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From Marc Prud'hommeaux <mprud...@apache.org>
Subject Re: Exceptions thrown from callbacks
Date Tue, 06 Feb 2007 02:19:43 GMT

I don't have any strong opinions either way. Wrapping is useful,  
because we can usually provide the FailedObject so that the user can  
more easily attempt some recovery. And I do agree that if a callback  
exception occurs during a commit()/flush() operation then we should  
wrap it (and it might as well be in a RollbackException). Summary: +1

As for whether to wrap the exceptions during non-flush/commit times  
(e.g., during a find() call), I'm a little less keen on it, but not  
really opposed. The reason is that the clause "Lifecycle callback  
methods may throw runtime exceptions" suggests to me (and,  
apparently, to the CTS authors) that they restricted the exception  
type to be runtime exceptions because they expect the unmodified  
exception will be thrown straight up the application. Summary: +0




On Feb 1, 2007, at 3:27 PM, Patrick Linskey wrote:

> Hi,
>
> There's a bit of ambiguity in the spec about what should happen  
> when an
> exception is thrown from a callback.
>
> I propose that we change OpenJPA's behavior to always wrap exceptions
> thrown from callbacks in a RollbackException. Additionally, I propose
> that if a callback is thrown from a direct flush() call or a find() or
> other data load, we should mark the transaction for rollback  
> instead of
> immediately rolling back the transaction.
>
>
> Details:
>
> Section 3.5 says:
>
> "Lifecycle callback methods may throw unchecked/runtime exceptions. A
> runtime exception thrown by a callback method that executes within a
> transaction causes that transaction to be rolled back."
>
> 3.5.6:
>
> "Lifecycle callback methods may throw runtime exceptions. A runtime
> exception thrown by a callback method that executes within a  
> transaction
> causes that transaction to be rolled back. No further lifecycle  
> callback
> methods will be invoked after a runtime exception is thrown."
>
> 3.7:
>
> "The PersistenceException is thrown by the persistence provider when a
> problem occurs. [...] All instances of PersistenceException except for
> instances of NoResultException and NonUniqueResultException will cause
> the current transaction, if one is active, to be marked for rollback."
>
> ...
>
> "The RollbackException is thrown by the persistence provider when
> EntityTransaction.commit() fails.
>
>
> So.... in my opinion, this means that if a callback fails during
> commit(), the exception thrown by the callback clearly should be  
> wrapped
> in a RollbackException. It is less clear to me what should happen if a
> callback fails at some other time, such as during a find() call. In my
> opinion, we should be wrapping the user-thrown exceptions in
> RollbackExceptions all the time.
>
> Further, I think that 3.7 trumps 3.5.6, so if an exception is thrown
> from a callback during a find(), we should be marking the transaction
> for rollback, rather than actually rolling it back.
>
> I've got changes in place that implement the behavior I just  
> described.
> The CTS tests surrounding this issue have been excluded, due to the
> ambiguity in the spec.
>
> Thoughts?
>
> -Patrick
>
> -- 
> Patrick Linskey
> BEA Systems, Inc.
>
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