Re: [PATCH 1/1] ls-refs.c: minimize number of refs visited

On Tue, Jan 19, 2021 at 05:52:04PM -0500, Jeff King wrote:

On Tue, Jan 19, 2021 at 05:23:36PM -0500, Taylor Blau wrote:

quoted

quoted

Having now looked carefully at the ls-refs code, it's a pure
prefix-match, too. So I think we _could_ rely on for_each_fullref_in()
returning us the correct full results, and not checking it further in
send_ref(). But I kind of like keeping it there as an extra check (and
one which could in theory grow more logic later).

Hmm. What if the caller asks for:

  ref-prefix refs/tags/a
  ref-prefix refs/tags/b

?

The LCP between those two is refs/tags, so send_ref() will presumably
get lots of reuslts that it doesn't care about (assuming there are tags
besides a and b).

Oh, you're right, of course. Ignore me. :)

Actually, I am not sure that we would look for "refs/tags/" in that case
(I did a quick test and we do not seem to). Which makes sense, as it is
cheaper to find the "a" and "b" hierarchies separately if there is a
very big "refs/tags/c" hierarchy.

But I agree that this is a good reason that callers should consider it
as an optimization which could return more results than expected.

-Peff