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

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package storage
import (
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"errors"
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"fmt"
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"log"
"os"
"path"
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"pkg/util"
"sync"
)
const (
SuperBlockSize = 8
)
type Volume struct {
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Id VolumeId
dir string
dataFile *os.File
nm *NeedleMap
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version Version
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replicaType ReplicationType
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accessLock sync.Mutex
}
func NewVolume(dirname string, id VolumeId, replicationType ReplicationType) (v *Volume, e error) {
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v = &Volume{dir: dirname, Id: id, replicaType: replicationType}
e = v.load()
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return
}
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func (v *Volume) load() error {
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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 {
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if os.IsPermission(e) {
if util.FileExists(fileName + ".cdb") {
v.dataFile, e = os.Open(fileName + ".dat")
}
}
if e != nil {
return fmt.Errorf("cannot create Volume Data %s.dat: %s", fileName, e)
}
}
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if v.replicaType == CopyNil {
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if e = v.readSuperBlock(); e != nil {
return e
}
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} else {
v.maybeWriteSuperBlock()
}
// TODO: if .idx not exists, but .cdb exists, then use (but don't load!) that
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if !util.FileIsWritable(v.dataFile.Name()) { //Read-Only
v.nm, e = NewFrozenNeedleMap(fileName)
} else {
indexFile, ie := os.OpenFile(fileName+".idx", os.O_RDWR|os.O_CREATE, 0644)
if ie != nil {
return fmt.Errorf("cannot create Volume Data %s.dat: %s", fileName, e)
}
v.nm, e = LoadNeedleMap(indexFile)
}
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return e
}
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func (v *Volume) Version() Version {
return v.version
}
func (v *Volume) Size() int64 {
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v.accessLock.Lock()
defer v.accessLock.Unlock()
stat, e := v.dataFile.Stat()
if e == nil {
return stat.Size()
}
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fmt.Printf("Failed to read file size %s %s\n", v.dataFile.Name(), e.Error())
return -1
}
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// a volume is writable, if its data file is writable and the index is not frozen
func (v *Volume) IsWritable() bool {
stat, e := v.dataFile.Stat()
if e != nil {
log.Printf("Failed to read file permission %s %s\n", v.dataFile.Name(), e.Error())
return false
}
// 4 for r, 2 for w, 1 for x
return stat.Mode().Perm()&0222 > 0 && !v.nm.IsFrozen()
}
func (v *Volume) Close() {
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v.accessLock.Lock()
defer v.accessLock.Unlock()
v.nm.Close()
v.dataFile.Close()
}
func (v *Volume) maybeWriteSuperBlock() {
stat, _ := v.dataFile.Stat()
if stat.Size() == 0 {
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v.version = CurrentVersion
header := make([]byte, SuperBlockSize)
header[0] = byte(v.version)
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header[1] = v.replicaType.Byte()
v.dataFile.Write(header)
}
}
func (v *Volume) readSuperBlock() (err error) {
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v.dataFile.Seek(0, 0)
header := make([]byte, SuperBlockSize)
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if _, e := v.dataFile.Read(header); e != nil {
return fmt.Errorf("cannot read superblock: %s", e)
}
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v.version, v.replicaType, err = ParseSuperBlock(header)
return err
}
func ParseSuperBlock(header []byte) (version Version, replicaType ReplicationType, err error) {
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version = Version(header[0])
if version == 0 {
err = errors.New("Zero version impossible - bad superblock!")
return
}
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if replicaType, err = NewReplicationTypeFromByte(header[1]); err != nil {
err = fmt.Errorf("cannot read replica type: %s", err)
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}
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return
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}
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func (v *Volume) NeedToReplicate() bool {
return v.replicaType.GetCopyCount() > 1
}
func (v *Volume) write(n *Needle) uint32 {
v.accessLock.Lock()
defer v.accessLock.Unlock()
offset, _ := v.dataFile.Seek(0, 2)
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ret := n.Append(v.dataFile, v.version)
nv, ok := v.nm.Get(n.Id)
if !ok || int64(nv.Offset)*8 < offset {
v.nm.Put(n.Id, uint32(offset/8), n.Size)
}
return ret
}
func (v *Volume) delete(n *Needle) uint32 {
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 {
v.nm.Delete(n.Id)
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v.dataFile.Seek(int64(nv.Offset*NeedlePaddingSize), 0)
n.Append(v.dataFile, v.version)
return nv.Size
}
return 0
}
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func (v *Volume) read(n *Needle) (int, error) {
v.accessLock.Lock()
defer v.accessLock.Unlock()
nv, ok := v.nm.Get(n.Id)
if ok && nv.Offset > 0 {
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v.dataFile.Seek(int64(nv.Offset)*NeedlePaddingSize, 0)
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return n.Read(v.dataFile, nv.Size, v.version)
}
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return -1, errors.New("Not Found")
}
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func (v *Volume) garbageLevel() float64 {
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return float64(v.nm.deletionByteCounter) / float64(v.ContentSize())
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}
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func (v *Volume) compact() error {
v.accessLock.Lock()
defer v.accessLock.Unlock()
filePath := path.Join(v.dir, v.Id.String())
return v.copyDataAndGenerateIndexFile(filePath+".dat", filePath+".cpd", filePath+".cpx")
}
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func (v *Volume) commitCompact() error {
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v.accessLock.Lock()
defer v.accessLock.Unlock()
v.dataFile.Close()
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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 {
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return e
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}
if e = os.Rename(path.Join(v.dir, v.Id.String()+".cpx"), path.Join(v.dir, v.Id.String()+".idx")); e != nil {
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return e
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}
if e = v.load(); e != nil {
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return e
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}
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return nil
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}
func (v *Volume) copyDataAndGenerateIndexFile(srcName, dstName, idxName string) (err error) {
src, err := os.OpenFile(srcName, os.O_RDONLY, 0644)
if err != nil {
return err
}
defer src.Close()
dst, err := os.OpenFile(dstName, os.O_WRONLY|os.O_CREATE, 0644)
if err != nil {
return err
}
defer dst.Close()
idx, err := os.OpenFile(idxName, os.O_WRONLY|os.O_CREATE, 0644)
if err != nil {
return err
}
defer idx.Close()
src.Seek(0, 0)
header := make([]byte, SuperBlockSize)
if _, error := src.Read(header); error == nil {
dst.Write(header)
}
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version, _, _ := ParseSuperBlock(header)
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n, rest := ReadNeedleHeader(src, version)
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nm := NewNeedleMap(idx)
old_offset := uint32(SuperBlockSize)
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new_offset := uint32(SuperBlockSize)
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for n != nil {
nv, ok := v.nm.Get(n.Id)
//log.Println("file size is", n.Size, "rest", rest)
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if !ok || nv.Offset*NeedlePaddingSize != old_offset {
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src.Seek(int64(rest), 1)
} else {
if nv.Size > 0 {
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nm.Put(n.Id, new_offset/NeedlePaddingSize, n.Size)
n.ReadNeedleBody(src, version, rest)
n.Append(dst, v.version)
new_offset += rest + NeedleHeaderSize
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//log.Println("saving key", n.Id, "volume offset", old_offset, "=>", new_offset, "data_size", n.Size, "rest", rest)
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} else {
src.Seek(int64(rest), 1)
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}
}
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old_offset += rest + NeedleHeaderSize
n, rest = ReadNeedleHeader(src, version)
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}
return nil
}
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func (v *Volume) ContentSize() uint64 {
return v.nm.fileByteCounter
}
// Walk over the contained needles (call the function with each NeedleValue till error is returned)
func (v *Volume) WalkValues(pedestrian func(*Needle) error) error {
pedplus := func(nv *NeedleValue) (err error) {
n := new(Needle)
if nv.Offset > 0 {
v.dataFile.Seek(int64(nv.Offset)*NeedlePaddingSize, 0)
if _, err = n.Read(v.dataFile, nv.Size, v.version); err != nil {
return
}
if err = pedestrian(n); err != nil {
return
}
}
return nil
}
return v.nm.Walk(pedplus)
}
// Walk over the keys
func (v *Volume) WalkKeys(pedestrian func(Key) error) error {
pedplus := func(nv *NeedleValue) (err error) {
if nv.Offset > 0 && nv.Key > 0 {
if err = pedestrian(nv.Key); err != nil {
return
}
}
return nil
}
return v.nm.Walk(pedplus)
}
func (v *Volume) String() string {
return fmt.Sprintf("%d@%s:v%d:r%s", v.Id, v.dataFile.Name(),
v.Version(), v.replicaType)
}