com.example.Counter c, org.kie.api.runtime.rule.FactHandle c__Handle__   ) throws java.lang.Exception { org.kie.api.runtime.rule.RuleContext kcontext = drools;
    // removing this comment line removes the loop
    c.setValue(1);
    { drools.update( c__Handle__, org.drools.core.util.bitmask.AllSetButLastBitMask.get(), com.example.Counter.class ); };
}

While the rule file without the comment line generates this code

public static void defaultConsequence(KnowledgeHelper drools,  com.example.Counter c, org.kie.api.runtime.rule.FactHandle c__Handle__   ) throws java.lang.Exception { org.kie.api.runtime.rule.RuleContext kcontext = drools;
    c.setValue(1);
    { drools.update( c__Handle__, new org.drools.core.util.bitmask.LongBitMask(2L), com.example.Counter.class ); };
}

Expected result is that comments should not affect engine behavior.

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