[infinispan-dev] Isolation level in Repeatable Read + remote get

[Dan Berindei]

Pedro, I'll integrate the PR as it is, and then you can experiment with my
proposal in another branch/PR.


On Tue, Jul 9, 2013 at 1:48 PM, Pedro Ruivo <pedro at infinispan.org> wrote:

>
>
> On 07/09/2013 11:46 AM, Galder Zamarreño wrote:
> >
> > On Jul 8, 2013, at 11:02 AM, Pedro Ruivo <pedro at infinispan.org> wrote:
> >
> >> Hi guys,
> >>
> >> re: ISPN-2840, ISPN-3235, ISPN-3236
> >> short: transaction isolation in repeatable read
> >>
> >> Dan came up with an idea (a good idea IMO) to change a little the logic
> >> how entries are put in the context for transactional caches.
> >>
> >> One of the Repeatable Read properties is after a key is accessed, the
> >> transaction should never see other concurrent transaction values, even
> >> if they commit first. In result, we can optimize the distributed mode by
> >> only do a remote get on the first time a transaction access a key.
> >>
> >> My idea (and the one implemented in the Pull Request)
> >
> > ^ Which pull req, link? You mean [1]?
>
> yes
>
> >
> > [1] https://github.com/infinispan/infinispan/pull/1937
> >
> >> was adding a flag
> >> to mark the entry as accessed. All future access to that key will not
> >> try to fetch the data from container neither from a remote location (we
> >> have a small but with last one).
> >>
> >> The Dan's idea is more simple but require some change in the
> >> EntryFactory logic.
> >
> > ^ Which is Dan's idea exactly?
>
> is the description below:
>
> >
> >> At this stage, we only put an entry in the
> >> transaction context if the following conditions are respected:
> >>
> >> * the entry exists in data container (i.e. the node is owner or it is
> in L1)
> >> * we put a RepeatableReadEntry with null value in the transaction
> context if
> >> ** the entry does not exist in the container but the node is owner
> >> ** the entry does not exist in the data container but the command has
> >> flags to skip the remote fetch (like IGNORE_RETURN_VALUE or
> >> SKIP_REMOTE_LOOKUP). Of course the conditional commands needs special
> >> attention here.
> >>
> >> Note: as usual, if the entry exists in the context, then nothing is
> done.
> >>
> >> At the TxDistributionInterceptor level, the check to see if the remote
> >> get should be done is simple as check if lookupEntries(k)==null.
> >>
> >> Dan, if I said something wrong let me know. If I was not clear at some
> >> point let me know too.
> >>
> >> Anyone see any issue with this approach?
> >> Any other suggestions?
> >>
> >> Cheers,
> >> Pedro Ruivo
> >> _______________________________________________
> >> infinispan-dev mailing list
> >> infinispan-dev at lists.jboss.org
> >> https://lists.jboss.org/mailman/listinfo/infinispan-dev
> >
> >
> > --
> > Galder Zamarreño
> > galder at redhat.com
> > twitter.com/galderz
> >
> > Project Lead, Escalante
> > http://escalante.io
> >
> > Engineer, Infinispan
> > http://infinispan.org
> >
> >
> > _______________________________________________
> > infinispan-dev mailing list
> > infinispan-dev at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/infinispan-dev
> >
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