bloom_test.go

package bloom

import (
	"bytes"
	"encoding/binary"
	"encoding/gob"
	"encoding/json"
	"math"
	"testing"
)

// This implementation of Bloom filters is _not_
// safe for concurrent use. Uncomment the following
// method and run go test -race
//
// func TestConcurrent(t *testing.T) {
// 	gmp := runtime.GOMAXPROCS(2)
// 	defer runtime.GOMAXPROCS(gmp)
//
// 	f := New(1000, 4)
// 	n1 := []byte("Bess")
// 	n2 := []byte("Jane")
// 	f.Add(n1)
// 	f.Add(n2)
//
// 	var wg sync.WaitGroup
// 	const try = 1000
// 	var err1, err2 error
//
// 	wg.Add(1)
// 	go func() {
// 		for i := 0; i < try; i++ {
// 			n1b := f.Test(n1)
// 			if !n1b {
// 				err1 = fmt.Errorf("%v should be in", n1)
// 				break
// 			}
// 		}
// 		wg.Done()
// 	}()
//
// 	wg.Add(1)
// 	go func() {
// 		for i := 0; i < try; i++ {
// 			n2b := f.Test(n2)
// 			if !n2b {
// 				err2 = fmt.Errorf("%v should be in", n2)
// 				break
// 			}
// 		}
// 		wg.Done()
// 	}()
//
// 	wg.Wait()
//
// 	if err1 != nil {
// 		t.Fatal(err1)
// 	}
// 	if err2 != nil {
// 		t.Fatal(err2)
// 	}
// }

func TestBasic(t *testing.T) {
	f := New(1000, 4)
	n1 := []byte("Bess")
	n2 := []byte("Jane")
	n3 := []byte("Emma")
	f.Add(n1)
	n3a := f.TestAndAdd(n3)
	n1b := f.Test(n1)
	n2b := f.Test(n2)
	n3b := f.Test(n3)
	if !n1b {
		t.Errorf("%v should be in.", n1)
	}
	if n2b {
		t.Errorf("%v should not be in.", n2)
	}
	if n3a {
		t.Errorf("%v should not be in the first time we look.", n3)
	}
	if !n3b {
		t.Errorf("%v should be in the second time we look.", n3)
	}
}

func TestBasicUint32(t *testing.T) {
	f := New(1000, 4)
	n1 := make([]byte, 4)
	n2 := make([]byte, 4)
	n3 := make([]byte, 4)
	n4 := make([]byte, 4)
	binary.BigEndian.PutUint32(n1, 100)
	binary.BigEndian.PutUint32(n2, 101)
	binary.BigEndian.PutUint32(n3, 102)
	binary.BigEndian.PutUint32(n4, 103)
	f.Add(n1)
	n3a := f.TestAndAdd(n3)
	n1b := f.Test(n1)
	n2b := f.Test(n2)
	n3b := f.Test(n3)
	f.Test(n4)
	if !n1b {
		t.Errorf("%v should be in.", n1)
	}
	if n2b {
		t.Errorf("%v should not be in.", n2)
	}
	if n3a {
		t.Errorf("%v should not be in the first time we look.", n3)
	}
	if !n3b {
		t.Errorf("%v should be in the second time we look.", n3)
	}
}

func TestNewWithLowNumbers(t *testing.T) {
	f := New(0, 0)
	if f.k != 1 {
		t.Errorf("%v should be 1", f.k)
	}
	if f.m != 1 {
		t.Errorf("%v should be 1", f.m)
	}
}

func TestString(t *testing.T) {
	f := NewWithEstimates(1000, 0.001)
	n1 := "Love"
	n2 := "is"
	n3 := "in"
	n4 := "bloom"
	f.AddString(n1)
	n3a := f.TestAndAddString(n3)
	n1b := f.TestString(n1)
	n2b := f.TestString(n2)
	n3b := f.TestString(n3)
	f.TestString(n4)
	if !n1b {
		t.Errorf("%v should be in.", n1)
	}
	if n2b {
		t.Errorf("%v should not be in.", n2)
	}
	if n3a {
		t.Errorf("%v should not be in the first time we look.", n3)
	}
	if !n3b {
		t.Errorf("%v should be in the second time we look.", n3)
	}

}

func testEstimated(n uint, maxFp float64, t *testing.T) {
	m, k := EstimateParameters(n, maxFp)
	f := NewWithEstimates(n, maxFp)
	fpRate := f.EstimateFalsePositiveRate(n)
	if fpRate > 1.5*maxFp {
		t.Errorf("False positive rate too high: n: %v; m: %v; k: %v; maxFp: %f; fpRate: %f, fpRate/maxFp: %f", n, m, k, maxFp, fpRate, fpRate/maxFp)
	}
}

func TestEstimated1000_0001(t *testing.T)   { testEstimated(1000, 0.000100, t) }
func TestEstimated10000_0001(t *testing.T)  { testEstimated(10000, 0.000100, t) }
func TestEstimated100000_0001(t *testing.T) { testEstimated(100000, 0.000100, t) }

func TestEstimated1000_001(t *testing.T)   { testEstimated(1000, 0.001000, t) }
func TestEstimated10000_001(t *testing.T)  { testEstimated(10000, 0.001000, t) }
func TestEstimated100000_001(t *testing.T) { testEstimated(100000, 0.001000, t) }

func TestEstimated1000_01(t *testing.T)   { testEstimated(1000, 0.010000, t) }
func TestEstimated10000_01(t *testing.T)  { testEstimated(10000, 0.010000, t) }
func TestEstimated100000_01(t *testing.T) { testEstimated(100000, 0.010000, t) }

func min(a, b uint) uint {
	if a < b {
		return a
	}
	return b
}

// The following function courtesy of Nick @turgon
// This helper function ranges over the input data, applying the hashing
// which returns the bit locations to set in the filter.
// For each location, increment a counter for that bit address.
//
// If the Bloom Filter's location() method distributes locations uniformly
// at random, a property it should inherit from its hash function, then
// each bit location in the filter should end up with roughly the same
// number of hits.  Importantly, the value of k should not matter.
//
// Once the results are collected, we can run a chi squared goodness of fit
// test, comparing the result histogram with the uniform distribition.
// This yields a test statistic with degrees-of-freedom of m-1.
func chiTestBloom(m, k, rounds uint, elements [][]byte) (succeeds bool) {
	f := New(m, k)
	results := make([]uint, m)
	chi := make([]float64, m)

	for _, data := range elements {
		h := baseHashes(data)
		for i := uint(0); i < f.k; i++ {
			results[f.location(h, i)]++
		}
	}

	// Each element of results should contain the same value: k * rounds / m.
	// Let's run a chi-square goodness of fit and see how it fares.
	var chiStatistic float64
	e := float64(k*rounds) / float64(m)
	for i := uint(0); i < m; i++ {
		chi[i] = math.Pow(float64(results[i])-e, 2.0) / e
		chiStatistic += chi[i]
	}

	// this tests at significant level 0.005 up to 20 degrees of freedom
	table := [20]float64{
		7.879, 10.597, 12.838, 14.86, 16.75, 18.548, 20.278,
		21.955, 23.589, 25.188, 26.757, 28.3, 29.819, 31.319, 32.801, 34.267,
		35.718, 37.156, 38.582, 39.997}
	df := min(m-1, 20)

	succeeds = table[df-1] > chiStatistic
	return

}

func TestLocation(t *testing.T) {
	var m, k, rounds uint

	m = 8
	k = 3

	rounds = 100000 // 15000000

	elements := make([][]byte, rounds)

	for x := uint(0); x < rounds; x++ {
		ctrlist := make([]uint8, 4)
		ctrlist[0] = uint8(x)
		ctrlist[1] = uint8(x >> 8)
		ctrlist[2] = uint8(x >> 16)
		ctrlist[3] = uint8(x >> 24)
		data := []byte(ctrlist)
		elements[x] = data
	}

	succeeds := chiTestBloom(m, k, rounds, elements)
	if !succeeds {
		t.Error("random assignment is too unrandom")
	}

}

func TestCap(t *testing.T) {
	f := New(1000, 4)
	if f.Cap() != f.m {
		t.Error("not accessing Cap() correctly")
	}
}

func TestK(t *testing.T) {
	f := New(1000, 4)
	if f.K() != f.k {
		t.Error("not accessing K() correctly")
	}
}

func TestMarshalUnmarshalJSON(t *testing.T) {
	f := New(1000, 4)
	data, err := json.Marshal(f)
	if err != nil {
		t.Fatal(err.Error())
	}

	var g BloomFilter
	err = json.Unmarshal(data, &g)
	if err != nil {
		t.Fatal(err.Error())
	}
	if g.m != f.m {
		t.Error("invalid m value")
	}
	if g.k != f.k {
		t.Error("invalid k value")
	}
	if g.b == nil {
		t.Fatal("bitset is nil")
	}
	if !g.b.Equal(f.b) {
		t.Error("bitsets are not equal")
	}
}

func TestUnmarshalInvalidJSON(t *testing.T) {
	data := []byte("{invalid}")

	var g BloomFilter
	err := g.UnmarshalJSON(data)
	if err == nil {
		t.Error("expected error while unmarshalling invalid data")
	}
}

func TestWriteToReadFrom(t *testing.T) {
	var b bytes.Buffer
	f := New(1000, 4)
	_, err := f.WriteTo(&b)
	if err != nil {
		t.Fatal(err)
	}

	g := New(1000, 1)
	_, err = g.ReadFrom(&b)
	if err != nil {
		t.Fatal(err)
	}
	if g.m != f.m {
		t.Error("invalid m value")
	}
	if g.k != f.k {
		t.Error("invalid k value")
	}
	if g.b == nil {
		t.Fatal("bitset is nil")
	}
	if !g.b.Equal(f.b) {
		t.Error("bitsets are not equal")
	}

	g.Test([]byte(""))
}

func TestReadWriteBinary(t *testing.T) {
	f := New(1000, 4)
	var buf bytes.Buffer
	bytesWritten, err := f.WriteTo(&buf)
	if err != nil {
		t.Fatal(err.Error())
	}
	if bytesWritten != int64(buf.Len()) {
		t.Errorf("incorrect write length %d != %d", bytesWritten, buf.Len())
	}

	var g BloomFilter
	bytesRead, err := g.ReadFrom(&buf)
	if err != nil {
		t.Fatal(err.Error())
	}
	if bytesRead != bytesWritten {
		t.Errorf("read unexpected number of bytes %d != %d", bytesRead, bytesWritten)
	}
	if g.m != f.m {
		t.Error("invalid m value")
	}
	if g.k != f.k {
		t.Error("invalid k value")
	}
	if g.b == nil {
		t.Fatal("bitset is nil")
	}
	if !g.b.Equal(f.b) {
		t.Error("bitsets are not equal")
	}
}

func TestEncodeDecodeGob(t *testing.T) {
	f := New(1000, 4)
	f.Add([]byte("one"))
	f.Add([]byte("two"))
	f.Add([]byte("three"))
	var buf bytes.Buffer
	err := gob.NewEncoder(&buf).Encode(f)
	if err != nil {
		t.Fatal(err.Error())
	}

	var g BloomFilter
	err = gob.NewDecoder(&buf).Decode(&g)
	if err != nil {
		t.Fatal(err.Error())
	}
	if g.m != f.m {
		t.Error("invalid m value")
	}
	if g.k != f.k {
		t.Error("invalid k value")
	}
	if g.b == nil {
		t.Fatal("bitset is nil")
	}
	if !g.b.Equal(f.b) {
		t.Error("bitsets are not equal")
	}
	if !g.Test([]byte("three")) {
		t.Errorf("missing value 'three'")
	}
	if !g.Test([]byte("two")) {
		t.Errorf("missing value 'two'")
	}
	if !g.Test([]byte("one")) {
		t.Errorf("missing value 'one'")
	}
}

func TestEqual(t *testing.T) {
	f := New(1000, 4)
	f1 := New(1000, 4)
	g := New(1000, 20)
	h := New(10, 20)
	n1 := []byte("Bess")
	f1.Add(n1)
	if !f.Equal(f) {
		t.Errorf("%v should be equal to itself", f)
	}
	if f.Equal(f1) {
		t.Errorf("%v should not be equal to %v", f, f1)
	}
	if f.Equal(g) {
		t.Errorf("%v should not be equal to %v", f, g)
	}
	if f.Equal(h) {
		t.Errorf("%v should not be equal to %v", f, h)
	}
}

func BenchmarkEstimated(b *testing.B) {
	for n := uint(100000); n <= 100000; n *= 10 {
		for fp := 0.1; fp >= 0.0001; fp /= 10.0 {
			f := NewWithEstimates(n, fp)
			f.EstimateFalsePositiveRate(n)
		}
	}
}

func BenchmarkSeparateTestAndAdd(b *testing.B) {
	f := NewWithEstimates(uint(b.N), 0.0001)
	key := make([]byte, 100)
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		binary.BigEndian.PutUint32(key, uint32(i))
		f.Test(key)
		f.Add(key)
	}
}

func BenchmarkCombinedTestAndAdd(b *testing.B) {
	f := NewWithEstimates(uint(b.N), 0.0001)
	key := make([]byte, 100)
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		binary.BigEndian.PutUint32(key, uint32(i))
		f.TestAndAdd(key)
	}
}

func TestMerge(t *testing.T) {
	f := New(1000, 4)
	n1 := []byte("f")
	f.Add(n1)

	g := New(1000, 4)
	n2 := []byte("g")
	g.Add(n2)

	h := New(999, 4)
	n3 := []byte("h")
	h.Add(n3)

	j := New(1000, 5)
	n4 := []byte("j")
	j.Add(n4)

	err := f.Merge(g)
	if err != nil {
		t.Errorf("There should be no error when merging two similar filters")
	}

	err = f.Merge(h)
	if err == nil {
		t.Errorf("There should be an error when merging filters with mismatched m")
	}

	err = f.Merge(j)
	if err == nil {
		t.Errorf("There should be an error when merging filters with mismatched k")
	}

	n2b := f.Test(n2)
	if !n2b {
		t.Errorf("The value doesn't exist after a valid merge")
	}

	n3b := f.Test(n3)
	if n3b {
		t.Errorf("The value exists after an invalid merge")
	}

	n4b := f.Test(n4)
	if n4b {
		t.Errorf("The value exists after an invalid merge")
	}
}

func TestCopy(t *testing.T) {
	f := New(1000, 4)
	n1 := []byte("f")
	f.Add(n1)

	// copy here instead of New
	g := f.Copy()
	n2 := []byte("g")
	g.Add(n2)

	n1fb := f.Test(n1)
	if !n1fb {
		t.Errorf("The value doesn't exist in original after making a copy")
	}

	n1gb := g.Test(n1)
	if !n1gb {
		t.Errorf("The value doesn't exist in the copy")
	}

	n2fb := f.Test(n2)
	if n2fb {
		t.Errorf("The value exists in the original, it should only exist in copy")
	}

	n2gb := g.Test(n2)
	if !n2gb {
		t.Errorf("The value doesn't exist in copy after Add()")
	}
}

func TestFrom(t *testing.T) {
	var (
		k    = uint(5)
		data = make([]uint64, 10)
		test = []byte("test")
	)

	bf := From(data, k)
	if bf.K() != k {
		t.Errorf("Constant k does not match the expected value")
	}

	if bf.Cap() != uint(len(data)*64) {
		t.Errorf("Capacity does not match the expected value")
	}

	if bf.Test(test) {
		t.Errorf("Bloom filter should not contain the value")
	}

	bf.Add(test)
	if !bf.Test(test) {
		t.Errorf("Bloom filter should contain the value")
	}

	// create a new Bloom filter from an existing (populated) data slice.
	bf = From(data, k)
	if !bf.Test(test) {
		t.Errorf("Bloom filter should contain the value")
	}
}

func TestTestLocations(t *testing.T) {
	f := NewWithEstimates(1000, 0.001)
	n1 := []byte("Love")
	n2 := []byte("is")
	n3 := []byte("in")
	n4 := []byte("bloom")
	f.Add(n1)
	n3a := f.TestLocations(Locations(n3, f.K()))
	f.Add(n3)
	n1b := f.TestLocations(Locations(n1, f.K()))
	n2b := f.TestLocations(Locations(n2, f.K()))
	n3b := f.TestLocations(Locations(n3, f.K()))
	n4b := f.TestLocations(Locations(n4, f.K()))
	if !n1b {
		t.Errorf("%v should be in.", n1)
	}
	if n2b {
		t.Errorf("%v should not be in.", n2)
	}
	if n3a {
		t.Errorf("%v should not be in the first time we look.", n3)
	}
	if !n3b {
		t.Errorf("%v should be in the second time we look.", n3)
	}
	if n4b {
		t.Errorf("%v should be in.", n4)
	}
}