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Message-ID: <1112602728.4250f868b4df0@webmail2.utbm.fr>
Date: Mon,  4 Apr 2005 10:18:48 +0200
From: "Melanie.Bats@UTBM.fr" <Melanie.Bats@utbm.fr>
To: Jakarta Commons Users List <commons-user@jakarta.apache.org>
Subject: Re: [transaction.locking] Modify the behaviour of the
 ReadWriteUpgradeLockManager
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Hi,

Selon Oliver Zeigermann <oliver.zeigermann@gmail.com>:
> If so that's exactly what the read/write lock and then the read/write
> lock manager does.

Thanks this seems to be what I need.

Mel

> 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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