Music: Defer probing for music driver until a music set is loaded

src/music/music_driver.hpp

@@ -12,6 +12,14 @@
 
 #include "../driver.h"
 
+#include <memory>
+#include <mutex>
+#if defined(__MINGW32__)
+#include "../3rdparty/mingw-std-threads/mingw.mutex.h"
+#endif
+
+extern std::mutex _music_driver_mutex;
+
 struct MusicSongInfo;
 
 /** Driver for all music playback. */
@@ -46,10 +54,20 @@ public:
 	 */
 	virtual bool IsInFailedState() { return false; }
 
+	static std::unique_ptr<MusicDriver> ExtractDriver()
+	{
+		Driver **dptr = DriverFactoryBase::GetActiveDriver(Driver::DT_MUSIC);
+		Driver *driver = *dptr;
+		*dptr = nullptr;
+		return std::unique_ptr<MusicDriver>(static_cast<MusicDriver*>(driver));
+	}
+
 	/**
 	 * Get the currently active instance of the music driver.
 	 */
 	static MusicDriver *GetInstance() {
+		std::unique_lock<std::mutex> lock(_music_driver_mutex);
+
 		return static_cast<MusicDriver*>(*DriverFactoryBase::GetActiveDriver(Driver::DT_MUSIC));
 	}
 };

src/music_gui.cpp

@@ -174,6 +174,7 @@ void MusicSystem::ChangePlaylist(PlaylistChoices pl)
  */
 void MusicSystem::ChangeMusicSet(const std::string &set_name)
 {
+	if (set_name != "NoMusic") InitMusicDriver(true);
 	BaseMusic::SetSet(set_name);
 	BaseMusic::ini_set = set_name;
 

src/openttd.cpp

@@ -97,6 +97,7 @@
 
 #include "3rdparty/cpp-btree/btree_set.h"
 
+#include <atomic>
 #include <mutex>
 #if defined(__MINGW32__)
 #include "3rdparty/mingw-std-threads/mingw.mutex.h"
@@ -135,6 +136,10 @@ NewGRFScanCallback *_request_newgrf_scan_callback = nullptr;
 
 SimpleChecksum64 _state_checksum;
 
+std::mutex _music_driver_mutex;
+static std::string _music_driver_params;
+static std::atomic<bool> _music_inited;
+
 /**
  * Error handling for fatal user errors.
  * @param s the string to print.
@@ -1010,7 +1015,13 @@ int openttd_main(int argc, char *argv[])
 	DriverFactoryBase::SelectDriver(sounddriver, Driver::DT_SOUND);
 
 	if (musicdriver.empty() && !_ini_musicdriver.empty()) musicdriver = _ini_musicdriver;
-	DriverFactoryBase::SelectDriver(musicdriver, Driver::DT_MUSIC);
+	_music_driver_params = std::move(musicdriver);
+	if (_music_driver_params.empty() && BaseMusic::GetUsedSet()->name == "NoMusic") {
+		DEBUG(driver, 1, "Deferring loading of music driver until a music set is loaded");
+		DriverFactoryBase::SelectDriver("null", Driver::DT_MUSIC);
+	} else {
+		InitMusicDriver(false);
+	}
 
 	GenerateWorld(GWM_EMPTY, 64, 64); // Make the viewport initialization happy
 	LoadIntroGame(false);
@@ -1041,6 +1052,22 @@ int openttd_main(int argc, char *argv[])
 	return ret;
 }
 
+void InitMusicDriver(bool init_volume)
+{
+	if (_music_inited.exchange(true)) return;
+
+	{
+		std::unique_lock<std::mutex> lock(_music_driver_mutex);
+
+		static std::unique_ptr<MusicDriver> old_driver;
+		old_driver = std::move(MusicDriver::ExtractDriver());
+
+		DriverFactoryBase::SelectDriver(_music_driver_params, Driver::DT_MUSIC);
+	}
+
+	if (init_volume) MusicDriver::GetInstance()->SetVolume(_settings_client.music.music_vol);
+}
+
 void HandleExitGameRequest()
 {
 	if (_game_mode == GM_MENU || _game_mode == GM_BOOTSTRAP) { // do not ask to quit on the main screen

src/openttd.h

@@ -91,6 +91,7 @@ void AskExitToGameMenu();
 int openttd_main(int argc, char *argv[]);
 void StateGameLoop();
 void HandleExitGameRequest();
+void InitMusicDriver(bool init_volume);
 
 void SwitchToMode(SwitchMode new_mode);