benchmark prepend golang

prepend_test.go

package main

import "testing"

func BenchmarkPrependAppend(b *testing.B) {
	s := []string{"one", "two", "three", "four"}
	word := "zero"
	for i := 0; i < b.N; i++ {
		s = append([]string{word}, s...)
	}
}

func BenchmarkPrependCopy(b *testing.B) {
	s := []string{"one", "two", "three", "four"}
	word := "zero"
	for i := 0; i < b.N; i++ {
		s = append(s, "")
		copy(s[1:], s)
		s[0] = word
	}
}

func BenchmarkPrependMake(b *testing.B) {
	s := []string{"one", "two", "three", "four"}
	word := "zero"
	for i := 0; i < b.N; i++ {
		res := make([]string, len(s)+1)
		res[0] = word
		copy(res[1:], s)
		s = res
	}
}

results

BenchmarkPrependAppend     20000            165476 ns/op          163872 B/op          2 allocs/op
BenchmarkPrependCopy      200000            170145 ns/op              91 B/op          0 allocs/op
BenchmarkPrependMake       20000            161054 ns/op          163856 B/op          1 allocs/op