refactor for reading super block

weed-fs/src/cmd/weed/fix.go

@@ -1,10 +1,10 @@
 package main
 
 import (
-  "pkg/storage"
 	"log"
 	"os"
 	"path"
+	"pkg/storage"
 	"strconv"
 )
 
@@ -44,10 +44,15 @@ func runFix(cmd *Command, args []string) bool {
 	}
 	defer indexFile.Close()
 
-  //skip the volume super block
-  dataFile.Seek(storage.SuperBlockSize, 0)
+	dataFile.Seek(0, 0)
+	header := make([]byte, storage.SuperBlockSize)
+	if _, e := dataFile.Read(header); e != nil {
+		log.Fatalf("cannot read superblock: %s", e)
+	}
+
+	ver, _, _ := storage.ParseSuperBlock(header)
 
-  n, rest := storage.ReadNeedle(dataFile)
+	n, rest := storage.ReadNeedle(dataFile, ver)
 	dataFile.Seek(int64(rest), 1)
 	nm := storage.NewNeedleMap(indexFile)
 	offset := uint32(storage.SuperBlockSize)
@@ -58,7 +63,7 @@ func runFix(cmd *Command, args []string) bool {
 			debug("saved", count, "with error", pe)
 		}
 		offset += rest + 16
-    n, rest = storage.ReadNeedle(dataFile)
+		n, rest = storage.ReadNeedle(dataFile, ver)
 		dataFile.Seek(int64(rest), 1)
 	}
 	return true

weed-fs/src/pkg/storage/needle_read_write.go

@@ -15,14 +15,14 @@ func (n *Needle) Append(w io.Writer) uint32 {
 	util.Uint32toBytes(header[12:16], n.Size)
 	w.Write(header)
 	w.Write(n.Data)
-	rest := 8 - ((n.Size + 16 + 4) % 8)
+	rest := 8 - ((16 + n.Size + 4) % 8)
 	util.Uint32toBytes(header[0:4], n.Checksum.Value())
-	w.Write(header[0 : rest+4])
+	w.Write(header[0 : 4+rest])
 	return n.Size
 }
 func (n *Needle) Read(r io.Reader, size uint32, version Version) (int, error) {
 	if version == Version1 {
-		bytes := make([]byte, size+16+4)
+		bytes := make([]byte, 16+size+4)
 		ret, e := r.Read(bytes)
 		n.Cookie = util.BytesToUint32(bytes[0:4])
 		n.Id = util.BytesToUint64(bytes[4:12])
@@ -37,8 +37,9 @@ func (n *Needle) Read(r io.Reader, size uint32, version Version) (int, error) {
 	}
 	return 0, errors.New("Unsupported Version!")
 }
-func ReadNeedle(r *os.File) (*Needle, uint32) {
-	n := new(Needle)
+func ReadNeedle(r *os.File, version Version) (n *Needle, bytesTillNextFile uint32) {
+	n = new(Needle)
+	if version == Version1 {
 		bytes := make([]byte, 16)
 		count, e := r.Read(bytes)
 		if count <= 0 || e != nil {
@@ -48,5 +49,8 @@ func ReadNeedle(r *os.File) (*Needle, uint32) {
 		n.Id = util.BytesToUint64(bytes[4:12])
 		n.Size = util.BytesToUint32(bytes[12:16])
 		rest := 8 - ((n.Size + 16 + 4) % 8)
-	return n, n.Size + 4 + rest
+		bytesTillNextFile = n.Size + 4 + rest
+	} else if version == Version2 {
+	}
+	return
 }

weed-fs/src/pkg/storage/volume.go

@@ -18,8 +18,8 @@ type Volume struct {
 	dataFile *os.File
 	nm       *NeedleMap
 
-	replicaType ReplicationType
 	version     Version
+	replicaType ReplicationType
 
 	accessLock sync.Mutex
 }
@@ -85,12 +85,17 @@ func (v *Volume) readSuperBlock() error {
 	if _, e := v.dataFile.Read(header); e != nil {
 		return fmt.Errorf("cannot read superblock: %s", e)
 	}
-	v.version = Version(header[0])
 	var err error
-	if v.replicaType, err = NewReplicationTypeFromByte(header[1]); err != nil {
-		return fmt.Errorf("cannot read replica type: %s", err)
+	v.version, v.replicaType, err = ParseSuperBlock(header)
+	return err
 }
-	return nil
+func ParseSuperBlock(header []byte) (version Version, replicaType ReplicationType, e error) {
+	version = Version(header[0])
+	var err error
+	if replicaType, err = NewReplicationTypeFromByte(header[1]); err != nil {
+		e = fmt.Errorf("cannot read replica type: %s", err)
+	}
+	return
 }
 func (v *Volume) NeedToReplicate() bool {
 	return v.replicaType.GetCopyCount() > 1
@@ -143,7 +148,7 @@ func (v *Volume) compact() error {
 	filePath := path.Join(v.dir, v.Id.String())
 	return v.copyDataAndGenerateIndexFile(filePath+".dat", filePath+".cpd", filePath+".cpx")
 }
-func (v *Volume) commitCompact() (error) {
+func (v *Volume) commitCompact() error {
 	v.accessLock.Lock()
 	defer v.accessLock.Unlock()
 	v.dataFile.Close()
@@ -185,7 +190,9 @@ func (v *Volume) copyDataAndGenerateIndexFile(srcName, dstName, idxName string)
 		dst.Write(header)
 	}
 
-	n, rest := ReadNeedle(src)
+	version, _, _ := ParseSuperBlock(header)
+
+	n, rest := ReadNeedle(src, version)
 	nm := NewNeedleMap(idx)
 	old_offset := uint32(SuperBlockSize)
 	new_offset := uint32(SuperBlockSize)
@@ -208,7 +215,7 @@ func (v *Volume) copyDataAndGenerateIndexFile(srcName, dstName, idxName string)
 			src.Seek(int64(rest-n.Size-4), 1)
 		}
 		old_offset += rest + 16
-		n, rest = ReadNeedle(src)
+		n, rest = ReadNeedle(src, version)
 	}
 
 	return nil