slice_test.go

package main

import (
	"runtime"
	"strconv"
	"strings"
	"sync"
	"testing"
)

func MapMake(list []string, op func(string) string) []string {
	output := make([]string, len(list))
	for i, v := range list {
		output[i] = op(v)
	}
	return output
}

func Map(list []string, op func(string) string) []string {
	output := make([]string, 0, len(list))
	for _, v := range list {
		output = append(output, op(v))
	}
	return output
}

func mapPart(list []string, out *[]string, op func(string) string, start int, end int, wg *sync.WaitGroup) {
	for i := start; i < end; i++ {
		(*out)[i] = op(list[i])
	}
	wg.Done()
}

func MapPar(list []string, op func(string) string) []string {
	runtime.GOMAXPROCS(2)
	output := make([]string, len(list))
	var wg sync.WaitGroup
	wg.Add(2)
	half := len(list) / 2
	go mapPart(list, &output, op, 0, half, &wg)
	go mapPart(list, &output, op, half, len(list), &wg)
	wg.Wait()
	return output
}

func makeSlice(n int) []string {
	out := []string{}
	for i := 0; i < n; i++ {
		out = append(out, strconv.Itoa(i))
	}
	return out
}

func BenchmarkSliceMake10(b *testing.B) {
	benchmarkSliceMakeN(10, b)
}
func BenchmarkSliceMake100(b *testing.B) {
	benchmarkSliceMakeN(100, b)
}
func BenchmarkSliceMake1000(b *testing.B) {
	benchmarkSliceMakeN(1000, b)
}
func BenchmarkSliceMake10000(b *testing.B) {
	benchmarkSliceMakeN(10000, b)
}

func benchmarkSliceMakeN(n int, b *testing.B) {
	in := makeSlice(n)
	for i := 0; i < b.N; i++ {
		out := MapMake(in, strings.ToUpper)
		if len(out) != n {
			b.Fatal("wrong length")
		}
	}
}

func BenchmarkSliceAppend10(b *testing.B) {
	benchmarkSliceAppendN(10, b)
}
func BenchmarkSliceAppend100(b *testing.B) {
	benchmarkSliceAppendN(100, b)
}
func BenchmarkSliceAppend1000(b *testing.B) {
	benchmarkSliceAppendN(1000, b)
}
func BenchmarkSliceAppend10000(b *testing.B) {
	benchmarkSliceAppendN(10000, b)
}

func benchmarkSliceAppendN(n int, b *testing.B) {
	in := makeSlice(n)
	for i := 0; i < b.N; i++ {
		out := Map(in, strings.ToUpper)
		if len(out) != n {
			b.Fatal("wrong length")
		}
	}
}

func BenchmarkSlicePar10(b *testing.B) {
	benchmarkSliceParN(10, b)
}
func BenchmarkSlicePar100(b *testing.B) {
	benchmarkSliceParN(100, b)
}
func BenchmarkSlicePar1000(b *testing.B) {
	benchmarkSliceParN(1000, b)
}
func BenchmarkSlicePar10000(b *testing.B) {
	benchmarkSliceParN(10000, b)
}

func benchmarkSliceParN(n int, b *testing.B) {
	in := makeSlice(n)
	for i := 0; i < b.N; i++ {
		out := MapPar(in, strings.ToUpper)
		if len(out) != n {
			b.Fatal("wrong length")
		}
	}
}