[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-6960) NullPointerException in PreCollectionRemove Listener

[Stefan Hildebrandt (JIRA)]

    [ https://hibernate.onjira.com/browse/HHH-6960?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=46425#comment-46425 ] 

Stefan Hildebrandt commented on HHH-6960:
-----------------------------------------

Some debugging:

collectionEntry lockes like this:

collectionEntry = org.hibernate.engine.spi.CollectionEntry at 7952
  snapshot = null
  role = null
  loadedPersister = null
  loadedKey = null
  reached = false
  processed = true
  doupdate = false
  doremove = true
  docreate = false
  ignore = false
  currentPersister = null
  currentKey = null

Looks like a remove event. Possible there was a remove event within a prior flush, thats removed the entity.

Code that checks this:
{code}
   private static final IdentityHashMap<PersistentCollection, CollectionEntry> identityHashMap
      = new IdentityHashMap<PersistentCollection, CollectionEntry>();

   @Override
   public void onPreRemoveCollection(PreCollectionRemoveEvent event) {
      CollectionEntry collectionEntry = getCollectionEntry( event );
      if ( collectionEntry != null
         && !(collectionEntry.isDoremove() &&identityHashMap.containsKey(event.getCollection()))
         && !collectionEntry.getLoadedPersister().isInverse() ) {
         onCollectionAction( event, null, collectionEntry.getSnapshot(), collectionEntry );
      }
      if(collectionEntry.isDoremove()){
         identityHashMap.put(event.getCollection(), collectionEntry);
      }
   }
{code}
All Tests are running!

After that, the following code seams to be save.
{code}
   @Override
   public void onPreRemoveCollection(PreCollectionRemoveEvent event) {
      CollectionEntry collectionEntry = getCollectionEntry( event );
      if ( collectionEntry != null
        && !(collectionEntry.getCurrentPersister() == null && collectionEntry.isDoremove() && collectionEntry.isProcessed())
         && !collectionEntry.getLoadedPersister().isInverse() ) {
         onCollectionAction( event, null, collectionEntry.getSnapshot(), collectionEntry );
      }
      if(collectionEntry.isDoremove()){
         identityHashMap.put(event.getCollection(), collectionEntry);
      }
   }
{code}

> NullPointerException in PreCollectionRemove Listener
> ----------------------------------------------------
>
>                 Key: HHH-6960
>                 URL: https://hibernate.onjira.com/browse/HHH-6960
>             Project: Hibernate ORM
>          Issue Type: Bug
>          Components: envers
>    Affects Versions: 4.0.0.Final
>         Environment: Hibernate 4.0.0 to MySQL
>            Reporter: Kevin Jordan
>            Assignee: Gail Badner
>
> I'm getting a NullPointerException on line 47 of EnversPreCollectionRemoveEventListenerImpl very consistently. I wasn't sure if it was due to lazy collections or not, but it seems that it fails if they're eagerly fetched or lazily fetched. I'm guessing it has something to do with getLoadedPersister() returning a null value since the comments for it say "This is only available late during the flush cycle". The stack trace is
> Quote:
> java.lang.NullPointerException
> at org.hibernate.envers.event.EnversPreCollectionRemoveEventListenerImpl.onPreRemoveCollection(EnversPreCollectionRemoveEventListenerImpl.java:47)
> at org.hibernate.action.internal.CollectionRemoveAction.preRemove(CollectionRemoveAction.java:143)
> at org.hibernate.action.internal.CollectionRemoveAction.execute(CollectionRemoveAction.java:104)
> at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:273)
> at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:265)
> at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:188)
> at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:323)
> at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:52)
> at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1081)
> at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:315)
> at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.beforeTransactionCommit(JdbcTransaction.java:101)
> at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:175)
> at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:73)
> ... 120 more

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