Re: [PATCH v4 4/6] update-index: use the bulk-checkin infrastructure

On Tue, Sep 21, 2021 at 6:27 PM Neeraj Singh [off-list ref] wrote:

On Tue, Sep 21, 2021 at 4:53 PM Ævar Arnfjörð Bjarmason
[off-list ref] wrote:

quoted

All of this makes me wonder why this isn't using tmp-objdir.c, i.e. we
could have our cake and eat it too by writing the "real" objects, and
then just renaming them between directories instead. But perhaps the
answer has something to do with the metadata issues I raised.

And well, tmp-objdir.c isn't going to help someone in practice that's
relying on this "update-index --stdin" behavior, as they won't know
where we staged the temporary files...

One motivation of the current design behind renaming the files is that
some networked filesystems don't seem to like cross-directory renames
much.  It also so happens that ReFS on Windows also prefers renames to
stay within the directory. Actually any filesystem would likely be
slightly faster,
since fewer objects are being modified (one dir versus two).

Whelp, as part of v5 I tried to make unpack-objects.c use the batch fsync
mode and now I see a strong reason to take your tmp-objdir suggestion. As
part of OBJ_REF_DELTA unpacking, we need access to the object while
we're in the plugged state. I didn't notice this at first, but got
lucky that I tested
that case first and hit an error.

V5 will create a tmp-objdir and add a new interface to install it as the primary
objdir.