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https://issues.apache.org/jira/browse/JDO-747?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15223983#comment-15223983
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Tilmann Zäschke commented on JDO-747:
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I think this is a bit more of 'change' of behaviour, not really a new feature.
The idea is that when concurrent transactions fail because of a delete() in one
of them, then there should be a way to recover the other transaction, for
example by calling {{refresh()}}. So the change in behaviour is that
{{refresh()}} should change the deleted object's state to something meaningful,
instead of failing.
As it happens, the outcome of this JIRA has changed a bit, so I have to catch
up myself with the latest development (the expected state of the refreshed
objects).
I'm currently working on the tests. After that I have the tests for SPR 751
(Java Optional) in my pipeline, so I could look into adapting the RI after
that. But it'll take a bit before I have time, and I wouldn't mind if someone
else could adapt the RI.
> Behavior of delete() with multiple concurrent Transactions
> ----------------------------------------------------------
>
> Key: JDO-747
> URL: https://issues.apache.org/jira/browse/JDO-747
> Project: JDO
> Issue Type: Improvement
> Components: specification
> Affects Versions: JDO 3.1
> Reporter: Tilmann Zäschke
> Priority: Minor
> Labels: concurrency, delete, documentation, refresh(),
> specification
> Fix For: JDO 3.2
>
> Attachments: JDO-StateTransition-logs-2015-12-04.zip,
> OptimisticCheckConsistency.java, OptimisticFailurePatch_JDO747.txt,
> StateTransitionPatch_JDO747_v4.txt
>
>
> In the Spec I could not find any statement regarding on how a transaction
> should behave if an object is deleted in a different concurrent transaction.
> Related Sections are Section 5.8 (how different methods should behave for
> different object states) and Section 12.6.1 (the behavior of refresh() and
> related methods).
> For example I wonder about the following situations. Suppose I have two
> optimistic sessions, pm1 and pm2, both access the same object. pm1 deletes
> the object and commits. Then what happens in pm2 if:
> 1. pm2 deletes the object and tries to commit, should that work? It's
> wouldn't be a real conflict if both delete it.
> 2. pm2 modifies the object (make dirty) and calls {{refresh()}}. Should I
> get an {{ObjectNotFound}} exception?
> 3. pm2 deletes the object and calls {{refresh()}}. According to the spec,
> {{refresh()}} should not change the object's state. But should it
> still fail with {{ObjectNotFound}}? If refresh should fail, how can I
> ever recover from such a situation, because I can't undelete the
> object?
> Is there a common understanding how this should work?
> IF there an external definition JDO relies on, then I think a reference to an
> external document might useful.
> If not, should the Spec define concurrent behavior?
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