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>

diff --git a/commit.c b/commit.c
index 44bc96d44d391209d3a60e9e8c1b98ed209e6b4a..c7aefbfd2868deddb1dc80a5a110f785b1289b7e 100644 (file)
--- 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;

diff --git a/revision.c b/revision.c
index 8764dde381111cfc9c8ea7eb3856223de9786ec9..7cc72fc02dede723f4a8d994cc7b813b08232a39 100644 (file)
--- a/revision.c
+++ b/revision.c
@@ -139,11 +139,32 @@ void mark_tree_uninteresting(struct tree *tree)
 
 void mark_parents_uninteresting(struct commit *commit)
 {
-       struct commit_list *parents = commit->parents;
+       struct commit_list *parents = NULL, *l;
+
+       for (l = commit->parents; l; l = l->next)
+               commit_list_insert(l->item, &parents);
 
        while (parents) {
                struct commit *commit = parents->item;
-               if (!(commit->object.flags & UNINTERESTING)) {
+               l = parents;
+               parents = parents->next;
+               free(l);
+
+               while (commit) {
+                       /*
+                        * A missing commit is ok iff its parent is marked
+                        * uninteresting.
+                        *
+                        * We just mark such a thing parsed, so that when
+                        * it is popped next time around, we won't be trying
+                        * to parse it and get an error.
+                        */
+                       if (!has_sha1_file(commit->object.sha1))
+                               commit->object.parsed = 1;
+
+                       if (commit->object.flags & UNINTERESTING)
+                               break;
+
                        commit->object.flags |= UNINTERESTING;
 
                        /*
@@ -154,21 +175,13 @@ void mark_parents_uninteresting(struct commit *commit)
                         * wasn't uninteresting), in which case we need
                         * to mark its parents recursively too..
                         */
-                       if (commit->parents)
-                               mark_parents_uninteresting(commit);
-               }
+                       if (!commit->parents)
+                               break;
 
-               /*
-                * A missing commit is ok iff its parent is marked
-                * uninteresting.
-                *
-                * We just mark such a thing parsed, so that when
-                * it is popped next time around, we won't be trying
-                * to parse it and get an error.
-                */
-               if (!has_sha1_file(commit->object.sha1))
-                       commit->object.parsed = 1;
-               parents = parents->next;
+                       for (l = commit->parents->next; l; l = l->next)
+                               commit_list_insert(l->item, &parents);
+                       commit = commit->parents->item;
+               }
        }
 }