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From Oliver Zeigermann <oliver.zeigerm...@gmail.com>
Subject Re: [transaction.locking] Modify the behaviour of the ReadWriteUpgradeLockManager
Date Sat, 02 Apr 2005 04:24:01 GMT
If so that's exactly what the read/write lock and then the read/write
lock manager does.

Oliver

On Apr 1, 2005 6:30 PM, Oliver Zeigermann <oliver.zeigermann@gmail.com> wrote:
> Still not quite clear, most likely because I am a bit dumb ;) What is
> the use of your kind of upgrade lock? Or is it that you want
> preference of the write lock over read locks, i.e. when more than one
> party is waiting for a lock, the one waiting for the write lock gets
> preference?
> 
> Oliver
> 
> 
> On Apr 1, 2005 9:31 AM, Melanie.Bats@UTBM.fr <Melanie.Bats@utbm.fr> wrote:
> > Hi,
> >
> > Selon Oliver Zeigermann <oliver.zeigermann@gmail.com>:
> > > Hmmm, not quite sure that I get this all right, but to me it seems you
> > > describe the simple read/write locks (without the upgrade step). Is
> > > that possible? If so you could simply use the ReadWriteLockManager.
> >
> > My lock manager has not exactly the same behaviour as the ReadWriteLockManager
> > and I think looks more like the ReadWriteUpgardeLockManager.
> >
> > I will try to explain what I want to do ;o)
> >
> > In my case :
> > * Read access requires a shared lock (S).
> > * Write access requires an exclusive lock (X).
> > * An upgrade lock (U) supports read with (potential) write access and prevents
> > further shared locks (S) for the same object. An upgrade lock (U) can be
> > converted to an exclusive lock (X) after the release of the existing shared
> > locks or back to a shared lock if no update action is needed (time out).
> >
> > So, the difference is when I have an upgrade lock on a data, it is impossible to
> > obtain shared locks, but locks that are already granted keep going on. With the
> > exclusive lock no other locks can be obtained or exist on the same data.
> >
> > I expect it's more clear?
> >
> > Is it possible to transform the ReadWriteUpgradeLockManager to obtain this ?
> >
> > Thanks for your help,
> >
> > Mel
> >
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> >
>

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