Re: [PATCH 0/4] repack: various corner cases for cruft-less MIDXs

On Wed, Sep 30, 2026 at 04:55:35PM -0400, Jeff King wrote:

On Tue, Sep 29, 2026 at 08:28:34PM -0500, Taylor Blau wrote:

quoted

This patch series fixes a few bugs I spotted while investigating the
cruft-less MIDX feature.

The bugs addressed are found in various corner cases, and, when
triggered, may result in a MIDX being written whose objects are not
closed under reachability. When this happens while the caller is trying
to write reachability bitmaps, bitmap generation may fail if one or more
selected commits are descendants of the open portion of the MIDX.

I think all of these are making things strictly better, but I did find a
few spots where the fixes might be incomplete. I'm not sure if that
argues for a re-roll or for punting those to future work. ;)

Thanks for the review. Like I wrote in my response to your review,
leaving it half-fixed felt dishonest, so fixes are included in the
subsequent round, though they do make the series a little longer.

There is a separate, pre-existing bug that I would like to fix outside
of this series, but only because it (a) is independent of this series,
and (b) I estimate that the fix is considerably more complex.

I agree with Stolee that an oidset is perhaps a better data structure
for storing the extra roots (which are in a kind-of random order anyway,
since we're pulling them in pack order from various packs). But it also
probably doesn't make that big a difference in practice (we'll skip
duplicates during the traversal, and you probably don't have that many
duplicate objects in a repo in the first place).

Yup.


Thanks,
Taylor