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Re: M3 ahead...

From: Greg Stein <gstein_at_lyra.org>
Date: 2001-08-08 02:56:46 CEST

I've been reading "txn_abort" as SVN's abort function. Sorry.

Otherwise, I know the difference... just not the function name :-)

Cheers,
-g

On Tue, Aug 07, 2001 at 06:44:14PM -0500, Jim Blandy wrote:
>
> Greg Stein <gstein@lyra.org> writes:
> > On Tue, Aug 07, 2001 at 11:08:47AM -0500, Jim Blandy wrote:
> > >
> > > subversion-dev@thewrittenword.com writes:
> > > > And how does Apache find out about the transaction ID that is needed
> > > > by txn_abort()? Does mod_dav_svn have this info?
> > >
> > > Ah, a careful reader! I don't know. :(
> >
> > As I mentioned before, Apache will never call txn_abort unless the *client*
> > sends a request to do that (e.g. DELETE the activity).
>
> I can't be sure, but it really sounds like you are confusing Berkeley
> DB transactions with Subversion transactions. txn_abort aborts a
> Berkeley DB transaction; it has nothing to do with deleting a DAV
> activity.
>
> If I understand Berkeley DB correctly, when a process working on a
> DB exits unexpectedly, it will leave locks in the shared memory area.
> These locks will need to be cleared out.
>
> Now that I think about it, it should be safe for
> svn_fs_berkeley_recover to simply abort all pending Berkeley DB
> transactions, since (at least in theory) it knows it is called when
> nobody else is writing to the database. So it's not necessary to
> recover the Berkeley DB transaction ID's.
>
> > There is no way for Apache to know that an SVN transaction needs to be
> > aborted. The death of a child process/thread is an insufficient trigger.
>
> For an SVN transaction, this is correct. For a Berkeley DB
> transaction (which is what txn_abort works with), however, if a child
> dies, then its Berkeley DB locks can certainly be disposed of --- and
> must be, I think.

-- 
Greg Stein, http://www.lyra.org/
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Received on Sat Oct 21 14:36:35 2006

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