minio/pkg/storage/donut/donut.go
Anand Babu (AB) Periasamy 9e304b53de donut spec v1 prototype
2015-02-18 15:52:12 -08:00

125 lines
2.6 KiB
Go

/*
* Mini Object Storage, (C) 2015 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package donut
import (
"bytes"
"encoding/binary"
"encoding/gob"
"io"
)
/*
** DONUT v1 Spec **
BlockStart uint32 // Magic="MINI"
VersionMajor uint16
VersionMinor uint16
VersionPatch uint16
VersionReserved uint16
Reserved uint64
GobHeaderLen uint32
GobHeader Sizeof(GobHeader)
BlockData uint32 // Magic="DATA"
Data []byte
BlockLen uint64
BlockEnd uint32 // Magic="INIM"
*/
type DonutHeader struct {
BlockStart uint32 // Magic="MINI"
VersionMajor uint16
VersionMinor uint16
VersionPatch uint16
VersionReserved uint16
Reserved uint64
GobHeaderLen uint32
}
type DonutGobHeader struct {
DataLen uint64
}
type DonutFooter struct {
BlockLen uint64
BlockEnd uint32 // Magic="INIM"
}
type Donut struct {
file io.Writer
}
func (donut Donut) Write(header Header, object io.Reader) error {
var newObjectBuffer bytes.Buffer
var headerBuffer bytes.Buffer
// create gob header
headerEncoder := gob.NewEncoder(&headerBuffer)
err := headerEncoder.Encode(header)
if err != nil {
return err
}
// prefix consists of a version number and a length
var headerPrefixBuffer bytes.Buffer
// write version
var version int
version = 1
err = binary.Write(&headerPrefixBuffer, binary.LittleEndian, version)
if err != nil {
return err
}
// write length
var headerLength int
headerLength = headerBuffer.Len()
err = binary.Write(&headerPrefixBuffer, binary.LittleEndian, headerLength)
if err != nil {
return err
}
// write header prefix
io.Copy(&newObjectBuffer, &headerPrefixBuffer)
// write header
io.Copy(&newObjectBuffer, &headerBuffer)
// write header marker
// TODO
// write data
_, err = io.Copy(&newObjectBuffer, object)
if err != nil {
return err
}
// write footer
// TODO
// write footer marker
// TODO
// write new object
_, err = io.Copy(donut.file, &newObjectBuffer)
if err != nil {
return err
}
return nil
}