Eliminate recursion in setting/clearing marks in commit list

Recursion in a DAG is generally a bad idea because it could be very
deep. Be defensive and avoid recursion in mark_parents_uninteresting()
and clear_commit_marks().

mark_parents_uninteresting() learns a trick from clear_commit_marks()
to avoid malloc() in (dominant) single-parent case.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/commit.c b/commit.c
index 44bc96d44..c7aefbfd2 100644
--- a/commit.c
+++ b/commit.c
@@ -421,7 +421,8 @@ struct commit *pop_most_recent_commit(struct commit_list **list,
 	return ret;
 }
 
-void clear_commit_marks(struct commit *commit, unsigned int mark)
+static void clear_commit_marks_1(struct commit_list **plist,
+				 struct commit *commit, unsigned int mark)
 {
 	while (commit) {
 		struct commit_list *parents;
@@ -436,12 +437,20 @@ void clear_commit_marks(struct commit *commit, unsigned int mark)
 			return;
 
 		while ((parents = parents->next))
-			clear_commit_marks(parents->item, mark);
+			commit_list_insert(parents->item, plist);
 
 		commit = commit->parents->item;
 	}
 }
 
+void clear_commit_marks(struct commit *commit, unsigned int mark)
+{
+	struct commit_list *list = NULL;
+	commit_list_insert(commit, &list);
+	while (list)
+		clear_commit_marks_1(&list, pop_commit(&list), mark);
+}
+
 void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 {
 	struct object *object;