Add --watch cmdline option to watch for changes to audio.conf and auto-apply them

Author: timschneeb

src/MainWindow.cpp

@@ -143,10 +143,11 @@ MainWindow::MainWindow(QString  exepath,
         Log::information("If you want to use this application with PulseAudio, you need to recompile this app with proper support enabled.");
         Log::information("Refer to the README for more detailed information.");
         Log::information("");
-        Log::debug("Blacklisted apps: " + AppConfig::instance().get<QString>(AppConfig::AudioAppBlocklist) /* explicitly use as QString here */);
+        Log::debug("MainWindow::ctor: Blacklisted apps: " + AppConfig::instance().get<QString>(AppConfig::AudioAppBlocklist) /* explicitly use as QString here */);
         audioService = new PipewireAudioService();
 #endif
         connect(&DspConfig::instance(), &DspConfig::updated, audioService, &IAudioService::update);
+        connect(&DspConfig::instance(), &DspConfig::updatedExternally, audioService, &IAudioService::update);
     }
 
 	// Prepare base UI

src/MainWindow.h

@@ -55,7 +55,7 @@ class MainWindow :
 public:
 	explicit MainWindow(QString  exepath,
 	                    bool     statupInTray,
-	                    bool     allowMultipleInst,
+                        bool     allowMultipleInst,
 	                    QWidget *parent = nullptr);
 	~MainWindow();
 

src/config/DspConfig.h

@@ -23,6 +23,7 @@
 
 #include <QObject>
 #include <QMetaEnum>
+#include <QFileSystemWatcher>
 
 using namespace std;
 
@@ -94,18 +95,30 @@ class DspConfig :
     };
     Q_ENUM(Type)
 
-	static DspConfig &instance()
+    static DspConfig &instance(bool watcherEnabled = false)
 	{
-		static DspConfig _instance;
+        static DspConfig _instance(watcherEnabled);
 		return _instance;
 	}
 
 	DspConfig(DspConfig const &)       = delete;
 	void operator= (DspConfig const &) = delete;
 
-	DspConfig()
+    DspConfig(bool watcherEnabled = false)
 	{
 		_conf = new ConfigContainer();
+
+        if(watcherEnabled)
+        {
+            Log::debug("DspConfig::ctor: File system watcher enabled");
+
+            _watcher = new QFileSystemWatcher(this);
+            if(!_watcher->addPath(AppConfig::instance().getDspConfPath()))
+            {
+                Log::warning(QString("DspConfig::ctor: Failed to register path %0 with QFileSystemWatcher").arg(AppConfig::instance().getDspConfPath()));
+            }
+            connect(_watcher, &QFileSystemWatcher::fileChanged, this, &DspConfig::fileChanged);
+        }
 	}
 
     void set(const Key &key,
@@ -222,6 +235,8 @@ class DspConfig :
 		_conf->setConfigMap(map);
 		emit configBuffered();
         emit updated(this);
+
+        save();
 	}
 
 	void loadDefault()
@@ -237,15 +252,30 @@ class DspConfig :
 			_conf->setConfigMap(map);
 			emit configBuffered();
             emit updated(this);
+
+            save();
 		}
 	}
 
 signals:
 	void configBuffered();
     void updated(DspConfig* self);
+    void updatedExternally(DspConfig* self);
+
+private slots:
+    void fileChanged(const QString &path)
+    {
+        if(_watcher->files().contains(path))
+        {
+            Log::debug("DspConfig::fileChanged: Config changed");
+            load();
+            emit updatedExternally(this);
+        }
+    }
 
 private:
 	ConfigContainer *_conf;
+    QFileSystemWatcher *_watcher;
 };
 
 #endif // DSPCONFIGWRAPPER_H

src/main.cpp

@@ -1,4 +1,5 @@
 #include "MainWindow.h"
+#include "config/DspConfig.h"
 
 #include "utils/FindBinary.h"
 
@@ -65,8 +66,10 @@ int main(int   argc,
 	parser.setApplicationDescription("JamesDSP for Linux");
 	parser.addHelpOption();
 
-	QCommandLineOption tray(QStringList() << "t" << "tray", "Start minimized in systray (forced)");
-	parser.addOption(tray);
+    QCommandLineOption tray(QStringList() << "t" << "tray", "Start minimized in systray (forced)");
+    parser.addOption(tray);
+    QCommandLineOption watch(QStringList() << "w" << "watch", "Watch audio.conf and apply changes made by external apps automatically");
+    parser.addOption(watch);
     QCommandLineOption minst(QStringList() << "m" << "allow-multiple-instances", "Allow multiple instances of this app");
     parser.addOption(minst);
     QCommandLineOption spinlck(QStringList() << "d" << "spinlock-on-crash", "Wait for debugger in case of crash");
@@ -81,8 +84,11 @@ int main(int   argc,
         setlocale(LC_NUMERIC, "C");
     }
 
+    // Prepare DspConfig based on cmdline argument
+    DspConfig::instance(parser.isSet(watch));
+
 	QApplication::setQuitOnLastWindowClosed(false);
-	MainWindow w(QString::fromLocal8Bit(exepath), parser.isSet(tray), parser.isSet(minst));
+    MainWindow w(QString::fromLocal8Bit(exepath), parser.isSet(tray), parser.isSet(minst));
 	w.setFixedSize(w.geometry().width(), w.geometry().height());
 	w.setGeometry(
 		QStyle::alignedRect(