From b2be7cb6bd797f40d998a80d61cc88a75632b193 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Tue, 28 Jun 2016 16:05:35 -0400
Subject: remove debug output and add a few suggestive comments

---
 libs/ardour/playlist.cc | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

(limited to 'libs/ardour/playlist.cc')

diff --git a/libs/ardour/playlist.cc b/libs/ardour/playlist.cc
index 7267ec8cdf..58405e4755 100644
--- a/libs/ardour/playlist.cc
+++ b/libs/ardour/playlist.cc
@@ -2675,7 +2675,13 @@ Playlist::uses_source (boost::shared_ptr<const Source> src, bool shallow) const
 	RegionReadLock rlock (const_cast<Playlist*> (this));
 
 	for (set<boost::shared_ptr<Region> >::const_iterator r = all_regions.begin(); r != all_regions.end(); ++r) {
-		if ((*r)->uses_source (src, true)) {
+		/* Note: passing the second argument as false can cause at best
+		   incredibly deep and time-consuming recursion, and at worst
+		   cycles if the user has managed to create cycles of reference
+		   between compound regions. We generally only this during
+		   cleanup, and @param shallow is passed as true.
+		*/
+		if ((*r)->uses_source (src, shallow)) {
 			return true;
 		}
 	}
-- 
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