add back last read chunk cache to reader and properly close the reader

weed/filer/reader_at.go

@@ -24,9 +24,12 @@ type ChunkReadAt struct {
 
 	fetchGroup      singleflight.Group
 	chunkCache      chunk_cache.ChunkCache
+	lastChunkFileId string
+	lastChunkData   []byte
 }
 
-// var _ = io.ReaderAt(&ChunkReadAt{})
+var _ = io.ReaderAt(&ChunkReadAt{})
+var _ = io.Closer(&ChunkReadAt{})
 
 type LookupFileIdFunctionType func(fileId string) (targetUrls []string, err error)
 
@@ -94,6 +97,12 @@ func NewChunkReaderAtFromClient(filerClient filer_pb.FilerClient, chunkViews []*
 	}
 }
 
+func (c *ChunkReadAt) Close() error {
+	c.lastChunkData = nil
+	c.lastChunkFileId = ""
+	return nil
+}
+
 func (c *ChunkReadAt) ReadAt(p []byte, offset int64) (n int, err error) {
 
 	c.readerLock.Lock()
@@ -162,6 +171,10 @@ func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) {
 
 func (c *ChunkReadAt) readFromWholeChunkData(chunkView *ChunkView, nextChunkViews ...*ChunkView) (chunkData []byte, err error) {
 
+	if c.lastChunkFileId == chunkView.FileId {
+		return c.lastChunkData, nil
+	}
+
 	v, doErr := c.readOneWholeChunk(chunkView)
 
 	if doErr != nil {
@@ -170,6 +183,9 @@ func (c *ChunkReadAt) readFromWholeChunkData(chunkView *ChunkView, nextChunkView
 
 	chunkData = v.([]byte)
 
+	c.lastChunkData = chunkData
+	c.lastChunkFileId = chunkView.FileId
+
 	for _, nextChunkView := range nextChunkViews {
 		if c.chunkCache != nil && nextChunkView != nil {
 			go c.readOneWholeChunk(nextChunkView)

weed/filesys/filehandle.go

@@ -202,6 +202,9 @@ func (fh *FileHandle) Release(ctx context.Context, req *fuse.ReleaseRequest) err
 		}
 
 		fh.f.wfs.ReleaseHandle(fh.f.fullpath(), fuse.HandleID(fh.handle))
+		if closer, ok := fh.f.reader.(io.Closer); ok {
+			closer.Close()
+		}
 	}
 
 	return nil