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package storage
import ( "bytes" "code.google.com/p/weed-fs/go/glog" "errors" "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 { Id VolumeId dir string Collection string dataFile *os.File nm NeedleMapper readOnly bool
SuperBlock
accessLock sync.Mutex }
func NewVolume(dirname string, collection string, id VolumeId, replicaPlacement *ReplicaPlacement) (v *Volume, e error) { v = &Volume{dir: dirname, Collection: collection, Id: id} v.SuperBlock = SuperBlock{ReplicaPlacement: replicaPlacement} e = v.load(true, true) return } 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) return } 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 } func (v *Volume) load(alsoLoadIndex bool, createDatIfMissing bool) error { var e error 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 } } 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 { e = v.readSuperBlock() } else { e = v.maybeWriteSuperBlock() } 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) } } 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() { v.accessLock.Lock() defer v.accessLock.Unlock() v.nm.Close() _ = v.dataFile.Close() } 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()) return e } if stat.Size() == 0 { v.SuperBlock.Version = CurrentVersion _, 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 } } } } return e } func (v *Volume) readSuperBlock() (err error) { if _, err = v.dataFile.Seek(0, 0); err != nil { return fmt.Errorf("cannot seek to the beginning of %s: %s", v.dataFile.Name(), err.Error()) } header := make([]byte, SuperBlockSize) if _, e := v.dataFile.Read(header); e != nil { return fmt.Errorf("cannot read superblock: %s", e.Error()) } v.SuperBlock, err = ParseSuperBlock(header) 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()) } return } func (v *Volume) NeedToReplicate() bool { return v.ReplicaPlacement.GetCopyCount() > 1 }
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) { 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) { 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() if v.isFileUnchanged(n) { size = n.Size glog.V(4).Infof("needle is unchanged!") 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 { 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 { if e := v.dataFile.Truncate(offset); e != nil { err = fmt.Errorf("%s\ncannot truncate %s: %s", err, v.dataFile.Name(), e.Error()) } return } nv, ok := v.nm.Get(n.Id) if !ok || int64(nv.Offset)*NeedlePaddingSize < offset { 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) { 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 } if _, err := v.dataFile.Seek(0, 2); err != nil { return size, err } n.Data = make([]byte, 0) _, err := n.Append(v.dataFile, v.Version()) return size, err } return 0, nil }
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()) } return -1, errors.New("Not Found") }
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() 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 }
func ScanVolumeFile(dirname string, collection string, id VolumeId, visitSuperBlock func(SuperBlock) error, visitNeedle func(n *Needle, offset int64) error) (err error) { var v *Volume if v, err = loadVolumeWithoutIndex(dirname, collection, id); err != nil { return errors.New("Failed to load volume:" + err.Error()) } if err = visitSuperBlock(v.SuperBlock); err != nil { return errors.New("Failed to read super block:" + err.Error()) }
version := v.Version()
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) } }
return }
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 }
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