From b8551eed7ef7ef691e274e7e7e3602a59c0b0c14 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Fri, 27 Oct 2023 00:39:03 +0200
Subject: [PATCH] Properly unload VST3 plugins

The InstrumentSelector keeps a PluginPtr reference to all
instruments. By default Ardour does not destroy the editor
at exit, So 3 instances of Instrument Selector can remain

 * TriggerClipPicker in the editor sidebar (owned by _editor)
 * TriggerClipPicker on the TriggerPage (owned by trigger_page)
 * SoundFileOmega (sfbrowser owned by Editor)

If a shared_ptr reference is retained, VST3 Module is not
unloaded at exit. This leads to issues with various plugins.
eg. Reason Rack does not terminate, Ardour hangs at exit.
---
 gtk2_ardour/ardour_ui.cc           |  3 +++
 gtk2_ardour/instrument_selector.cc | 11 +++++++++++
 gtk2_ardour/instrument_selector.h  |  3 +++
 3 files changed, 17 insertions(+)

diff --git a/gtk2_ardour/ardour_ui.cc b/gtk2_ardour/ardour_ui.cc
index 3713af741c..bac5f11826 100644
--- a/gtk2_ardour/ardour_ui.cc
+++ b/gtk2_ardour/ardour_ui.cc
@@ -146,6 +146,7 @@
 #include "gui_object.h"
 #include "gui_thread.h"
 #include "idleometer.h"
+#include "instrument_selector.h"
 #include "io_plugin_window.h"
 #include "keyboard.h"
 #include "keyeditor.h"
@@ -868,6 +869,8 @@ ARDOUR_UI::~ARDOUR_UI ()
 		recorder->cleanup ();
 	}
 
+	InstrumentSelector::DropPluginInfoPtr ();
+
 	if (getenv ("ARDOUR_RUNNING_UNDER_VALGRIND")) {
 		// don't bother at 'real' exit. the OS cleans up for us.
 		delete big_clock; big_clock = 0;
diff --git a/gtk2_ardour/instrument_selector.cc b/gtk2_ardour/instrument_selector.cc
index e5ef5fc912..3c06ba3ad9 100644
--- a/gtk2_ardour/instrument_selector.cc
+++ b/gtk2_ardour/instrument_selector.cc
@@ -29,6 +29,8 @@
 using namespace Gtk;
 using namespace ARDOUR;
 
+sigc::signal<void> InstrumentSelector::DropPluginInfoPtr;
+
 InstrumentSelector::InstrumentSelector (InstrumentListDisposition disp)
 	: _reasonable_synth_id (0)
 	, _gmsynth_id (UINT32_MAX)
@@ -37,6 +39,15 @@ InstrumentSelector::InstrumentSelector (InstrumentListDisposition disp)
 	refill ();
 
 	PluginManager::instance ().PluginListChanged.connect (_update_connection, invalidator (*this), boost::bind (&InstrumentSelector::refill, this), gui_context());
+	DropPluginInfoPtr.connect (sigc::mem_fun (*this, &InstrumentSelector::drop_plugin_ptr));
+}
+
+void
+InstrumentSelector::drop_plugin_ptr()
+{
+	unset_model ();
+	clear ();
+	_instrument_list->clear ();
 }
 
 void
diff --git a/gtk2_ardour/instrument_selector.h b/gtk2_ardour/instrument_selector.h
index d2e180c614..687b40b681 100644
--- a/gtk2_ardour/instrument_selector.h
+++ b/gtk2_ardour/instrument_selector.h
@@ -50,6 +50,8 @@ public:
 	ARDOUR::PluginInfoPtr selected_instrument () const;
 	std::string selected_instrument_name () const;
 
+	static sigc::signal<void> DropPluginInfoPtr;
+
 private:
 	struct InstrumentListColumns : public Gtk::TreeModel::ColumnRecord {
 		InstrumentListColumns() {
@@ -62,6 +64,7 @@ private:
 
 	void build_instrument_list();
 	void refill();
+	void drop_plugin_ptr();
 
 	std::string					 _longest_instrument_name;