path: root/swarm/bmt/bmt_test.go

// 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"
    crand "crypto/rand"
    "encoding/binary"
    "fmt"
    "io"
    "math/rand"
    "sync"
    "sync/atomic"
    "testing"
    "time"

    "github.com/ethereum/go-ethereum/crypto/sha3"
)

// the actual data length generated (could be longer than max datalength of the BMT)
const BufferSize = 4128

func sha3hash(data ...[]byte) []byte {
    h := sha3.NewKeccak256()
    for _, v := range data {
        h.Write(v)
    }
    return h.Sum(nil)
}

// TestRefHasher tests that the RefHasher computes the expected BMT hash for
// all data lengths between 0 and 256 bytes
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 _, x := range tests {
        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 := make([]byte, length)
                    if _, err := io.ReadFull(crand.Reader, data); err != nil && err != io.EOF {
                        t.Fatal(err)
                    }
                    expected := x.expected(data)
                    actual := NewRefHasher(sha3.NewKeccak256, segmentCount).Hash(data)
                    if !bytes.Equal(actual, expected) {
                        t.Fatalf("expected %x, got %x", expected, actual)
                    }
                })
            }
        }
    }
}

func TestHasherCorrectness(t *testing.T) {
    err := testHasher(testBaseHasher)
    if err != nil {
        t.Fatal(err)
    }
}

func testHasher(f func(BaseHasherFunc, []byte, int, int) error) error {
    data := newData(BufferSize)
    hasher := sha3.NewKeccak256
    size := hasher().Size()
    counts := []int{1, 2, 3, 4, 5, 8, 16, 32, 64, 128}

    var err error
    for _, count := range counts {
        max := count * size
        incr := 1
        for n := 1; n <= max; n += incr {
            err = f(hasher, data, n, count)
            if err != nil {
                return err
            }
        }
    }
    return nil
}

// 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)
    })
}

func testHasherReuse(poolsize int, t *testing.T) {
    hasher := sha3.NewKeccak256
    pool := NewTreePool(hasher, SegmentCount, poolsize)
    defer pool.Drain(0)
    bmt := New(pool)

    for i := 0; i < 100; i++ {
        data := newData(BufferSize)
        n := rand.Intn(bmt.DataLength())
        err := testHasherCorrectness(bmt, hasher, data, n, SegmentCount)
        if err != nil {
            t.Fatal(err)
        }
    }
}

// Tests if pool can be cleanly reused even in concurrent use
func TestBMTHasherConcurrentUse(t *testing.T) {
    hasher := sha3.NewKeccak256
    pool := NewTreePool(hasher, SegmentCount, PoolSize)
    defer pool.Drain(0)
    cycles := 100
    errc := make(chan error)

    for i := 0; i < cycles; i++ {
        go func() {
            bmt := New(pool)
            data := newData(BufferSize)
            n := rand.Intn(bmt.DataLength())
            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
            }
        }
    }
}

// helper function that creates  a tree pool
func testBaseHasher(hasher BaseHasherFunc, d []byte, n, count int) error {
    pool := NewTreePool(hasher, count, 1)
    defer pool.Drain(0)
    bmt := New(pool)
    return testHasherCorrectness(bmt, hasher, d, n, count)
}

// 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 := Hash(bmt, span, data)
    if !bytes.Equal(got, exp) {
        return fmt.Errorf("wrong hash: expected %x, got %x", exp, got)
    }
    return err
}

func BenchmarkSHA3_4k(t *testing.B)   { benchmarkSHA3(4096, t) }
func BenchmarkSHA3_2k(t *testing.B)   { benchmarkSHA3(4096/2, t) }
func BenchmarkSHA3_1k(t *testing.B)   { benchmarkSHA3(4096/4, t) }
func BenchmarkSHA3_512b(t *testing.B) { benchmarkSHA3(4096/8, t) }
func BenchmarkSHA3_256b(t *testing.B) { benchmarkSHA3(4096/16, t) }
func BenchmarkSHA3_128b(t *testing.B) { benchmarkSHA3(4096/32, t) }

func BenchmarkBMTBaseline_4k(t *testing.B)   { benchmarkBMTBaseline(4096, t) }
func BenchmarkBMTBaseline_2k(t *testing.B)   { benchmarkBMTBaseline(4096/2, t) }
func BenchmarkBMTBaseline_1k(t *testing.B)   { benchmarkBMTBaseline(4096/4, t) }
func BenchmarkBMTBaseline_512b(t *testing.B) { benchmarkBMTBaseline(4096/8, t) }
func BenchmarkBMTBaseline_256b(t *testing.B) { benchmarkBMTBaseline(4096/16, t) }
func BenchmarkBMTBaseline_128b(t *testing.B) { benchmarkBMTBaseline(4096/32, t) }

func BenchmarkRefHasher_4k(t *testing.B)   { benchmarkRefHasher(4096, t) }
func BenchmarkRefHasher_2k(t *testing.B)   { benchmarkRefHasher(4096/2, t) }
func BenchmarkRefHasher_1k(t *testing.B)   { benchmarkRefHasher(4096/4, t) }
func BenchmarkRefHasher_512b(t *testing.B) { benchmarkRefHasher(4096/8, t) }
func BenchmarkRefHasher_256b(t *testing.B) { benchmarkRefHasher(4096/16, t) }
func BenchmarkRefHasher_128b(t *testing.B) { benchmarkRefHasher(4096/32, t) }

func BenchmarkBMTHasher_4k(t *testing.B)   { benchmarkBMTHasher(4096, t) }
func BenchmarkBMTHasher_2k(t *testing.B)   { benchmarkBMTHasher(4096/2, t) }
func BenchmarkBMTHasher_1k(t *testing.B)   { benchmarkBMTHasher(4096/4, t) }
func BenchmarkBMTHasher_512b(t *testing.B) { benchmarkBMTHasher(4096/8, t) }
func BenchmarkBMTHasher_256b(t *testing.B) { benchmarkBMTHasher(4096/16, t) }
func BenchmarkBMTHasher_128b(t *testing.B) { benchmarkBMTHasher(4096/32, t) }

func BenchmarkBMTHasherNoPool_4k(t *testing.B)   { benchmarkBMTHasherPool(1, 4096, t) }
func BenchmarkBMTHasherNoPool_2k(t *testing.B)   { benchmarkBMTHasherPool(1, 4096/2, t) }
func BenchmarkBMTHasherNoPool_1k(t *testing.B)   { benchmarkBMTHasherPool(1, 4096/4, t) }
func BenchmarkBMTHasherNoPool_512b(t *testing.B) { benchmarkBMTHasherPool(1, 4096/8, t) }
func BenchmarkBMTHasherNoPool_256b(t *testing.B) { benchmarkBMTHasherPool(1, 4096/16, t) }
func BenchmarkBMTHasherNoPool_128b(t *testing.B) { benchmarkBMTHasherPool(1, 4096/32, t) }

func BenchmarkBMTHasherPool_4k(t *testing.B)   { benchmarkBMTHasherPool(PoolSize, 4096, t) }
func BenchmarkBMTHasherPool_2k(t *testing.B)   { benchmarkBMTHasherPool(PoolSize, 4096/2, t) }
func BenchmarkBMTHasherPool_1k(t *testing.B)   { benchmarkBMTHasherPool(PoolSize, 4096/4, t) }
func BenchmarkBMTHasherPool_512b(t *testing.B) { benchmarkBMTHasherPool(PoolSize, 4096/8, t) }
func BenchmarkBMTHasherPool_256b(t *testing.B) { benchmarkBMTHasherPool(PoolSize, 4096/16, t) }
func BenchmarkBMTHasherPool_128b(t *testing.B) { benchmarkBMTHasherPool(PoolSize, 4096/32, t) }

// benchmarks simple sha3 hash on chunks
func benchmarkSHA3(n int, t *testing.B) {
    data := newData(n)
    hasher := sha3.NewKeccak256
    h := hasher()

    t.ReportAllocs()
    t.ResetTimer()
    for i := 0; i < t.N; i++ {
        h.Reset()
        h.Write(data)
        h.Sum(nil)
    }
}

// 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(n int, t *testing.B) {
    hasher := sha3.NewKeccak256
    hashSize := hasher().Size()
    data := newData(hashSize)

    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 {
                    h.Reset()
                    h.Write(data)
                    h.Sum(nil)
                }
            }()
        }
        wg.Wait()
    }
}

// benchmarks BMT Hasher
func benchmarkBMTHasher(n int, t *testing.B) {
    data := newData(n)
    hasher := sha3.NewKeccak256
    pool := NewTreePool(hasher, SegmentCount, PoolSize)

    t.ReportAllocs()
    t.ResetTimer()
    for i := 0; i < t.N; i++ {
        bmt := New(pool)
        Hash(bmt, nil, data)
    }
}

// benchmarks 100 concurrent bmt hashes with pool capacity
func benchmarkBMTHasherPool(poolsize, n int, t *testing.B) {
    data := newData(n)
    hasher := sha3.NewKeccak256
    pool := NewTreePool(hasher, SegmentCount, poolsize)
    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)
                Hash(bmt, nil, data)
            }()
        }
        wg.Wait()
    }
}

// benchmarks the reference hasher
func benchmarkRefHasher(n int, t *testing.B) {
    data := newData(n)
    hasher := sha3.NewKeccak256
    rbmt := NewRefHasher(hasher, 128)

    t.ReportAllocs()
    t.ResetTimer()
    for i := 0; i < t.N; i++ {
        rbmt.Hash(data)
    }
}

func newData(bufferSize int) []byte {
    data := make([]byte, bufferSize)
    _, err := io.ReadFull(crand.Reader, data)
    if err != nil {
        panic(err.Error())
    }
    return data
}