Add erasure package in its full form v1.0

pkg/storage/erasure/erasure_encode.go

@@ -0,0 +1,157 @@
+/*
+ * 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 CFLAGS: -O0
+// #include <stdlib.h>
+// #include "ec-code.h"
+// #include "ec-common.h"
+import "C"
+import (
+	"errors"
+	"unsafe"
+)
+
+const (
+	VANDERMONDE = iota
+	CAUCHY
+)
+
+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
+}