Subject: Re: [PATCH 4/6] refs: drop unused params from the reflog iterator callback

From: Junio C Hamano <[email-masked]>
Date: Mon, 19 Feb 2024 16:14:16 -0800

Patrick Steinhardt <[email-masked]> writes:

> The ref and reflog iterators share much of the same underlying code to
> iterate over the corresponding entries. This results in some weird code
> because the reflog iterator also exposes an object ID as well as a flag
> to the callback function. Neither of these fields do refer to the reflog
> though -- they refer to the corresponding ref with the same name. This
> is quite misleading. In practice at least the object ID cannot really be
> implemented in any other way as a reflog does not have a specific object
> ID in the first place. This is further stressed by the fact that none of
> the callbacks except for our test helper make use of these fields.

Interesting observation.  Of course this will make the callstack
longer by another level of indirection ...

> +struct do_for_each_reflog_help {
> +	each_reflog_fn *fn;
> +	void *cb_data;
> +};
> +
> +static int do_for_each_reflog_helper(struct repository *r UNUSED,
> +				     const char *refname,
> +				     const struct object_id *oid UNUSED,
> +				     int flags,
> +				     void *cb_data)
> +{
> +	struct do_for_each_reflog_help *hp = cb_data;
> +	return hp->fn(refname, hp->cb_data);
> +}

... but I think it would be worth it.

> +/*
> + * The signature for the callback function for the {refs_,}for_each_reflog()
> + * functions below. The memory pointed to by the refname argument is only
> + * guaranteed to be valid for the duration of a single callback invocation.
> + */
> +typedef int each_reflog_fn(const char *refname, void *cb_data);
> +
>  /*
>   * Calls the specified function for each reflog file until it returns nonzero,
>   * and returns the value. Reflog file order is unspecified.
>   */
> -int refs_for_each_reflog(struct ref_store *refs, each_ref_fn fn, void *cb_data);
> -int for_each_reflog(each_ref_fn fn, void *cb_data);
> +int refs_for_each_reflog(struct ref_store *refs, each_reflog_fn fn, void *cb_data);
> +int for_each_reflog(each_reflog_fn fn, void *cb_data);

Nice simplification.