minio/cmd/erasure-decode_test.go
2019-02-13 18:29:36 +05:30

393 lines
21 KiB
Go

/*
* Minio Cloud Storage, (C) 2016, 2017 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 cmd
import (
"bytes"
"context"
"io"
"math/rand"
"testing"
crand "crypto/rand"
humanize "github.com/dustin/go-humanize"
)
func (a badDisk) ReadFile(volume string, path string, offset int64, buf []byte, verifier *BitrotVerifier) (n int64, err error) {
return 0, errFaultyDisk
}
var erasureDecodeTests = []struct {
dataBlocks int
onDisks, offDisks int
blocksize, data int64
offset int64
length int64
algorithm BitrotAlgorithm
shouldFail, shouldFailQuorum bool
}{
{dataBlocks: 2, onDisks: 4, offDisks: 0, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false}, // 0
{dataBlocks: 3, onDisks: 6, offDisks: 0, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: SHA256, shouldFail: false, shouldFailQuorum: false}, // 1
{dataBlocks: 4, onDisks: 8, offDisks: 0, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 2
{dataBlocks: 5, onDisks: 10, offDisks: 0, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 1, length: oneMiByte - 1, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false}, // 3
{dataBlocks: 6, onDisks: 12, offDisks: 0, blocksize: int64(oneMiByte), data: oneMiByte, offset: oneMiByte, length: 0, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false},
// 4
{dataBlocks: 7, onDisks: 14, offDisks: 0, blocksize: int64(oneMiByte), data: oneMiByte, offset: 3, length: 1024, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 5
{dataBlocks: 8, onDisks: 16, offDisks: 0, blocksize: int64(oneMiByte), data: oneMiByte, offset: 4, length: 8 * 1024, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 6
{dataBlocks: 7, onDisks: 14, offDisks: 7, blocksize: int64(blockSizeV1), data: oneMiByte, offset: oneMiByte, length: 1, algorithm: DefaultBitrotAlgorithm, shouldFail: true, shouldFailQuorum: false}, // 7
{dataBlocks: 6, onDisks: 12, offDisks: 6, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 8
{dataBlocks: 5, onDisks: 10, offDisks: 5, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false}, // 9
{dataBlocks: 4, onDisks: 8, offDisks: 4, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: SHA256, shouldFail: false, shouldFailQuorum: false}, // 10
{dataBlocks: 3, onDisks: 6, offDisks: 3, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 11
{dataBlocks: 2, onDisks: 4, offDisks: 2, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 12
{dataBlocks: 2, onDisks: 4, offDisks: 1, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 13
{dataBlocks: 3, onDisks: 6, offDisks: 2, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 14
{dataBlocks: 4, onDisks: 8, offDisks: 3, blocksize: int64(2 * oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 15
{dataBlocks: 5, onDisks: 10, offDisks: 6, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: true}, // 16
{dataBlocks: 5, onDisks: 10, offDisks: 2, blocksize: int64(blockSizeV1), data: 2 * oneMiByte, offset: oneMiByte, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 17
{dataBlocks: 5, onDisks: 10, offDisks: 1, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false}, // 18
{dataBlocks: 6, onDisks: 12, offDisks: 3, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: SHA256, shouldFail: false, shouldFailQuorum: false},
// 19
{dataBlocks: 6, onDisks: 12, offDisks: 7, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: true}, // 20
{dataBlocks: 8, onDisks: 16, offDisks: 8, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 21
{dataBlocks: 8, onDisks: 16, offDisks: 9, blocksize: int64(oneMiByte), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: true}, // 22
{dataBlocks: 8, onDisks: 16, offDisks: 7, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 23
{dataBlocks: 2, onDisks: 4, offDisks: 1, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 24
{dataBlocks: 2, onDisks: 4, offDisks: 0, blocksize: int64(blockSizeV1), data: oneMiByte, offset: 0, length: oneMiByte, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 25
{dataBlocks: 2, onDisks: 4, offDisks: 0, blocksize: int64(blockSizeV1), data: int64(blockSizeV1) + 1, offset: 0, length: int64(blockSizeV1) + 1, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false}, // 26
{dataBlocks: 2, onDisks: 4, offDisks: 0, blocksize: int64(blockSizeV1), data: int64(2 * blockSizeV1), offset: 12, length: int64(blockSizeV1) + 17, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false}, // 27
{dataBlocks: 3, onDisks: 6, offDisks: 0, blocksize: int64(blockSizeV1), data: int64(2 * blockSizeV1), offset: 1023, length: int64(blockSizeV1) + 1024, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 28
{dataBlocks: 4, onDisks: 8, offDisks: 0, blocksize: int64(blockSizeV1), data: int64(2 * blockSizeV1), offset: 11, length: int64(blockSizeV1) + 2*1024, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 29
{dataBlocks: 6, onDisks: 12, offDisks: 0, blocksize: int64(blockSizeV1), data: int64(2 * blockSizeV1), offset: 512, length: int64(blockSizeV1) + 8*1024, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 30
{dataBlocks: 8, onDisks: 16, offDisks: 0, blocksize: int64(blockSizeV1), data: int64(2 * blockSizeV1), offset: int64(blockSizeV1), length: int64(blockSizeV1) - 1, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 31
{dataBlocks: 2, onDisks: 4, offDisks: 0, blocksize: int64(blockSizeV1), data: int64(oneMiByte), offset: -1, length: 3, algorithm: DefaultBitrotAlgorithm, shouldFail: true, shouldFailQuorum: false}, // 32
{dataBlocks: 2, onDisks: 4, offDisks: 0, blocksize: int64(blockSizeV1), data: int64(oneMiByte), offset: 1024, length: -1, algorithm: DefaultBitrotAlgorithm, shouldFail: true, shouldFailQuorum: false}, // 33
{dataBlocks: 4, onDisks: 6, offDisks: 0, blocksize: int64(blockSizeV1), data: int64(blockSizeV1), offset: 0, length: int64(blockSizeV1), algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false}, // 34
{dataBlocks: 4, onDisks: 6, offDisks: 1, blocksize: int64(blockSizeV1), data: int64(2 * blockSizeV1), offset: 12, length: int64(blockSizeV1) + 17, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false}, // 35
{dataBlocks: 4, onDisks: 6, offDisks: 3, blocksize: int64(blockSizeV1), data: int64(2 * blockSizeV1), offset: 1023, length: int64(blockSizeV1) + 1024, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: true}, // 36
{dataBlocks: 8, onDisks: 12, offDisks: 4, blocksize: int64(blockSizeV1), data: int64(2 * blockSizeV1), offset: 11, length: int64(blockSizeV1) + 2*1024, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false}, // 37
}
func TestErasureDecode(t *testing.T) {
for i, test := range erasureDecodeTests {
setup, err := newErasureTestSetup(test.dataBlocks, test.onDisks-test.dataBlocks, test.blocksize)
if err != nil {
t.Fatalf("Test %d: failed to create test setup: %v", i, err)
}
erasure, err := NewErasure(context.Background(), test.dataBlocks, test.onDisks-test.dataBlocks, test.blocksize)
if err != nil {
setup.Remove()
t.Fatalf("Test %d: failed to create ErasureStorage: %v", i, err)
}
disks := setup.disks
data := make([]byte, test.data)
if _, err = io.ReadFull(crand.Reader, data); err != nil {
setup.Remove()
t.Fatalf("Test %d: failed to generate random test data: %v", i, err)
}
writeAlgorithm := test.algorithm
if !test.algorithm.Available() {
writeAlgorithm = DefaultBitrotAlgorithm
}
buffer := make([]byte, test.blocksize, 2*test.blocksize)
writers := make([]io.Writer, len(disks))
for i, disk := range disks {
writers[i] = newBitrotWriter(disk, "testbucket", "object", erasure.ShardFileSize(test.data), writeAlgorithm, erasure.ShardSize())
}
n, err := erasure.Encode(context.Background(), bytes.NewReader(data[:]), writers, buffer, erasure.dataBlocks+1)
closeBitrotWriters(writers)
if err != nil {
setup.Remove()
t.Fatalf("Test %d: failed to create erasure test file: %v", i, err)
}
if n != test.data {
setup.Remove()
t.Fatalf("Test %d: failed to create erasure test file", i)
}
for i, w := range writers {
if w == nil {
disks[i] = nil
}
}
// Get the checksums of the current part.
bitrotReaders := make([]io.ReaderAt, len(disks))
for index, disk := range disks {
if disk == OfflineDisk {
continue
}
tillOffset := erasure.ShardFileTillOffset(test.offset, test.length, test.data)
bitrotReaders[index] = newBitrotReader(disk, "testbucket", "object", tillOffset, writeAlgorithm, bitrotWriterSum(writers[index]), erasure.ShardSize())
}
writer := bytes.NewBuffer(nil)
err = erasure.Decode(context.Background(), writer, bitrotReaders, test.offset, test.length, test.data)
closeBitrotReaders(bitrotReaders)
if err != nil && !test.shouldFail {
t.Errorf("Test %d: should pass but failed with: %v", i, err)
}
if err == nil && test.shouldFail {
t.Errorf("Test %d: should fail but it passed", i)
}
if err == nil {
if content := writer.Bytes(); !bytes.Equal(content, data[test.offset:test.offset+test.length]) {
t.Errorf("Test %d: read retruns wrong file content.", i)
}
}
for i, r := range bitrotReaders {
if r == nil {
disks[i] = OfflineDisk
}
}
if err == nil && !test.shouldFail {
bitrotReaders = make([]io.ReaderAt, len(disks))
for index, disk := range disks {
if disk == OfflineDisk {
continue
}
tillOffset := erasure.ShardFileTillOffset(test.offset, test.length, test.data)
bitrotReaders[index] = newBitrotReader(disk, "testbucket", "object", tillOffset, writeAlgorithm, bitrotWriterSum(writers[index]), erasure.ShardSize())
}
for j := range disks[:test.offDisks] {
if bitrotReaders[j] == nil {
continue
}
switch r := bitrotReaders[j].(type) {
case *wholeBitrotReader:
r.disk = badDisk{nil}
case *streamingBitrotReader:
r.disk = badDisk{nil}
}
}
if test.offDisks > 0 {
bitrotReaders[0] = nil
}
writer.Reset()
err = erasure.Decode(context.Background(), writer, bitrotReaders, test.offset, test.length, test.data)
closeBitrotReaders(bitrotReaders)
if err != nil && !test.shouldFailQuorum {
t.Errorf("Test %d: should pass but failed with: %v", i, err)
}
if err == nil && test.shouldFailQuorum {
t.Errorf("Test %d: should fail but it passed", i)
}
if !test.shouldFailQuorum {
if content := writer.Bytes(); !bytes.Equal(content, data[test.offset:test.offset+test.length]) {
t.Errorf("Test %d: read retruns wrong file content", i)
}
}
}
setup.Remove()
}
}
// Test erasureDecode with random offset and lengths.
// This test is t.Skip()ed as it a long time to run, hence should be run
// explicitly after commenting out t.Skip()
func TestErasureDecodeRandomOffsetLength(t *testing.T) {
// Comment the following line to run this test.
t.SkipNow()
// Initialize environment needed for the test.
dataBlocks := 7
parityBlocks := 7
blockSize := int64(1 * humanize.MiByte)
setup, err := newErasureTestSetup(dataBlocks, parityBlocks, blockSize)
if err != nil {
t.Error(err)
return
}
defer setup.Remove()
disks := setup.disks
erasure, err := NewErasure(context.Background(), dataBlocks, parityBlocks, blockSize)
if err != nil {
t.Fatalf("failed to create ErasureStorage: %v", err)
}
// Prepare a slice of 5MiB with random data.
data := make([]byte, 5*humanize.MiByte)
length := int64(len(data))
_, err = rand.Read(data)
if err != nil {
t.Fatal(err)
}
writers := make([]io.Writer, len(disks))
for i, disk := range disks {
if disk == nil {
continue
}
writers[i] = newBitrotWriter(disk, "testbucket", "object", erasure.ShardFileSize(length), DefaultBitrotAlgorithm, erasure.ShardSize())
}
// 10000 iterations with random offsets and lengths.
iterations := 10000
// Create a test file to read from.
buffer := make([]byte, blockSize, 2*blockSize)
n, err := erasure.Encode(context.Background(), bytes.NewReader(data), writers, buffer, erasure.dataBlocks+1)
closeBitrotWriters(writers)
if err != nil {
t.Fatal(err)
}
if n != length {
t.Errorf("erasureCreateFile returned %d, expected %d", n, length)
}
// To generate random offset/length.
r := rand.New(rand.NewSource(UTCNow().UnixNano()))
buf := &bytes.Buffer{}
// Verify erasure.Decode() for random offsets and lengths.
for i := 0; i < iterations; i++ {
offset := r.Int63n(length)
readLen := r.Int63n(length - offset)
expected := data[offset : offset+readLen]
// Get the checksums of the current part.
bitrotReaders := make([]io.ReaderAt, len(disks))
for index, disk := range disks {
if disk == OfflineDisk {
continue
}
tillOffset := erasure.ShardFileTillOffset(offset, readLen, length)
bitrotReaders[index] = newStreamingBitrotReader(disk, "testbucket", "object", tillOffset, DefaultBitrotAlgorithm, erasure.ShardSize())
}
err = erasure.Decode(context.Background(), buf, bitrotReaders, offset, readLen, length)
closeBitrotReaders(bitrotReaders)
if err != nil {
t.Fatal(err, offset, readLen)
}
got := buf.Bytes()
if !bytes.Equal(expected, got) {
t.Fatalf("read data is different from what was expected, offset=%d length=%d", offset, readLen)
}
buf.Reset()
}
}
// Benchmarks
func benchmarkErasureDecode(data, parity, dataDown, parityDown int, size int64, b *testing.B) {
setup, err := newErasureTestSetup(data, parity, blockSizeV1)
if err != nil {
b.Fatalf("failed to create test setup: %v", err)
}
defer setup.Remove()
disks := setup.disks
erasure, err := NewErasure(context.Background(), data, parity, blockSizeV1)
if err != nil {
b.Fatalf("failed to create ErasureStorage: %v", err)
}
writers := make([]io.Writer, len(disks))
for i, disk := range disks {
if disk == nil {
continue
}
writers[i] = newBitrotWriter(disk, "testbucket", "object", erasure.ShardFileSize(size), DefaultBitrotAlgorithm, erasure.ShardSize())
}
content := make([]byte, size)
buffer := make([]byte, blockSizeV1, 2*blockSizeV1)
_, err = erasure.Encode(context.Background(), bytes.NewReader(content), writers, buffer, erasure.dataBlocks+1)
closeBitrotWriters(writers)
if err != nil {
b.Fatalf("failed to create erasure test file: %v", err)
}
for i := 0; i < dataDown; i++ {
writers[i] = nil
}
for i := data; i < data+parityDown; i++ {
writers[i] = nil
}
b.ResetTimer()
b.SetBytes(size)
b.ReportAllocs()
for i := 0; i < b.N; i++ {
bitrotReaders := make([]io.ReaderAt, len(disks))
for index, disk := range disks {
if writers[index] == nil {
continue
}
tillOffset := erasure.ShardFileTillOffset(0, size, size)
bitrotReaders[index] = newStreamingBitrotReader(disk, "testbucket", "object", tillOffset, DefaultBitrotAlgorithm, erasure.ShardSize())
}
if err = erasure.Decode(context.Background(), bytes.NewBuffer(content[:0]), bitrotReaders, 0, size, size); err != nil {
panic(err)
}
closeBitrotReaders(bitrotReaders)
}
}
func BenchmarkErasureDecodeQuick(b *testing.B) {
const size = 12 * 1024 * 1024
b.Run(" 00|00 ", func(b *testing.B) { benchmarkErasureDecode(2, 2, 0, 0, size, b) })
b.Run(" 00|X0 ", func(b *testing.B) { benchmarkErasureDecode(2, 2, 0, 1, size, b) })
b.Run(" X0|00 ", func(b *testing.B) { benchmarkErasureDecode(2, 2, 1, 0, size, b) })
b.Run(" X0|X0 ", func(b *testing.B) { benchmarkErasureDecode(2, 2, 1, 1, size, b) })
}
func BenchmarkErasureDecode_4_64KB(b *testing.B) {
const size = 64 * 1024
b.Run(" 00|00 ", func(b *testing.B) { benchmarkErasureDecode(2, 2, 0, 0, size, b) })
b.Run(" 00|X0 ", func(b *testing.B) { benchmarkErasureDecode(2, 2, 0, 1, size, b) })
b.Run(" X0|00 ", func(b *testing.B) { benchmarkErasureDecode(2, 2, 1, 0, size, b) })
b.Run(" X0|X0 ", func(b *testing.B) { benchmarkErasureDecode(2, 2, 1, 1, size, b) })
b.Run(" 00|XX ", func(b *testing.B) { benchmarkErasureDecode(2, 2, 0, 2, size, b) })
b.Run(" XX|00 ", func(b *testing.B) { benchmarkErasureDecode(2, 2, 2, 0, size, b) })
}
func BenchmarkErasureDecode_8_20MB(b *testing.B) {
const size = 20 * 1024 * 1024
b.Run(" 0000|0000 ", func(b *testing.B) { benchmarkErasureDecode(4, 4, 0, 0, size, b) })
b.Run(" 0000|X000 ", func(b *testing.B) { benchmarkErasureDecode(4, 4, 0, 1, size, b) })
b.Run(" X000|0000 ", func(b *testing.B) { benchmarkErasureDecode(4, 4, 1, 0, size, b) })
b.Run(" X000|X000 ", func(b *testing.B) { benchmarkErasureDecode(4, 4, 1, 1, size, b) })
b.Run(" 0000|XXXX ", func(b *testing.B) { benchmarkErasureDecode(4, 4, 0, 4, size, b) })
b.Run(" XX00|XX00 ", func(b *testing.B) { benchmarkErasureDecode(4, 4, 2, 2, size, b) })
b.Run(" XXXX|0000 ", func(b *testing.B) { benchmarkErasureDecode(4, 4, 4, 0, size, b) })
}
func BenchmarkErasureDecode_12_30MB(b *testing.B) {
const size = 30 * 1024 * 1024
b.Run(" 000000|000000 ", func(b *testing.B) { benchmarkErasureDecode(6, 6, 0, 0, size, b) })
b.Run(" 000000|X00000 ", func(b *testing.B) { benchmarkErasureDecode(6, 6, 0, 1, size, b) })
b.Run(" X00000|000000 ", func(b *testing.B) { benchmarkErasureDecode(6, 6, 1, 0, size, b) })
b.Run(" X00000|X00000 ", func(b *testing.B) { benchmarkErasureDecode(6, 6, 1, 1, size, b) })
b.Run(" 000000|XXXXXX ", func(b *testing.B) { benchmarkErasureDecode(6, 6, 0, 6, size, b) })
b.Run(" XXX000|XXX000 ", func(b *testing.B) { benchmarkErasureDecode(6, 6, 3, 3, size, b) })
b.Run(" XXXXXX|000000 ", func(b *testing.B) { benchmarkErasureDecode(6, 6, 6, 0, size, b) })
}
func BenchmarkErasureDecode_16_40MB(b *testing.B) {
const size = 40 * 1024 * 1024
b.Run(" 00000000|00000000 ", func(b *testing.B) { benchmarkErasureDecode(8, 8, 0, 0, size, b) })
b.Run(" 00000000|X0000000 ", func(b *testing.B) { benchmarkErasureDecode(8, 8, 0, 1, size, b) })
b.Run(" X0000000|00000000 ", func(b *testing.B) { benchmarkErasureDecode(8, 8, 1, 0, size, b) })
b.Run(" X0000000|X0000000 ", func(b *testing.B) { benchmarkErasureDecode(8, 8, 1, 1, size, b) })
b.Run(" 00000000|XXXXXXXX ", func(b *testing.B) { benchmarkErasureDecode(8, 8, 0, 8, size, b) })
b.Run(" XXXX0000|XXXX0000 ", func(b *testing.B) { benchmarkErasureDecode(8, 8, 4, 4, size, b) })
b.Run(" XXXXXXXX|00000000 ", func(b *testing.B) { benchmarkErasureDecode(8, 8, 8, 0, size, b) })
}