[rules-users] Multithreaded update of facts in Drools 5.5 - how to ensure that a nested value isn't null

[Per Sterner]

Hello,

My question is:
How can I ensure that a nested property isn't null (in a multithreaded 
environment)?

This is the rule:

rule Drools Test3: Concurrency
dialect java
when
 $testObj : TestObject(
 $ref : subObject,
 $ref != null,
 $ref.message != null
 )
then
 System.out.println(Received-04-A:  + $testObj);
end

I am getting the following exception if I try to modify the fact in 
different threads.

  java.lang.NullPointerException: null
  at 
ConditionEvaluator8d1e3555e8c34810957bbb1670f51176.evaluate(null:-1)
  at 
org.drools.rule.constraint.MvelConstraint.evaluate(MvelConstraint.java:200)
  at 
org.drools.rule.constraint.MvelConstraint.isAllowed(MvelConstraint.java:157)
  at org.drools.reteoo.AlphaNode.modifyObject(AlphaNode.java:154)
  at 
org.drools.reteoo.SingleObjectSinkAdapter.propagateModifyObject(SingleObjectSinkAdapter.java:68)
  at org.drools.reteoo.AlphaNode.modifyObject(AlphaNode.java:157)
  at 
org.drools.reteoo.SingleObjectSinkAdapter.propagateModifyObject(SingleObjectSinkAdapter.java:68)
  at 
org.drools.reteoo.ObjectTypeNode.modifyObject(ObjectTypeNode.java:314)
  at 
org.drools.reteoo.EntryPointNode.modifyObject(EntryPointNode.java:265)
  at org.drools.common.NamedEntryPoint.update(NamedEntryPoint.java:483)
  at 
org.drools.common.AbstractWorkingMemory.update(AbstractWorkingMemory.java:976)
  at 
org.drools.common.AbstractWorkingMemory.update(AbstractWorkingMemory.java:949)
  at 
org.drools.impl.StatefulKnowledgeSessionImpl.update(StatefulKnowledgeSessionImpl.java:284)
 [...]

There are two threads running which modify the same reference in a 
testobject (subObject). They trigger a queued update of the fact.


One solution would be:
- insert the nested object in drools
- and modify the rule:

rule Drools Test3: Concurrency 2
dialect java
when
 $subObj : TestObject(
 message != null
 )
 $testObj : TestObject(
 subObject == $subObj
 )
then
 System.out.println(Received-04-A:  + $testObj);
end

Can I achieve a thread safety differently?

Thanks and regards,

   Per Sterner

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[rules-users] WorkingMemoryEntryPoints

[Per Sterner]

Hello,

We are upgrading our project from Drools 5.3 to Drools 5.5.0 and got 
some problems. We tried to locate the problem and it seems there is a 
problem with the WorkingMemoryEntryPoints?

In our project everything is in WorkingMemoryEntryPoints. In this 
example all facts are in test_me. We removed the dependencies to the 
memoryentrypoint and then it works.

The problem is with the WorkingMemoryEntryPoints that the Rule TestRule 
- set state_2 is triggered more then two times.
The output is:
SETTING STATE 2
STATE 2
STATE 1
STATE 1
SETTING STATE 2
STATE 2
SETTING STATE 2
STATE 2
SETTING STATE 2
STATE 2
[...]

If we remove the entrypoints the output is:
SETTING STATE 2
STATE 2
SETTING STATE 2
STATE 2
[And that's it]

Is there something with the usage from the WorkingMemoryEntryPoints or 
is this a bug?

Regards,

   Per Sterner

TestObject.java
---
public class TestObject {

 private String stateAsString;

 public void setStateAsString(final String stateAsString) {
 this.stateAsString = stateAsString;
 }

 public String getStateAsString() {
 return stateAsString;
 }

}
---
MyTicker.java
---
public class MyTicker {

 private final long timeStart;
 private long time;

 public MyTicker() {
 timeStart = System.currentTimeMillis();
 }

 public long getTime() {
 return time;
 }

 public void setTime(final long time) {
 this.time = time;
 }

 public long getTimeStart() {
 return timeStart;
 }
}
---
DroolsTest.java
---
public class DroolsTest {

 public static void main(final String[] args) {
 KnowledgeBuilder kbuilder = 
KnowledgeBuilderFactory.newKnowledgeBuilder();
kbuilder.add(ResourceFactory.newClassPathResource(TestDrools.drl, 
Init.class), ResourceType.DRL);

 if (kbuilder.hasErrors()) {
 System.out.println(kbuilder.getErrors().toString());
 throw new RuntimeException(Unable to compile 
\HelloWorld.drl\.);
 }

 final CollectionKnowledgePackage pkgs = 
kbuilder.getKnowledgePackages();
 final KnowledgeBase kbase = 
KnowledgeBaseFactory.newKnowledgeBase();
 kbase.addKnowledgePackages(pkgs);

 final StatefulKnowledgeSession ksession = 
kbase.newStatefulKnowledgeSession();

 TestObject testObject1 = new TestObject();
 testObject1.setStateAsString(STATE_1);

 TestObject testObject2 = new TestObject();
 testObject2.setStateAsString(STATE_1);

 TestCache testCache = new TestCache();

 MyTicker ticker = new MyTicker();
 ticker.setTime(System.currentTimeMillis());

 WorkingMemoryEntryPoint e = 
ksession.getWorkingMemoryEntryPoint(test_me);

 e.insert(testObject1);
 e.insert(testObject2);
 e.insert(testCache);
 FactHandle tickerHandle = e.insert(ticker);

 DroolsTickerThread droolsTickerThread = new 
DroolsTickerThread(droolstickerthread, ticker, ksession, tickerHandle);
 droolsTickerThread.start();

 }

 public static class DroolsTickerThread extends Thread {

 private final DroolsTicker ticker;
 private final StatefulKnowledgeSession ksession;
 private final FactHandle tickerHandle;

 public DroolsTickerThread(final String name, final DroolsTicker 
ticker, final StatefulKnowledgeSession ksession,
 final FactHandle tickerHandle) {
 super(name);
 this.ticker = ticker;
 this.ksession = ksession;
 this.tickerHandle = tickerHandle;
 }

 @Override
 public void run() {
 WorkingMemoryEntryPoint entry = 
ksession.getWorkingMemoryEntryPoint(test_me);
 while (!isInterrupted()) {
 try {
 ticker.setTime(System.currentTimeMillis());
 entry.update(tickerHandle, ticker);
 ksession.fireAllRules();
 Thread.sleep(1000);
 } catch (InterruptedException e) {
 break;
 }
 }
 };
 }

}
---
TestCache.java
---
public class TestCache {

 private long lastCheckTimestamp = 0;

 public void setLastCheckTimestamp(final long lastCheckTimestamp) {
 this.lastCheckTimestamp = lastCheckTimestamp;
 }

 public long getLastCheckTimestamp() {
 return lastCheckTimestamp

Re: [rules-users] Why does it seem like salience is being ignored?

[Per Sterner]

Hello,

isn't there just mussing a '\n' before the word saliance in the line

rule += rule rule1a salience 100 \n;

?

Regards,

  Per Sterner

Am 14.07.12 20:18, schrieb Ladd:
 I just tried the same test using 5.3.0 and got the same results.  Rule1b
 fires first.

 --
 View this message in context: 
 http://drools.46999.n3.nabble.com/Why-does-it-seem-like-salience-is-being-ignored-tp4018669p4018687.html
 Sent from the Drools: User forum mailing list archive at Nabble.com.
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Re: [rules-users] Drools 5.4.0.FINAL and OSGI. Unable to instantiate service for Class 'org.drools.concurrent.ExecutorProvider'

[Per Sterner]

Hello,

perhaps it is an equinox /eclipse.osgi problem?

The drools-api and the drools-core bundle have the same packages 
'org.drools.concurrent'.

I wrote a little test bundle which only does a dynamic-import like the 
'drools-api' bundle.

The class org.drools.concurrent.ExecutorProviderFactory can be found 
with 'Class.forName()'.

But the class org.drools.concurrent.ExecutorProviderImpl can't be found.

(If I manually require drools-core 'Class.forName()' works for 
org.drools.concurrent.ExecutorProviderImpl)

I have tried eclipse.osgi 3.6.1 , 3.7.2 and the current 3.8.0

Regards,

   Per Sterner


On 01.06.2012 03:29, Mark Proctor wrote:
 Looks like you have some classpath issues and using the incorrect jar
 versions.

 On 29/05/2012 14:30, Per Sterner wrote:
 [ERROR] [System] - Caused by: java.lang.ClassNotFoundException:
 org.drools.concurrent.ExecutorProviderImpl
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Re: [rules-users] Drools 5.4.0.FINAL and OSGI. Unable to instantiate service for Class 'org.drools.concurrent.ExecutorProvider'

[Per Sterner]

I just found an old eclipse forum entry:

http://www.eclipse.org/forums/index.php/mv/msg/90154/278597/#msg_278597


On 01.06.2012 03:29, Mark Proctor wrote:
 Looks like you have some classpath issues and using the incorrect jar
 versions.

 On 29/05/2012 14:30, Per Sterner wrote:
 [ERROR] [System] - Caused by: java.lang.ClassNotFoundException:
 org.drools.concurrent.ExecutorProviderImpl
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[rules-users] Drools 5.4.0.FINAL and OSGI. Unable to instantiate service for Class 'org.drools.concurrent.ExecutorProvider'

[Per Sterner]

);
 e.printStackTrace();

 if (exception != null) {
 exception = new MyDroolsException(msg, exception);
 } else {
 exception = new MyDroolsException(msg);
 }

 exception = new MyDroolsException(e.getMessage(), 
exception);

 continue;
 }

 // All done!
 break;
 }

 final CollectionKnowledgePackage pkgs = 
kbuilder.getKnowledgePackages();
 droolsSession.getKnowledgeBase().addKnowledgePackages(pkgs);

 if (exception != null) {
 throw new MyDroolsException(Error while adding 
resources!, exception);
 }
 }

 public KnowledgeBuilderFactoryService 
getDroolsKnowledgeBuilderFactoryService() {
 return droolsKnowledgeBuilderFactoryService;
 }

 public void setDroolsKnowledgeBuilderFactoryService(
 KnowledgeBuilderFactoryService 
droolsKnowledgeBuilderFactoryService) {
 this.droolsKnowledgeBuilderFactoryService = 
droolsKnowledgeBuilderFactoryService;
 }

 public ResourceFactoryService getDroolsResourceFactoryService() {
 return droolsResourceFactoryService;
 }

 public void setDroolsResourceFactoryService(
 ResourceFactoryService droolsResourceFactoryService) {
 this.droolsResourceFactoryService = droolsResourceFactoryService;
 }

 public KnowledgeBaseFactoryService 
getDroolsKnowledgeBaseFactoryService() {
 return droolsKnowledgeBaseFactoryService;
 }

 public void setDroolsKnowledgeBaseFactoryService(
 KnowledgeBaseFactoryService 
droolsKnowledgeBaseFactoryService) {
 this.droolsKnowledgeBaseFactoryService = 
droolsKnowledgeBaseFactoryService;
 }

}

Some of the bundles in my runtime are:

39ACTIVE  org.drools.core_5.4.0.Final
66ACTIVE  org.drools.compiler_5.4.0.Final
78ACTIVE  org.drools.templates_5.4.0.Final
94ACTIVE  org.drools.internalapi_5.4.0.Final
136ACTIVE  org.drools.decisiontables_5.4.0.Final
189ACTIVE  org.drools.api_5.4.0.Final
191ACTIVE  org.mvel2_2.1.0.drools16
6ACTIVE  org.jbpm.flow.core_5.3.0.Final
13ACTIVE  org.jbpm.bpmn2_5.3.0.Final
71ACTIVE  org.jbpm.flow.builder_5.3.0.Final
142ACTIVE  org.jbpm.flow-persistence-jpa_5.3.0.FINAL

regards,

   Per Sterner

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[rules-users] Rule, import with wildcards and variable / patternBinding

[Per Sterner]

Hello,

Yesterday I wanted to upgrade my drools version to 5.3 (from 5.1). I got 
the exception java.lang.NoClassDefFoundError: 
de/pelle7/testpackage/event/myEvent (wrong name: 
de/pelle7/testpackage/event/MyEvent) while adding my resources.
I removed the import wildcards and the error disappeard.

Finally I found the problem:
I used the patternBinding 'myEvent' and there is a class called 
'MyEvent' and I used an wildcard import where the class 'MyEvent' is 
located.

Example code:

package de.pelle7.testrules.impl.drools

import de.pelle7.testpackage.event.*

rule Test rule 1
dialect java
salience 50
when
 myEvent : MyEvent( )
 myEvent2 : MyEvent( data == myEvent.data ) -- here the Exception 
is thrown
then
 System.err.println(Output);
end

My solution is that I replaced all my pattern bindings with the suffix 
'$' which is more convenient.


Perhaps it would be nice to produce an rule-compilation error. with a 
line notice.

Regard,

   Per Sterner
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