refactor

weed/storage/needle/needle_read.go

@@ -61,36 +61,17 @@ func (n *Needle) ReadBytes(bytes []byte, offset int64, size Size, version Versio
 		stats.VolumeServerHandlerCounter.WithLabelValues(stats.ErrorSizeMismatch).Inc()
 		return fmt.Errorf("entry not found: offset %d found id %x size %d, expected size %d", offset, n.Id, n.Size, size)
 	}
-	switch version {
-	case Version1:
+	if version == Version1 {
 		n.Data = bytes[NeedleHeaderSize : NeedleHeaderSize+size]
-		// fallthrough to checksum logic below
-	case Version2:
+	} else {
 		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])
-		newChecksum := NewCRC(n.Data)
-		if checksum != newChecksum.Value() && checksum != uint32(newChecksum) {
-			// the crc.Value() function is to be deprecated. this double checking is for backward compatibility
-			// with seaweed version using crc.Value() instead of uint32(crc), which appears in commit 056c480eb
-			// and switch appeared in version 3.09.
-			stats.VolumeServerHandlerCounter.WithLabelValues(stats.ErrorCRC).Inc()
-			return errors.New("CRC error! Data On Disk Corrupted")
-		}
-		n.Checksum = newChecksum
+	err = n.readNeedleTail(bytes[NeedleHeaderSize+size:], version)
+	if err != nil {
+		return err
 	}
 	return nil
 }
@@ -260,14 +241,11 @@ func (n *Needle) ReadNeedleBodyBytes(needleBody []byte, version Version) (err er
 	switch version {
 	case Version1:
 		n.Data = needleBody[:n.Size]
-		n.Checksum = NewCRC(n.Data)
+		err = n.readNeedleTail(needleBody[n.Size:], version)
 	case Version2, Version3:
 		err = n.readNeedleDataVersion2(needleBody[0:n.Size])
-		n.Checksum = NewCRC(n.Data)
-
-		if version == Version3 {
-			tsOffset := n.Size + NeedleChecksumSize
-			n.AppendAtNs = util.BytesToUint64(needleBody[tsOffset : tsOffset+TimestampSize])
+		if err == nil {
+			err = n.readNeedleTail(needleBody[n.Size:], version)
 		}
 	default:
 		err = fmt.Errorf("unsupported version %d!", version)

weed/storage/needle/needle_read_page.go

@@ -2,11 +2,12 @@ package needle
 
 import (
 	"fmt"
+	"io"
+
 	"github.com/seaweedfs/seaweedfs/weed/glog"
 	"github.com/seaweedfs/seaweedfs/weed/storage/backend"
 	. "github.com/seaweedfs/seaweedfs/weed/storage/types"
 	"github.com/seaweedfs/seaweedfs/weed/util"
-	"io"
 )
 
 // ReadNeedleData uses a needle without n.Data to read the content
@@ -78,10 +79,7 @@ func (n *Needle) ReadNeedleMeta(r backend.BackendStorageFile, offset int64, size
 		index, err = n.readNeedleDataVersion2NonData(metaSlice)
 	}
 
-	n.Checksum = CRC(util.BytesToUint32(metaSlice[index : index+NeedleChecksumSize]))
-	if version == Version3 {
-		n.AppendAtNs = util.BytesToUint64(metaSlice[index+NeedleChecksumSize : index+NeedleChecksumSize+TimestampSize])
-	}
+	err = n.readNeedleTail(metaSlice[index:], version)
 	return err
 
 }

weed/storage/needle/needle_read_tail.go

@@ -0,0 +1,35 @@
+package needle
+
+import (
+	"errors"
+
+	"github.com/seaweedfs/seaweedfs/weed/stats"
+	. "github.com/seaweedfs/seaweedfs/weed/storage/types"
+	"github.com/seaweedfs/seaweedfs/weed/util"
+)
+
+func (n *Needle) readNeedleTail(needleBody []byte, version Version) error {
+
+	// for all versions, we need to read the checksum
+	if len(n.Data) > 0 {
+		expectedChecksum := CRC(util.BytesToUint32(needleBody[0:NeedleChecksumSize]))
+		dataChecksum := NewCRC(n.Data)
+		if expectedChecksum != dataChecksum {
+			// the crc.Value() function is to be deprecated. this double checking is for backward compatibility
+			// with seaweed version using crc.Value() instead of uint32(crc), which appears in commit 056c480eb
+			// and switch appeared in version 3.09.
+			stats.VolumeServerHandlerCounter.WithLabelValues(stats.ErrorCRC).Inc()
+			return errors.New("CRC error! Data On Disk Corrupted")
+		}
+		n.Checksum = dataChecksum
+	} else {
+		// when data is skipped from reading, just read the checksum
+		n.Checksum = CRC(util.BytesToUint32(needleBody[0:NeedleChecksumSize]))
+	}
+
+	if version == Version3 {
+		tsOffset := NeedleChecksumSize
+		n.AppendAtNs = util.BytesToUint64(needleBody[tsOffset : tsOffset+TimestampSize])
+	}
+	return nil
+}