Fix Sf2 player freezing on project unloading with shared SoundFonts (#6950)

* Require FluidSynth >= 1.1.7

* Use `fluid_sfont_t` directly without sharing

* Adjust formatting a bit

CMakeLists.txt

@@ -540,7 +540,7 @@ ENDIF()
 
 # check for Fluidsynth
 IF(WANT_SF2)
-	find_package(FluidSynth 1.1.0)
+	find_package(FluidSynth 1.1.7)
 	if(FluidSynth_FOUND)
 		SET(LMMS_HAVE_FLUIDSYNTH TRUE)
 		if(FluidSynth_VERSION_STRING VERSION_GREATER_EQUAL 2)

plugins/Sf2Player/Sf2Player.cpp

@@ -121,12 +121,6 @@ struct Sf2PluginData
 
 
 
-// Static map of current sfonts
-QMap<QString, Sf2Font*> Sf2Instrument::s_fonts;
-QMutex Sf2Instrument::s_fontsMutex;
-
-
-
 Sf2Instrument::Sf2Instrument( InstrumentTrack * _instrument_track ) :
 	Instrument( _instrument_track, &sf2player_plugin_descriptor ),
 	m_srcState( nullptr ),
@@ -375,31 +369,12 @@ void Sf2Instrument::freeFont()
 {
 	m_synthMutex.lock();
 
-	if ( m_font != nullptr )
+	if (m_font != nullptr)
 	{
-		s_fontsMutex.lock();
-		--(m_font->refCount);
-
-		// No more references
-		if( m_font->refCount <= 0 )
-		{
-			qDebug() << "Really deleting " << m_filename;
-
-			fluid_synth_sfunload( m_synth, m_fontId, true );
-			s_fonts.remove( m_filename );
-			delete m_font;
-		}
-		// Just remove our reference
-		else
-		{
-			qDebug() << "un-referencing " << m_filename;
-
-			fluid_synth_remove_sfont( m_synth, m_font->fluidFont );
-		}
-		s_fontsMutex.unlock();
-
+		fluid_synth_sfunload(m_synth, m_fontId, true);
 		m_font = nullptr;
 	}
+
 	m_synthMutex.unlock();
 }
 
@@ -413,49 +388,29 @@ void Sf2Instrument::openFile( const QString & _sf2File, bool updateTrackName )
 	char * sf2Ascii = qstrdup( qPrintable( PathUtil::toAbsolute( _sf2File ) ) );
 	QString relativePath = PathUtil::toShortestRelative( _sf2File );
 
-	// free reference to soundfont if one is selected
+	// free the soundfont if one is selected
 	freeFont();
 
 	m_synthMutex.lock();
-	s_fontsMutex.lock();
 
-	// Increment Reference
-	if( s_fonts.contains( relativePath ) )
+	bool loaded = false;
+	if (fluid_is_soundfont(sf2Ascii))
 	{
-		qDebug() << "Using existing reference to " << relativePath;
+		m_fontId = fluid_synth_sfload(m_synth, sf2Ascii, true);
 
-		m_font = s_fonts[ relativePath ];
-
-		m_font->refCount++;
-
-		m_fontId = fluid_synth_add_sfont( m_synth, m_font->fluidFont );
-	}
-
-	// Add to map, if doesn't exist.
-	else
-	{
-		bool loaded = false;
-		if( fluid_is_soundfont( sf2Ascii ) )
+		if (fluid_synth_sfcount(m_synth) > 0)
 		{
-			m_fontId = fluid_synth_sfload( m_synth, sf2Ascii, true );
-
-			if( fluid_synth_sfcount( m_synth ) > 0 )
-			{
-				// Grab this sf from the top of the stack and add to list
-				m_font = new Sf2Font( fluid_synth_get_sfont( m_synth, 0 ) );
-				s_fonts.insert( relativePath, m_font );
-				loaded = true;
-			}
-		}
-
-		if(!loaded)
-		{
-			collectErrorForUI( Sf2Instrument::tr( "A soundfont %1 could not be loaded." ).
-				arg( QFileInfo( _sf2File ).baseName() ) );
+			// Grab this sf from the top of the stack and add to list
+			m_font = fluid_synth_get_sfont(m_synth, 0);
+			loaded = true;
 		}
 	}
 
-	s_fontsMutex.unlock();
+	if (!loaded)
+	{
+		collectErrorForUI(Sf2Instrument::tr("A soundfont %1 could not be loaded.").arg(QFileInfo(_sf2File).baseName()));
+	}
+
 	m_synthMutex.unlock();
 
 	if( m_fontId >= 0 )
@@ -627,12 +582,12 @@ void Sf2Instrument::reloadSynth()
 	{
 		// Now, delete the old one and replace
 		m_synthMutex.lock();
-		fluid_synth_remove_sfont( m_synth, m_font->fluidFont );
+		fluid_synth_remove_sfont( m_synth, m_font );
 		delete_fluid_synth( m_synth );
 
 		// New synth
 		m_synth = new_fluid_synth( m_settings );
-		m_fontId = fluid_synth_add_sfont( m_synth, m_font->fluidFont );
+		m_fontId = fluid_synth_add_sfont( m_synth, m_font );
 		m_synthMutex.unlock();
 
 		// synth program change (set bank and patch)

plugins/Sf2Player/Sf2Player.h

@@ -114,16 +114,12 @@ public slots:
 	void updateTuning();
 
 private:
-	static QMutex s_fontsMutex;
-	static QMap<QString, Sf2Font*> s_fonts;
-	static int (* s_origFree)( fluid_sfont_t * );
-
 	SRC_STATE * m_srcState;
 
 	fluid_settings_t* m_settings;
 	fluid_synth_t* m_synth;
 
-	Sf2Font* m_font;
+	fluid_sfont_t* m_font;
 
 	int m_fontId;
 	QString m_filename;
@@ -177,22 +173,6 @@ signals:
 } ;
 
 
-
-// A soundfont in our font-map
-class Sf2Font
-{
-	MM_OPERATORS
-public:
-	Sf2Font( fluid_sfont_t * f ) :
-		fluidFont( f ),
-		refCount( 1 )
-	{};
-
-	fluid_sfont_t * fluidFont;
-	int refCount;
-};
-
-
 namespace gui
 {