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Re: change_rev_prop atomicity

From: David Glasser <glasser_at_mit.edu>
Date: 2007-02-12 14:16:39 CET

On 2/12/07, Chia-liang Kao <clkao@clkao.org> wrote:
> While trying to see how to have fs->change_rev_prop_if_value_is() implemented
> for better atomicity, I saw something interesting in the related code.
>
> In libsvn_fs_fs/revs-txns.c: svn_fs_fs__change_rev_prop, the __set_rev_prop
> called is loading the revision proplist hash, changing the value for what is
> requested, and writing back the whole hash as the new proplist. The code is
> vulnerable for race condition when two clients are setting different revision
> properties on the same revision at the same time.

Taking a look at the same code, I agree with CL that this is a race
condition. While of course revprops are unversioned and we shouldn't
be too worried about two clients changing the same revprop at the same
time, if two clients try to change *different* revprops on the same
revision at the same time it looks like you could lose one change.

--dave

-- 
David Glasser | glasser_at_mit.edu | http://www.davidglasser.net/
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Received on Mon Feb 12 14:16:55 2007

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