add GetExtendTTL

backend/imagecache.go

@@ -95,6 +95,20 @@ func (i *ImageCache) GetResetTTL(key string, resetTTL bool) (image.Image, error)
 	return nil, ErrNotFound
 }
 
+// Gets the image if it exists and extends TTL to time.Now + ttl iff the image would expire before then
+func (i *ImageCache) GetExtendTTL(key string, ttl time.Duration) (image.Image, error) {
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+	if v, ok := i.cache[key]; ok {
+		v.lastAccessed = time.Now().Unix()
+		if v.expiresAt < time.Now().Add(ttl).Unix() {
+			v.expiresAt = time.Now().Add(ttl).Unix()
+		}
+		return v.val, nil
+	}
+	return nil, ErrNotFound
+}
+
 func (i *ImageCache) GetWithNewTTL(key string, newTtl time.Duration) (image.Image, error) {
 	i.mu.RLock()
 	defer i.mu.RUnlock()

backend/imagemanager.go

@@ -42,7 +42,8 @@ func NewImageManager(ctx context.Context, s *ServerManager, baseCacheDir string)
 }
 
 func (i *ImageManager) GetAlbumThumbnailFromCache(albumID string) (image.Image, bool) {
-	if img, err := i.thumbnailCache.GetResetTTL(albumID, true); err == nil && img != nil {
+	img, err := i.thumbnailCache.GetExtendTTL(albumID, i.thumbnailCache.DefaultTTL)
+	if err == nil && img != nil {
 		return img, true
 	}
 	return nil, false