cleaner code, better error handling

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

@@ -2,6 +2,7 @@ package storage
 
 import (
 	"errors"
+	"fmt"
 	"log"
 	"os"
 	"path"
@@ -10,6 +11,7 @@ import (
 
 const (
 	SuperBlockSize = 8
+	Version        = 1
 )
 
 type Volume struct {
@@ -20,6 +22,8 @@ type Volume struct {
 
 	replicaType ReplicationType
 
+	version uint8
+
 	accessLock sync.Mutex
 }
 
@@ -28,23 +32,26 @@ func NewVolume(dirname string, id VolumeId, replicationType ReplicationType) (v
 	v.load()
 	return
 }
-func (v *Volume) load() {
+func (v *Volume) load() error {
 	var e error
 	fileName := path.Join(v.dir, v.Id.String())
 	v.dataFile, e = os.OpenFile(fileName+".dat", os.O_RDWR|os.O_CREATE, 0644)
 	if e != nil {
-		log.Fatalf("New Volume [ERROR] %s\n", e)
+		return fmt.Errorf("cannot create Volume Data %s.dat: %s", fileName, e)
 	}
 	if v.replicaType == CopyNil {
-		v.readSuperBlock()
+		if e = v.readSuperBlock(); e != nil {
+			return e
+		}
 	} else {
 		v.maybeWriteSuperBlock()
 	}
 	indexFile, ie := os.OpenFile(fileName+".idx", os.O_RDWR|os.O_CREATE, 0644)
 	if ie != nil {
-		log.Fatalf("Write Volume Index [ERROR] %s\n", ie)
+		return fmt.Errorf("cannot create Volume Data %s.dat: %s", fileName, e)
 	}
 	v.nm = LoadNeedleMap(indexFile)
+	return nil
 }
 func (v *Volume) Size() int64 {
 	stat, e := v.dataFile.Stat()
@@ -61,17 +68,23 @@ func (v *Volume) maybeWriteSuperBlock() {
 	stat, _ := v.dataFile.Stat()
 	if stat.Size() == 0 {
 		header := make([]byte, SuperBlockSize)
-		header[0] = 1
+		header[0] = Version
 		header[1] = v.replicaType.Byte()
 		v.dataFile.Write(header)
 	}
 }
-func (v *Volume) readSuperBlock() {
+func (v *Volume) readSuperBlock() error {
 	v.dataFile.Seek(0, 0)
 	header := make([]byte, SuperBlockSize)
-	if _, error := v.dataFile.Read(header); error == nil {
-		v.replicaType, _ = NewReplicationTypeFromByte(header[1])
+	if _, e := v.dataFile.Read(header); e != nil {
+		return fmt.Errorf("cannot read superblock: %s", e)
 	}
+	v.version = header[0]
+	var err error
+	if v.replicaType, err = NewReplicationTypeFromByte(header[1]); err != nil {
+		return fmt.Errorf("cannot read replica type: %s", err)
+	}
+	return nil
 }
 func (v *Volume) NeedToReplicate() bool {
 	return v.replicaType.GetCopyCount() > 1
@@ -123,9 +136,16 @@ func (v *Volume) commitCompact() (int, error) {
 	v.accessLock.Lock()
 	defer v.accessLock.Unlock()
 	v.dataFile.Close()
-	os.Rename(path.Join(v.dir, v.Id.String()+".cpd"), path.Join(v.dir, v.Id.String()+".dat"))
-	os.Rename(path.Join(v.dir, v.Id.String()+".cpx"), path.Join(v.dir, v.Id.String()+".idx"))
-	v.load()
+	var e error
+	if e = os.Rename(path.Join(v.dir, v.Id.String()+".cpd"), path.Join(v.dir, v.Id.String()+".dat")); e != nil {
+		return 0, e
+	}
+	if e = os.Rename(path.Join(v.dir, v.Id.String()+".cpx"), path.Join(v.dir, v.Id.String()+".idx")); e != nil {
+		return 0, e
+	}
+	if e = v.load(); e != nil {
+		return 0, e
+	}
 	return 0, nil
 }