map.go

/*
cpu: Apple M1
BenchmarkString1
BenchmarkString1-8   	    3292	    362786 ns/op
BenchmarkString2
BenchmarkString2-8   	   27062	     43746 ns/op
PASS
*/

package foo

import (
	"fmt"
	"strconv"
	"strings"
	"testing"
)

func String1(m map[string]string) string {
	return fmt.Sprintf("%v", m)
}

func String2(m map[string]string) string {
	res := make([]string, 0, len(m))
	for k, v := range m {
		res = append(res, k+"="+v)
	}
	return strings.Join(res, ",")
}

var global string

func BenchmarkString1(b *testing.B) {
	m := inputMap()
	b.ResetTimer()
	var local string
	for i := 0; i < b.N; i++ {
		local = String1(m)
	}
	global = local
}

func BenchmarkString2(b *testing.B) {
	m := inputMap()
	b.ResetTimer()
	var local string
	for i := 0; i < b.N; i++ {
		local = String2(m)
	}
	global = local
}

func inputMap() map[string]string {
	l := 1000
	m := make(map[string]string, l)
	for i := 0; i < l; i++ {
		v := strings.Repeat("-", 10)
		m[v+strconv.Itoa(i)] = v
	}
	return m
}