The mark_parents_uninteresting() function uses two loops:
an outer one to process our queue of pending parents, and an
inner one to process first-parent chains. This is a clever
optimization from 941ba8db57 (Eliminate recursion in
setting/clearing marks in commit list, 2012-01-14) to limit
the number of linked-list allocations when following
single-parent chains.
Unfortunately, this makes the result a little hard to read.
Let's replace the list with a stack. Then we don't have to
worry about doing this double-loop optimization, as we'll
just reuse the top element of the stack as we pop/push.
Signed-off-by: Jeff King <peff@xxxxxxxx>
---
The diff makes a lot more sense with "-w".
revision.c | 67 +++++++++++++++++++++++++++++++++++-------------------
1 file changed, 43 insertions(+), 24 deletions(-)
diff --git a/revision.c b/revision.c
index cee4f3a4b4..89ff9a99ce 100644
--- a/revision.c
+++ b/revision.c
@@ -92,38 +92,57 @@ void mark_tree_uninteresting(struct tree *tree)
mark_tree_contents_uninteresting(tree);
}
-void mark_parents_uninteresting(struct commit *commit)
+struct commit_stack {
+ struct commit **items;
+ size_t nr, alloc;
+};
+#define COMMIT_STACK_INIT { NULL, 0, 0 }
+
+static void commit_stack_push(struct commit_stack *stack, struct commit *commit)
{
- struct commit_list *parents = NULL, *l;
+ ALLOC_GROW(stack->items, stack->nr + 1, stack->alloc);
+ stack->items[stack->nr++] = commit;
+}
- for (l = commit->parents; l; l = l->next)
- commit_list_insert(l->item, &parents);
+static struct commit *commit_stack_pop(struct commit_stack *stack)
+{
+ return stack->nr ? stack->items[--stack->nr] : NULL;
+}
- while (parents) {
- struct commit *commit = pop_commit(&parents);
+static void commit_stack_clear(struct commit_stack *stack)
+{
+ FREE_AND_NULL(stack->items);
+ stack->nr = stack->alloc = 0;
+}
- while (commit) {
- if (commit->object.flags & UNINTERESTING)
- break;
+void mark_parents_uninteresting(struct commit *commit)
+{
+ struct commit_stack pending = COMMIT_STACK_INIT;
+ struct commit_list *l;
- commit->object.flags |= UNINTERESTING;
+ for (l = commit->parents; l; l = l->next)
+ commit_stack_push(&pending, l->item);
- /*
- * Normally we haven't parsed the parent
- * yet, so we won't have a parent of a parent
- * here. However, it may turn out that we've
- * reached this commit some other way (where it
- * wasn't uninteresting), in which case we need
- * to mark its parents recursively too..
- */
- if (!commit->parents)
- break;
+ while (pending.nr > 0) {
+ struct commit *commit = commit_stack_pop(&pending);
- for (l = commit->parents->next; l; l = l->next)
- commit_list_insert(l->item, &parents);
- commit = commit->parents->item;
- }
+ if (commit->object.flags & UNINTERESTING)
+ return;
+ commit->object.flags |= UNINTERESTING;
+
+ /*
+ * Normally we haven't parsed the parent
+ * yet, so we won't have a parent of a parent
+ * here. However, it may turn out that we've
+ * reached this commit some other way (where it
+ * wasn't uninteresting), in which case we need
+ * to mark its parents recursively too..
+ */
+ for (l = commit->parents; l; l = l->next)
+ commit_stack_push(&pending, l->item);
}
+
+ commit_stack_clear(&pending);
}
static void add_pending_object_with_path(struct rev_info *revs,
--
2.17.0.988.gec4b43b3e5
