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minio/pkg/donut/encoder.go

91 lines
2.5 KiB

/*
* Minio Cloud 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 (
encoding "github.com/minio/minio/pkg/erasure"
"github.com/minio/minio/pkg/probe"
)
// encoder internal struct
type encoder struct {
encoder *encoding.Erasure
k, m uint8
technique encoding.Technique
}
// getErasureTechnique - convert technique string into Technique type
func getErasureTechnique(technique string) (encoding.Technique, *probe.Error) {
switch true {
case technique == "Cauchy":
return encoding.Cauchy, nil
case technique == "Vandermonde":
return encoding.Cauchy, nil
default:
return encoding.None, probe.NewError(InvalidErasureTechnique{Technique: technique})
}
}
// newEncoder - instantiate a new encoder
func newEncoder(k, m uint8, technique string) (encoder, *probe.Error) {
e := encoder{}
t, err := getErasureTechnique(technique)
if err != nil {
return encoder{}, err.Trace()
}
{
params, err := encoding.ValidateParams(k, m, t)
if err != nil {
return encoder{}, probe.NewError(err)
}
e.encoder = encoding.NewErasure(params)
e.k = k
e.m = m
e.technique = t
return e, nil
}
}
// TODO - think again if this is needed
// GetEncodedBlockLen - wrapper around erasure function with the same name
func (e encoder) GetEncodedBlockLen(dataLength int) (int, *probe.Error) {
if dataLength <= 0 {
return 0, probe.NewError(InvalidArgument{})
}
return encoding.GetEncodedBlockLen(dataLength, e.k), nil
}
// Encode - erasure code input bytes
func (e encoder) Encode(data []byte) ([][]byte, *probe.Error) {
if data == nil {
return nil, probe.NewError(InvalidArgument{})
}
encodedData, err := e.encoder.Encode(data)
if err != nil {
return nil, probe.NewError(err)
}
return encodedData, nil
}
// Decode - erasure decode input encoded bytes
func (e encoder) Decode(encodedData [][]byte, dataLength int) ([]byte, *probe.Error) {
decodedData, err := e.encoder.Decode(encodedData, dataLength)
if err != nil {
return nil, probe.NewError(err)
}
return decodedData, nil
}