[jbosscache-dev] JBoss Cache weakness handling heuristic transaction outcomes - [Fwd: [Fwd: New case comment notification. Case Number 00017677]]

[Galder Zamarreno]

Manik Surtani wrote:
> 
> On 21 Aug 2007, at 15:44, Jonathan Halliday wrote:
> 
>> Manik Surtani wrote:
>>> Sorry about the slow response on this.
>>> While making JBC an XA resource is on the roadmap, it isn't something 
>>> scheduled for any imminent release [1], as this is a pretty big 
>>> change for the JBC codebase (and more importantly, a big feature 
>>> change which would involve a lot of compatibility testing).
>>> For the time being, treating STATUS_UNKNOWN as a rollback would help, 
>>> but only provided the database (and any other resources participating 
>>> in the tx) has rolled back as well.  Jonathan, correct me if I am 
>>> wrong, but there is no way to know this unless we are an XA resource 
>>> as well, am I right?
>>
>> Actually in heuristic outcomes you still won't necessarily know what 
>> the db did. The transaction manger will tell you what it decided, but 
>> not what each individual resource actually did. For that you would 
>> need JBossTS specific code rather than general XAResource code. You 
>> can partially address that by making the cache the last resource but 
>> you won't eliminate it entirely.
>>
>>> So is it reasonable to treat a STATUS_UNKNOWN as a rollback, and 
>>> document this limitation, until JBCACHE-70?
>>
>> yes, or toss anything that is affected out of the cache and let it be 
>> reread from the db on the next tx, which would prevent you ever 
>> getting out of sync. Or course that assumes the data is backed by some 
>> store e.g. the db, which is the case only for EJBs. General purpose 
>> use of the cache is a more difficult case.
> 
> Perhaps a switch for this behaviour?  By default, do a rollback, unless 
> -Dorg.jboss.cache.tx.heuristic_outcome_purge = true?

By purge, you mean?
- rollback modifications
- and commit the tx

> 
> What do you guys think?
> 
> Cheers,
> -- 
> Manik Surtani
> 
> Lead, JBoss Cache
> JBoss, a division of Red Hat
> 
> 
> 

-- 
Galder Zamarreño
Sr. Software Maintenance Engineer
JBoss, a division of Red Hat