a bit refactoring

weed/storage/needle/needle_read.go

@@ -3,12 +3,13 @@ package needle
 import (
 	"errors"
 	"fmt"
+	"io"
+
 	"github.com/seaweedfs/seaweedfs/weed/glog"
 	"github.com/seaweedfs/seaweedfs/weed/stats"
 	"github.com/seaweedfs/seaweedfs/weed/storage/backend"
 	. "github.com/seaweedfs/seaweedfs/weed/storage/types"
 	"github.com/seaweedfs/seaweedfs/weed/util"
-	"io"
 )
 
 const (
@@ -52,7 +53,6 @@ func ReadNeedleBlob(r backend.BackendStorageFile, offset int64, size Size, versi
 func (n *Needle) ReadBytes(bytes []byte, offset int64, size Size, version Version) (err error) {
 	n.ParseNeedleHeader(bytes)
 	if n.Size != size {
-		// cookie is not always passed in for this API. Use size to do preliminary checking.
 		if OffsetSize == 4 && offset < int64(MaxPossibleVolumeSize) {
 			stats.VolumeServerHandlerCounter.WithLabelValues(stats.ErrorSizeMismatchOffsetSize).Inc()
 			glog.Errorf("entry not found1: offset %d found id %x size %d, expected size %d", offset, n.Id, n.Size, size)
@@ -64,11 +64,21 @@ func (n *Needle) ReadBytes(bytes []byte, offset int64, size Size, version Versio
 	switch version {
 	case Version1:
 		n.Data = bytes[NeedleHeaderSize : NeedleHeaderSize+size]
-	case Version2, Version3:
-		err = n.readNeedleDataVersion2(bytes[NeedleHeaderSize : NeedleHeaderSize+int(n.Size)])
-	}
-	if err != nil && err != io.EOF {
-		return err
+		// fallthrough to checksum logic below
+	case Version2:
+		err := n.readNeedleDataVersion2(bytes[NeedleHeaderSize : NeedleHeaderSize+int(size)])
+		if err != nil && err != io.EOF {
+			return err
+		}
+	case Version3:
+		err := n.readNeedleDataVersion2(bytes[NeedleHeaderSize : NeedleHeaderSize+int(size)])
+		if err != nil && err != io.EOF {
+			return err
+		}
+		tsOffset := NeedleHeaderSize + size + NeedleChecksumSize
+		n.AppendAtNs = util.BytesToUint64(bytes[tsOffset : tsOffset+TimestampSize])
+	default:
+		return fmt.Errorf("unsupported version %d", version)
 	}
 	if size > 0 {
 		checksum := util.BytesToUint32(bytes[NeedleHeaderSize+size : NeedleHeaderSize+size+NeedleChecksumSize])
@@ -82,10 +92,6 @@ func (n *Needle) ReadBytes(bytes []byte, offset int64, size Size, version Versio
 		}
 		n.Checksum = newChecksum
 	}
-	if version == Version3 {
-		tsOffset := NeedleHeaderSize + size + NeedleChecksumSize
-		n.AppendAtNs = util.BytesToUint64(bytes[tsOffset : tsOffset+TimestampSize])
-	}
 	return nil
 }
 
@@ -95,7 +101,6 @@ func (n *Needle) ReadData(r backend.BackendStorageFile, offset int64, size Size,
 	if err != nil {
 		return err
 	}
-
 	err = n.ReadBytes(bytes, offset, size, version)
 	if err == ErrorSizeMismatch && OffsetSize == 4 {
 		offset = offset + int64(MaxPossibleVolumeSize)