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package storage
import (
"errors"
"fmt"
"io"
"os"
"path"
"sync"
)
const (
SuperBlockSize = 8
)
type SuperBlock struct {
Version Version
ReplicaType ReplicationType
}
func (s *SuperBlock) Bytes() []byte {
header := make([]byte, SuperBlockSize)
header[0] = byte(s.Version)
header[1] = s.ReplicaType.Byte()
return header
}
type Volume struct {
Id VolumeId
dir string
dataFile *os.File
nm *NeedleMap
SuperBlock
accessLock sync.Mutex
}
func NewVolume(dirname string, id VolumeId, replicationType ReplicationType) (v *Volume, e error) {
v = &Volume{dir: dirname, Id: id}
v.SuperBlock = SuperBlock{ReplicaType: replicationType}
e = v.load(true)
return
}
func LoadVolumeOnly(dirname string, id VolumeId) (v *Volume, e error) {
v = &Volume{dir: dirname, Id: id}
v.SuperBlock = SuperBlock{ReplicaType: CopyNil}
e = v.load(false)
return
}
func (v *Volume) load(alsoLoadIndex bool) 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 {
return fmt.Errorf("cannot create Volume Data %s.dat: %s", fileName, e)
}
if v.ReplicaType == CopyNil {
e = v.readSuperBlock()
} else {
e = v.maybeWriteSuperBlock()
}
if e == nil && alsoLoadIndex {
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)
}
return e
}
func (v *Volume) Version() Version {
return v.SuperBlock.Version
}
func (v *Volume) Size() int64 {
v.accessLock.Lock()
defer v.accessLock.Unlock()
stat, e := v.dataFile.Stat()
if e == nil {
return stat.Size()
}
fmt.Printf("Failed to read file size %s %s\n", 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 {
fmt.Printf("failed to stat datafile %s: %s", v.dataFile, e)
return e
}
if stat.Size() == 0 {
v.SuperBlock.Version = CurrentVersion
_, e = v.dataFile.Write(v.SuperBlock.Bytes())
}
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, err)
}
header := make([]byte, SuperBlockSize)
if _, e := v.dataFile.Read(header); e != nil {
return fmt.Errorf("cannot read superblock: %s", e)
}
v.SuperBlock, err = ParseSuperBlock(header)
return err
}
func ParseSuperBlock(header []byte) (superBlock SuperBlock, err error) {
superBlock.Version = Version(header[0])
if superBlock.ReplicaType, err = NewReplicationTypeFromByte(header[1]); err != nil {
err = fmt.Errorf("cannot read replica type: %s", err)
}
return
}
func (v *Volume) NeedToReplicate() bool {
return v.ReplicaType.GetCopyCount() > 1
}
func (v *Volume) write(n *Needle) (size uint32, err error) {
v.accessLock.Lock()
defer v.accessLock.Unlock()
var offset int64
if offset, err = v.dataFile.Seek(0, 2); err != nil {
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, e)
}
return
}
nv, ok := v.nm.Get(n.Id)
if !ok || int64(nv.Offset)*NeedlePaddingSize < offset {
_, err = v.nm.Put(n.Id, uint32(offset/NeedlePaddingSize), n.Size)
}
return
}
func (v *Volume) delete(n *Needle) (uint32, error) {
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 {
var err error
if err = v.nm.Delete(n.Id); err != nil {
return nv.Size, err
}
if _, err = v.dataFile.Seek(int64(nv.Offset*NeedlePaddingSize), 0); err != nil {
return nv.Size, err
}
_, err = n.Append(v.dataFile, v.Version())
return nv.Size, err
}
return 0, nil
}
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 {
if _, err := v.dataFile.Seek(int64(nv.Offset)*NeedlePaddingSize, 0); err != nil {
return -1, err
}
return n.Read(v.dataFile, nv.Size, v.Version())
}
return -1, errors.New("Not Found")
}
func (v *Volume) garbageLevel() float64 {
return float64(v.nm.deletionByteCounter) / float64(v.ContentSize())
}
func (v *Volume) compact() error {
v.accessLock.Lock()
defer v.accessLock.Unlock()
filePath := path.Join(v.dir, v.Id.String())
return v.copyDataAndGenerateIndexFile(filePath+".cpd", filePath+".cpx")
}
func (v *Volume) commitCompact() error {
v.accessLock.Lock()
defer v.accessLock.Unlock()
_ = v.dataFile.Close()
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 e
}
if e = os.Rename(path.Join(v.dir, v.Id.String()+".cpx"), path.Join(v.dir, v.Id.String()+".idx")); e != nil {
return e
}
if e = v.load(true); e != nil {
return e
}
return nil
}
func ScanVolumeFile(dirname string, id VolumeId,
visitSuperBlock func(SuperBlock) error,
visitNeedle func(n *Needle, offset uint32) error) (err error) {
var v *Volume
if v, err = LoadVolumeOnly(dirname, id); err != nil {
return
}
if err = visitSuperBlock(v.SuperBlock); err != nil {
return
}
version := v.Version()
offset := uint32(SuperBlockSize)
n, rest, e := ReadNeedleHeader(v.dataFile, version)
if e != nil {
err = fmt.Errorf("cannot read needle header: %s", e)
return
}
for n != nil {
if err = n.ReadNeedleBody(v.dataFile, version, rest); err != nil {
err = fmt.Errorf("cannot read needle body: %s", err)
return
}
if err = visitNeedle(n, offset); err != nil {
return
}
offset += NeedleHeaderSize + rest
if n, rest, err = ReadNeedleHeader(v.dataFile, version); err != nil {
if err == io.EOF {
return nil
}
return fmt.Errorf("cannot read needle header: %s", err)
}
}
return
}
func (v *Volume) copyDataAndGenerateIndexFile(dstName, idxName string) (err error) {
var (
dst, idx *os.File
)
if dst, err = os.OpenFile(dstName, os.O_WRONLY|os.O_CREATE, 0644); err != nil {
return
}
defer dst.Close()
if idx, err = os.OpenFile(idxName, os.O_WRONLY|os.O_CREATE, 0644); err != nil {
return
}
defer idx.Close()
nm := NewNeedleMap(idx)
new_offset := uint32(SuperBlockSize)
err = ScanVolumeFile(v.dir, v.Id, func(superBlock SuperBlock) error {
_, err = dst.Write(superBlock.Bytes())
return err
}, func(n *Needle, offset uint32) error {
nv, ok := v.nm.Get(n.Id)
//log.Println("file size is", n.Size, "rest", rest)
if ok && nv.Offset*NeedlePaddingSize == offset {
if nv.Size > 0 {
if _, err = nm.Put(n.Id, new_offset/NeedlePaddingSize, n.Size); err != nil {
return fmt.Errorf("cannot put needle: %s", err)
}
if _, err = n.Append(dst, v.Version()); err != nil {
return fmt.Errorf("cannot append needle: %s", err)
}
new_offset += n.DiskSize()
//log.Println("saving key", n.Id, "volume offset", old_offset, "=>", new_offset, "data_size", n.Size, "rest", rest)
}
}
return nil
})
return
}
func (v *Volume) ContentSize() uint64 {
return v.nm.fileByteCounter
}
|
