You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
119 lines
2.8 KiB
119 lines
2.8 KiB
/*
|
|
* 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 erasure1
|
|
|
|
import (
|
|
"bytes"
|
|
"encoding/binary"
|
|
"encoding/gob"
|
|
"errors"
|
|
"io"
|
|
"strconv"
|
|
)
|
|
|
|
// Version - format version
|
|
const (
|
|
Version = uint32(1)
|
|
)
|
|
|
|
// DataHeader represents the structure serialized to gob.
|
|
type DataHeader struct {
|
|
// object + block stored
|
|
Key string
|
|
// chunk index of encoded block
|
|
ChunkIndex uint8
|
|
// Original Length of the block output
|
|
OriginalLength uint32
|
|
// Data Blocks
|
|
EncoderK uint8
|
|
// Parity Blocks
|
|
EncoderM uint8
|
|
// Matrix Technique
|
|
EncoderTechnique EncoderTechnique
|
|
}
|
|
|
|
// EncoderTechnique specified the Matrix type used in encoding
|
|
type EncoderTechnique int
|
|
|
|
const (
|
|
// Vandermonde matrix type
|
|
Vandermonde EncoderTechnique = iota
|
|
// Cauchy matrix type
|
|
Cauchy
|
|
)
|
|
|
|
// validate populated header
|
|
func validateHeader(header DataHeader) error {
|
|
if header.Key == "" {
|
|
return errors.New("Empty Key")
|
|
}
|
|
|
|
if header.EncoderTechnique > 1 {
|
|
return errors.New("Invalid encoder technique")
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// Write returns error upon any failure
|
|
func Write(target io.Writer, key string, part uint8, length uint32, k, m uint8, technique EncoderTechnique, data io.Reader) error {
|
|
header := DataHeader{
|
|
Key: key,
|
|
ChunkIndex: part,
|
|
OriginalLength: length,
|
|
EncoderK: k,
|
|
EncoderM: m,
|
|
EncoderTechnique: technique,
|
|
}
|
|
|
|
if err := validateHeader(header); err != nil {
|
|
return err
|
|
}
|
|
|
|
var headerBuffer bytes.Buffer
|
|
// encode header
|
|
encoder := gob.NewEncoder(&headerBuffer)
|
|
encoder.Encode(header)
|
|
|
|
// write version
|
|
binary.Write(target, binary.LittleEndian, Version)
|
|
|
|
// write encoded header
|
|
if _, err := io.Copy(target, &headerBuffer); err != nil {
|
|
return err
|
|
}
|
|
// write data
|
|
if _, err := io.Copy(target, data); err != nil {
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// ReadHeader - read an erasure block
|
|
func ReadHeader(reader io.Reader) (dataHeader DataHeader, err error) {
|
|
versionArray := make([]byte, 4)
|
|
if err := binary.Read(reader, binary.LittleEndian, versionArray); err != nil {
|
|
return dataHeader, err
|
|
}
|
|
version := binary.LittleEndian.Uint32(versionArray)
|
|
if version > Version || version == 0 {
|
|
return dataHeader, errors.New("Unknown version: " + strconv.FormatUint(uint64(version), 10))
|
|
}
|
|
decoder := gob.NewDecoder(reader)
|
|
err = decoder.Decode(&dataHeader)
|
|
return dataHeader, err
|
|
}
|
|
|