Breakable training, added cache

src/scanner/MediaScanner.cpp

@@ -225,6 +225,9 @@ MediaScanner::stop(void)
 {
 	_running = false;
 
+	for (auto& addon : _addons)
+		addon->requestStop();
+
 	_scheduleTimer.cancel();
 
 	_ioService.stop();

src/scanner/MediaScannerAddon.hpp

@@ -28,6 +28,7 @@ class MediaScannerAddon
 	public:
 
 		virtual void refreshSettings() = 0;
+		virtual void requestStop() = 0;
 
 		virtual void trackAdded(Database::IdType trackId) = 0;
 		virtual void trackToRemove(Database::IdType trackId) = 0;