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Magic as numbers are faster to encode and compare

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master
Anand Babu (AB) Periasamy 10 years ago
parent eab19e3ce4
commit ec36a598c9
1 changed files with 32 additions and 26 deletions
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  1. 58
      pkg/storage/donut/donut.go

58
pkg/storage/donut/donut.go
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@ -25,7 +25,7 @@ import (
DONUT v1 Spec
**********************
BlockStart [4]byte // Magic="MINI"
BlockStart [4]byte // Magic="MINI"=1229867341
VersionMajor uint16
VersionMinor uint16
VersionPatch uint16
@ -33,15 +33,21 @@ import (
Reserved uint64
GobHeaderLen uint32
GobHeader io.Reader // matches length
BlockData [4]byte // Magic="DATA"
BlockData [4]byte // Magic="DATA"=1096040772
Data io.Reader // matches length
BlockLen uint64 // length to block start
BlockEnd [4]byte // Magic="INIM"
BlockEnd [4]byte // Magic="INIM"=1229867341
*/
type DonutStructure struct {
BlockStart [4]byte // Magic="MINI"
var (
MagicMINI = binary.LittleEndian.Uint32([]byte{'M', 'I', 'N', 'I'})
MagicDATA = binary.LittleEndian.Uint32([]byte{'D', 'A', 'T', 'A'})
MagicINIM = binary.LittleEndian.Uint32([]byte{'I', 'N', 'I', 'M'})
)
type DonutFormat struct {
BlockStart uint32 // Magic="MINI"=1229867341
VersionMajor uint16
VersionMinor uint16
VersionPatch uint16
@ -49,15 +55,15 @@ type DonutStructure struct {
Reserved uint64
GobHeaderLen uint32
GobHeader GobHeader
BlockData [4]byte
BlockData uint32 // Magic="DATA"=1096040772
Data io.Reader
BlockLen uint64
BlockEnd [4]byte
BlockEnd uint32
}
type DonutFooter struct {
BlockLen uint64
BlockEnd uint32 // Magic="INIM"
BlockEnd uint32 // Magic="INIM"=1229867341
}
type Donut struct {
@ -70,8 +76,8 @@ type GobHeader struct{}
func (donut *Donut) Write(gobHeader GobHeader, object io.Reader) error {
// TODO mutex
// Create bytes buffer representing the new object
donutStructure := DonutStructure{
BlockStart: [4]byte{'M', 'I', 'N', 'I'},
donutFormat := DonutFormat{
BlockStart: MagicMINI,
VersionMajor: 1,
VersionMinor: 0,
VersionPatch: 0,
@ -79,30 +85,30 @@ func (donut *Donut) Write(gobHeader GobHeader, object io.Reader) error {
Reserved: 0,
GobHeaderLen: 0,
GobHeader: gobHeader,
BlockData: [4]byte{'D', 'A', 'T', 'A'},
BlockData: MagicDATA,
Data: object,
BlockLen: 0,
BlockEnd: [4]byte{'I', 'N', 'I', 'M'},
BlockEnd: MagicINIM,
}
if err := donut.WriteStructure(donut.file, donutStructure); err != nil {
if err := donut.WriteFormat(donut.file, donutFormat); err != nil {
return err
}
return nil
}
func (donut *Donut) WriteStructure(target io.Writer, donutStructure DonutStructure) error {
err := binary.Write(target, binary.LittleEndian, donutStructure.BlockStart)
err = binary.Write(target, binary.LittleEndian, donutStructure.VersionMajor)
err = binary.Write(target, binary.LittleEndian, donutStructure.VersionMinor)
err = binary.Write(target, binary.LittleEndian, donutStructure.VersionPatch)
err = binary.Write(target, binary.LittleEndian, donutStructure.VersionReserved)
err = binary.Write(target, binary.LittleEndian, donutStructure.Reserved)
err = binary.Write(target, binary.LittleEndian, donutStructure.GobHeaderLen)
err = binary.Write(target, binary.LittleEndian, donutStructure.GobHeader)
err = binary.Write(target, binary.LittleEndian, donutStructure.BlockData)
err = binary.Write(target, binary.LittleEndian, donutStructure.Data)
err = binary.Write(target, binary.LittleEndian, donutStructure.BlockLen)
err = binary.Write(target, binary.LittleEndian, donutStructure.BlockEnd)
func (donut *Donut) WriteFormat(target io.Writer, donutFormat DonutFormat) error {
err := binary.Write(target, binary.LittleEndian, donutFormat.BlockStart)
err = binary.Write(target, binary.LittleEndian, donutFormat.VersionMajor)
err = binary.Write(target, binary.LittleEndian, donutFormat.VersionMinor)
err = binary.Write(target, binary.LittleEndian, donutFormat.VersionPatch)
err = binary.Write(target, binary.LittleEndian, donutFormat.VersionReserved)
err = binary.Write(target, binary.LittleEndian, donutFormat.Reserved)
err = binary.Write(target, binary.LittleEndian, donutFormat.GobHeaderLen)
err = binary.Write(target, binary.LittleEndian, donutFormat.GobHeader)
err = binary.Write(target, binary.LittleEndian, donutFormat.BlockData)
err = binary.Write(target, binary.LittleEndian, donutFormat.Data)
err = binary.Write(target, binary.LittleEndian, donutFormat.BlockLen)
err = binary.Write(target, binary.LittleEndian, donutFormat.BlockEnd)
return err
}

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