Call `ffmpeg` in batches

persistence/playlist_track_repository.go

@@ -120,17 +120,7 @@ func (r *playlistTrackRepository) Update(mediaFileIds []string) error {
 	}
 
 	// Break the track list in chunks to avoid hitting SQLITE_MAX_FUNCTION_ARG limit
-	numTracks := len(mediaFileIds)
-	const chunkSize = 50
-	var chunks [][]string
-	for i := 0; i < numTracks; i += chunkSize {
-		end := i + chunkSize
-		if end > numTracks {
-			end = numTracks
-		}
-
-		chunks = append(chunks, mediaFileIds[i:end])
-	}
+	chunks := utils.BreakUpStringSlice(mediaFileIds, 50)
 
 	// Add new tracks, chunk by chunk
 	pos := 1

scanner/tag_scanner.go

@@ -31,8 +31,18 @@ func NewTagScanner(rootFolder string, ds model.DataStore) *TagScanner {
 	}
 }
 
-type ArtistMap map[string]bool
-type AlbumMap map[string]bool
+type (
+	ArtistMap map[string]bool
+	AlbumMap  map[string]bool
+)
+
+const (
+	// batchSize used for albums/artists updates
+	batchSize = 5
+
+	// filesBatchSize used for extract file metadata
+	filesBatchSize = 100
+)
 
 // Scan algorithm overview:
 // For each changed: Get all files from DB that starts with the folder, scan each file:
@@ -162,29 +172,33 @@ func (s *TagScanner) processChangedDir(ctx context.Context, dir string, updatedA
 	numPurgedTracks := 0
 
 	if len(filesToUpdate) > 0 {
-		// Load tracks Metadata from the folder
-		newTracks, err := s.loadTracks(filesToUpdate)
-		if err != nil {
-			return err
-		}
+		// Break the file list in chunks to avoid calling ffmpeg with too many parameters
+		chunks := utils.BreakUpStringSlice(filesToUpdate, filesBatchSize)
+		for _, chunk := range chunks {
+			// Load tracks Metadata from the folder
+			newTracks, err := s.loadTracks(chunk)
+			if err != nil {
+				return err
+			}
 
-		// If track from folder is newer than the one in DB, update/insert in DB
-		log.Trace("Updating mediaFiles in DB", "dir", dir, "files", filesToUpdate, "numFiles", len(filesToUpdate))
-		for i := range newTracks {
-			n := newTracks[i]
-			err := s.ds.MediaFile(ctx).Put(&n)
-			if err != nil {
-				return err
+			// If track from folder is newer than the one in DB, update/insert in DB
+			log.Trace("Updating mediaFiles in DB", "dir", dir, "files", chunk, "numFiles", len(chunk))
+			for i := range newTracks {
+				n := newTracks[i]
+				err := s.ds.MediaFile(ctx).Put(&n)
+				if err != nil {
+					return err
+				}
+				err = s.updateAlbum(ctx, n.AlbumID, updatedAlbums)
+				if err != nil {
+					return err
+				}
+				err = s.updateArtist(ctx, n.AlbumArtistID, updatedArtists)
+				if err != nil {
+					return err
+				}
+				numUpdatedTracks++
 			}
-			err = s.updateAlbum(ctx, n.AlbumID, updatedAlbums)
-			if err != nil {
-				return err
-			}
-			err = s.updateArtist(ctx, n.AlbumArtistID, updatedArtists)
-			if err != nil {
-				return err
-			}
-			numUpdatedTracks++
 		}
 	}
 
@@ -213,7 +227,7 @@ func (s *TagScanner) processChangedDir(ctx context.Context, dir string, updatedA
 
 func (s *TagScanner) updateAlbum(ctx context.Context, albumId string, updatedAlbums AlbumMap) error {
 	updatedAlbums[albumId] = true
-	if len(updatedAlbums) > 5 {
+	if len(updatedAlbums) >= batchSize {
 		err := s.flushAlbums(ctx, updatedAlbums)
 		if err != nil {
 			return err
@@ -224,7 +238,7 @@ func (s *TagScanner) updateAlbum(ctx context.Context, albumId string, updatedAlb
 
 func (s *TagScanner) updateArtist(ctx context.Context, artistId string, updatedArtists ArtistMap) error {
 	updatedArtists[artistId] = true
-	if len(updatedArtists) > 5 {
+	if len(updatedArtists) >= batchSize {
 		err := s.flushArtists(ctx, updatedArtists)
 		if err != nil {
 			return err

utils/strings.go

@@ -38,3 +38,17 @@ func MoveString(array []string, srcIndex int, dstIndex int) []string {
 	value := array[srcIndex]
 	return InsertString(RemoveString(array, srcIndex), value, dstIndex)
 }
+
+func BreakUpStringSlice(mediaFileIds []string, chunkSize int) [][]string {
+	numTracks := len(mediaFileIds)
+	var chunks [][]string
+	for i := 0; i < numTracks; i += chunkSize {
+		end := i + chunkSize
+		if end > numTracks {
+			end = numTracks
+		}
+
+		chunks = append(chunks, mediaFileIds[i:end])
+	}
+	return chunks
+}

utils/strings_test.go

@@ -60,4 +60,25 @@ var _ = Describe("Strings", func() {
 			Expect(MoveString([]string{"1", "2", "3"}, 1, 1)).To(ConsistOf("1", "2", "3"))
 		})
 	})
+
+	Describe("BreakUpStringSlice", func() {
+		It("returns no chunks if slice is empty", func() {
+			var slice []string
+			chunks := BreakUpStringSlice(slice, 10)
+			Expect(chunks).To(HaveLen(0))
+		})
+		It("returns the slice in one chunk if len < chunkSize", func() {
+			slice := []string{"a", "b", "c"}
+			chunks := BreakUpStringSlice(slice, 10)
+			Expect(chunks).To(HaveLen(1))
+			Expect(chunks[0]).To(ConsistOf("a", "b", "c"))
+		})
+		It("breaks up the slice if len > chunkSize", func() {
+			slice := []string{"a", "b", "c", "d", "e"}
+			chunks := BreakUpStringSlice(slice, 3)
+			Expect(chunks).To(HaveLen(2))
+			Expect(chunks[0]).To(ConsistOf("a", "b", "c"))
+			Expect(chunks[1]).To(ConsistOf("d", "e"))
+		})
+	})
 })