Re: [PATCH v2 08/24] midx: respect 'core.multiPackIndex' when writing

From: Jeff King <peff@peff.net>
Date: Jul 27, 2021, 17:42 UTC
Message-ID: <YQBFi70c1wfXdKQf@coredump.intra.peff.net>
In-Reply-To: <YQBEIrRfcq5dhpZn@nand.local>

On Tue, Jul 27, 2021 at 01:36:34PM -0400, Taylor Blau wrote:

Show 15 quoted lines

> > But now the internal midx writing code can never call close_midx() on
> > that, because it does not own it to close. Can we simply drop the
> > close_midx() call there?
> >
> > This would all make much more sense to me if write_midx_internal()
> > simply took a conceptually read-only midx as a parameter, and the caller
> > passed in the appropriate one (probably even using
> > prepare_multi_pack_index_one() to get it).
> 
> No, we can't drop the close_midx() call there because we must close the
> MIDX file on Windows before moving a new one into place. My feeling is
> we should always be working on the r->objects->multi_pack_index pointer,
> and calling close_object_store() there instead of close_midx().
> 
> Does that seem like a reasonable approach to you?

Yes, though I'd have said that it is the responsibility of the caller (who knows we are operating with r->objects->multi_pack_index) to do that closing. But maybe it's not possible if the rename-into-place happens at too low a level.

BTW, yet another weirdness: close_object_store() will call close_midx() on the outermost midx struct, ignoring o->multi_pack_index->next entirely. So that's a leak, but also means we may not be closing the midx we're interested in (since write_midx_internal() takes an object-dir parameter, and we could be pointing to some other object-dir's midx).

-Peff