From: Jeff King <peff@peff.net>
Date: Sat, 12 May 2018 09:22:41 GMT
Subject: Re: [PATCH 01/12] blame: use commit-slab for blame suspects instead of commit->util
Message-ID: <20180512092241.GD28279@sigill.intra.peff.net>
In-Reply-To: <20180512080028.29611-2-pclouds@gmail.com>

On Sat, May 12, 2018 at 10:00:17AM +0200, Nguyễn Thái Ngọc Duy wrote:

> +define_commit_slab(blame_suspects, struct blame_origin *);
> +static struct blame_suspects blame_suspects;
> +
> +struct blame_origin *get_blame_suspects(struct commit *commit)
> +{
> +	struct blame_origin **result;
> +
> +	result = blame_suspects_peek(&blame_suspects, commit);
> +
> +	return result ? *result : NULL;
> +}

Hmm. You need this helper because you want to be able to peek and get a
NULL. But that's already what _at() would return, with the only
difference that we may extend the slab just to return NULL.

I wonder how much it matters in practice. We'd generally be extending
the slab to hit every commit anyway in this case, I would think.

I suppose it doesn't actually simplify the code that much to do it that
way, though. We could get rid of this helper, but the caller would still
look like:

  for (p = *blame_suspects_at(o->commit); p; p = p->next)

which is actually slightly uglier than get_blame_suspects(), because we
have to do the pointer-dereference ourselves.

-Peff