update

utils/cache/spread_fs.go

@@ -0,0 +1,110 @@
+package cache
+
+import (
+	"crypto/sha1"
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/djherbis/atime"
+	"github.com/djherbis/fscache"
+	"github.com/djherbis/stream"
+	"github.com/navidrome/navidrome/log"
+)
+
+type spreadFS struct {
+	root string
+	mode os.FileMode
+	init func() error
+}
+
+// NewSpreadFS returns a FileSystem rooted at directory dir. This FS hashes the key and
+// distributes all files in a layout like XX/XX/XXXXXXXXXX. Ex:
+//
+//		Key is abc123.300x300.jpg
+//	    Hash would be: c574aeb3caafcf93ee337f0cf34e31a428ba3f13
+//	    File in cache would be: c5 / 74 / c574aeb3caafcf93ee337f0cf34e31a428ba3f13
+//
+// The idea is to avoid having too many files in one dir, which could potentially cause performance issues
+// and may hit limitations depending on the OS.
+// See discussion here: https://github.com/djherbis/fscache/issues/8#issuecomment-614319323
+//
+// dir is created with specified mode if it doesn't exist.
+func NewSpreadFS(dir string, mode os.FileMode) (*spreadFS, error) {
+	f := &spreadFS{root: dir, mode: mode, init: func() error {
+		return os.MkdirAll(dir, mode)
+	}}
+	return f, f.init()
+}
+
+func (sfs *spreadFS) Reload(f func(key string, name string)) error {
+	count := 0
+	err := filepath.WalkDir(sfs.root, func(absoluteFilePath string, de fs.DirEntry, err error) error {
+		if err != nil {
+			log.Error("Error loading cache", "dir", sfs.root, err)
+		}
+		path, err := filepath.Rel(sfs.root, absoluteFilePath)
+		if err != nil {
+			return nil //nolint:nilerr
+		}
+
+		// Skip if name is not in the format XX/XX/XXXXXXXXXXXX
+		parts := strings.Split(path, string(os.PathSeparator))
+		if len(parts) != 3 || len(parts[0]) != 2 || len(parts[1]) != 2 || len(parts[2]) != 40 {
+			return nil
+		}
+
+		f(absoluteFilePath, absoluteFilePath)
+		count++
+		return nil
+	})
+	if err == nil {
+		log.Debug("Loaded cache", "dir", sfs.root, "numItems", count)
+	}
+	return err
+}
+
+func (sfs *spreadFS) Create(name string) (stream.File, error) {
+	path := filepath.Dir(name)
+	err := os.MkdirAll(path, sfs.mode)
+	if err != nil {
+		return nil, err
+	}
+	return os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)
+}
+
+func (sfs *spreadFS) Open(name string) (stream.File, error) {
+	return os.Open(name)
+}
+
+func (sfs *spreadFS) Remove(name string) error {
+	return os.Remove(name)
+}
+
+func (sfs *spreadFS) Stat(name string) (fscache.FileInfo, error) {
+	stat, err := os.Stat(name)
+	if err != nil {
+		return fscache.FileInfo{}, err
+	}
+	return fscache.FileInfo{FileInfo: stat, Atime: atime.Get(stat)}, nil
+}
+
+func (sfs *spreadFS) RemoveAll() error {
+	if err := os.RemoveAll(sfs.root); err != nil {
+		return err
+	}
+	return sfs.init()
+}
+
+func (sfs *spreadFS) KeyMapper(key string) string {
+	// When running the Haunter, fscache can call this KeyMapper with the cached filepath instead of the key.
+	// That's because we don't inform the original cache keys when reloading in the Reload function above.
+	// If that's the case, just return the file path, as it is the actual mapped key.
+	if strings.HasPrefix(key, sfs.root) {
+		return key
+	}
+	hash := fmt.Sprintf("%x", sha1.Sum([]byte(key)))
+	return filepath.Join(sfs.root, hash[0:2], hash[2:4], hash)
+}