Subject: Re: [PATCH 1/6] refs/files: remove duplicate check in `split_symref_update()`

From: Patrick Steinhardt <[email-masked]>
Date: Fri, 7 Feb 2025 17:12:37 +0100

On Fri, Feb 07, 2025 at 08:34:36AM +0100, Karthik Nayak wrote:
> In split_symref_update(), there were two redundant checks:
>    - At the start: checking if refname exists in `affected_refnames`.
>    - After adding refname: checking if the item added to
>      `affected_refnames` contains the util field.

Okay, it took me a bit longer to understand what's going on here. What
you're saying is that we already use `string_list_has_string()` at the
start of `split_symref_update()`, and if that returns true then we would
bail out. Consequently, it is impossible for `string_list_insert()` to
find a preexisting values.

Makes sense, but I think that could be explained a bit better.

> diff --git a/refs/files-backend.c b/refs/files-backend.c
> index 29f08dced40418eb815072c6335e0c3d1a45c7d8..c6a3f6d6261a894e1c294bb1329fdf8079a39eb4 100644
> --- a/refs/files-backend.c
> +++ b/refs/files-backend.c
> @@ -2846,13 +2838,7 @@ static int files_transaction_prepare(struct ref_store *ref_store,
>  		if (update->flags & REF_LOG_ONLY)
>  			continue;
>  
> -		item = string_list_append(&affected_refnames, update->refname);
> -		/*
> -		 * We store a pointer to update in item->util, but at
> -		 * the moment we never use the value of this field
> -		 * except to check whether it is non-NULL.
> -		 */
> -		item->util = update;
> +		string_list_append(&affected_refnames, update->refname);

Nice to see this and other code removed.

Patrick