seaweedfs/weed/storage/volume_read_write.go

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package storage
import (
"bytes"
"errors"
"fmt"
"io"
"os"
"time"
"github.com/chrislusf/seaweedfs/weed/glog"
. "github.com/chrislusf/seaweedfs/weed/storage/types"
)
var ErrorNotFound = errors.New("not found")
// isFileUnchanged checks whether this needle to write is same as last one.
// It requires serialized access in the same volume.
func (v *Volume) isFileUnchanged(n *Needle) bool {
if v.Ttl.String() != "" {
return false
}
nv, ok := v.nm.Get(n.Id)
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if ok && !nv.Offset.IsZero() {
oldNeedle := new(Needle)
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err := oldNeedle.ReadData(v.dataFile, nv.Offset.ToAcutalOffset(), nv.Size, v.Version())
if err != nil {
glog.V(0).Infof("Failed to check updated file %v", err)
return false
}
if oldNeedle.Checksum == n.Checksum && bytes.Equal(oldNeedle.Data, n.Data) {
n.DataSize = oldNeedle.DataSize
return true
}
}
return false
}
// Destroy removes everything related to this volume
func (v *Volume) Destroy() (err error) {
if v.readOnly {
err = fmt.Errorf("%s is read-only", v.dataFile.Name())
return
}
v.Close()
os.Remove(v.FileName() + ".dat")
os.Remove(v.FileName() + ".idx")
os.Remove(v.FileName() + ".cpd")
os.Remove(v.FileName() + ".cpx")
os.Remove(v.FileName() + ".ldb")
os.Remove(v.FileName() + ".bdb")
return
}
// AppendBlob append a blob to end of the data file, used in replication
func (v *Volume) AppendBlob(b []byte) (offset int64, err error) {
if v.readOnly {
err = fmt.Errorf("%s is read-only", v.dataFile.Name())
return
}
v.dataFileAccessLock.Lock()
defer v.dataFileAccessLock.Unlock()
if offset, err = v.dataFile.Seek(0, 2); err != nil {
glog.V(0).Infof("failed to seek the end of file: %v", err)
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(0).Infof("failed to align in datafile %s: %v", v.dataFile.Name(), err)
return
}
}
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_, err = v.dataFile.Write(b)
return
}
func (v *Volume) writeNeedle(n *Needle) (offset uint64, 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.dataFileAccessLock.Lock()
defer v.dataFileAccessLock.Unlock()
if v.isFileUnchanged(n) {
size = n.DataSize
glog.V(4).Infof("needle is unchanged!")
return
}
n.AppendAtNs = uint64(time.Now().UnixNano())
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if offset, size, _, err = n.Append(v.dataFile, v.Version()); err != nil {
return
}
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nv, ok := v.nm.Get(n.Id)
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if !ok || uint64(nv.Offset.ToAcutalOffset()) < offset {
if err = v.nm.Put(n.Id, ToOffset(int64(offset)), n.Size); err != nil {
glog.V(4).Infof("failed to save in needle map %d: %v", n.Id, err)
}
}
if v.lastModifiedTime < n.LastModified {
v.lastModifiedTime = n.LastModified
}
return
}
func (v *Volume) deleteNeedle(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.dataFileAccessLock.Lock()
defer v.dataFileAccessLock.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)
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if ok && nv.Size != TombstoneFileSize {
size := nv.Size
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n.Data = nil
n.AppendAtNs = uint64(time.Now().UnixNano())
offset, _, _, err := n.Append(v.dataFile, v.Version())
if err != nil {
return size, err
}
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if err = v.nm.Delete(n.Id, ToOffset(int64(offset))); err != nil {
return size, err
}
return size, err
}
return 0, nil
}
// read fills in Needle content by looking up n.Id from NeedleMapper
func (v *Volume) readNeedle(n *Needle) (int, error) {
nv, ok := v.nm.Get(n.Id)
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if !ok || nv.Offset.IsZero() {
v.compactingWg.Wait()
nv, ok = v.nm.Get(n.Id)
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if !ok || nv.Offset.IsZero() {
return -1, ErrorNotFound
}
}
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if nv.Size == TombstoneFileSize {
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return -1, errors.New("already deleted")
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}
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if nv.Size == 0 {
return 0, nil
}
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err := n.ReadData(v.dataFile, nv.Offset.ToAcutalOffset(), nv.Size, v.Version())
if err != nil {
return 0, err
}
bytesRead := len(n.Data)
if !n.HasTtl() {
return bytesRead, nil
}
ttlMinutes := n.Ttl.Minutes()
if ttlMinutes == 0 {
return bytesRead, nil
}
if !n.HasLastModifiedDate() {
return bytesRead, nil
}
if uint64(time.Now().Unix()) < n.LastModified+uint64(ttlMinutes*60) {
return bytesRead, nil
}
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return -1, ErrorNotFound
}
type VolumeFileScanner interface {
VisitSuperBlock(SuperBlock) error
ReadNeedleBody() bool
VisitNeedle(n *Needle, offset int64) error
}
func ScanVolumeFile(dirname string, collection string, id VolumeId,
needleMapKind NeedleMapType,
volumeFileScanner VolumeFileScanner) (err error) {
var v *Volume
if v, err = loadVolumeWithoutIndex(dirname, collection, id, needleMapKind); err != nil {
return fmt.Errorf("failed to load volume %d: %v", id, err)
}
if err = volumeFileScanner.VisitSuperBlock(v.SuperBlock); err != nil {
return fmt.Errorf("failed to process volume %d super block: %v", id, err)
}
defer v.Close()
version := v.Version()
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offset := int64(v.SuperBlock.BlockSize())
return ScanVolumeFileFrom(version, v.dataFile, offset, volumeFileScanner)
}
func ScanVolumeFileFrom(version Version, dataFile *os.File, offset int64, volumeFileScanner VolumeFileScanner) (err error) {
n, rest, e := ReadNeedleHeader(dataFile, version, offset)
if e != nil {
if e == io.EOF {
return nil
}
return fmt.Errorf("cannot read %s at offset %d: %v", dataFile.Name(), offset, e)
}
for n != nil {
if volumeFileScanner.ReadNeedleBody() {
if err = n.ReadNeedleBody(dataFile, version, offset+NeedleEntrySize, rest); err != nil {
glog.V(0).Infof("cannot read needle body: %v", err)
//err = fmt.Errorf("cannot read needle body: %v", err)
//return
}
}
err := volumeFileScanner.VisitNeedle(n, offset)
if err == io.EOF {
return nil
}
if err != nil {
glog.V(0).Infof("visit needle error: %v", err)
}
offset += NeedleEntrySize + rest
glog.V(4).Infof("==> new entry offset %d", offset)
if n, rest, err = ReadNeedleHeader(dataFile, version, offset); err != nil {
if err == io.EOF {
return nil
}
return fmt.Errorf("cannot read needle header at offset %d: %v", offset, err)
}
glog.V(4).Infof("new entry needle size:%d rest:%d", n.Size, rest)
}
return nil
}