seaweedfs/go/storage/needle_read_write.go

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package storage
import (
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"errors"
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"fmt"
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"io"
"os"
"code.google.com/p/weed-fs/go/util"
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)
const (
FlagGzip = 0x01
FlagHasName = 0x02
FlagHasMime = 0x04
)
func (n *Needle) DiskSize() uint32 {
padding := NeedlePaddingSize - ((NeedleHeaderSize + n.Size + NeedleChecksumSize) % NeedlePaddingSize)
return NeedleHeaderSize + n.Size + padding + NeedleChecksumSize
}
func (n *Needle) Append(w io.Writer, version Version) (size uint32, err error) {
if s, ok := w.(io.Seeker); ok {
if end, e := s.Seek(0, 1); e == nil {
defer func(s io.Seeker, off int64) {
if err != nil {
if _, e = s.Seek(off, 0); e != nil {
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fmt.Printf("Failed to seek %s back to %d with error: %s\n", w, off, e)
}
}
}(s, end)
} else {
err = fmt.Errorf("Cnnot Read Current Volume Position: %s", e)
return
}
}
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switch version {
case Version1:
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header := make([]byte, NeedleHeaderSize)
util.Uint32toBytes(header[0:4], n.Cookie)
util.Uint64toBytes(header[4:12], n.Id)
n.Size = uint32(len(n.Data))
size = n.Size
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util.Uint32toBytes(header[12:16], n.Size)
if _, err = w.Write(header); err != nil {
return
}
if _, err = w.Write(n.Data); err != nil {
return
}
padding := NeedlePaddingSize - ((NeedleHeaderSize + n.Size + NeedleChecksumSize) % NeedlePaddingSize)
util.Uint32toBytes(header[0:NeedleChecksumSize], n.Checksum.Value())
_, err = w.Write(header[0 : NeedleChecksumSize+padding])
return
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case Version2:
header := make([]byte, NeedleHeaderSize)
util.Uint32toBytes(header[0:4], n.Cookie)
util.Uint64toBytes(header[4:12], n.Id)
n.DataSize, n.NameSize, n.MimeSize = uint32(len(n.Data)), uint8(len(n.Name)), uint8(len(n.Mime))
if n.DataSize > 0 {
n.Size = 4 + n.DataSize + 1
if n.HasName() {
n.Size = n.Size + 1 + uint32(n.NameSize)
}
if n.HasMime() {
n.Size = n.Size + 1 + uint32(n.MimeSize)
}
}
size = n.DataSize
util.Uint32toBytes(header[12:16], n.Size)
if _, err = w.Write(header); err != nil {
return
}
if n.DataSize > 0 {
util.Uint32toBytes(header[0:4], n.DataSize)
if _, err = w.Write(header[0:4]); err != nil {
return
}
if _, err = w.Write(n.Data); err != nil {
return
}
util.Uint8toBytes(header[0:1], n.Flags)
if _, err = w.Write(header[0:1]); err != nil {
return
}
}
if n.HasName() {
util.Uint8toBytes(header[0:1], n.NameSize)
if _, err = w.Write(header[0:1]); err != nil {
return
}
if _, err = w.Write(n.Name); err != nil {
return
}
}
if n.HasMime() {
util.Uint8toBytes(header[0:1], n.MimeSize)
if _, err = w.Write(header[0:1]); err != nil {
return
}
if _, err = w.Write(n.Mime); err != nil {
return
}
}
padding := NeedlePaddingSize - ((NeedleHeaderSize + n.Size + NeedleChecksumSize) % NeedlePaddingSize)
util.Uint32toBytes(header[0:NeedleChecksumSize], n.Checksum.Value())
_, err = w.Write(header[0 : NeedleChecksumSize+padding])
return n.DataSize, err
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}
return 0, fmt.Errorf("Unsupported Version! (%d)", version)
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}
func (n *Needle) Read(r io.Reader, size uint32, version Version) (ret int, err error) {
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switch version {
case Version1:
bytes := make([]byte, NeedleHeaderSize+size+NeedleChecksumSize)
if ret, err = r.Read(bytes); err != nil {
return
}
n.readNeedleHeader(bytes)
n.Data = bytes[NeedleHeaderSize : NeedleHeaderSize+size]
checksum := util.BytesToUint32(bytes[NeedleHeaderSize+size : NeedleHeaderSize+size+NeedleChecksumSize])
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if checksum != NewCRC(n.Data).Value() {
return 0, errors.New("CRC error! Data On Disk Corrupted!")
}
return
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case Version2:
if size == 0 {
return 0, nil
}
bytes := make([]byte, NeedleHeaderSize+size+NeedleChecksumSize)
if ret, err = r.Read(bytes); err != nil {
return
}
if ret != int(NeedleHeaderSize+size+NeedleChecksumSize) {
return 0, errors.New("File Entry Not Found!")
}
n.readNeedleHeader(bytes)
if n.Size != size {
return 0, fmt.Errorf("File Entry Not Found! Needle %d Memory %d", n.Size, size)
}
n.readNeedleDataVersion2(bytes[NeedleHeaderSize : NeedleHeaderSize+int(n.Size)])
checksum := util.BytesToUint32(bytes[NeedleHeaderSize+n.Size : NeedleHeaderSize+n.Size+NeedleChecksumSize])
if checksum != NewCRC(n.Data).Value() {
return 0, errors.New("CRC error! Data On Disk Corrupted!")
}
return
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}
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return 0, fmt.Errorf("Unsupported Version! (%d)", version)
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}
func (n *Needle) readNeedleHeader(bytes []byte) {
n.Cookie = util.BytesToUint32(bytes[0:4])
n.Id = util.BytesToUint64(bytes[4:12])
n.Size = util.BytesToUint32(bytes[12:NeedleHeaderSize])
}
func (n *Needle) readNeedleDataVersion2(bytes []byte) {
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index, lenBytes := 0, len(bytes)
if index < lenBytes {
n.DataSize = util.BytesToUint32(bytes[index : index+4])
index = index + 4
n.Data = bytes[index : index+int(n.DataSize)]
index = index + int(n.DataSize)
n.Flags = bytes[index]
index = index + 1
}
if index < lenBytes && n.HasName() {
n.NameSize = uint8(bytes[index])
index = index + 1
n.Name = bytes[index : index+int(n.NameSize)]
index = index + int(n.NameSize)
}
if index < lenBytes && n.HasMime() {
n.MimeSize = uint8(bytes[index])
index = index + 1
n.Mime = bytes[index : index+int(n.MimeSize)]
}
}
func ReadNeedleHeader(r *os.File, version Version) (n *Needle, bodyLength uint32, err error) {
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n = new(Needle)
if version == Version1 || version == Version2 {
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bytes := make([]byte, NeedleHeaderSize)
var count int
count, err = r.Read(bytes)
if count <= 0 || err != nil {
return nil, 0, err
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}
n.readNeedleHeader(bytes)
padding := NeedlePaddingSize - ((n.Size + NeedleHeaderSize + NeedleChecksumSize) % NeedlePaddingSize)
bodyLength = n.Size + NeedleChecksumSize + padding
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}
return
}
//n should be a needle already read the header
//the input stream will read until next file entry
func (n *Needle) ReadNeedleBody(r *os.File, version Version, bodyLength uint32) (err error) {
if bodyLength <= 0 {
return nil
}
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switch version {
case Version1:
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bytes := make([]byte, bodyLength)
if _, err = r.Read(bytes); err != nil {
return
}
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n.Data = bytes[:n.Size]
n.Checksum = NewCRC(n.Data)
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case Version2:
bytes := make([]byte, bodyLength)
if _, err = r.Read(bytes); err != nil {
return
}
n.readNeedleDataVersion2(bytes[0:n.Size])
n.Checksum = NewCRC(n.Data)
default:
err = fmt.Errorf("Unsupported Version! (%d)", version)
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}
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return
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}
func (n *Needle) IsGzipped() bool {
return n.Flags&FlagGzip > 0
}
func (n *Needle) SetGzipped() {
n.Flags = n.Flags | FlagGzip
}
func (n *Needle) HasName() bool {
return n.Flags&FlagHasName > 0
}
func (n *Needle) SetHasName() {
n.Flags = n.Flags | FlagHasName
}
func (n *Needle) HasMime() bool {
return n.Flags&FlagHasMime > 0
}
func (n *Needle) SetHasMime() {
n.Flags = n.Flags | FlagHasMime
}