Re: [PATCH] match_push_refs(): nobody sets src->peer_ref anymore

From: Jeff King <peff@peff.net>
Date: Mar 5, 2013, 05:45 UTC
Message-ID: <20130305054456.GA12446@sigill.intra.peff.net>
In-Reply-To: <7vlia2x05q.fsf@alter.siamese.dyndns.org>

On Mon, Mar 04, 2013 at 02:36:33PM -0800, Junio C Hamano wrote:

Show 15 quoted lines

> In ancient times, we used to disallow the same source ref to be
> pushed to more than one places, e.g. "git push there master:master
> master:naster" was disallowed.  We later lifted this restriction
> with db27ee63929f (send-pack: allow the same source to be pushed
> more than once., 2005-08-06) and there no longer is anybody that
> sets peer_ref for the source side of the ref list in the push
> codepath since then.
> 
> Remove one leftover no-op in a loop that iterates over the source
> side of ref list (i.e. our local ref) to see if it can/should be
> sent to a matching destination ref while skipping ones that is
> marked with peer_ref (which will never exist, so we do not skip
> anything).
> 
> Signed-off-by: Junio C Hamano <gitster@pobox.com>

This looks good to me. I was curious how difficult it would be to verify the "no longer is anybody that sets peer_ref" claim. It's actually quite easy. All of the call-sites just feed the result of get_local_heads(), which is easy to verify does not ever set peer_ref. Looking at the current code, I think you could even drop the "src" parameter and just have match_push_refs call get_local_heads() itself, though that does feel like a step backwards in terms of function generality.

As an aside, I have always found the embedded "next" and "peer_ref" pointers in "struct ref" to be hacky. They are not properties of the ref at all, and the "refs to fetch" list would be more logically represented as a list of pairs of refs (and then I would not have to ever remember whether the peer is the local or remote ref in a given case). Probably not worth worrying about at this point, though, as the code fallout would be significant for little gain.

-Peff