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minio/pkgs/erasure/encode.go

161 lines
3.7 KiB

/*
* Mini Object Storage, (C) 2014 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.
*/
// +build amd64
package erasure
// #cgo CPPFLAGS: -Iisal/include
// #cgo LDFLAGS: isal/isa-l.a
// #include <stdlib.h>
// #include <erasure-code.h>
//
// #include "common.h"
import "C"
import (
"errors"
//"fmt"
"unsafe"
)
const (
VANDERMONDE = iota
CAUCHY = iota
)
const (
K = 10
M = 3
)
// EncoderParams is a configuration set for building an encoder. It is created using ValidateParams.
type EncoderParams struct {
k,
m,
technique int // cauchy or vandermonde matrix (RS)
}
// Encoder is an object used to encode and decode data.
type Encoder struct {
p *EncoderParams
k,
m C.int
encode_matrix,
encode_tbls,
decode_matrix,
decode_tbls *C.uint8_t
}
// ParseEncoderParams creates an EncoderParams object.
//
// k and n represent the matrix size, which corresponds to the protection level.
//
// technique is the matrix type. Valid inputs are CAUCHY (recommended) or VANDERMONDE.
func ParseEncoderParams(k, m, technique int) (*EncoderParams, error) {
if k < 1 {
return nil, errors.New("k cannot be zero")
}
if m < 1 {
return nil, errors.New("m cannot be zero")
}
if k+m > 255 {
return nil, errors.New("(k + m) cannot be bigger than Galois field GF(2^8) - 1")
}
switch technique {
case VANDERMONDE:
break
case CAUCHY:
break
default:
return nil, errors.New("Technique can be either vandermonde or cauchy")
}
return &EncoderParams{
k: k,
m: m,
technique: technique,
}, nil
}
// NewEncoder creates an encoder with a given set of parameters.
func NewEncoder(ep *EncoderParams) *Encoder {
var k = C.int(ep.k)
var m = C.int(ep.m)
var encode_matrix *C.uint8_t
var encode_tbls *C.uint8_t
C.minio_init_encoder(C.int(ep.technique), k, m, &encode_matrix,
&encode_tbls)
return &Encoder{
p: ep,
k: k,
m: m,
encode_matrix: encode_matrix,
encode_tbls: encode_tbls,
decode_matrix: nil,
decode_tbls: nil,
}
}
// Encode encodes a block of data. The input is the original data. The output
// is a 2 tuple containing (k + m) chunks of erasure encoded data and the
// length of the original object.
func (e *Encoder) Encode(block []byte) ([][]byte, int) {
var block_len = len(block)
chunk_size := int(C.minio_calc_chunk_size(e.k, C.uint32_t(block_len)))
chunk_len := chunk_size * e.p.k
pad_len := chunk_len - block_len
if pad_len > 0 {
s := make([]byte, pad_len)
// Expand with new padded blocks to the byte array
block = append(block, s...)
}
coded_len := chunk_size * e.p.m
c := make([]byte, coded_len)
block = append(block, c...)
// Allocate chunks
chunks := make([][]byte, e.p.k+e.p.m)
pointers := make([]*byte, e.p.k+e.p.m)
var i int
// Add data blocks to chunks
for i = 0; i < e.p.k; i++ {
chunks[i] = block[i*chunk_size : (i+1)*chunk_size]
pointers[i] = &chunks[i][0]
}
for i = e.p.k; i < (e.p.k + e.p.m); i++ {
chunks[i] = make([]byte, chunk_size)
pointers[i] = &chunks[i][0]
}
data := (**C.uint8_t)(unsafe.Pointer(&pointers[:e.p.k][0]))
coding := (**C.uint8_t)(unsafe.Pointer(&pointers[e.p.k:][0]))
C.ec_encode_data(C.int(chunk_size), e.k, e.m, e.encode_tbls, data,
coding)
return chunks, block_len
}