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From Lenny Primak <lpri...@hope.nyc.ny.us>
Subject Re: PATCH: tapestry-jpa EntityManagerObjectProvider fixes entities not associated with correct entity manager issue
Date Wed, 14 Nov 2012 01:21:29 GMT
I didn't look at this in detail, but proxies are sometimes thread-local, and not really singletons.
Also, your patch isn't a real patch.  it's a replacement, and harder to incorporate for committers,
if it is indeed necessary.

On Nov 13, 2012, at 8:09 PM, John wrote:

> Hi,
> 
> The original code is like below, note how the proxy provided acts like a singleton. I'll
take a look at the JIRA, thanks.
> 
> public class EntityManagerObjectProvider implements ObjectProvider
> {
>    private EntityManager proxy;
>    public <T> T provide(final Class<T> objectType, final AnnotationProvider
annotationProvider,
>            final ObjectLocator locator)
>    {
>        if (objectType.equals(EntityManager.class))
>            return objectType.cast(getOrCreateProxy(annotationProvider, locator));
>        return null;
>    }
> 
>    private synchronized EntityManager getOrCreateProxy(
>            final AnnotationProvider annotationProvider, final ObjectLocator objectLocator)
>    {
>        if (proxy == null)
>        {
>          ...
>        }
>        return proxy;
>  ----- Original Message ----- 
>  From: Lenny Primak 
>  To: Tapestry development 
>  Cc: <dev@tapestry.apache.org> 
>  Sent: Wednesday, November 14, 2012 12:52 AM
>  Subject: Re: PATCH: tapestry-jpa EntityManagerObjectProvider fixes entities not associated
with correct entity manager issue
> 
> 
>  I am not sure why the existing code doesn't work for you as it works fine in my environment.

>  Another thing is that patches belong in JIRA and cannot be taken from mailing lists
due to copyright issues. 
> 
>  Perhaps Igor can shed some light on this?
> 
>  On Nov 13, 2012, at 7:48 PM, "John" <john@quivinco.com> wrote:
> 
>> I put this on the users group recently to complete a thread, it belongs here really
I suppose.
>> 
>> The problem manifests when multiple PUs are defined in persistence.xml and then referred
to in classes using the @PersistenceContext(unitName= annotation. As it is in 5.3.6 the first
EntityManager wired up gets injected to all successive EntityManager instances and the unitName=
value is ignored. Probem was caused by reusing a class variable. The bug makes it seem that
entities are not wired to the EntityManager as you would expect, in fact the reference passed
in is bad.
>> 
>> Also refactored to use PlasticProxyFactory.
>> 
>> John
>> 
>> 
>> ----- Original Message ----- From: John
>> To: Tapestry users
>> Sent: Tuesday, November 13, 2012 7:51 AM
>> Subject: PATCH: tapestry-jpa EntityManagerObjectProvider fixes entities not associated
with correct entity manager issue
>> 
>> 
>> This looks like a bug where a class member variable is used to cache the EntityManager
that is subsequently handed to all the PersistenceContext annotations regardless of the unitName,
like I said.
>> 
>> The following replacement class is tested working and handles multiple persistence
units correctly as per the original Tapestry docs, just put it on your classpath first. Maybe
someone on the developer side can check this out and commit it to the build cycle.
>> 
>> 
>> package org.apache.tapestry5.internal.jpa;
>> 
>> import javax.persistence.EntityManager;
>> import javax.persistence.PersistenceContext;
>> 
>> import org.apache.tapestry5.ioc.AnnotationProvider;
>> import org.apache.tapestry5.ioc.ObjectCreator;
>> import org.apache.tapestry5.ioc.ObjectLocator;
>> import org.apache.tapestry5.ioc.ObjectProvider;
>> import org.apache.tapestry5.ioc.services.PlasticProxyFactory;
>> import org.apache.tapestry5.jpa.EntityManagerManager;
>> 
>> /**
>> * A patched version to use PlasticProxyFactory and not cache the EntityManager as
a class member.
>> * @author John Coleman
>> */
>> public class EntityManagerObjectProvider implements ObjectProvider
>> {
>> 
>>  /**
>>   * {@inheritDoc}
>>   */
>>  public <T> T provide(final Class<T> objectType, final AnnotationProvider
annotationProvider,
>>          final ObjectLocator locator)
>>  {
>>      if (objectType.equals(EntityManager.class))
>>          return objectType.cast(getOrCreateProxy(annotationProvider, locator));
>> 
>>      return null;
>>  }
>> 
>>  private synchronized EntityManager getOrCreateProxy(
>>          final AnnotationProvider annotationProvider, final ObjectLocator objectLocator)
>>  {
>>          final PlasticProxyFactory proxyFactory = objectLocator.getService("PlasticProxyFactory",
>>            PlasticProxyFactory.class);
>> 
>>           final PersistenceContext annotation = annotationProvider
>>                          .getAnnotation(PersistenceContext.class);
>> 
>>          EntityManager proxy = proxyFactory.createProxy(EntityManager.class, new
ObjectCreator<EntityManager>()
>>          {
>>              public EntityManager createObject()
>>              {
>>                  final EntityManagerManager entityManagerManager = objectLocator
>>                          .getService(EntityManagerManager.class);
>> 
>>                  return JpaInternalUtils.getEntityManager(entityManagerManager, annotation);
>>              }
>>          }, "<EntityManagerProxy>");
>> 
>>      return proxy;
>>  }
>> 
>> } 
>> 
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>> 
> 
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