Donut structure refined
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ab80c0ce12
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1 changed files with 34 additions and 68 deletions
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@ -17,42 +17,39 @@
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package donut
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import (
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"bytes"
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"encoding/binary"
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"encoding/gob"
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"io"
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)
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/*
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** DONUT v1 Spec **
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BlockStart uint32 // Magic="MINI"
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BlockStart [4]byte // Magic="MINI"
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VersionMajor uint16
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VersionMinor uint16
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VersionPatch uint16
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VersionReserved uint16
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Reserved uint64
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GobHeaderLen uint32
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GobHeader Sizeof(GobHeader)
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BlockData uint32 // Magic="DATA"
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Data []byte
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BlockLen uint64
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BlockEnd uint32 // Magic="INIM"
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GobHeader io.Reader // matches length
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BlockData [4]byte // Magic="DATA"
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Data io.Reader // matches length
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BlockLen uint64 // length to block start
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BlockEnd [4]byte // Magic="INIM"
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*/
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type DonutHeader struct {
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BlockStart uint32 // Magic="MINI"
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type DonutStructure struct {
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BlockStart [4]byte // Magic="MINI"
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VersionMajor uint16
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VersionMinor uint16
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VersionPatch uint16
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VersionReserved uint16
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Reserved uint64
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GobHeaderLen uint32
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}
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type DonutGobHeader struct {
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DataLen uint64
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GobHeader GobHeader
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BlockData [4]byte
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Data io.Reader
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BlockLen uint64
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BlockEnd [4]byte
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}
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type DonutFooter struct {
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@ -62,63 +59,32 @@ type DonutFooter struct {
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type Donut struct {
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file io.Writer
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// mutex
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}
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func (donut Donut) Write(header Header, object io.Reader) error {
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var newObjectBuffer bytes.Buffer
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var headerBuffer bytes.Buffer
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type GobHeader struct{}
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// create gob header
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headerEncoder := gob.NewEncoder(&headerBuffer)
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err := headerEncoder.Encode(header)
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if err != nil {
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return err
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func (donut *Donut) Write(gobHeader GobHeader, object io.Reader) error {
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// TODO mutex
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// Create bytes buffer representing the new object
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donutStructure := DonutStructure{
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BlockStart: [4]byte{'M', 'I', 'N', 'I'},
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VersionMajor: 1,
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VersionMinor: 0,
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VersionPatch: 0,
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VersionReserved: 0,
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Reserved: 0,
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GobHeaderLen: 0,
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GobHeader: gobHeader,
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BlockData: [4]byte{'D', 'A', 'T', 'A'},
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Data: object,
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BlockLen: 0,
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BlockEnd: [4]byte{'I', 'N', 'I', 'M'},
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}
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// prefix consists of a version number and a length
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var headerPrefixBuffer bytes.Buffer
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// write version
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var version int
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version = 1
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err = binary.Write(&headerPrefixBuffer, binary.LittleEndian, version)
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if err != nil {
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return err
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}
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// write length
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var headerLength int
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headerLength = headerBuffer.Len()
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err = binary.Write(&headerPrefixBuffer, binary.LittleEndian, headerLength)
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if err != nil {
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return err
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}
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// write header prefix
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io.Copy(&newObjectBuffer, &headerPrefixBuffer)
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// write header
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io.Copy(&newObjectBuffer, &headerBuffer)
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// write header marker
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// TODO
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// write data
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_, err = io.Copy(&newObjectBuffer, object)
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if err != nil {
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return err
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}
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// write footer
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// TODO
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// write footer marker
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// TODO
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// write new object
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_, err = io.Copy(donut.file, &newObjectBuffer)
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if err != nil {
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if err := WriteStructure(donut.file, donutStructure); err != nil {
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return err
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}
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return nil
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}
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func WriteStructure(target io.Writer, donutStructure DonutStructure) error { return nil }
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