Device change watchdog timer no longer freezes main thread while CddaSongLoader is active.

src/devices/cddadevice.cpp

@@ -77,6 +77,10 @@ void CddaDevice::SongsLoaded(const SongList& songs) {
 }
 
 void CddaDevice::CheckDiscChanged() {
+  // do nothing if loader is currently reading;
+  // we'd just block until it's finished
+  if (cdda_song_loader_.IsActive()) return;
+
   Q_ASSERT(cdio_);
   if (cdio_get_media_changed(cdio_) == 1) {
     emit DiscChanged();

src/devices/cddasongloader.cpp

@@ -50,9 +50,11 @@ QUrl CddaSongLoader::GetUrlFromTrack(int track_number) const {
   return CddaDevice::TrackStrToUrl(track);
 }
 
+bool CddaSongLoader::IsActive() const { return loading_future_.isRunning(); }
+
 void CddaSongLoader::LoadSongs() {
   // only dispatch a new thread for loading tracks if not already running.
-  if (!loading_future_.isRunning()) {
+  if (!IsActive()) {
     loading_future_ =
         QtConcurrent::run(this, &CddaSongLoader::LoadSongsFromCdda);
   }

src/devices/cddasongloader.h

@@ -45,6 +45,7 @@ class CddaSongLoader : public QObject {
   // Signals declared below will be emitted anytime new information will be
   // available.
   void LoadSongs();
+  bool IsActive() const;
 
  signals:
   void SongsLoaded(const SongList& songs);

src/ripper/ripcddialog.h

@@ -47,8 +47,8 @@ class RipCDDialog : public QDialog {
   ~RipCDDialog();
 
  protected:
-  void closeEvent(QCloseEvent* event);
-  void showEvent(QShowEvent* event);
+  void closeEvent(QCloseEvent* event) override;
+  void showEvent(QShowEvent* event) override;
 
  private slots:
   void ClickedRipButton();