Gordon,
I believe that your usage of "synchronized" is "flushed" in my vocabulary.
So to address such distinction, consider expanding the LifeCycleState enum
definition.
Actually this thread perhaps is entering a broader scope:
1. Does JPA make the persistent life cycle state of entities explicit
(i.e. appears at API)?
Similar persistence specification (without naming names ;), made
life cycle states more explicit and their transition rules more detailed
than where currently JPA stands in this respect.
The sketch of LifeCycleState enum {NEW, REMOVED, DIRTY,...} etc is
a nudge in such direction.
2. Does JPA allow access to managed entities filtered by their life
cycle states?
Regards --
Pinaki
From: Gordon Yorke <gordon.yorke_at_oracle.com>
To: jsr338-experts_at_jpa-spec.java.net
Date: 06/20/11 12:42 PM
Subject: [jsr338-experts] Re: Standardized Access to ChangeSet
Within a transaction there are two sets of changes. One set , the
"unsynchronized" changes, are changes made to the Entities that have not
yet been synchronized to the database. The other set, the "synchronized"
changes, are those changes that have been synchronized to the database
through a flush operation but are not yet committed.
--Gordon
Pinaki Poddar wrote:
> unsynchronized changes from the synchronized changes
Would you please elaborate "(un)synchronized" as used in this context?
Regards --
Pinaki
From: Gordon Yorke <gordon.yorke_at_oracle.com>
To: jsr338-experts_at_jpa-spec.java.net
Date: 06/20/11 12:09 PM
Subject: [jsr338-experts] Re: Standardized Access to ChangeSet
Access to managed entities for any active persistence context is an useful
feature at any point of time.
Why would you like to restrict only at flush() via callback?
By providing the information at flush() time it is easy to define what is
returned without a plethora of API to distinguish the unsynchronized
changes from the synchronized changes in the transaction. There's little
value in combining both sets of changes into a single set.
Also retrieving the list of "dirty" entities could be quite "expensive" in
some providers or deployment environments but the work to calculate the
changes will already have been completed during the flush() operation.
Based on your example if you are expecting that only the unsynchronized
changes are available through these sets then these APIs along with the
EntityManager event would be fine, although I would suggest changing the
names to reflect the EntityManager operations (ie.
LifeCycleState.REMOVED).
--Gordon
Pinaki Poddar wrote:
Hi Gordon/Adam and all,
I should have clarified
a) the returned Sets be immutable. The elements of the set are live.
b) returned set reflects the state of the member entities at the time of
invocation.
Set<Object> deleted = em.getEntities(LifeCycleState.DELETED); // say
return a set with 2 entities
em.remove(another); // another is not a member of deleted set
assertFalse(deleted.contains(another));
Set<Object> deleted2 = em.getEntities(LifeCycleState.DELETED);
assertTrue(deleted.contains(another));
c) Other possibility is to return an Iterator<> instead which is always
'live'.
d) the methods return empty set if EntityManager is not in an active
transaction.
Access to managed entities for any active persistence context is an
useful feature at any point of time.
Why would you like to restrict only at flush() via callback?
Regards --
Pinaki
From: Gordon Yorke <gordon.yorke_at_oracle.com>
To: jsr338-experts_at_jpa-spec.java.net
Date: 06/20/11 11:13 AM
Subject: [jsr338-experts] Re: Standardized Access to ChangeSet
Hello Adam,
Would the "dirty" set include unsynchronized persisted and removed
Entities? It would likely be better to have separate sets for these.
Without configuration these sets would have to be cleared as the
EntityManager is cleared. What effect do you see EntityManager.clear()
having on these sets?
As an alternative to the sets an EntityManager lifecycle listener
could be notified of the sets on EntityManager.flush() and the
application could track the same sets as need across flushes.
--Gordon
Adam Bien wrote:
> HI All,
>
> I would like to propose additional EntityManager methods:
>
> Set<Class> updated = EntityManager#getUpdatedEntities(Class<T>.class);
> Set<Class> deleted = EntityManager#getDeletedEntities(Class<T>.class);
> Set<Class> created = EntityManager#getCreatedEntities(Class<T>.class);
> Set<Class> dirty = EntityManager#getDirty(Class<T>.class);
>
> We had to use provider-specific EntityManager extensions to access the
dirty entities for the implementation of replication or historization.
>
> Such methods would be also useful for debugging purposes,
>
> thanks in advance,
>
> adam
>
>
>