Re: Exceptions thrown from callbacks

[Marc Prud'hommeaux]

I don't recall the details about why we made that decision, but I  
prefer
wrapping in a RollbackException for consistency. It sucks to have  
to do:

I agree that that sucks. Of course, if they want their application to  
be portable, then they'll need to put in that logic anyway :)

Do you have any opinion about the rollback vs. mark-for-rollback  
distinction?

Well, section 3.5 suggests that it should be rolled back immediately,  
but then if we start wrapping in a PersistenceException, then 3.7  
says that it should just be marked for rollback. Tricky. I guess I  
favor immediate rollback, just since section 3.5 is so explicit in  
saying that it should happen.



On Feb 5, 2007, at 6:27 PM, Patrick Linskey wrote:

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

I don't recall the details about why we made that decision, but I  
prefer
wrapping in a RollbackException for consistency. It sucks to have  
to do:

try {
    em.find(...);
    em.commit();
} catch (RollbackException re) {
    if (re.getCause() instanceof MySpecialException) {
        // custom logic
    } else {
        throw re;
    }
} catch (MySpecialException mse) {
    // same custom logic as above
}


Do you have any opinion about the rollback vs. mark-for-rollback
distinction?

-Patrick

--
Patrick Linskey
BEA Systems, Inc.

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-----Original Message-----
From: Marc Prud'hommeaux [mailto:[EMAIL PROTECTED] On
Behalf Of Marc Prud'hommeaux
Sent: Monday, February 05, 2007 6:20 PM
To: open-jpa-dev@incubator.apache.org
Subject: Re: Exceptions thrown from callbacks


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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information  of  BEA Systems,  Inc.,  its subsidiaries  and
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or entity named in this message. If you are not the intended
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and have received this message in error, please immediately return
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by email and then delete it.