Re: [PATCH 4/6] builtin/submodule--helper: store update_clone information in a struct

From: Junio C Hamano <gitster@pobox.com>
Date: Jul 16, 2018, 19:37 UTC
Message-ID: <xmqqo9f7t1jy.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <20180712194754.71979-5-sbeller@google.com>

Stefan Beller <sbeller@google.com> writes:

Show 7 quoted lines

> The information that is printed for update_submodules in
> 'submodule--helper update-clone' and consumed by 'git submodule update'
> is stored as a string per submodule. This made sense at the time of
> 48308681b07 (git submodule update: have a dedicated helper for cloning,
> 2016-02-29), but as we want to migrate the rest of the submodule update
> into C, we're better off having access to the raw information in a helper
> struct.

The reasoning above makes sense, but I have a few niggles on the naming.

 * Anything you'd place to keep track of the state is "information",
   so a whole "_information" suffix to the structure name does not
   add much value.  We've seen our fair share of (meaningless)
   "_data" suffix used in many places but I think the overly long
   "_information" that is equally meaningless trumps them.  I think
   we also have "_info", but if we are not going to have a beter
   name, let's not be original and stick to "_data" like other
   existing codepath.  An alternative with more meaningful name is
   of course better, though, but it is not all that much worth to
   spend too many braincycles on it.

 * Is the fact that these parameters necessary to help populating
   the submodule repository are sent on a line to external process
   the most important aspect of the submodule_lines[] array?  As
   this step is a preparation to migrate out of that line/text
   oriented IPC, I think line-ness is the least important and
   interesting thing to name the variable with.

If I were writing this patch, perhaps I'd do

	struct update_clone_data *update_clone;
	int update_clone_nr, update_clone_alloc;

following my gut, but since you've been thinking about submodule longer than I have, perhaps you can come up with a better name.

Show 18 quoted lines

> @@ -1463,8 +1469,9 @@ struct submodule_update_clone {
>  	const char *recursive_prefix;
>  	const char *prefix;
>  
> -	/* Machine-readable status lines to be consumed by git-submodule.sh */
> -	struct string_list projectlines;
> +	/* to be consumed by git-submodule.sh */
> +	struct submodule_update_clone_information *submodule_lines;
> +	int submodule_lines_nr; int submodule_lines_alloc;
>  
>  	/* If we want to stop as fast as possible and return an error */
>  	unsigned quickstop : 1;
> @@ -1478,7 +1485,7 @@ struct submodule_update_clone {
>  #define SUBMODULE_UPDATE_CLONE_INIT {0, MODULE_LIST_INIT, 0, \
>  	SUBMODULE_UPDATE_STRATEGY_INIT, 0, 0, -1, STRING_LIST_INIT_DUP, 0, \
>  	NULL, NULL, NULL, \
> -	STRING_LIST_INIT_DUP, 0, NULL, 0, 0}
> +	NULL, 0, 0, 0, NULL, 0, 0, 0}

The structure definition and this macro definition are nearby, so it is not crucial, but its probably not a bad idea to switch to C99 initializers for a thing like this to make it more readable, once the code around this area stabilizes back again sufficiently (IOW, let's not distract ourselves in the middle of adding a new feature like this one).