Re: [PATCH] ref-filter: reuse --contains traversal results

[Jeff King <peff@peff.net>]

On Mon, Jun 08, 2026 at 07:35:57PM -0400, Tamir Duberstein wrote:

> > So I think a better rule here is to tweak the selection in
> > commit_contains() to select the depth-first algorithm when we have
> > generation numbers enabled. There's a patch in an old thread, which was
> > revived a week or two ago by Kristofer (cc'd):
> >
> >   https://lore.kernel.org/git/20260527070510.3510836-1-krka@spotify.com/
> 
> Very good catch, thank you. I reproduced the regression with a
> 100,000-commit history and generation numbers disabled. The parent
> took 13.0 ms, the unconditional depth-first version took 238.4 ms, and
> the generation-aware version took 9.1 ms.
> 
> I didn't find a patch in that thread, so I will reroll using the
> memoized walk for tags or when generation numbers are enabled, while
> retaining the breadth-first walk otherwise. If someone else would
> prefer to send that patch, that is fine by me as well.

It's just this:

diff --git a/commit-reach.c b/commit-reach.c
index 9b3ea46d6f..cdea0030b8 100644
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -799,7 +799,8 @@ static enum contains_result contains_tag_algo(struct commit *candidate,
 int commit_contains(struct ref_filter *filter, struct commit *commit,
 		    struct commit_list *list, struct contains_cache *cache)
 {
-	if (filter->with_commit_tag_algo)
+	if (filter->with_commit_tag_algo ||
+	    generation_numbers_enabled(the_repository))
 		return contains_tag_algo(commit, list, cache) == CONTAINS_YES;
 	return repo_is_descendant_of(the_repository, commit, list);
 }

from:

  https://lore.kernel.org/git/20230324191009.GA536967@coredump.intra.peff.net/

But I won't be surprised if you recreated the identical patch yourself. ;)

-Peff