745 lines
16 KiB
Go
745 lines
16 KiB
Go
// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime_test
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import (
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"fmt"
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"math"
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"math/rand"
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. "runtime"
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"strings"
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"testing"
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"unsafe"
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)
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func TestMemHash32Equality(t *testing.T) {
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if *UseAeshash {
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t.Skip("skipping since AES hash implementation is used")
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}
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var b [4]byte
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r := rand.New(rand.NewSource(1234))
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seed := uintptr(r.Uint64())
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for i := 0; i < 100; i++ {
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randBytes(r, b[:])
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got := MemHash32(unsafe.Pointer(&b), seed)
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want := MemHash(unsafe.Pointer(&b), seed, 4)
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if got != want {
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t.Errorf("MemHash32(%x, %v) = %v; want %v", b, seed, got, want)
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}
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}
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}
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func TestMemHash64Equality(t *testing.T) {
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if *UseAeshash {
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t.Skip("skipping since AES hash implementation is used")
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}
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var b [8]byte
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r := rand.New(rand.NewSource(1234))
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seed := uintptr(r.Uint64())
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for i := 0; i < 100; i++ {
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randBytes(r, b[:])
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got := MemHash64(unsafe.Pointer(&b), seed)
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want := MemHash(unsafe.Pointer(&b), seed, 8)
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if got != want {
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t.Errorf("MemHash64(%x, %v) = %v; want %v", b, seed, got, want)
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}
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}
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}
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// Smhasher is a torture test for hash functions.
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// https://code.google.com/p/smhasher/
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// This code is a port of some of the Smhasher tests to Go.
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//
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// The current AES hash function passes Smhasher. Our fallback
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// hash functions don't, so we only enable the difficult tests when
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// we know the AES implementation is available.
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// Sanity checks.
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// hash should not depend on values outside key.
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// hash should not depend on alignment.
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func TestSmhasherSanity(t *testing.T) {
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r := rand.New(rand.NewSource(1234))
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const REP = 10
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const KEYMAX = 128
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const PAD = 16
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const OFFMAX = 16
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for k := 0; k < REP; k++ {
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for n := 0; n < KEYMAX; n++ {
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for i := 0; i < OFFMAX; i++ {
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var b [KEYMAX + OFFMAX + 2*PAD]byte
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var c [KEYMAX + OFFMAX + 2*PAD]byte
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randBytes(r, b[:])
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randBytes(r, c[:])
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copy(c[PAD+i:PAD+i+n], b[PAD:PAD+n])
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if BytesHash(b[PAD:PAD+n], 0) != BytesHash(c[PAD+i:PAD+i+n], 0) {
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t.Errorf("hash depends on bytes outside key")
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}
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}
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}
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}
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}
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type HashSet struct {
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m map[uintptr]struct{} // set of hashes added
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n int // number of hashes added
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}
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func newHashSet() *HashSet {
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return &HashSet{make(map[uintptr]struct{}), 0}
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}
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func (s *HashSet) add(h uintptr) {
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s.m[h] = struct{}{}
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s.n++
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}
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func (s *HashSet) addS(x string) {
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s.add(StringHash(x, 0))
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}
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func (s *HashSet) addB(x []byte) {
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s.add(BytesHash(x, 0))
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}
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func (s *HashSet) addS_seed(x string, seed uintptr) {
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s.add(StringHash(x, seed))
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}
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func (s *HashSet) check(t *testing.T) {
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const SLOP = 10.0
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collisions := s.n - len(s.m)
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//fmt.Printf("%d/%d\n", len(s.m), s.n)
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pairs := int64(s.n) * int64(s.n-1) / 2
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expected := float64(pairs) / math.Pow(2.0, float64(hashSize))
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stddev := math.Sqrt(expected)
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if float64(collisions) > expected+SLOP*(3*stddev+1) {
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t.Errorf("unexpected number of collisions: got=%d mean=%f stddev=%f", collisions, expected, stddev)
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}
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}
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// a string plus adding zeros must make distinct hashes
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func TestSmhasherAppendedZeros(t *testing.T) {
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s := "hello" + strings.Repeat("\x00", 256)
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h := newHashSet()
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for i := 0; i <= len(s); i++ {
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h.addS(s[:i])
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}
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h.check(t)
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}
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// All 0-3 byte strings have distinct hashes.
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func TestSmhasherSmallKeys(t *testing.T) {
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h := newHashSet()
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var b [3]byte
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for i := 0; i < 256; i++ {
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b[0] = byte(i)
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h.addB(b[:1])
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for j := 0; j < 256; j++ {
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b[1] = byte(j)
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h.addB(b[:2])
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if !testing.Short() {
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for k := 0; k < 256; k++ {
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b[2] = byte(k)
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h.addB(b[:3])
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}
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}
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}
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}
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h.check(t)
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}
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// Different length strings of all zeros have distinct hashes.
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func TestSmhasherZeros(t *testing.T) {
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N := 256 * 1024
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if testing.Short() {
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N = 1024
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}
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h := newHashSet()
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b := make([]byte, N)
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for i := 0; i <= N; i++ {
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h.addB(b[:i])
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}
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h.check(t)
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}
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// Strings with up to two nonzero bytes all have distinct hashes.
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func TestSmhasherTwoNonzero(t *testing.T) {
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if testing.Short() {
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t.Skip("Skipping in short mode")
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}
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h := newHashSet()
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for n := 2; n <= 16; n++ {
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twoNonZero(h, n)
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}
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h.check(t)
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}
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func twoNonZero(h *HashSet, n int) {
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b := make([]byte, n)
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// all zero
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h.addB(b[:])
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// one non-zero byte
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for i := 0; i < n; i++ {
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for x := 1; x < 256; x++ {
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b[i] = byte(x)
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h.addB(b[:])
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b[i] = 0
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}
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}
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// two non-zero bytes
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for i := 0; i < n; i++ {
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for x := 1; x < 256; x++ {
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b[i] = byte(x)
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for j := i + 1; j < n; j++ {
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for y := 1; y < 256; y++ {
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b[j] = byte(y)
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h.addB(b[:])
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b[j] = 0
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}
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}
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b[i] = 0
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}
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}
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}
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// Test strings with repeats, like "abcdabcdabcdabcd..."
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func TestSmhasherCyclic(t *testing.T) {
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if testing.Short() {
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t.Skip("Skipping in short mode")
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}
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r := rand.New(rand.NewSource(1234))
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const REPEAT = 8
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const N = 1000000
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for n := 4; n <= 12; n++ {
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h := newHashSet()
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b := make([]byte, REPEAT*n)
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for i := 0; i < N; i++ {
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b[0] = byte(i * 79 % 97)
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b[1] = byte(i * 43 % 137)
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b[2] = byte(i * 151 % 197)
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b[3] = byte(i * 199 % 251)
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randBytes(r, b[4:n])
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for j := n; j < n*REPEAT; j++ {
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b[j] = b[j-n]
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}
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h.addB(b)
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}
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h.check(t)
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}
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}
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// Test strings with only a few bits set
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func TestSmhasherSparse(t *testing.T) {
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if testing.Short() {
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t.Skip("Skipping in short mode")
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}
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sparse(t, 32, 6)
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sparse(t, 40, 6)
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sparse(t, 48, 5)
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sparse(t, 56, 5)
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sparse(t, 64, 5)
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sparse(t, 96, 4)
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sparse(t, 256, 3)
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sparse(t, 2048, 2)
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}
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func sparse(t *testing.T, n int, k int) {
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b := make([]byte, n/8)
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h := newHashSet()
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setbits(h, b, 0, k)
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h.check(t)
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}
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// set up to k bits at index i and greater
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func setbits(h *HashSet, b []byte, i int, k int) {
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h.addB(b)
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if k == 0 {
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return
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}
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for j := i; j < len(b)*8; j++ {
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b[j/8] |= byte(1 << uint(j&7))
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setbits(h, b, j+1, k-1)
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b[j/8] &= byte(^(1 << uint(j&7)))
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}
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}
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// Test all possible combinations of n blocks from the set s.
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// "permutation" is a bad name here, but it is what Smhasher uses.
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func TestSmhasherPermutation(t *testing.T) {
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if testing.Short() {
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t.Skip("Skipping in short mode")
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}
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permutation(t, []uint32{0, 1, 2, 3, 4, 5, 6, 7}, 8)
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permutation(t, []uint32{0, 1 << 29, 2 << 29, 3 << 29, 4 << 29, 5 << 29, 6 << 29, 7 << 29}, 8)
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permutation(t, []uint32{0, 1}, 20)
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permutation(t, []uint32{0, 1 << 31}, 20)
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permutation(t, []uint32{0, 1, 2, 3, 4, 5, 6, 7, 1 << 29, 2 << 29, 3 << 29, 4 << 29, 5 << 29, 6 << 29, 7 << 29}, 6)
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}
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func permutation(t *testing.T, s []uint32, n int) {
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b := make([]byte, n*4)
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h := newHashSet()
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genPerm(h, b, s, 0)
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h.check(t)
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}
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func genPerm(h *HashSet, b []byte, s []uint32, n int) {
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h.addB(b[:n])
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if n == len(b) {
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return
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}
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for _, v := range s {
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b[n] = byte(v)
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b[n+1] = byte(v >> 8)
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b[n+2] = byte(v >> 16)
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b[n+3] = byte(v >> 24)
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genPerm(h, b, s, n+4)
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}
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}
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type Key interface {
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clear() // set bits all to 0
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random(r *rand.Rand) // set key to something random
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bits() int // how many bits key has
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flipBit(i int) // flip bit i of the key
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hash() uintptr // hash the key
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name() string // for error reporting
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}
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type BytesKey struct {
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b []byte
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}
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func (k *BytesKey) clear() {
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for i := range k.b {
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k.b[i] = 0
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}
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}
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func (k *BytesKey) random(r *rand.Rand) {
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randBytes(r, k.b)
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}
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func (k *BytesKey) bits() int {
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return len(k.b) * 8
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}
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func (k *BytesKey) flipBit(i int) {
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k.b[i>>3] ^= byte(1 << uint(i&7))
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}
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func (k *BytesKey) hash() uintptr {
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return BytesHash(k.b, 0)
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}
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func (k *BytesKey) name() string {
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return fmt.Sprintf("bytes%d", len(k.b))
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}
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type Int32Key struct {
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i uint32
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}
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func (k *Int32Key) clear() {
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k.i = 0
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}
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func (k *Int32Key) random(r *rand.Rand) {
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k.i = r.Uint32()
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}
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func (k *Int32Key) bits() int {
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return 32
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}
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func (k *Int32Key) flipBit(i int) {
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k.i ^= 1 << uint(i)
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}
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func (k *Int32Key) hash() uintptr {
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return Int32Hash(k.i, 0)
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}
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func (k *Int32Key) name() string {
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return "int32"
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}
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type Int64Key struct {
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i uint64
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}
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func (k *Int64Key) clear() {
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k.i = 0
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}
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func (k *Int64Key) random(r *rand.Rand) {
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k.i = uint64(r.Uint32()) + uint64(r.Uint32())<<32
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}
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func (k *Int64Key) bits() int {
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return 64
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}
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func (k *Int64Key) flipBit(i int) {
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k.i ^= 1 << uint(i)
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}
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func (k *Int64Key) hash() uintptr {
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return Int64Hash(k.i, 0)
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}
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func (k *Int64Key) name() string {
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return "int64"
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}
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type EfaceKey struct {
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i interface{}
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}
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func (k *EfaceKey) clear() {
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k.i = nil
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}
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func (k *EfaceKey) random(r *rand.Rand) {
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k.i = uint64(r.Int63())
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}
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func (k *EfaceKey) bits() int {
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// use 64 bits. This tests inlined interfaces
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// on 64-bit targets and indirect interfaces on
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// 32-bit targets.
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return 64
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}
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func (k *EfaceKey) flipBit(i int) {
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k.i = k.i.(uint64) ^ uint64(1)<<uint(i)
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}
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func (k *EfaceKey) hash() uintptr {
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return EfaceHash(k.i, 0)
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}
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func (k *EfaceKey) name() string {
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return "Eface"
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}
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type IfaceKey struct {
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i interface {
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F()
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}
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}
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type fInter uint64
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func (x fInter) F() {
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}
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func (k *IfaceKey) clear() {
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k.i = nil
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}
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func (k *IfaceKey) random(r *rand.Rand) {
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k.i = fInter(r.Int63())
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}
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func (k *IfaceKey) bits() int {
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// use 64 bits. This tests inlined interfaces
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// on 64-bit targets and indirect interfaces on
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// 32-bit targets.
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return 64
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}
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func (k *IfaceKey) flipBit(i int) {
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k.i = k.i.(fInter) ^ fInter(1)<<uint(i)
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}
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func (k *IfaceKey) hash() uintptr {
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return IfaceHash(k.i, 0)
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}
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func (k *IfaceKey) name() string {
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return "Iface"
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}
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// Flipping a single bit of a key should flip each output bit with 50% probability.
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func TestSmhasherAvalanche(t *testing.T) {
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if testing.Short() {
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t.Skip("Skipping in short mode")
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}
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avalancheTest1(t, &BytesKey{make([]byte, 2)})
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avalancheTest1(t, &BytesKey{make([]byte, 4)})
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avalancheTest1(t, &BytesKey{make([]byte, 8)})
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avalancheTest1(t, &BytesKey{make([]byte, 16)})
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avalancheTest1(t, &BytesKey{make([]byte, 32)})
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avalancheTest1(t, &BytesKey{make([]byte, 200)})
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avalancheTest1(t, &Int32Key{})
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avalancheTest1(t, &Int64Key{})
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avalancheTest1(t, &EfaceKey{})
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avalancheTest1(t, &IfaceKey{})
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}
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func avalancheTest1(t *testing.T, k Key) {
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const REP = 100000
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r := rand.New(rand.NewSource(1234))
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n := k.bits()
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// grid[i][j] is a count of whether flipping
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// input bit i affects output bit j.
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grid := make([][hashSize]int, n)
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for z := 0; z < REP; z++ {
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// pick a random key, hash it
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k.random(r)
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h := k.hash()
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// flip each bit, hash & compare the results
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for i := 0; i < n; i++ {
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k.flipBit(i)
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d := h ^ k.hash()
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k.flipBit(i)
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// record the effects of that bit flip
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g := &grid[i]
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for j := 0; j < hashSize; j++ {
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g[j] += int(d & 1)
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d >>= 1
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}
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}
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}
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// Each entry in the grid should be about REP/2.
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// More precisely, we did N = k.bits() * hashSize experiments where
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// each is the sum of REP coin flips. We want to find bounds on the
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// sum of coin flips such that a truly random experiment would have
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// all sums inside those bounds with 99% probability.
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N := n * hashSize
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var c float64
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// find c such that Prob(mean-c*stddev < x < mean+c*stddev)^N > .9999
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for c = 0.0; math.Pow(math.Erf(c/math.Sqrt(2)), float64(N)) < .9999; c += .1 {
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}
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c *= 4.0 // allowed slack - we don't need to be perfectly random
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mean := .5 * REP
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stddev := .5 * math.Sqrt(REP)
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low := int(mean - c*stddev)
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high := int(mean + c*stddev)
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for i := 0; i < n; i++ {
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for j := 0; j < hashSize; j++ {
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x := grid[i][j]
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if x < low || x > high {
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t.Errorf("bad bias for %s bit %d -> bit %d: %d/%d\n", k.name(), i, j, x, REP)
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}
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}
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}
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}
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// All bit rotations of a set of distinct keys
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func TestSmhasherWindowed(t *testing.T) {
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windowed(t, &Int32Key{})
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windowed(t, &Int64Key{})
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windowed(t, &BytesKey{make([]byte, 128)})
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}
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func windowed(t *testing.T, k Key) {
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if testing.Short() {
|
|
t.Skip("Skipping in short mode")
|
|
}
|
|
const BITS = 16
|
|
|
|
for r := 0; r < k.bits(); r++ {
|
|
h := newHashSet()
|
|
for i := 0; i < 1<<BITS; i++ {
|
|
k.clear()
|
|
for j := 0; j < BITS; j++ {
|
|
if i>>uint(j)&1 != 0 {
|
|
k.flipBit((j + r) % k.bits())
|
|
}
|
|
}
|
|
h.add(k.hash())
|
|
}
|
|
h.check(t)
|
|
}
|
|
}
|
|
|
|
// All keys of the form prefix + [A-Za-z0-9]*N + suffix.
|
|
func TestSmhasherText(t *testing.T) {
|
|
if testing.Short() {
|
|
t.Skip("Skipping in short mode")
|
|
}
|
|
text(t, "Foo", "Bar")
|
|
text(t, "FooBar", "")
|
|
text(t, "", "FooBar")
|
|
}
|
|
func text(t *testing.T, prefix, suffix string) {
|
|
const N = 4
|
|
const S = "ABCDEFGHIJKLMNOPQRSTabcdefghijklmnopqrst0123456789"
|
|
const L = len(S)
|
|
b := make([]byte, len(prefix)+N+len(suffix))
|
|
copy(b, prefix)
|
|
copy(b[len(prefix)+N:], suffix)
|
|
h := newHashSet()
|
|
c := b[len(prefix):]
|
|
for i := 0; i < L; i++ {
|
|
c[0] = S[i]
|
|
for j := 0; j < L; j++ {
|
|
c[1] = S[j]
|
|
for k := 0; k < L; k++ {
|
|
c[2] = S[k]
|
|
for x := 0; x < L; x++ {
|
|
c[3] = S[x]
|
|
h.addB(b)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
h.check(t)
|
|
}
|
|
|
|
// Make sure different seed values generate different hashes.
|
|
func TestSmhasherSeed(t *testing.T) {
|
|
h := newHashSet()
|
|
const N = 100000
|
|
s := "hello"
|
|
for i := 0; i < N; i++ {
|
|
h.addS_seed(s, uintptr(i))
|
|
}
|
|
h.check(t)
|
|
}
|
|
|
|
// size of the hash output (32 or 64 bits)
|
|
const hashSize = 32 + int(^uintptr(0)>>63<<5)
|
|
|
|
func randBytes(r *rand.Rand, b []byte) {
|
|
for i := range b {
|
|
b[i] = byte(r.Uint32())
|
|
}
|
|
}
|
|
|
|
func benchmarkHash(b *testing.B, n int) {
|
|
s := strings.Repeat("A", n)
|
|
|
|
for i := 0; i < b.N; i++ {
|
|
StringHash(s, 0)
|
|
}
|
|
b.SetBytes(int64(n))
|
|
}
|
|
|
|
func BenchmarkHash5(b *testing.B) { benchmarkHash(b, 5) }
|
|
func BenchmarkHash16(b *testing.B) { benchmarkHash(b, 16) }
|
|
func BenchmarkHash64(b *testing.B) { benchmarkHash(b, 64) }
|
|
func BenchmarkHash1024(b *testing.B) { benchmarkHash(b, 1024) }
|
|
func BenchmarkHash65536(b *testing.B) { benchmarkHash(b, 65536) }
|
|
|
|
func TestArrayHash(t *testing.T) {
|
|
if Compiler == "gccgo" {
|
|
t.Skip("does not work on gccgo without better escape analysis")
|
|
}
|
|
|
|
// Make sure that "" in arrays hash correctly. The hash
|
|
// should at least scramble the input seed so that, e.g.,
|
|
// {"","foo"} and {"foo",""} have different hashes.
|
|
|
|
// If the hash is bad, then all (8 choose 4) = 70 keys
|
|
// have the same hash. If so, we allocate 70/8 = 8
|
|
// overflow buckets. If the hash is good we don't
|
|
// normally allocate any overflow buckets, and the
|
|
// probability of even one or two overflows goes down rapidly.
|
|
// (There is always 1 allocation of the bucket array. The map
|
|
// header is allocated on the stack.)
|
|
f := func() {
|
|
// Make the key type at most 128 bytes. Otherwise,
|
|
// we get an allocation per key.
|
|
type key [8]string
|
|
m := make(map[key]bool, 70)
|
|
|
|
// fill m with keys that have 4 "foo"s and 4 ""s.
|
|
for i := 0; i < 256; i++ {
|
|
var k key
|
|
cnt := 0
|
|
for j := uint(0); j < 8; j++ {
|
|
if i>>j&1 != 0 {
|
|
k[j] = "foo"
|
|
cnt++
|
|
}
|
|
}
|
|
if cnt == 4 {
|
|
m[k] = true
|
|
}
|
|
}
|
|
if len(m) != 70 {
|
|
t.Errorf("bad test: (8 choose 4) should be 70, not %d", len(m))
|
|
}
|
|
}
|
|
if n := testing.AllocsPerRun(10, f); n > 6 {
|
|
t.Errorf("too many allocs %f - hash not balanced", n)
|
|
}
|
|
}
|
|
func TestStructHash(t *testing.T) {
|
|
// See the comment in TestArrayHash.
|
|
f := func() {
|
|
type key struct {
|
|
a, b, c, d, e, f, g, h string
|
|
}
|
|
m := make(map[key]bool, 70)
|
|
|
|
// fill m with keys that have 4 "foo"s and 4 ""s.
|
|
for i := 0; i < 256; i++ {
|
|
var k key
|
|
cnt := 0
|
|
if i&1 != 0 {
|
|
k.a = "foo"
|
|
cnt++
|
|
}
|
|
if i&2 != 0 {
|
|
k.b = "foo"
|
|
cnt++
|
|
}
|
|
if i&4 != 0 {
|
|
k.c = "foo"
|
|
cnt++
|
|
}
|
|
if i&8 != 0 {
|
|
k.d = "foo"
|
|
cnt++
|
|
}
|
|
if i&16 != 0 {
|
|
k.e = "foo"
|
|
cnt++
|
|
}
|
|
if i&32 != 0 {
|
|
k.f = "foo"
|
|
cnt++
|
|
}
|
|
if i&64 != 0 {
|
|
k.g = "foo"
|
|
cnt++
|
|
}
|
|
if i&128 != 0 {
|
|
k.h = "foo"
|
|
cnt++
|
|
}
|
|
if cnt == 4 {
|
|
m[k] = true
|
|
}
|
|
}
|
|
if len(m) != 70 {
|
|
t.Errorf("bad test: (8 choose 4) should be 70, not %d", len(m))
|
|
}
|
|
}
|
|
if n := testing.AllocsPerRun(10, f); n > 6 {
|
|
t.Errorf("too many allocs %f - hash not balanced", n)
|
|
}
|
|
}
|
|
|
|
var sink uint64
|
|
|
|
func BenchmarkAlignedLoad(b *testing.B) {
|
|
var buf [16]byte
|
|
p := unsafe.Pointer(&buf[0])
|
|
var s uint64
|
|
for i := 0; i < b.N; i++ {
|
|
s += ReadUnaligned64(p)
|
|
}
|
|
sink = s
|
|
}
|
|
|
|
func BenchmarkUnalignedLoad(b *testing.B) {
|
|
var buf [16]byte
|
|
p := unsafe.Pointer(&buf[1])
|
|
var s uint64
|
|
for i := 0; i < b.N; i++ {
|
|
s += ReadUnaligned64(p)
|
|
}
|
|
sink = s
|
|
}
|
|
|
|
func TestCollisions(t *testing.T) {
|
|
if testing.Short() {
|
|
t.Skip("Skipping in short mode")
|
|
}
|
|
for i := 0; i < 16; i++ {
|
|
for j := 0; j < 16; j++ {
|
|
if j == i {
|
|
continue
|
|
}
|
|
var a [16]byte
|
|
m := make(map[uint16]struct{}, 1<<16)
|
|
for n := 0; n < 1<<16; n++ {
|
|
a[i] = byte(n)
|
|
a[j] = byte(n >> 8)
|
|
m[uint16(BytesHash(a[:], 0))] = struct{}{}
|
|
}
|
|
if len(m) <= 1<<15 {
|
|
t.Errorf("too many collisions i=%d j=%d outputs=%d out of 65536\n", i, j, len(m))
|
|
}
|
|
}
|
|
}
|
|
}
|