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// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package slices
import (
"math/rand"
"sort"
"strings"
"testing"
)
// These benchmarks compare sorting a large slice of int with sort.Ints vs.
// slices.Sort
func makeRandomInts(n int) []int {
rand.Seed(42)
ints := make([]int, n)
for i := 0; i < n; i++ {
ints[i] = rand.Intn(n)
}
return ints
}
func makeSortedInts(n int) []int {
ints := make([]int, n)
for i := 0; i < n; i++ {
ints[i] = i
}
return ints
}
func makeReversedInts(n int) []int {
ints := make([]int, n)
for i := 0; i < n; i++ {
ints[i] = n - i
}
return ints
}
const N = 100_000
func BenchmarkSortInts(b *testing.B) {
for i := 0; i < b.N; i++ {
b.StopTimer()
ints := makeRandomInts(N)
b.StartTimer()
sort.Ints(ints)
}
}
func BenchmarkSlicesSortInts(b *testing.B) {
for i := 0; i < b.N; i++ {
b.StopTimer()
ints := makeRandomInts(N)
b.StartTimer()
Sort(ints)
}
}
func BenchmarkSlicesSortInts_Sorted(b *testing.B) {
for i := 0; i < b.N; i++ {
b.StopTimer()
ints := makeSortedInts(N)
b.StartTimer()
Sort(ints)
}
}
func BenchmarkSlicesSortInts_Reversed(b *testing.B) {
for i := 0; i < b.N; i++ {
b.StopTimer()
ints := makeReversedInts(N)
b.StartTimer()
Sort(ints)
}
}
// Since we're benchmarking these sorts against each other, make sure that they
// generate similar results.
func TestIntSorts(t *testing.T) {
ints := makeRandomInts(200)
ints2 := Clone(ints)
sort.Ints(ints)
Sort(ints2)
for i := range ints {
if ints[i] != ints2[i] {
t.Fatalf("ints2 mismatch at %d; %d != %d", i, ints[i], ints2[i])
}
}
}
// The following is a benchmark for sorting strings.
// makeRandomStrings generates n random strings with alphabetic runes of
// varying lenghts.
func makeRandomStrings(n int) []string {
rand.Seed(42)
var letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
ss := make([]string, n)
for i := 0; i < n; i++ {
var sb strings.Builder
slen := 2 + rand.Intn(50)
for j := 0; j < slen; j++ {
sb.WriteRune(letters[rand.Intn(len(letters))])
}
ss[i] = sb.String()
}
return ss
}
func TestStringSorts(t *testing.T) {
ss := makeRandomStrings(200)
ss2 := Clone(ss)
sort.Strings(ss)
Sort(ss2)
for i := range ss {
if ss[i] != ss2[i] {
t.Fatalf("ss2 mismatch at %d; %s != %s", i, ss[i], ss2[i])
}
}
}
func BenchmarkSortStrings(b *testing.B) {
for i := 0; i < b.N; i++ {
b.StopTimer()
ss := makeRandomStrings(N)
b.StartTimer()
sort.Strings(ss)
}
}
func BenchmarkSlicesSortStrings(b *testing.B) {
for i := 0; i < b.N; i++ {
b.StopTimer()
ss := makeRandomStrings(N)
b.StartTimer()
Sort(ss)
}
}
// These benchmarks compare sorting a slice of structs with sort.Sort vs.
// slices.SortFunc.
type myStruct struct {
a, b, c, d string
n int
}
type myStructs []*myStruct
func (s myStructs) Len() int { return len(s) }
func (s myStructs) Less(i, j int) bool { return s[i].n < s[j].n }
func (s myStructs) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func makeRandomStructs(n int) myStructs {
rand.Seed(42)
structs := make([]*myStruct, n)
for i := 0; i < n; i++ {
structs[i] = &myStruct{n: rand.Intn(n)}
}
return structs
}
func TestStructSorts(t *testing.T) {
ss := makeRandomStructs(200)
ss2 := make([]*myStruct, len(ss))
for i := range ss {
ss2[i] = &myStruct{n: ss[i].n}
}
sort.Sort(ss)
SortFunc(ss2, func(a, b *myStruct) bool { return a.n < b.n })
for i := range ss {
if *ss[i] != *ss2[i] {
t.Fatalf("ints2 mismatch at %d; %v != %v", i, *ss[i], *ss2[i])
}
}
}
func BenchmarkSortStructs(b *testing.B) {
for i := 0; i < b.N; i++ {
b.StopTimer()
ss := makeRandomStructs(N)
b.StartTimer()
sort.Sort(ss)
}
}
func BenchmarkSortFuncStructs(b *testing.B) {
lessFunc := func(a, b *myStruct) bool { return a.n < b.n }
for i := 0; i < b.N; i++ {
b.StopTimer()
ss := makeRandomStructs(N)
b.StartTimer()
SortFunc(ss, lessFunc)
}
}
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