refactoring: use interface

weed/filer2/reader_at.go

@@ -19,7 +19,7 @@ type ChunkReadAt struct {
 	readerLock   sync.Mutex
 	fileSize     int64
 
-	chunkCache *chunk_cache.TieredChunkCache
+	chunkCache chunk_cache.ChunkCache
 }
 
 // var _ = io.ReaderAt(&ChunkReadAt{})
@@ -53,7 +53,7 @@ func LookupFn(filerClient filer_pb.FilerClient) LookupFileIdFunctionType {
 	}
 }
 
-func NewChunkReaderAtFromClient(filerClient filer_pb.FilerClient, chunkViews []*ChunkView, chunkCache *chunk_cache.TieredChunkCache, fileSize int64) *ChunkReadAt {
+func NewChunkReaderAtFromClient(filerClient filer_pb.FilerClient, chunkViews []*ChunkView, chunkCache chunk_cache.ChunkCache, fileSize int64) *ChunkReadAt {
 
 	return &ChunkReadAt{
 		chunkViews:   chunkViews,

weed/util/chunk_cache/chunk_cache.go

@@ -13,6 +13,11 @@ const (
 	onDiskCacheSizeLimit1 = 4 * memCacheSizeLimit
 )
 
+type ChunkCache interface {
+	GetChunk(fileId string, minSize uint64) (data []byte)
+	SetChunk(fileId string, data []byte)
+}
+
 // a global cache for recently accessed file chunks
 type TieredChunkCache struct {
 	memCache   *ChunkCacheInMemory