refactor

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
+}