pub fn start_metadata_job(
drive_root: PathBuf,
db: Arc<Mutex<Database>>,
cancel: Arc<AtomicBool>,
) -> (Receiver<MetadataProgress>, JoinHandle<()>)pub fn start_metadata_job(
drive_root: PathBuf,
db: Arc<Mutex<Database>>,
cancel: Arc<AtomicBool>,
) -> (Receiver<MetadataProgress>, JoinHandle<()>)