Re: [PATCH v2 4/7] worktree: inline `worktree_ref()` into its only caller

From: Eric Sunshine <sunshine@sunshineco.com>
To: "Martin Ågren" <martin.agren@gmail.com>
Cc: Git List <git@vger.kernel.org>,
	Junio C Hamano <gitster@pobox.com>, Taylor Blau <me@ttaylorr.com>
Subject: Re: [PATCH v2 4/7] worktree: inline `worktree_ref()` into its only caller
Date: Mon, 28 Sep 2020 01:30:24 -0400	[thread overview]
Message-ID: <CAPig+cSBPFdF=hM5ho9_g6NCGAprh1mFFT5zX-C9huT3-Qkzow@mail.gmail.com> (raw)
In-Reply-To: <c4825f461e0408970f2adb272098bd6f2a80ef78.1600281351.git.martin.agren@gmail.com>

On Sun, Sep 27, 2020 at 9:16 AM Martin Ågren <martin.agren@gmail.com> wrote:
> We have `strbuf_worktree_ref()`, which works on a strbuf, and a wrapper
> for it, `worktree_ref()` which returns a string. We even make this
> wrapper available through worktree.h. But it only has a single caller,
> sitting right next to it in worktree.c.
>
> Just inline the wrapper into its only caller. This means the caller can
> quite naturally reuse a single strbuf. We currently achieve something
> similar by having a static strbuf in the wrapper.
>
> Signed-off-by: Martin Ågren <martin.agren@gmail.com>
> ---
> diff --git a/worktree.c b/worktree.c
> @@ -548,18 +548,10 @@ void strbuf_worktree_ref(const struct worktree *wt,
> -const char *worktree_ref(const struct worktree *wt, const char *refname)
> -{
> -       static struct strbuf sb = STRBUF_INIT;
> -
> -       strbuf_reset(&sb);
> -       strbuf_worktree_ref(wt, &sb, refname);
> -       return sb.buf;
> -}
> -
>  int other_head_refs(each_ref_fn fn, void *cb_data)
>  {
> +       struct strbuf refname = STRBUF_INIT;
> @@ -571,14 +563,17 @@ int other_head_refs(each_ref_fn fn, void *cb_data)
> +               strbuf_reset(&refname);

If I understand correctly, this strbuf_reset() -- which, I suppose,
moved here from the retired worktree_ref() -- is no longer needed now
that the strbuf stopped being static. So, this line should be dropped
from the patch.

> +               strbuf_worktree_ref(wt, &refname, "HEAD");
>                 if (!refs_read_ref_full(get_main_ref_store(the_repository),
> -                                       worktree_ref(wt, "HEAD"),
> +                                       refname.buf,
>                                         RESOLVE_REF_READING,
>                                         &oid, &flag))
> -                       ret = fn(worktree_ref(wt, "HEAD"), &oid, flag, cb_data);
> +                       ret = fn(refname.buf, &oid, flag, cb_data);

One wonders why the original made two calls to worktree_ref() with
identical arguments. Doing so seems to suggest that something about
HEAD might change between the calls, but that doesn't seem to be the
case. The message of the commit[1] which introduced the two calls to
worktree_ref() doesn't explain the reason, and spelunking through the
code doesn't immediately reveal why it was done that way either. So,
presumably(?), it is indeed safe to fold them into a single call to
strbuf_worktree_ref().

[1]: ab3e1f78ae (revision.c: better error reporting on ref from
different worktrees, 2018-10-21)