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From "Xiaoqin Feng (JIRA)" <>
Subject [jira] Updated: (OPENJPA-722) persist - clear - merge scenario doesn't work
Date Thu, 25 Sep 2008 22:35:44 GMT


Xiaoqin Feng updated OPENJPA-722:

    Attachment: openjpa-722-V2.patch

Yes, we shouldn't save PCState in pcDetachedState since pcDetachedStaet is used for loaded
field, version info to make attach process more efficient.
V2 patch is attached.
Here is my solution:
1. Our assumption according to EntityManager.clear() API is ""EntityManager.clear() will not
flush new, dirty, removed entities in context but just detach all managed entities".

At first I thought we need to pass along flush=false from BrokerImpl.detachAll(OpCallbacks
call, boolean flush) to DetachManager _flushBeforeDetach as openjpa-591 mentioned. Then I
realized in BrokerImpl.detachAllInternal(), new DetachManager(this, true, call).detachAll
(new ManagedObjectCollection(states)) actually pass in full=true so _flushBeforeDetach has
no effect in this case and flush logic in DetachManager will be skipped. 

So I reverted my change in V1 patch for this part.

2. To make not flushed new entity to be inserted after merge, we don't save DetachedStateManager
in detached object. When it merged back, exisitng openjpa framework could handle it correctly
and add it to insert list.

3. To make not flushed dirty entity to be updated after merge, we save dirty flag BitSet when
it is detached. 

4. As for removed entity, according to EJB3.0 persist spec 3.2.5,  remove call actually remove
the entity from context, em.contains(obj) return false. It is not a managed entity and shouldn't
be detached for EntityManager.clear() and not suppose to merge it back and be removed from
DB in next commit/flush. User suppose to flush it before calling clear().
Although I found openjpa may detach deleted-not-flushed entity as a side effect, we don't
need to support merge scenario as I claimed above.

sm.isNew() && !sm.isDeleted() && !sm.isFlushed() in DetachManager.useDetachedStateManager()
also make sure PNewDeletedState and PNewFlushedDeletedState will not be merged and take as
a PNEW state and get inserted.

> persist - clear - merge scenario doesn't work
> ---------------------------------------------
>                 Key: OPENJPA-722
>                 URL:
>             Project: OpenJPA
>          Issue Type: Sub-task
>          Components: kernel
>    Affects Versions: 1.0.3, 1.1.0, 1.2.0
>            Reporter: Xiaoqin Feng
>            Assignee: Jeremy Bauer
>         Attachments: openjpa-722-fromQin.patch, openjpa-722-V2.patch,,
> EntityManager.clear() now don't  flush new object but only detach it.
> But DetachManager still flush dirty object and assume detached objects are in clean state.
> When the "new" object is merged back and transaction commit,  because the object state
lost its original state PNEW, it will not be added to insert list  and not flushed to DB.
> According to the EntityManager.clear() API,  changes made to entities that have not been
flushed to the database will not be persisted.  When they merges back to persistent context,
they all should kept there original state.
> I added the following test to org.apache.openjpa.persistence.simple.TestEntityManagerClear.
>     public void testClearMerge() {
>         // Create EntityManager and Start a transaction (1)
>         begin();
>         // Insert a new object then clear persistent context
>         AllFieldTypes testObject1 = new AllFieldTypes();
>         testObject1.setStringField("my test object1");
>         persist(testObject1);
>         //Object1 is not flushed to DB but only detached by clear().
>         em.clear();
>         em.merge(testObject1);
>         //expect the PCState is same as before detached, 
>         //so it is PNew instead of PCLEAN and is add to insert list.
>         commit();
>         //Start a new transaction
>         begin();
>         // Attempt retrieve of Object1 from previous PC (should exist)
>         assertEquals(1, query("select x from AllFieldTypes x "
>             + "where x.stringField = 'my test object1'").
>                 getResultList().size());
>         // Rollback the transaction and close everything
>         rollback();
>     }

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