thumbnailer: allow passing 0 as cache size

thumbnail/Thumbnailer.go

@@ -44,34 +44,42 @@ type Thumbnailer struct {
 	afmt   AspectFormat
 	sfmt   ScaleFormat
 
-	thumbCache *lru.Cache // threadsafe
+	thumbCache *lru.Cache // threadsafe, might be nil
 }
 
-func NewThumbnailer(Width, Height, MaxCacheSize int) *Thumbnailer {
+func NewThumbnailer(Width, Height int, MaxCacheSize uint) *Thumbnailer {
 	return NewThumbnailerEx(Width, Height, MaxCacheSize, OUTPUT__DEFAULT, ASPECT__DEFAULT, SCALEFMT__DEFAULT)
 }
 
-func NewThumbnailerEx(Width, Height, MaxCacheSize int, of OutputFormat, af AspectFormat, sf ScaleFormat) *Thumbnailer {
-	thumbCache, err := lru.New(MaxCacheSize)
-	if err != nil {
-		panic(err)
-	}
+func NewThumbnailerEx(Width, Height int, MaxCacheSize uint, of OutputFormat, af AspectFormat, sf ScaleFormat) *Thumbnailer {
 
-	return &Thumbnailer{
+	ret := &Thumbnailer{
 		width:      Width,
 		height:     Height,
 		ofmt:       of,
 		afmt:       af,
 		sfmt:       sf,
-		thumbCache: thumbCache,
+		thumbCache: nil,
 	}
+
+	if MaxCacheSize > 0 {
+		thumbCache, err := lru.New(int(MaxCacheSize))
+		if err != nil {
+			panic(err)
+		}
+		ret.thumbCache = thumbCache
+	}
+
+	return ret
 }
 
 func (this *Thumbnailer) RenderFile(absPath string) ([]byte, error) {
 
-	thumb, ok := this.thumbCache.Get(absPath)
-	if ok {
-		return thumb.([]byte), nil
+	if this.thumbCache != nil {
+		thumb, ok := this.thumbCache.Get(absPath)
+		if ok {
+			return thumb.([]byte), nil
+		}
 	}
 
 	// Add to cache
@@ -80,8 +88,11 @@ func (this *Thumbnailer) RenderFile(absPath string) ([]byte, error) {
 		return nil, err
 	}
 
-	this.thumbCache.Add(absPath, thumb)
-	return thumb.([]byte), nil
+	if this.thumbCache != nil {
+		this.thumbCache.Add(absPath, thumb)
+	}
+
+	return thumb, nil
 }
 
 func FiletypeSupported(ext string) bool {