seaweedfs/go/storage/volume.go

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package storage
import (
"bytes"
"code.google.com/p/weed-fs/go/glog"
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"errors"
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"fmt"
"io"
"os"
"path"
"sync"
"time"
)
const (
SuperBlockSize = 8
)
type SuperBlock struct {
Version Version
ReplicaPlacement *ReplicaPlacement
}
func (s *SuperBlock) Bytes() []byte {
header := make([]byte, SuperBlockSize)
header[0] = byte(s.Version)
header[1] = s.ReplicaPlacement.Byte()
return header
}
type Volume struct {
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Id VolumeId
dir string
Collection string
dataFile *os.File
nm NeedleMapper
readOnly bool
SuperBlock
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accessLock sync.Mutex
}
func NewVolume(dirname string, collection string, id VolumeId, replicaPlacement *ReplicaPlacement) (v *Volume, e error) {
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v = &Volume{dir: dirname, Collection: collection, Id: id}
v.SuperBlock = SuperBlock{ReplicaPlacement: replicaPlacement}
e = v.load(true, true)
return
}
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func loadVolumeWithoutIndex(dirname string, collection string, id VolumeId) (v *Volume, e error) {
v = &Volume{dir: dirname, Collection: collection, Id: id}
v.SuperBlock = SuperBlock{}
e = v.load(false, false)
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return
}
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func (v *Volume) FileName() (fileName string) {
if v.Collection == "" {
fileName = path.Join(v.dir, v.Id.String())
} else {
fileName = path.Join(v.dir, v.Collection+"_"+v.Id.String())
}
return
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}
func (v *Volume) load(alsoLoadIndex bool, createDatIfMissing bool) error {
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var e error
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fileName := v.FileName()
if exists, canRead, canWrite, _ := checkFile(fileName + ".dat"); exists {
if !canRead {
return fmt.Errorf("cannot read Volume Data file %s.dat", fileName)
}
if canWrite {
v.dataFile, e = os.OpenFile(fileName+".dat", os.O_RDWR|os.O_CREATE, 0644)
} else {
glog.V(0).Infoln("opening " + fileName + ".dat in READONLY mode")
v.dataFile, e = os.Open(fileName + ".dat")
v.readOnly = true
}
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} else {
if createDatIfMissing {
v.dataFile, e = os.OpenFile(fileName+".dat", os.O_RDWR|os.O_CREATE, 0644)
} else {
return fmt.Errorf("Volume Data file %s.dat does not exist.", fileName)
}
}
if e != nil {
if !os.IsPermission(e) {
return fmt.Errorf("cannot load Volume Data %s.dat: %s", fileName, e.Error())
}
}
if v.ReplicaPlacement == nil {
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e = v.readSuperBlock()
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} else {
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e = v.maybeWriteSuperBlock()
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}
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if e == nil && alsoLoadIndex {
if v.readOnly {
if v.ensureConvertIdxToCdb(fileName) {
v.nm, e = OpenCdbMap(fileName + ".cdb")
return e
}
}
var indexFile *os.File
if v.readOnly {
glog.V(1).Infoln("open to read file", fileName+".idx")
if indexFile, e = os.OpenFile(fileName+".idx", os.O_RDONLY, 0644); e != nil {
return fmt.Errorf("cannot read Volume Index %s.idx: %s", fileName, e.Error())
}
} else {
glog.V(1).Infoln("open to write file", fileName+".idx")
if indexFile, e = os.OpenFile(fileName+".idx", os.O_RDWR|os.O_CREATE, 0644); e != nil {
return fmt.Errorf("cannot write Volume Index %s.idx: %s", fileName, e.Error())
}
}
glog.V(0).Infoln("loading file", fileName+".idx", "readonly", v.readOnly)
if v.nm, e = LoadNeedleMap(indexFile); e != nil {
glog.V(0).Infoln("loading error:", e)
}
}
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return e
}
func (v *Volume) Version() Version {
return v.SuperBlock.Version
}
func (v *Volume) Size() int64 {
stat, e := v.dataFile.Stat()
if e == nil {
return stat.Size()
}
glog.V(0).Infof("Failed to read file size %s %s", v.dataFile.Name(), e.Error())
return -1
}
func (v *Volume) Close() {
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v.accessLock.Lock()
defer v.accessLock.Unlock()
v.nm.Close()
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_ = v.dataFile.Close()
}
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func (v *Volume) maybeWriteSuperBlock() error {
stat, e := v.dataFile.Stat()
if e != nil {
glog.V(0).Infof("failed to stat datafile %s: %s", v.dataFile, e.Error())
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return e
}
if stat.Size() == 0 {
v.SuperBlock.Version = CurrentVersion
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_, e = v.dataFile.Write(v.SuperBlock.Bytes())
if e != nil && os.IsPermission(e) {
//read-only, but zero length - recreate it!
if v.dataFile, e = os.Create(v.dataFile.Name()); e == nil {
if _, e = v.dataFile.Write(v.SuperBlock.Bytes()); e == nil {
v.readOnly = false
}
}
}
}
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return e
}
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func (v *Volume) readSuperBlock() (err error) {
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if _, err = v.dataFile.Seek(0, 0); err != nil {
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return fmt.Errorf("cannot seek to the beginning of %s: %s", v.dataFile.Name(), err.Error())
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}
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header := make([]byte, SuperBlockSize)
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if _, e := v.dataFile.Read(header); e != nil {
return fmt.Errorf("cannot read superblock: %s", e.Error())
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}
v.SuperBlock, err = ParseSuperBlock(header)
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return err
}
func ParseSuperBlock(header []byte) (superBlock SuperBlock, err error) {
superBlock.Version = Version(header[0])
if superBlock.ReplicaPlacement, err = NewReplicaPlacementFromByte(header[1]); err != nil {
err = fmt.Errorf("cannot read replica type: %s", err.Error())
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}
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return
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}
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func (v *Volume) NeedToReplicate() bool {
return v.ReplicaPlacement.GetCopyCount() > 1
}
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func (v *Volume) isFileUnchanged(n *Needle) bool {
nv, ok := v.nm.Get(n.Id)
if ok && nv.Offset > 0 {
oldNeedle := new(Needle)
oldNeedle.Read(v.dataFile, int64(nv.Offset)*NeedlePaddingSize, nv.Size, v.Version())
if oldNeedle.Checksum == n.Checksum && bytes.Equal(oldNeedle.Data, n.Data) {
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n.Size = oldNeedle.Size
return true
}
}
return false
}
func (v *Volume) Destroy() (err error) {
if v.readOnly {
err = fmt.Errorf("%s is read-only", v.dataFile.Name())
return
}
v.Close()
err = os.Remove(v.dataFile.Name())
if err != nil {
return
}
err = v.nm.Destroy()
return
}
func (v *Volume) write(n *Needle) (size uint32, err error) {
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glog.V(4).Infof("writing needle %s", NewFileIdFromNeedle(v.Id, n).String())
if v.readOnly {
err = fmt.Errorf("%s is read-only", v.dataFile.Name())
return
}
v.accessLock.Lock()
defer v.accessLock.Unlock()
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if v.isFileUnchanged(n) {
size = n.Size
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glog.V(4).Infof("needle is unchanged!")
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return
}
var offset int64
if offset, err = v.dataFile.Seek(0, 2); err != nil {
return
}
//ensure file writing starting from aligned positions
if offset%NeedlePaddingSize != 0 {
offset = offset + (NeedlePaddingSize - offset%NeedlePaddingSize)
if offset, err = v.dataFile.Seek(offset, 0); err != nil {
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glog.V(4).Infof("failed to align in datafile %s: %s", v.dataFile.Name(), err.Error())
return
}
}
if size, err = n.Append(v.dataFile, v.Version()); err != nil {
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if e := v.dataFile.Truncate(offset); e != nil {
err = fmt.Errorf("%s\ncannot truncate %s: %s", err, v.dataFile.Name(), e.Error())
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}
return
}
nv, ok := v.nm.Get(n.Id)
if !ok || int64(nv.Offset)*NeedlePaddingSize < offset {
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if _, err = v.nm.Put(n.Id, uint32(offset/NeedlePaddingSize), n.Size); err != nil {
glog.V(4).Infof("failed to save in needle map %d: %s", n.Id, err.Error())
}
}
return
}
func (v *Volume) delete(n *Needle) (uint32, error) {
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glog.V(4).Infof("delete needle %s", NewFileIdFromNeedle(v.Id, n).String())
if v.readOnly {
return 0, fmt.Errorf("%s is read-only", v.dataFile.Name())
}
v.accessLock.Lock()
defer v.accessLock.Unlock()
nv, ok := v.nm.Get(n.Id)
//fmt.Println("key", n.Id, "volume offset", nv.Offset, "data_size", n.Size, "cached size", nv.Size)
if ok {
size := nv.Size
if err := v.nm.Delete(n.Id); err != nil {
return size, err
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}
if _, err := v.dataFile.Seek(0, 2); err != nil {
return size, err
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}
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n.Data = make([]byte, 0)
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_, err := n.Append(v.dataFile, v.Version())
return size, err
}
return 0, nil
}
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func (v *Volume) read(n *Needle) (int, error) {
nv, ok := v.nm.Get(n.Id)
if ok && nv.Offset > 0 {
return n.Read(v.dataFile, int64(nv.Offset)*NeedlePaddingSize, nv.Size, v.Version())
}
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return -1, errors.New("Not Found")
}
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func (v *Volume) freeze() error {
if v.readOnly {
return nil
}
nm, ok := v.nm.(*NeedleMap)
if !ok {
return nil
}
v.accessLock.Lock()
defer v.accessLock.Unlock()
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bn, _ := baseFilename(v.dataFile.Name())
cdbFn := bn + ".cdb"
glog.V(0).Infof("converting %s to %s", nm.indexFile.Name(), cdbFn)
err := DumpNeedleMapToCdb(cdbFn, nm)
if err != nil {
return err
}
if v.nm, err = OpenCdbMap(cdbFn); err != nil {
return err
}
nm.indexFile.Close()
os.Remove(nm.indexFile.Name())
v.readOnly = true
return nil
}
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func ScanVolumeFile(dirname string, collection string, id VolumeId,
visitSuperBlock func(SuperBlock) error,
visitNeedle func(n *Needle, offset int64) error) (err error) {
var v *Volume
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if v, err = loadVolumeWithoutIndex(dirname, collection, id); err != nil {
return errors.New("Failed to load volume:" + err.Error())
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}
if err = visitSuperBlock(v.SuperBlock); err != nil {
return errors.New("Failed to read super block:" + err.Error())
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}
version := v.Version()
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offset := int64(SuperBlockSize)
n, rest, e := ReadNeedleHeader(v.dataFile, version, offset)
if e != nil {
err = fmt.Errorf("cannot read needle header: %s", e)
return
}
for n != nil {
if err = n.ReadNeedleBody(v.dataFile, version, offset+int64(NeedleHeaderSize), rest); err != nil {
err = fmt.Errorf("cannot read needle body: %s", err)
return
}
if err = visitNeedle(n, offset); err != nil {
return
}
offset += int64(NeedleHeaderSize) + int64(rest)
if n, rest, err = ReadNeedleHeader(v.dataFile, version, offset); err != nil {
if err == io.EOF {
return nil
}
return fmt.Errorf("cannot read needle header: %s", err)
}
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}
return
}
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func (v *Volume) ContentSize() uint64 {
return v.nm.ContentSize()
}
func checkFile(filename string) (exists, canRead, canWrite bool, modTime time.Time) {
exists = true
fi, err := os.Stat(filename)
if os.IsNotExist(err) {
exists = false
return
}
if fi.Mode()&0400 != 0 {
canRead = true
}
if fi.Mode()&0200 != 0 {
canWrite = true
}
modTime = fi.ModTime()
return
}
func (v *Volume) ensureConvertIdxToCdb(fileName string) (cdbCanRead bool) {
var indexFile *os.File
var e error
_, cdbCanRead, cdbCanWrite, cdbModTime := checkFile(fileName + ".cdb")
_, idxCanRead, _, idxModeTime := checkFile(fileName + ".idx")
if cdbCanRead && cdbModTime.After(idxModeTime) {
return true
}
if !cdbCanWrite {
return false
}
if !idxCanRead {
glog.V(0).Infoln("Can not read file", fileName+".idx!")
return false
}
glog.V(2).Infoln("opening file", fileName+".idx")
if indexFile, e = os.Open(fileName + ".idx"); e != nil {
glog.V(0).Infoln("Failed to read file", fileName+".idx !")
return false
}
defer indexFile.Close()
glog.V(0).Infof("converting %s.idx to %s.cdb", fileName, fileName)
if e = ConvertIndexToCdb(fileName+".cdb", indexFile); e != nil {
glog.V(0).Infof("error converting %s.idx to %s.cdb: %s", fileName, fileName, e.Error())
return false
}
return true
}