From: Junio C Hamano <gitster@pobox.com>
Date: Thu, 01 Aug 2024 16:51:53 GMT
Subject: Re: [PATCH v2 3/3] ref-filter: populate symref from iterator
Message-ID: <xmqqwml0uqxi.fsf@gitster.g>
In-Reply-To: <3e147e7d850773f44b48d1b86e89aef1415a0ccd.1722524334.git.gitgitgadget@gmail.com>

"John Cai via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: John Cai <johncai86@gmail.com>
>
> With a previous commit, the reference the symbolic ref points to is saved
> in the ref iterator records. Instead of making a separate call to
> resolve_refdup() each time, we can just populate the ref_array_item with
> the value from the iterator.
>
> Signed-off-by: John Cai <johncai86@gmail.com>
> ---
>  ref-filter.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/ref-filter.c b/ref-filter.c
> index 39997890feb..08997e59662 100644
> --- a/ref-filter.c
> +++ b/ref-filter.c
> @@ -2783,7 +2783,7 @@ static int filter_ref_kind(struct ref_filter *filter, const char *refname)
>  	return ref_kind_from_refname(refname);
>  }
>  
> -static struct ref_array_item *apply_ref_filter(const char *refname, const struct object_id *oid,
> +static struct ref_array_item *apply_ref_filter(const char *refname, const char *referent, const struct object_id *oid,
>  			    int flag, struct ref_filter *filter)
>  {
>  	struct ref_array_item *ref;
> @@ -2852,6 +2852,8 @@ static struct ref_array_item *apply_ref_filter(const char *refname, const struct
>  	ref->commit = commit;
>  	ref->flag = flag;
>  	ref->kind = kind;
> +	if (flag & REF_ISSYMREF)
> +		ref->symref = xstrdup_or_null(referent);
>  
>  	return ref;
>  }

What is curious is that we do not lose any code from
populate_value() with this change.

Is that because of this piece of code near the beginning of it?

	CALLOC_ARRAY(ref->value, used_atom_cnt);

	if (need_symref && (ref->flag & REF_ISSYMREF) && !ref->symref) {
		ref->symref = refs_resolve_refdup(get_main_ref_store(the_repository),
						  ref->refname,
						  RESOLVE_REF_READING,
						  NULL, NULL);
		if (!ref->symref)
			ref->symref = xstrdup("");
	}

That is, if we somehow know the value of ref->symref for a ref that
is known to be a symbolic ref (and when we know we need symref
information in the output), we do not bother calling refs_resolve
here to obtain the value.

Thanks.