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Re: [Gnu-arch-users] [BUG] FEATURE PLANS: revlib locking
From: |
Tom Lord |
Subject: |
Re: [Gnu-arch-users] [BUG] FEATURE PLANS: revlib locking |
Date: |
Sat, 29 May 2004 10:15:58 -0700 (PDT) |
> From: Aaron Bentley <address@hidden>
> Andrew Suffield wrote:
> > On Sat, May 29, 2004 at 08:55:28AM -0400, Aaron Bentley wrote:
> >>... I think it would make sense to have an
> >>invented-here locking mechanism that would definitely work on NFS, and
> >>maybe even SMB.
> > Not gonna happen. There does not exist a method by which you can
> > reliably acquire a lock without prior knowledge of the system or
> > arbitrarily restricting the set of supported systems.
> I mean a system specifically for locking revlibs, so we can make a lot
> of assumptions we otherwise couldn't.
It would be acceptable to have two kinds of locking, selectable by a
per-library parameter. One should just use flock since it is exactly
the right thing for a library which is (only) on a local filesystem.
The other can be a kind of "lease" locking (expiring locks) which tla
has to update periodically -- we can use timestamps and filenames for
that.
The lease locking can't be perfect but it can be probabilistically
very good.
-t
Re: [Gnu-arch-users] [BUG] FEATURE PLANS: revlib locking, Tom Lord, 2004/05/29