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Re: [Gnu-arch-users] Re: Questions from a Subversion user
From: |
Andrew Suffield |
Subject: |
Re: [Gnu-arch-users] Re: Questions from a Subversion user |
Date: |
Mon, 18 Aug 2003 17:46:35 +0100 |
User-agent: |
Mutt/1.5.4i |
On Mon, Aug 18, 2003 at 09:10:52AM -0700, Tom Lord wrote:
> > From: John Goerzen <address@hidden>
>
> > > arch supports a bunch of transports: ftp, sftp, http, and others.
> arch
> > > implements its own locking scheme. I am not sure what you mean by
> > > "insure integrity."
>
> > What I'm talking about is multiple users writing to the repository at
> > once. FTP (and SFTP, and HTTP) doesn't implement anything like
> > flock() -- and the best that one normally can do is creating
> > lockfiles, which have inherent race conditions and are thus
> > unreliable. It'd be really easy to have two people running a STOR on
> > the same file at once -- with likely disastrous results.
>
> The locking mechnanisms in arch do not have race conditions and are
> robust for multi-user concurrent access. They rely only on some
> least-common-denominator properties of `mkdir' and `rename' -- safe,
> even, on NFS.
No Files are Safe.
It's always possible that your mkdir()/rename() lands on the wrong
thing entirely, because NFS has gotten its inode numbers in a twist
again :P
[Of course, when this happens then your files are being eaten alive, so
a few abused locks are the least of your worries]
[Yeah, it's that bad]
--
.''`. ** Debian GNU/Linux ** | Andrew Suffield
: :' : http://www.debian.org/ |
`. `' |
`- -><- |
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Re: [Gnu-arch-users] Questions from a Subversion user, Andrew Suffield, 2003/08/18