/usr/share/gocode/src/github.com/syndtr/goleveldb/leveldb/filter/bloom_test.go is in golang-github-syndtr-goleveldb-dev 0.0~git20170725.0.b89cc31-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 | // Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package filter
import (
"encoding/binary"
"github.com/syndtr/goleveldb/leveldb/util"
"testing"
)
type harness struct {
t *testing.T
bloom Filter
generator FilterGenerator
filter []byte
}
func newHarness(t *testing.T) *harness {
bloom := NewBloomFilter(10)
return &harness{
t: t,
bloom: bloom,
generator: bloom.NewGenerator(),
}
}
func (h *harness) add(key []byte) {
h.generator.Add(key)
}
func (h *harness) addNum(key uint32) {
var b [4]byte
binary.LittleEndian.PutUint32(b[:], key)
h.add(b[:])
}
func (h *harness) build() {
b := &util.Buffer{}
h.generator.Generate(b)
h.filter = b.Bytes()
}
func (h *harness) reset() {
h.filter = nil
}
func (h *harness) filterLen() int {
return len(h.filter)
}
func (h *harness) assert(key []byte, want, silent bool) bool {
got := h.bloom.Contains(h.filter, key)
if !silent && got != want {
h.t.Errorf("assert on '%v' failed got '%v', want '%v'", key, got, want)
}
return got
}
func (h *harness) assertNum(key uint32, want, silent bool) bool {
var b [4]byte
binary.LittleEndian.PutUint32(b[:], key)
return h.assert(b[:], want, silent)
}
func TestBloomFilter_Empty(t *testing.T) {
h := newHarness(t)
h.build()
h.assert([]byte("hello"), false, false)
h.assert([]byte("world"), false, false)
}
func TestBloomFilter_Small(t *testing.T) {
h := newHarness(t)
h.add([]byte("hello"))
h.add([]byte("world"))
h.build()
h.assert([]byte("hello"), true, false)
h.assert([]byte("world"), true, false)
h.assert([]byte("x"), false, false)
h.assert([]byte("foo"), false, false)
}
func nextN(n int) int {
switch {
case n < 10:
n += 1
case n < 100:
n += 10
case n < 1000:
n += 100
default:
n += 1000
}
return n
}
func TestBloomFilter_VaryingLengths(t *testing.T) {
h := newHarness(t)
var mediocre, good int
for n := 1; n < 10000; n = nextN(n) {
h.reset()
for i := 0; i < n; i++ {
h.addNum(uint32(i))
}
h.build()
got := h.filterLen()
want := (n * 10 / 8) + 40
if got > want {
t.Errorf("filter len test failed, '%d' > '%d'", got, want)
}
for i := 0; i < n; i++ {
h.assertNum(uint32(i), true, false)
}
var rate float32
for i := 0; i < 10000; i++ {
if h.assertNum(uint32(i+1000000000), true, true) {
rate++
}
}
rate /= 10000
if rate > 0.02 {
t.Errorf("false positive rate is more than 2%%, got %v, at len %d", rate, n)
}
if rate > 0.0125 {
mediocre++
} else {
good++
}
}
t.Logf("false positive rate: %d good, %d mediocre", good, mediocre)
if mediocre > good/5 {
t.Error("mediocre false positive rate is more than expected")
}
}
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