submodule: extract get_fetch_task()

get_next_submodule() configures the parallel submodule fetch by
performing two functions:

* iterate the index to find submodules
* configure the child processes to fetch the submodules found in the
  previous step

Extract the index iterating code into an iterator function,
get_fetch_task(), so that get_next_submodule() is agnostic of how
to find submodules. This prepares for a subsequent commit will teach the
fetch machinery to also iterate through the list of changed
submodules (in addition to the index).

Signed-off-by: Glen Choo <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: chooglen

submodule.c

@@ -1389,6 +1389,7 @@ struct fetch_task {
 	struct repository *repo;
 	const struct submodule *sub;
 	unsigned free_sub : 1; /* Do we need to free the submodule? */
+	const char *default_argv; /* The default fetch mode. */
 
 	struct oid_array *commits; /* Ensure these commits are fetched */
 };
@@ -1466,14 +1467,11 @@ static struct repository *get_submodule_repo_for(struct repository *r,
 	return ret;
 }
 
-static int get_next_submodule(struct child_process *cp,
-			      struct strbuf *err, void *data, void **task_cb)
+static struct fetch_task *
+get_fetch_task(struct submodule_parallel_fetch *spf, struct strbuf *err)
 {
-	struct submodule_parallel_fetch *spf = data;
-
 	for (; spf->count < spf->r->index->cache_nr; spf->count++) {
 		const struct cache_entry *ce = spf->r->index->cache[spf->count];
-		const char *default_argv;
 		struct fetch_task *task;
 
 		if (!S_ISGITLINK(ce->ce_mode))
@@ -1493,40 +1491,23 @@ static int get_next_submodule(struct child_process *cp,
 					&spf->changed_submodule_names,
 					task->sub->name))
 				continue;
-			default_argv = "on-demand";
+			task->default_argv = "on-demand";
 			break;
 		case RECURSE_SUBMODULES_ON:
-			default_argv = "yes";
+			task->default_argv = "yes";
 			break;
 		case RECURSE_SUBMODULES_OFF:
 			continue;
 		}
 
 		task->repo = get_submodule_repo_for(spf->r, task->sub->path, null_oid());
 		if (task->repo) {
-			struct strbuf submodule_prefix = STRBUF_INIT;
-			child_process_init(cp);
-			cp->dir = task->repo->gitdir;
-			prepare_submodule_repo_env_in_gitdir(&cp->env_array);
-			cp->git_cmd = 1;
 			if (!spf->quiet)
 				strbuf_addf(err, _("Fetching submodule %s%s\n"),
 					    spf->prefix, ce->name);
-			strvec_init(&cp->args);
-			strvec_pushv(&cp->args, spf->args.v);
-			strvec_push(&cp->args, default_argv);
-			strvec_push(&cp->args, "--submodule-prefix");
-
-			strbuf_addf(&submodule_prefix, "%s%s/",
-						       spf->prefix,
-						       task->sub->path);
-			strvec_push(&cp->args, submodule_prefix.buf);
 
 			spf->count++;
-			*task_cb = task;
-
-			strbuf_release(&submodule_prefix);
-			return 1;
+			return task;
 		} else {
 			struct strbuf empty_submodule_path = STRBUF_INIT;
 
@@ -1550,6 +1531,36 @@ static int get_next_submodule(struct child_process *cp,
 			strbuf_release(&empty_submodule_path);
 		}
 	}
+	return NULL;
+}
+
+static int get_next_submodule(struct child_process *cp, struct strbuf *err,
+			      void *data, void **task_cb)
+{
+	struct submodule_parallel_fetch *spf = data;
+	struct fetch_task *task = get_fetch_task(spf, err);
+
+	if (task) {
+		struct strbuf submodule_prefix = STRBUF_INIT;
+
+		child_process_init(cp);
+		cp->dir = task->repo->gitdir;
+		prepare_submodule_repo_env_in_gitdir(&cp->env_array);
+		cp->git_cmd = 1;
+		strvec_init(&cp->args);
+		strvec_pushv(&cp->args, spf->args.v);
+		strvec_push(&cp->args, task->default_argv);
+		strvec_push(&cp->args, "--submodule-prefix");
+
+		strbuf_addf(&submodule_prefix, "%s%s/",
+						spf->prefix,
+						task->sub->path);
+		strvec_push(&cp->args, submodule_prefix.buf);
+		*task_cb = task;
+
+		strbuf_release(&submodule_prefix);
+		return 1;
+	}
 
 	if (spf->oid_fetch_tasks_nr) {
 		struct fetch_task *task =