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

[Manik Surtani]

No - by purge, I mean remove all affected nodes from the cache,  
thereby assuming that the cache is backed by a DB and will be  
populated again.


On 21 Aug 2007, at 16:10, Galder Zamarreno wrote:

>
>
> 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

--
Manik Surtani

Lead, JBoss Cache
JBoss, a division of Red Hat