Subject: [PATCH 6/6] submodule: refactor logic to determine changed submodules

From: Brandon Williams <[email-masked]>
Date: Fri, 28 Apr 2017 16:54:02 -0700

There are currently two instances (fetch and push) where we want to
determine if submodules have changed given some revision specification.
These two instances don't use the same logic to generate a list of
changed submodules and as a result there is a fair amount of code
duplication.

This patch refactors these two code paths such that they both use the
same logic to generate a list of changed submodules.  This also makes it
easier for future callers to be able to reuse this logic as they only
need to create an argv_array with the revision specification to be using
during the revision walk.

Signed-off-by: Brandon Williams <[email-masked]>
---
 submodule.c | 247 ++++++++++++++++++++++++++----------------------------------
 1 file changed, 105 insertions(+), 142 deletions(-)

diff --git a/submodule.c b/submodule.c
index 100d31d39..88093779e 100644
--- a/submodule.c
+++ b/submodule.c
@@ -617,6 +617,94 @@ const struct submodule *submodule_from_ce(const struct cache_entry *ce)
 	return submodule_from_path(null_sha1, ce->name);
 }
 
+static struct oid_array *submodule_commits(struct string_list *submodules,
+					   const char *path)
+{
+	struct string_list_item *item;
+
+	item = string_list_insert(submodules, path);
+	if (item->util)
+		return (struct oid_array *) item->util;
+
+	/* NEEDSWORK: should we have oid_array_init()? */
+	item->util = xcalloc(1, sizeof(struct oid_array));
+	return (struct oid_array *) item->util;
+}
+
+static void collect_changed_submodules_cb(struct diff_queue_struct *q,
+					  struct diff_options *options,
+					  void *data)
+{
+	int i;
+	struct string_list *changed = data;
+
+	for (i = 0; i < q->nr; i++) {
+		struct diff_filepair *p = q->queue[i];
+		struct oid_array *commits;
+		if (!S_ISGITLINK(p->two->mode))
+			continue;
+
+		if (S_ISGITLINK(p->one->mode)) {
+			/*
+			 * NEEDSWORK: We should honor the name configured in
+			 * the .gitmodules file of the commit we are examining
+			 * here to be able to correctly follow submodules
+			 * being moved around.
+			 */
+			commits = submodule_commits(changed, p->two->path);
+			oid_array_append(commits, &p->two->oid);
+		} else {
+			/* Submodule is new or was moved here */
+			/*
+			 * NEEDSWORK: When the .git directories of submodules
+			 * live inside the superprojects .git directory some
+			 * day we should fetch new submodules directly into
+			 * that location too when config or options request
+			 * that so they can be checked out from there.
+			 */
+			continue;
+		}
+	}
+}
+
+/*
+ * Collect the paths of submodules in 'changed' which have changed based on
+ * the revisions as specified in 'argv'.  Each entry in 'changed' will also
+ * have a corresponding 'struct oid_array' (in the 'util' field) which lists
+ * what the submodule pointers were updated to during the change.
+ */
+static void collect_changed_submodules(struct string_list *changed,
+				       struct argv_array *argv)
+{
+	struct rev_info rev;
+	const struct commit *commit;
+
+	init_revisions(&rev, NULL);
+	setup_revisions(argv->argc, argv->argv, &rev, NULL);
+	if (prepare_revision_walk(&rev))
+		die("revision walk setup failed");
+
+	while ((commit = get_revision(&rev))) {
+		struct rev_info diff_rev;
+
+		init_revisions(&diff_rev, NULL);
+		diff_rev.diffopt.output_format |= DIFF_FORMAT_CALLBACK;
+		diff_rev.diffopt.format_callback = collect_changed_submodules_cb;
+		diff_rev.diffopt.format_callback_data = changed;
+		diff_tree_combined_merge(commit, 1, &diff_rev);
+	}
+
+	reset_revision_walk();
+}
+
+static void free_submodules_oids(struct string_list *submodules)
+{
+	struct string_list_item *item;
+	for_each_string_list_item(item, submodules)
+		oid_array_clear((struct oid_array *) item->util);
+	string_list_clear(submodules, 1);
+}
+
 static int has_remote(const char *refname, const struct object_id *oid,
 		      int flags, void *cb_data)
 {
@@ -719,92 +807,31 @@ static int submodule_needs_pushing(const char *path, struct oid_array *commits)
 	return 0;
 }
 
-static struct oid_array *submodule_commits(struct string_list *submodules,
-					    const char *path)
-{
-	struct string_list_item *item;
-
-	item = string_list_insert(submodules, path);
-	if (item->util)
-		return (struct oid_array *) item->util;
-
-	/* NEEDSWORK: should we have oid_array_init()? */
-	item->util = xcalloc(1, sizeof(struct oid_array));
-	return (struct oid_array *) item->util;
-}
-
-static void collect_submodules_from_diff(struct diff_queue_struct *q,
-					 struct diff_options *options,
-					 void *data)
-{
-	int i;
-	struct string_list *submodules = data;
-
-	for (i = 0; i < q->nr; i++) {
-		struct diff_filepair *p = q->queue[i];
-		struct oid_array *commits;
-		if (!S_ISGITLINK(p->two->mode))
-			continue;
-		commits = submodule_commits(submodules, p->two->path);
-		oid_array_append(commits, &p->two->oid);
-	}
-}
-
-static void find_unpushed_submodule_commits(struct commit *commit,
-		struct string_list *needs_pushing)
-{
-	struct rev_info rev;
-
-	init_revisions(&rev, NULL);
-	rev.diffopt.output_format |= DIFF_FORMAT_CALLBACK;
-	rev.diffopt.format_callback = collect_submodules_from_diff;
-	rev.diffopt.format_callback_data = needs_pushing;
-	diff_tree_combined_merge(commit, 1, &rev);
-}
-
-static void free_submodules_oids(struct string_list *submodules)
-{
-	struct string_list_item *item;
-	for_each_string_list_item(item, submodules)
-		oid_array_clear((struct oid_array *) item->util);
-	string_list_clear(submodules, 1);
-}
-
 int find_unpushed_submodules(struct oid_array *commits,
 		const char *remotes_name, struct string_list *needs_pushing)
 {
-	struct rev_info rev;
-	struct commit *commit;
 	struct string_list submodules = STRING_LIST_INIT_DUP;
 	struct string_list_item *submodule;
 	struct argv_array argv = ARGV_ARRAY_INIT;
 
-	init_revisions(&rev, NULL);
-
 	/* argv.argv[0] will be ignored by setup_revisions */
 	argv_array_push(&argv, "find_unpushed_submodules");
 	oid_array_for_each_unique(commits, append_oid_to_argv, &argv);
 	argv_array_push(&argv, "--not");
 	argv_array_pushf(&argv, "--remotes=%s", remotes_name);
 
-	setup_revisions(argv.argc, argv.argv, &rev, NULL);
-	if (prepare_revision_walk(&rev))
-		die("revision walk setup failed");
-
-	while ((commit = get_revision(&rev)) != NULL)
-		find_unpushed_submodule_commits(commit, &submodules);
-
-	reset_revision_walk();
-	argv_array_clear(&argv);
+	collect_changed_submodules(&submodules, &argv);
 
 	for_each_string_list_item(submodule, &submodules) {
-		struct oid_array *commits = (struct oid_array *) submodule->util;
+		struct oid_array *commits = submodule->util;
+		const char *path = submodule->string;
 
-		if (submodule_needs_pushing(submodule->string, commits))
-			string_list_insert(needs_pushing, submodule->string);
+		if (submodule_needs_pushing(path, commits))
+			string_list_insert(needs_pushing, path);
 	}
 
 	free_submodules_oids(&submodules);
+	argv_array_clear(&argv);
 
 	return needs_pushing->nr;
 }
@@ -921,61 +948,6 @@ int push_unpushed_submodules(struct oid_array *commits,
 	return ret;
 }
 
-static int is_submodule_commit_present(const char *path, unsigned char sha1[20])
-{
-	int is_present = 0;
-	if (!add_submodule_odb(path) && lookup_commit_reference(sha1)) {
-		/* Even if the submodule is checked out and the commit is
-		 * present, make sure it is reachable from a ref. */
-		struct child_process cp = CHILD_PROCESS_INIT;
-		const char *argv[] = {"rev-list", "-n", "1", NULL, "--not", "--all", NULL};
-		struct strbuf buf = STRBUF_INIT;
-
-		argv[3] = sha1_to_hex(sha1);
-		cp.argv = argv;
-		prepare_submodule_repo_env(&cp.env_array);
-		cp.git_cmd = 1;
-		cp.no_stdin = 1;
-		cp.dir = path;
-		if (!capture_command(&cp, &buf, 1024) && !buf.len)
-			is_present = 1;
-
-		strbuf_release(&buf);
-	}
-	return is_present;
-}
-
-static void submodule_collect_changed_cb(struct diff_queue_struct *q,
-					 struct diff_options *options,
-					 void *data)
-{
-	int i;
-	for (i = 0; i < q->nr; i++) {
-		struct diff_filepair *p = q->queue[i];
-		if (!S_ISGITLINK(p->two->mode))
-			continue;
-
-		if (S_ISGITLINK(p->one->mode)) {
-			/* NEEDSWORK: We should honor the name configured in
-			 * the .gitmodules file of the commit we are examining
-			 * here to be able to correctly follow submodules
-			 * being moved around. */
-			struct string_list_item *path;
-			path = unsorted_string_list_lookup(&changed_submodule_paths, p->two->path);
-			if (!path && !is_submodule_commit_present(p->two->path, p->two->oid.hash))
-				string_list_append(&changed_submodule_paths, p->two->path);
-		} else {
-			/* Submodule is new or was moved here */
-			/* NEEDSWORK: When the .git directories of submodules
-			 * live inside the superprojects .git directory some
-			 * day we should fetch new submodules directly into
-			 * that location too when config or options request
-			 * that so they can be checked out from there. */
-			continue;
-		}
-	}
-}
-
 static int append_oid_to_array(const char *ref, const struct object_id *oid,
 			       int flags, void *data)
 {
@@ -996,45 +968,36 @@ void check_for_new_submodule_commits(struct object_id *oid)
 
 static void calculate_changed_submodule_paths(void)
 {
-	struct rev_info rev;
-	struct commit *commit;
 	struct argv_array argv = ARGV_ARRAY_INIT;
+	struct string_list changed_submodules = STRING_LIST_INIT_DUP;
+	const struct string_list_item *item;
 
 	/* No need to check if there are no submodules configured */
 	if (!submodule_from_path(NULL, NULL))
 		return;
 
-	init_revisions(&rev, NULL);
 	argv_array_push(&argv, "--"); /* argv[0] program name */
 	oid_array_for_each_unique(&ref_tips_after_fetch,
 				   append_oid_to_argv, &argv);
 	argv_array_push(&argv, "--not");
 	oid_array_for_each_unique(&ref_tips_before_fetch,
 				   append_oid_to_argv, &argv);
-	setup_revisions(argv.argc, argv.argv, &rev, NULL);
-	if (prepare_revision_walk(&rev))
-		die("revision walk setup failed");
 
 	/*
 	 * Collect all submodules (whether checked out or not) for which new
 	 * commits have been recorded upstream in "changed_submodule_paths".
 	 */
-	while ((commit = get_revision(&rev))) {
-		struct commit_list *parent = commit->parents;
-		while (parent) {
-			struct diff_options diff_opts;
-			diff_setup(&diff_opts);
-			DIFF_OPT_SET(&diff_opts, RECURSIVE);
-			diff_opts.output_format |= DIFF_FORMAT_CALLBACK;
-			diff_opts.format_callback = submodule_collect_changed_cb;
-			diff_setup_done(&diff_opts);
-			diff_tree_sha1(parent->item->object.oid.hash, commit->object.oid.hash, "", &diff_opts);
-			diffcore_std(&diff_opts);
-			diff_flush(&diff_opts);
-			parent = parent->next;
-		}
+	collect_changed_submodules(&changed_submodules, &argv);
+
+	for_each_string_list_item(item, &changed_submodules) {
+		struct oid_array *commits = item->util;
+		const char *path = item->string;
+
+		if (!submodule_has_commits(path, commits))
+			string_list_append(&changed_submodule_paths, path);
 	}
 
+	free_submodules_oids(&changed_submodules);
 	argv_array_clear(&argv);
 	oid_array_clear(&ref_tips_before_fetch);
 	oid_array_clear(&ref_tips_after_fetch);
-- 
2.13.0.rc0.306.g87b477812d-goog