Merge branch 'jk/still-interesting' into maint

"git rev-list --objects $old --not --all" to see if everything that
is reachable from $old is already connected to the existing refs
was very inefficient.

* jk/still-interesting:
  limit_list: avoid quadratic behavior from still_interesting

revision.c

@@ -345,14 +345,24 @@ static struct commit *handle_commit(struct rev_info *revs,
 	die("%s is unknown object", name);
 }
 
-static int everybody_uninteresting(struct commit_list *orig)
+static int everybody_uninteresting(struct commit_list *orig,
+				   struct commit **interesting_cache)
 {
 	struct commit_list *list = orig;
+
+	if (*interesting_cache) {
+		struct commit *commit = *interesting_cache;
+		if (!(commit->object.flags & UNINTERESTING))
+			return 0;
+	}
+
 	while (list) {
 		struct commit *commit = list->item;
 		list = list->next;
 		if (commit->object.flags & UNINTERESTING)
 			continue;
+		if (interesting_cache)
+			*interesting_cache = commit;
 		return 0;
 	}
 	return 1;
@@ -940,7 +950,8 @@ static void cherry_pick_list(struct commit_list *list, struct rev_info *revs)
 /* How many extra uninteresting commits we want to see.. */
 #define SLOP 5
 
-static int still_interesting(struct commit_list *src, unsigned long date, int slop)
+static int still_interesting(struct commit_list *src, unsigned long date, int slop,
+			     struct commit **interesting_cache)
 {
 	/*
 	 * No source list at all? We're definitely done..
@@ -959,7 +970,7 @@ static int still_interesting(struct commit_list *src, unsigned long date, int sl
 	 * Does the source list still have interesting commits in
 	 * it? Definitely not done..
 	 */
-	if (!everybody_uninteresting(src))
+	if (!everybody_uninteresting(src, interesting_cache))
 		return SLOP;
 
 	/* Ok, we're closing in.. */
@@ -1078,6 +1089,7 @@ static int limit_list(struct rev_info *revs)
 	struct commit_list *newlist = NULL;
 	struct commit_list **p = &newlist;
 	struct commit_list *bottom = NULL;
+	struct commit *interesting_cache = NULL;
 
 	if (revs->ancestry_path) {
 		bottom = collect_bottom_commits(list);
@@ -1094,6 +1106,9 @@ static int limit_list(struct rev_info *revs)
 		list = list->next;
 		free(entry);
 
+		if (commit == interesting_cache)
+			interesting_cache = NULL;
+
 		if (revs->max_age != -1 && (commit->date < revs->max_age))
 			obj->flags |= UNINTERESTING;
 		if (add_parents_to_list(revs, commit, &list, NULL) < 0)
@@ -1102,7 +1117,7 @@ static int limit_list(struct rev_info *revs)
 			mark_parents_uninteresting(commit);
 			if (revs->show_all)
 				p = &commit_list_insert(commit, p)->next;
-			slop = still_interesting(list, date, slop);
+			slop = still_interesting(list, date, slop, &interesting_cache);
 			if (slop)
 				continue;
 			/* If showing all, add the whole pending list to the end */