(libs) call ARDOUR::init_post_engine() from within libardour rather than requiring "users" of the library to arrange for it

libs/ardour/ardour/ardour.h

@@ -62,7 +62,7 @@ namespace ARDOUR {
 	 * @return true if Ardour library was successfully initialized
 	 */
 	LIBARDOUR_API bool init (bool with_vst, bool try_optimization, const char* localedir);
-	LIBARDOUR_API void init_post_engine ();
+	LIBARDOUR_API void init_post_engine (uint32_t);
 	LIBARDOUR_API void cleanup ();
 	LIBARDOUR_API bool no_auto_connect ();
 	LIBARDOUR_API void make_property_quarks ();

libs/ardour/ardour/audioengine.h

@@ -196,7 +196,7 @@ class LIBARDOUR_API AudioEngine : public PortManager, public SessionHandlePtr
 	   started and stopped
 	*/
 
-	PBD::Signal0<void> Running;
+	PBD::Signal1<void,uint32_t> Running;
 	PBD::Signal0<void> Stopped;
 
 	/* these two are emitted when a device reset is initiated/finished
@@ -306,6 +306,7 @@ class LIBARDOUR_API AudioEngine : public PortManager, public SessionHandlePtr
 	Glib::Threads::Cond        _hw_devicelist_update_condition;
 	Glib::Threads::Mutex       _devicelist_update_lock;
 	gint                       _stop_hw_devicelist_processing;
+	uint32_t                   _start_cnt;
 
 	void start_hw_event_processing();
 	void stop_hw_event_processing();

libs/ardour/audioengine.cc

@@ -98,6 +98,7 @@ AudioEngine::AudioEngine ()
 	, _hw_devicelist_update_thread(0)
 	, _hw_devicelist_update_count(0)
 	, _stop_hw_devicelist_processing(0)
+	, _start_cnt (0)
 #ifdef SILENCE_AFTER_SECONDS
 	, _silence_countdown (0)
 	, _silence_hit_cnt (0)
@@ -929,9 +930,11 @@ AudioEngine::start (bool for_latency)
 	PortManager::fill_midi_port_info ();
 
 	if (!for_latency) {
-		Running(); /* EMIT SIGNAL */
+		Running (_start_cnt); /* EMIT SIGNAL */
 	}
 
+	_start_cnt++;
+
 	return 0;
 }
 

libs/ardour/globals.cc

@@ -161,6 +161,8 @@ extern void setup_enum_writer ();
 */
 PBD::PropertyChange ARDOUR::bounds_change;
 
+static PBD::ScopedConnection engine_startup_connection;
+
 void
 setup_hardware_optimization (bool try_optimization)
 {
@@ -559,6 +561,9 @@ ARDOUR::init (bool use_windows_vst, bool try_optimization, const char* localedir
 
 	ARDOUR::AudioEngine::create ();
 
+	/* This will run only once in whatever thread calls AudioEngine::start() */
+	ARDOUR::AudioEngine::instance()->Running.connect_same_thread (engine_startup_connection, ARDOUR::init_post_engine);
+
 	/* it is unfortunate that we need to include reserved names here that
 	   refer to control surfaces. But there's no way to ensure a complete
 	   lack of collisions without doing this, since the control surface
@@ -594,7 +599,7 @@ ARDOUR::init (bool use_windows_vst, bool try_optimization, const char* localedir
 }
 
 void
-ARDOUR::init_post_engine ()
+ARDOUR::init_post_engine (uint32_t /* ignored */)
 {
 	XMLNode* node;
 
@@ -617,6 +622,12 @@ ARDOUR::init_post_engine ()
 	/* find plugins */
 
 	ARDOUR::PluginManager::instance().refresh (!Config->get_discover_vst_on_start());
+
+	/* Don't do this again - we are only meant to execute on the first
+	 * engine start, not any subsequence starts
+	 */
+
+	engine_startup_connection.disconnect ();
 }
 
 void
@@ -626,6 +637,8 @@ void
 		return;
 	}
 
+	engine_startup_connection.disconnect ();
+
 	delete &ControlProtocolManager::instance();
 	ARDOUR::AudioEngine::destroy ();
 

libs/ardour/test/audio_engine_test.cc

@@ -51,8 +51,6 @@ AudioEngineTest::test_start ()
 
 	CPPUNIT_ASSERT (backend);
 
-	init_post_engine ();
-
 	CPPUNIT_ASSERT (engine->start () == 0);
 
 	Glib::usleep(2000);

libs/ardour/test/test_util.cc

@@ -105,8 +105,6 @@ create_and_start_dummy_backend ()
 	CPPUNIT_ASSERT (engine);
 	CPPUNIT_ASSERT (engine->set_backend ("None (Dummy)", "Unit-Test", ""));
 
-	init_post_engine ();
-
 	CPPUNIT_ASSERT (engine->start () == 0);
 }