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"
)
// 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)
if ok && nv.Offset > 0 {
oldNeedle := new(Needle)
err := oldNeedle.ReadData(v.dataFile, int64(nv.Offset)*NeedlePaddingSize, nv.Size, v.Version())
if err != nil {
glog.V(0).Infof("Failed to check updated file %v", err)
return false
}
defer oldNeedle.ReleaseMemory()
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()
err = os.Remove(v.dataFile.Name())
if err != nil {
return
}
err = v.nm.Destroy()
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
}
}
v.dataFile.Write(b)
return
}
func (v *Volume) writeNeedle(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.dataFileAccessLock.Lock()
defer v.dataFileAccessLock.Unlock()
if v.isFileUnchanged(n) {
size = n.DataSize
glog.V(4).Infof("needle is unchanged!")
return
}
var offset int64
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
}
}
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: %v", err, v.dataFile.Name(), e)
}
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: %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)
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 = nil
_, err := n.Append(v.dataFile, v.Version())
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)
if !ok || nv.Offset == 0 {
return -1, errors.New("Not Found")
}
err := n.ReadData(v.dataFile, int64(nv.Offset)*NeedlePaddingSize, 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
}
n.ReleaseMemory()
return -1, errors.New("Not Found")
}
func ScanVolumeFile(dirname string, collection string, id VolumeId,
needleMapKind NeedleMapType,
visitSuperBlock func(SuperBlock) error,
readNeedleBody bool,
visitNeedle func(n *Needle, offset int64) error) (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 = visitSuperBlock(v.SuperBlock); err != nil {
return fmt.Errorf("Failed to process volume %d super block: %v", id, err)
}
version := v.Version()
offset := int64(SuperBlockSize)
n, rest, e := ReadNeedleHeader(v.dataFile, version, offset)
if e != nil {
err = fmt.Errorf("cannot read needle header: %v", e)
return
}
for n != nil {
if readNeedleBody {
if err = n.ReadNeedleBody(v.dataFile, version, offset+int64(NeedleHeaderSize), rest); err != nil {
glog.V(0).Infof("cannot read needle body: %v", err)
//err = fmt.Errorf("cannot read needle body: %v", err)
//return
}
if n.DataSize >= n.Size {
// this should come from a bug reported on #87 and #93
// fixed in v0.69
// remove this whole "if" clause later, long after 0.69
oldRest, oldSize := rest, n.Size
padding := NeedlePaddingSize - ((n.Size + NeedleHeaderSize + NeedleChecksumSize) % NeedlePaddingSize)
n.Size = 0
rest = n.Size + NeedleChecksumSize + padding
if rest%NeedlePaddingSize != 0 {
rest += (NeedlePaddingSize - rest%NeedlePaddingSize)
}
glog.V(4).Infof("Adjusting n.Size %d=>0 rest:%d=>%d %+v", oldSize, oldRest, rest, n)
}
}
if err = visitNeedle(n, offset); err != nil {
glog.V(0).Infof("visit needle error: %v", err)
}
offset += int64(NeedleHeaderSize) + int64(rest)
glog.V(4).Infof("==> new entry offset %d", offset)
if n, rest, err = ReadNeedleHeader(v.dataFile, version, offset); err != nil {
if err == io.EOF {
return nil
}
return fmt.Errorf("cannot read needle header: %v", err)
}
glog.V(4).Infof("new entry needle size:%d rest:%d", n.Size, rest)
}
return
}