From d7f631757a0f981f4e7219ec1353b09f3cf80d52 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Wed, 31 May 2023 01:14:53 +0200
Subject: [PATCH] Tweak Source removal

* Do not emit signal with source-lock mutex held
* explicitly drop references when called directly; notably from
  EditorSources::remove_selected_sources
---
 libs/ardour/ardour/session.h |  2 +-
 libs/ardour/session.cc       | 15 ++++++++++++---
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h
index fe48b7afe1..0233514383 100644
--- a/libs/ardour/ardour/session.h
+++ b/libs/ardour/ardour/session.h
@@ -853,7 +853,7 @@ public:
 	static PBD::Signal4<void, std::string, std::string, bool, samplepos_t> Exported;
 
 	void add_source (std::shared_ptr<Source>);
-	void remove_source (std::weak_ptr<Source>);
+	void remove_source (std::weak_ptr<Source>, bool drop_references = true);
 
 	void cleanup_regions();
 	bool can_cleanup_peakfiles () const;
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index 653e3487c5..77f80fbb08 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -4613,14 +4613,14 @@ Session::add_source (std::shared_ptr<Source> source)
 			}
 		}
 
-		source->DropReferences.connect_same_thread (*this, boost::bind (&Session::remove_source, this, std::weak_ptr<Source> (source)));
+		source->DropReferences.connect_same_thread (*this, boost::bind (&Session::remove_source, this, std::weak_ptr<Source> (source), false));
 
 		SourceAdded (std::weak_ptr<Source> (source)); /* EMIT SIGNAL */
 	}
 }
 
 void
-Session::remove_source (std::weak_ptr<Source> src)
+Session::remove_source (std::weak_ptr<Source> src, bool drop_references)
 {
 	if (deletion_in_progress ()) {
 		return;
@@ -4638,12 +4638,21 @@ Session::remove_source (std::weak_ptr<Source> src)
 
 		if ((i = sources.find (source->id())) != sources.end()) {
 			sources.erase (i);
-			SourceRemoved (src); /* EMIT SIGNAL */
 		} else {
 			return;
 		}
 	}
 
+	SourceRemoved (src); /* EMIT SIGNAL */
+	if (drop_references) {
+		/* It would not matter to recurse here, the
+		 * source was already removed from the sources.
+		 * But there is no need to take the source_lock again.
+		 */
+		source->drop_references ();
+	}
+	assert (!source->used ());
+
 	if (source->empty ()) {
 		/* No need to save when empty sources are removed.
 		 * This is likely due to disk-writer initial dummies