Trigger a UI refresh when the scanner finds changes.

Closes #1025

scanner/scanner.go

@@ -35,7 +35,8 @@ var (
 )
 
 type FolderScanner interface {
-	Scan(ctx context.Context, lastModifiedSince time.Time, progress chan uint32) error
+	// Scan process finds any changes after `lastModifiedSince` and returns the number of changes found
+	Scan(ctx context.Context, lastModifiedSince time.Time, progress chan uint32) (int64, error)
 }
 
 var isScanning utils.AtomicBool
@@ -89,11 +90,17 @@ func (s *scanner) rescan(ctx context.Context, mediaFolder string, fullRescan boo
 	progress, cancel := s.startProgressTracker(mediaFolder)
 	defer cancel()
 
-	err := folderScanner.Scan(ctx, lastModifiedSince, progress)
+	changeCount, err := folderScanner.Scan(ctx, lastModifiedSince, progress)
 	if err != nil {
 		log.Error("Error importing MediaFolder", "folder", mediaFolder, err)
 	}
 
+	if changeCount > 0 {
+		log.Debug(ctx, "Detected changes in the music folder. Sending refresh event",
+			"folder", mediaFolder, "changeCount", changeCount)
+		s.broker.SendMessage(&events.RefreshResource{})
+	}
+
 	s.updateLastModifiedSince(mediaFolder, start)
 	return err
 }

scanner/tag_scanner.go

@@ -36,15 +36,16 @@ func NewTagScanner(rootFolder string, ds model.DataStore, cacheWarmer core.Cache
 	}
 }
 
-type (
-	counters struct {
-		added     int64
-		updated   int64
-		deleted   int64
-		playlists int64
-	}
-	dirMap map[string]dirStats
-)
+type dirMap map[string]dirStats
+
+type counters struct {
+	added     int64
+	updated   int64
+	deleted   int64
+	playlists int64
+}
+
+func (cnt *counters) total() int64 { return cnt.added + cnt.updated + cnt.deleted }
 
 const (
 	// filesBatchSize used for batching file metadata extraction
@@ -67,13 +68,13 @@ const (
 //      If the playlist is not in the DB, import it, setting sync = true
 //      If the playlist is in the DB and sync == true, import it, or else skip it
 // Delete all empty albums, delete all empty artists, clean-up playlists
-func (s *TagScanner) Scan(ctx context.Context, lastModifiedSince time.Time, progress chan uint32) error {
+func (s *TagScanner) Scan(ctx context.Context, lastModifiedSince time.Time, progress chan uint32) (int64, error) {
 	ctx = s.withAdminUser(ctx)
 	start := time.Now()
 
 	allDBDirs, err := s.getDBDirTree(ctx)
 	if err != nil {
-		return err
+		return 0, err
 	}
 
 	allFSDirs := dirMap{}
@@ -101,19 +102,19 @@ func (s *TagScanner) Scan(ctx context.Context, lastModifiedSince time.Time, prog
 
 	if err := <-walkerError; err != nil {
 		log.Error("Scan was interrupted by error. See errors above", err)
-		return err
+		return 0, err
 	}
 
 	// If the media folder is empty, abort to avoid deleting all data
 	if len(allFSDirs) <= 1 {
 		log.Error(ctx, "Media Folder is empty. Aborting scan.", "folder", s.rootFolder)
-		return nil
+		return 0, nil
 	}
 
 	deletedDirs := s.getDeletedDirs(ctx, allFSDirs, allDBDirs)
 	if len(deletedDirs)+len(changedDirs) == 0 {
 		log.Debug(ctx, "No changes found in Music Folder", "folder", s.rootFolder, "elapsed", time.Since(start))
-		return nil
+		return 0, nil
 	}
 
 	for _, dir := range deletedDirs {
@@ -146,7 +147,7 @@ func (s *TagScanner) Scan(ctx context.Context, lastModifiedSince time.Time, prog
 	log.Info("Finished processing Music Folder", "folder", s.rootFolder, "elapsed", time.Since(start),
 		"added", s.cnt.added, "updated", s.cnt.updated, "deleted", s.cnt.deleted, "playlistsImported", s.cnt.playlists)
 
-	return err
+	return s.cnt.total(), err
 }
 
 func (s *TagScanner) getRootFolderWalker(ctx context.Context) (walkResults, chan error) {