plugeth/swarm/bmt/bmt_test.go

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// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package bmt
import (
"bytes"
"encoding/binary"
"fmt"
"math/rand"
"sync"
"sync/atomic"
"testing"
"time"
"github.com/ethereum/go-ethereum/swarm/testutil"
"golang.org/x/crypto/sha3"
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)
// the actual data length generated (could be longer than max datalength of the BMT)
const BufferSize = 4128
const (
// segmentCount is the maximum number of segments of the underlying chunk
// Should be equal to max-chunk-data-size / hash-size
// Currently set to 128 == 4096 (default chunk size) / 32 (sha3.keccak256 size)
segmentCount = 128
)
var counts = []int{1, 2, 3, 4, 5, 8, 9, 15, 16, 17, 32, 37, 42, 53, 63, 64, 65, 111, 127, 128}
// calculates the Keccak256 SHA3 hash of the data
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func sha3hash(data ...[]byte) []byte {
h := sha3.NewLegacyKeccak256()
return doSum(h, nil, data...)
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}
// TestRefHasher tests that the RefHasher computes the expected BMT hash for
// some small data lengths
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func TestRefHasher(t *testing.T) {
// the test struct is used to specify the expected BMT hash for
// segment counts between from and to and lengths from 1 to datalength
type test struct {
from int
to int
expected func([]byte) []byte
}
var tests []*test
// all lengths in [0,64] should be:
//
// sha3hash(data)
//
tests = append(tests, &test{
from: 1,
to: 2,
expected: func(d []byte) []byte {
data := make([]byte, 64)
copy(data, d)
return sha3hash(data)
},
})
// all lengths in [3,4] should be:
//
// sha3hash(
// sha3hash(data[:64])
// sha3hash(data[64:])
// )
//
tests = append(tests, &test{
from: 3,
to: 4,
expected: func(d []byte) []byte {
data := make([]byte, 128)
copy(data, d)
return sha3hash(sha3hash(data[:64]), sha3hash(data[64:]))
},
})
// all segmentCounts in [5,8] should be:
//
// sha3hash(
// sha3hash(
// sha3hash(data[:64])
// sha3hash(data[64:128])
// )
// sha3hash(
// sha3hash(data[128:192])
// sha3hash(data[192:])
// )
// )
//
tests = append(tests, &test{
from: 5,
to: 8,
expected: func(d []byte) []byte {
data := make([]byte, 256)
copy(data, d)
return sha3hash(sha3hash(sha3hash(data[:64]), sha3hash(data[64:128])), sha3hash(sha3hash(data[128:192]), sha3hash(data[192:])))
},
})
// run the tests
for i, x := range tests {
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for segmentCount := x.from; segmentCount <= x.to; segmentCount++ {
for length := 1; length <= segmentCount*32; length++ {
t.Run(fmt.Sprintf("%d_segments_%d_bytes", segmentCount, length), func(t *testing.T) {
data := testutil.RandomBytes(i, length)
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expected := x.expected(data)
actual := NewRefHasher(sha3.NewLegacyKeccak256, segmentCount).Hash(data)
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if !bytes.Equal(actual, expected) {
t.Fatalf("expected %x, got %x", expected, actual)
}
})
}
}
}
}
// tests if hasher responds with correct hash comparing the reference implementation return value
func TestHasherEmptyData(t *testing.T) {
hasher := sha3.NewLegacyKeccak256
var data []byte
for _, count := range counts {
t.Run(fmt.Sprintf("%d_segments", count), func(t *testing.T) {
pool := NewTreePool(hasher, count, PoolSize)
defer pool.Drain(0)
bmt := New(pool)
rbmt := NewRefHasher(hasher, count)
refHash := rbmt.Hash(data)
expHash := syncHash(bmt, nil, data)
if !bytes.Equal(expHash, refHash) {
t.Fatalf("hash mismatch with reference. expected %x, got %x", refHash, expHash)
}
})
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}
}
// tests sequential write with entire max size written in one go
func TestSyncHasherCorrectness(t *testing.T) {
data := testutil.RandomBytes(1, BufferSize)
hasher := sha3.NewLegacyKeccak256
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size := hasher().Size()
var err error
for _, count := range counts {
t.Run(fmt.Sprintf("segments_%v", count), func(t *testing.T) {
max := count * size
var incr int
capacity := 1
pool := NewTreePool(hasher, count, capacity)
defer pool.Drain(0)
for n := 0; n <= max; n += incr {
incr = 1 + rand.Intn(5)
bmt := New(pool)
err = testHasherCorrectness(bmt, hasher, data, n, count)
if err != nil {
t.Fatal(err)
}
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}
})
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}
}
// tests order-neutral concurrent writes with entire max size written in one go
func TestAsyncCorrectness(t *testing.T) {
data := testutil.RandomBytes(1, BufferSize)
hasher := sha3.NewLegacyKeccak256
size := hasher().Size()
whs := []whenHash{first, last, random}
for _, double := range []bool{false, true} {
for _, wh := range whs {
for _, count := range counts {
t.Run(fmt.Sprintf("double_%v_hash_when_%v_segments_%v", double, wh, count), func(t *testing.T) {
max := count * size
var incr int
capacity := 1
pool := NewTreePool(hasher, count, capacity)
defer pool.Drain(0)
for n := 1; n <= max; n += incr {
incr = 1 + rand.Intn(5)
bmt := New(pool)
d := data[:n]
rbmt := NewRefHasher(hasher, count)
exp := rbmt.Hash(d)
got := syncHash(bmt, nil, d)
if !bytes.Equal(got, exp) {
t.Fatalf("wrong sync hash for datalength %v: expected %x (ref), got %x", n, exp, got)
}
sw := bmt.NewAsyncWriter(double)
got = asyncHashRandom(sw, nil, d, wh)
if !bytes.Equal(got, exp) {
t.Fatalf("wrong async hash for datalength %v: expected %x, got %x", n, exp, got)
}
}
})
}
}
}
}
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// Tests that the BMT hasher can be synchronously reused with poolsizes 1 and PoolSize
func TestHasherReuse(t *testing.T) {
t.Run(fmt.Sprintf("poolsize_%d", 1), func(t *testing.T) {
testHasherReuse(1, t)
})
t.Run(fmt.Sprintf("poolsize_%d", PoolSize), func(t *testing.T) {
testHasherReuse(PoolSize, t)
})
}
// tests if bmt reuse is not corrupting result
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func testHasherReuse(poolsize int, t *testing.T) {
hasher := sha3.NewLegacyKeccak256
pool := NewTreePool(hasher, segmentCount, poolsize)
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defer pool.Drain(0)
bmt := New(pool)
for i := 0; i < 100; i++ {
data := testutil.RandomBytes(1, BufferSize)
n := rand.Intn(bmt.Size())
err := testHasherCorrectness(bmt, hasher, data, n, segmentCount)
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if err != nil {
t.Fatal(err)
}
}
}
// Tests if pool can be cleanly reused even in concurrent use by several hasher
func TestBMTConcurrentUse(t *testing.T) {
hasher := sha3.NewLegacyKeccak256
pool := NewTreePool(hasher, segmentCount, PoolSize)
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defer pool.Drain(0)
cycles := 100
errc := make(chan error)
for i := 0; i < cycles; i++ {
go func() {
bmt := New(pool)
data := testutil.RandomBytes(1, BufferSize)
n := rand.Intn(bmt.Size())
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errc <- testHasherCorrectness(bmt, hasher, data, n, 128)
}()
}
LOOP:
for {
select {
case <-time.NewTimer(5 * time.Second).C:
t.Fatal("timed out")
case err := <-errc:
if err != nil {
t.Fatal(err)
}
cycles--
if cycles == 0 {
break LOOP
}
}
}
}
// Tests BMT Hasher io.Writer interface is working correctly
// even multiple short random write buffers
func TestBMTWriterBuffers(t *testing.T) {
hasher := sha3.NewLegacyKeccak256
for _, count := range counts {
t.Run(fmt.Sprintf("%d_segments", count), func(t *testing.T) {
errc := make(chan error)
pool := NewTreePool(hasher, count, PoolSize)
defer pool.Drain(0)
n := count * 32
bmt := New(pool)
data := testutil.RandomBytes(1, n)
rbmt := NewRefHasher(hasher, count)
refHash := rbmt.Hash(data)
expHash := syncHash(bmt, nil, data)
if !bytes.Equal(expHash, refHash) {
t.Fatalf("hash mismatch with reference. expected %x, got %x", refHash, expHash)
}
attempts := 10
f := func() error {
bmt := New(pool)
bmt.Reset()
var buflen int
for offset := 0; offset < n; offset += buflen {
buflen = rand.Intn(n-offset) + 1
read, err := bmt.Write(data[offset : offset+buflen])
if err != nil {
return err
}
if read != buflen {
return fmt.Errorf("incorrect read. expected %v bytes, got %v", buflen, read)
}
}
hash := bmt.Sum(nil)
if !bytes.Equal(hash, expHash) {
return fmt.Errorf("hash mismatch. expected %x, got %x", hash, expHash)
}
return nil
}
for j := 0; j < attempts; j++ {
go func() {
errc <- f()
}()
}
timeout := time.NewTimer(2 * time.Second)
for {
select {
case err := <-errc:
if err != nil {
t.Fatal(err)
}
attempts--
if attempts == 0 {
return
}
case <-timeout.C:
t.Fatalf("timeout")
}
}
})
}
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}
// helper function that compares reference and optimised implementations on
// correctness
func testHasherCorrectness(bmt *Hasher, hasher BaseHasherFunc, d []byte, n, count int) (err error) {
span := make([]byte, 8)
if len(d) < n {
n = len(d)
}
binary.BigEndian.PutUint64(span, uint64(n))
data := d[:n]
rbmt := NewRefHasher(hasher, count)
exp := sha3hash(span, rbmt.Hash(data))
got := syncHash(bmt, span, data)
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if !bytes.Equal(got, exp) {
return fmt.Errorf("wrong hash: expected %x, got %x", exp, got)
}
return err
}
//
func BenchmarkBMT(t *testing.B) {
for size := 4096; size >= 128; size /= 2 {
t.Run(fmt.Sprintf("%v_size_%v", "SHA3", size), func(t *testing.B) {
benchmarkSHA3(t, size)
})
t.Run(fmt.Sprintf("%v_size_%v", "Baseline", size), func(t *testing.B) {
benchmarkBMTBaseline(t, size)
})
t.Run(fmt.Sprintf("%v_size_%v", "REF", size), func(t *testing.B) {
benchmarkRefHasher(t, size)
})
t.Run(fmt.Sprintf("%v_size_%v", "BMT", size), func(t *testing.B) {
benchmarkBMT(t, size)
})
}
}
type whenHash = int
const (
first whenHash = iota
last
random
)
func BenchmarkBMTAsync(t *testing.B) {
whs := []whenHash{first, last, random}
for size := 4096; size >= 128; size /= 2 {
for _, wh := range whs {
for _, double := range []bool{false, true} {
t.Run(fmt.Sprintf("double_%v_hash_when_%v_size_%v", double, wh, size), func(t *testing.B) {
benchmarkBMTAsync(t, size, wh, double)
})
}
}
}
}
func BenchmarkPool(t *testing.B) {
caps := []int{1, PoolSize}
for size := 4096; size >= 128; size /= 2 {
for _, c := range caps {
t.Run(fmt.Sprintf("poolsize_%v_size_%v", c, size), func(t *testing.B) {
benchmarkPool(t, c, size)
})
}
}
}
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// benchmarks simple sha3 hash on chunks
func benchmarkSHA3(t *testing.B, n int) {
data := testutil.RandomBytes(1, n)
hasher := sha3.NewLegacyKeccak256
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h := hasher()
t.ReportAllocs()
t.ResetTimer()
for i := 0; i < t.N; i++ {
doSum(h, nil, data)
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}
}
// benchmarks the minimum hashing time for a balanced (for simplicity) BMT
// by doing count/segmentsize parallel hashings of 2*segmentsize bytes
// doing it on n PoolSize each reusing the base hasher
// the premise is that this is the minimum computation needed for a BMT
// therefore this serves as a theoretical optimum for concurrent implementations
func benchmarkBMTBaseline(t *testing.B, n int) {
hasher := sha3.NewLegacyKeccak256
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hashSize := hasher().Size()
data := testutil.RandomBytes(1, hashSize)
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t.ReportAllocs()
t.ResetTimer()
for i := 0; i < t.N; i++ {
count := int32((n-1)/hashSize + 1)
wg := sync.WaitGroup{}
wg.Add(PoolSize)
var i int32
for j := 0; j < PoolSize; j++ {
go func() {
defer wg.Done()
h := hasher()
for atomic.AddInt32(&i, 1) < count {
doSum(h, nil, data)
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}
}()
}
wg.Wait()
}
}
// benchmarks BMT Hasher
func benchmarkBMT(t *testing.B, n int) {
data := testutil.RandomBytes(1, n)
hasher := sha3.NewLegacyKeccak256
pool := NewTreePool(hasher, segmentCount, PoolSize)
bmt := New(pool)
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t.ReportAllocs()
t.ResetTimer()
for i := 0; i < t.N; i++ {
syncHash(bmt, nil, data)
}
}
// benchmarks BMT hasher with asynchronous concurrent segment/section writes
func benchmarkBMTAsync(t *testing.B, n int, wh whenHash, double bool) {
data := testutil.RandomBytes(1, n)
hasher := sha3.NewLegacyKeccak256
pool := NewTreePool(hasher, segmentCount, PoolSize)
bmt := New(pool).NewAsyncWriter(double)
idxs, segments := splitAndShuffle(bmt.SectionSize(), data)
rand.Shuffle(len(idxs), func(i int, j int) {
idxs[i], idxs[j] = idxs[j], idxs[i]
})
t.ReportAllocs()
t.ResetTimer()
for i := 0; i < t.N; i++ {
asyncHash(bmt, nil, n, wh, idxs, segments)
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}
}
// benchmarks 100 concurrent bmt hashes with pool capacity
func benchmarkPool(t *testing.B, poolsize, n int) {
data := testutil.RandomBytes(1, n)
hasher := sha3.NewLegacyKeccak256
pool := NewTreePool(hasher, segmentCount, poolsize)
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cycles := 100
t.ReportAllocs()
t.ResetTimer()
wg := sync.WaitGroup{}
for i := 0; i < t.N; i++ {
wg.Add(cycles)
for j := 0; j < cycles; j++ {
go func() {
defer wg.Done()
bmt := New(pool)
syncHash(bmt, nil, data)
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}()
}
wg.Wait()
}
}
// benchmarks the reference hasher
func benchmarkRefHasher(t *testing.B, n int) {
data := testutil.RandomBytes(1, n)
hasher := sha3.NewLegacyKeccak256
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rbmt := NewRefHasher(hasher, 128)
t.ReportAllocs()
t.ResetTimer()
for i := 0; i < t.N; i++ {
rbmt.Hash(data)
}
}
// Hash hashes the data and the span using the bmt hasher
func syncHash(h *Hasher, span, data []byte) []byte {
h.ResetWithLength(span)
h.Write(data)
return h.Sum(nil)
}
func splitAndShuffle(secsize int, data []byte) (idxs []int, segments [][]byte) {
l := len(data)
n := l / secsize
if l%secsize > 0 {
n++
}
for i := 0; i < n; i++ {
idxs = append(idxs, i)
end := (i + 1) * secsize
if end > l {
end = l
}
section := data[i*secsize : end]
segments = append(segments, section)
}
rand.Shuffle(n, func(i int, j int) {
idxs[i], idxs[j] = idxs[j], idxs[i]
})
return idxs, segments
}
// splits the input data performs a random shuffle to mock async section writes
func asyncHashRandom(bmt SectionWriter, span []byte, data []byte, wh whenHash) (s []byte) {
idxs, segments := splitAndShuffle(bmt.SectionSize(), data)
return asyncHash(bmt, span, len(data), wh, idxs, segments)
}
// mock for async section writes for BMT SectionWriter
// requires a permutation (a random shuffle) of list of all indexes of segments
// and writes them in order to the appropriate section
// the Sum function is called according to the wh parameter (first, last, random [relative to segment writes])
func asyncHash(bmt SectionWriter, span []byte, l int, wh whenHash, idxs []int, segments [][]byte) (s []byte) {
bmt.Reset()
if l == 0 {
return bmt.Sum(nil, l, span)
}
c := make(chan []byte, 1)
hashf := func() {
c <- bmt.Sum(nil, l, span)
}
maxsize := len(idxs)
var r int
if wh == random {
r = rand.Intn(maxsize)
}
for i, idx := range idxs {
bmt.Write(idx, segments[idx])
if (wh == first || wh == random) && i == r {
go hashf()
}
}
if wh == last {
return bmt.Sum(nil, l, span)
}
return <-c
}