Re: [PATCH 5/5] shallow: use struct 'shallow_lock' for additional safety

[Eric Sunshine <sunshine@sunshineco.com>]

On Wed, Apr 29, 2020 at 6:39 PM Taylor Blau <me@ttaylorr.com> wrote:
> [...]
> This patch introduces that type as a thin wrapper around 'struct
> lockfile', and updates the two aforementioned functions and their
> callers to use it.
>
> Signed-off-by: Taylor Blau <me@ttaylorr.com>
> ---
> diff --git a/shallow.h b/shallow.h
> @@ -10,12 +10,22 @@ void set_alternate_shallow_file(struct repository *r, const char *path, int over
> +/*
> + * shallow_lock is a thin wrapper around 'struct lock_file' in order to restrict
> + * which locks can be used with '{commit,rollback}_shallow_file()'.
> + */
> +struct shallow_lock {
> +       struct lock_file lk;
> +};

The documentation comment for 'shallow_lock' may help newcomers to C
but probably doesn't add much value for seasoned programmers. If this
is the sort of idiom we want to introduce (or exists already in this
codebase) -- declaring a specific C type to avoid accidental use of an
unrelated lock -- then it's probably better documented in
CodingGuidelines rather than repeating it at each point in the code
which employs the idiom.