Re: [Gnu-arch-users] [BUG] FEATURE PLANS: revlib locking

[Tom Lord]

    > 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