From 3c4801bc969e10692570e11fbdfec0685ac7fead Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Fri, 2 Oct 2020 15:01:01 +0200
Subject: [PATCH] VST3: common factory instantiating and release

This may address some issues with multiple references
(and incremental releases) of a plugin's factory.
---
 libs/ardour/ardour/vst3_module.h | 15 +++++++++++++--
 libs/ardour/ardour/vst3_plugin.h |  1 -
 libs/ardour/vst3_module.cc       | 24 ++++++++++++++++++++++++
 libs/ardour/vst3_plugin.cc       | 18 ++++--------------
 libs/ardour/vst3_scan.cc         | 10 +---------
 5 files changed, 42 insertions(+), 26 deletions(-)

diff --git a/libs/ardour/ardour/vst3_module.h b/libs/ardour/ardour/vst3_module.h
index b88f58d250..579f24316b 100644
--- a/libs/ardour/ardour/vst3_module.h
+++ b/libs/ardour/ardour/vst3_module.h
@@ -23,23 +23,34 @@
 
 #include "ardour/libardour_visibility.h"
 
+namespace Steinberg {
+	class IPluginFactory;
+}
+
 namespace ARDOUR {
 
 class LIBARDOUR_API VST3PluginModule
 {
 public:
 	static boost::shared_ptr<VST3PluginModule> load (std::string const& path);
-	VST3PluginModule () {}
+
+	VST3PluginModule () : _factory (0) {}
 	virtual ~VST3PluginModule () {}
 
-	virtual void* fn_ptr (const char* name) const = 0;
+	Steinberg::IPluginFactory* factory ();
 
 protected:
+	void release_factory ();
+
 	virtual bool init () = 0;
 	virtual bool exit () = 0;
+	virtual void* fn_ptr (const char* name) const = 0;
 
+private:
 	/* prevent copy construction */
 	VST3PluginModule (VST3PluginModule const&);
+
+	Steinberg::IPluginFactory* _factory;
 };
 
 } // namespace ARDOUR
diff --git a/libs/ardour/ardour/vst3_plugin.h b/libs/ardour/ardour/vst3_plugin.h
index 60edebf923..11431eb06d 100644
--- a/libs/ardour/ardour/vst3_plugin.h
+++ b/libs/ardour/ardour/vst3_plugin.h
@@ -176,7 +176,6 @@ private:
 	std::vector <Vst::IConnectionPoint*> _connections;
 
 	FUID                  _fuid;
-	IPluginFactory*       _factory;
 	Vst::IComponent*      _component;
 	Vst::IEditController* _controller;
 	IPlugView*            _view;
diff --git a/libs/ardour/vst3_module.cc b/libs/ardour/vst3_module.cc
index 584e776c39..dc3fb0fa02 100644
--- a/libs/ardour/vst3_module.cc
+++ b/libs/ardour/vst3_module.cc
@@ -31,6 +31,7 @@
 #include "pbd/error.h"
 #include "pbd/failed_constructor.h"
 
+#include "vst3/pluginterfaces/base/ipluginbase.h"
 #include "ardour/vst3_module.h"
 
 #include "pbd/i18n.h"
@@ -72,6 +73,7 @@ public:
 
 	~VST3MacModule ()
 	{
+		release_factory ();
 		if (_bundle) {
 			exit ();
 			CFRelease (_bundle);
@@ -126,6 +128,7 @@ public:
 
 	~VST3WindowsModule ()
 	{
+		release_factory ();
 		if (_handle) {
 			exit ();
 			FreeLibrary (_handle);
@@ -186,6 +189,7 @@ public:
 
 	~VST3LinuxModule ()
 	{
+		release_factory ();
 		if (_dll) {
 			exit ();
 			dlclose (_dll);
@@ -217,6 +221,26 @@ private:
 
 #endif
 
+Steinberg::IPluginFactory*
+VST3PluginModule::factory ()
+{
+	if (!_factory) {
+		GetFactoryProc fp = (GetFactoryProc)fn_ptr ("GetPluginFactory");
+		if (fp) {
+			_factory = fp ();
+		}
+	}
+	return _factory;
+}
+
+void
+VST3PluginModule::release_factory ()
+{
+	if (_factory) {
+		_factory->release ();
+	}
+}
+
 boost::shared_ptr<VST3PluginModule>
 VST3PluginModule::load (std::string const& path)
 {
diff --git a/libs/ardour/vst3_plugin.cc b/libs/ardour/vst3_plugin.cc
index 414a82419f..a1660a19f6 100644
--- a/libs/ardour/vst3_plugin.cc
+++ b/libs/ardour/vst3_plugin.cc
@@ -941,7 +941,6 @@ VST3PluginInfo::is_instrument () const
 
 VST3PI::VST3PI (boost::shared_ptr<ARDOUR::VST3PluginModule> m, std::string unique_id)
 	: _module (m)
-	, _factory (0)
 	, _component (0)
 	, _controller (0)
 	, _view (0)
@@ -954,13 +953,9 @@ VST3PI::VST3PI (boost::shared_ptr<ARDOUR::VST3PluginModule> m, std::string uniqu
 	, _n_factory_presets (0)
 {
 	using namespace std;
+	IPluginFactory* factory = m->factory ();
 
-	GetFactoryProc fp = (GetFactoryProc)m->fn_ptr ("GetPluginFactory");
-	if (!fp) {
-		throw failed_constructor ();
-	}
-
-	if (!(_factory = fp ())) {
+	if (!factory) {
 		throw failed_constructor ();
 	}
 
@@ -968,7 +963,7 @@ VST3PI::VST3PI (boost::shared_ptr<ARDOUR::VST3PluginModule> m, std::string uniqu
 		throw failed_constructor ();
 	}
 
-	if (_factory->createInstance (_fuid.toTUID (), Vst::IComponent::iid, (void**)&_component) != kResultTrue) {
+	if (factory->createInstance (_fuid.toTUID (), Vst::IComponent::iid, (void**)&_component) != kResultTrue) {
 		throw failed_constructor ();
 	}
 
@@ -980,7 +975,7 @@ VST3PI::VST3PI (boost::shared_ptr<ARDOUR::VST3PluginModule> m, std::string uniqu
 	if (!_controller) {
 		TUID controllerCID;
 		if (_component->getControllerClassId (controllerCID) == kResultTrue) {
-			if (_factory->createInstance (controllerCID, Vst::IEditController::iid, (void**)&_controller) != kResultTrue) {
+			if (factory->createInstance (controllerCID, Vst::IEditController::iid, (void**)&_controller) != kResultTrue) {
 				throw failed_constructor ();
 			}
 			if (_controller && (_controller->initialize (HostApplication::getHostContext ()) != kResultOk)) {
@@ -1137,13 +1132,8 @@ VST3PI::terminate ()
 
 	_component->release ();
 
-	if (_factory) {
-		_factory->release ();
-	}
-
 	_controller = 0;
 	_component  = 0;
-	_factory  = 0;
 }
 
 bool
diff --git a/libs/ardour/vst3_scan.cc b/libs/ardour/vst3_scan.cc
index 5cb76be6c4..4360e9abeb 100644
--- a/libs/ardour/vst3_scan.cc
+++ b/libs/ardour/vst3_scan.cc
@@ -90,14 +90,7 @@ ARDOUR::discover_vst3 (boost::shared_ptr<VST3PluginModule> m, std::vector<VST3In
 {
 	using namespace std;
 
-	GetFactoryProc fp = (GetFactoryProc)m->fn_ptr ("GetPluginFactory");
-
-	if (!fp) {
-		cerr << "Failed to find 'GetPluginFactory' function\n";
-		return false;
-	}
-
-	IPluginFactory* factory = fp ();
+	IPluginFactory* factory = m->factory ();
 
 	if (!factory) {
 		cerr << "Failed to get VST3 plug-in factory\n";
@@ -199,7 +192,6 @@ ARDOUR::discover_vst3 (boost::shared_ptr<VST3PluginModule> m, std::vector<VST3In
 		}
 	}
 
-	factory->release ();
 	return true;
 }