builtin/submodule--helper: factor out submodule updating

Separate the command line parsing from the actual execution of the command
within the repository. For now there is not a lot of execution as
most of it is still in git-submodule.sh.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/submodule--helper.c

@@ -1474,6 +1474,8 @@ struct submodule_update_clone {
 	/* failed clones to be retried again */
 	const struct cache_entry **failed_clones;
 	int failed_clones_nr, failed_clones_alloc;
+
+	int max_jobs;
 };
 #define SUBMODULE_UPDATE_CLONE_INIT {0, MODULE_LIST_INIT, 0, \
 	SUBMODULE_UPDATE_STRATEGY_INIT, 0, 0, -1, STRING_LIST_INIT_DUP, 0, \
@@ -1716,11 +1718,36 @@ static int git_update_clone_config(const char *var, const char *value,
 	return 0;
 }
 
+static int update_submodules(struct submodule_update_clone *suc)
+{
+	struct string_list_item *item;
+
+	run_processes_parallel(suc->max_jobs,
+			       update_clone_get_next_task,
+			       update_clone_start_failure,
+			       update_clone_task_finished,
+			       suc);
+
+	/*
+	 * We saved the output and put it out all at once now.
+	 * That means:
+	 * - the listener does not have to interleave their (checkout)
+	 *   work with our fetching.  The writes involved in a
+	 *   checkout involve more straightforward sequential I/O.
+	 * - the listener can avoid doing any work if fetching failed.
+	 */
+	if (suc->quickstop)
+		return 1;
+
+	for_each_string_list_item(item, &suc->projectlines)
+		fprintf(stdout, "%s", item->string);
+
+	return 0;
+}
+
 static int update_clone(int argc, const char **argv, const char *prefix)
 {
 	const char *update = NULL;
-	int max_jobs = 1;
-	struct string_list_item *item;
 	struct pathspec pathspec;
 	struct submodule_update_clone suc = SUBMODULE_UPDATE_CLONE_INIT;
 
@@ -1742,7 +1769,7 @@ static int update_clone(int argc, const char **argv, const char *prefix)
 		OPT_STRING(0, "depth", &suc.depth, "<depth>",
 			   N_("Create a shallow clone truncated to the "
 			      "specified number of revisions")),
-		OPT_INTEGER('j', "jobs", &max_jobs,
+		OPT_INTEGER('j', "jobs", &suc.max_jobs,
 			    N_("parallel jobs")),
 		OPT_BOOL(0, "recommend-shallow", &suc.recommend_shallow,
 			    N_("whether the initial clone should follow the shallow recommendation")),
@@ -1758,8 +1785,8 @@ static int update_clone(int argc, const char **argv, const char *prefix)
 	};
 	suc.prefix = prefix;
 
-	update_clone_config_from_gitmodules(&max_jobs);
-	git_config(git_update_clone_config, &max_jobs);
+	update_clone_config_from_gitmodules(&suc.max_jobs);
+	git_config(git_update_clone_config, &suc.max_jobs);
 
 	argc = parse_options(argc, argv, prefix, module_update_clone_options,
 			     git_submodule_helper_usage, 0);
@@ -1774,27 +1801,7 @@ static int update_clone(int argc, const char **argv, const char *prefix)
 	if (pathspec.nr)
 		suc.warn_if_uninitialized = 1;
 
-	run_processes_parallel(max_jobs,
-			       update_clone_get_next_task,
-			       update_clone_start_failure,
-			       update_clone_task_finished,
-			       &suc);
-
-	/*
-	 * We saved the output and put it out all at once now.
-	 * That means:
-	 * - the listener does not have to interleave their (checkout)
-	 *   work with our fetching.  The writes involved in a
-	 *   checkout involve more straightforward sequential I/O.
-	 * - the listener can avoid doing any work if fetching failed.
-	 */
-	if (suc.quickstop)
-		return 1;
-
-	for_each_string_list_item(item, &suc.projectlines)
-		fprintf(stdout, "%s", item->string);
-
-	return 0;
+	return update_submodules(&suc);
 }
 
 static int resolve_relative_path(int argc, const char **argv, const char *prefix)