Zero padding benchmarks

padding_bench_test.go

package strings

import (
	"bytes"
	"fmt"
	"strings"
	"testing"
)

var (
	padResult string
	zeroes    = 2
)

func BenchmarkPadWithSprintf(b *testing.B) {
	var (
		padder string
		result string
	)

	for i := 0; i < b.N; i++ {
		padder = fmt.Sprintf("%%0%dd", zeroes)
		result = fmt.Sprintf(padder, i)
	}

	padResult = result
}

func BenchmarkPadWithMinimalSprint(b *testing.B) {
	var (
		padder string
		result string
	)

	for i := 0; i < b.N; i++ {
		padder = "%0" + fmt.Sprint(zeroes) + "d"
		result = fmt.Sprintf(padder, i)
	}

	padResult = result
}

func BenchmarkPadWithBuffer(b *testing.B) {
	var result string

	for i := 0; i < b.N; i++ {
		s := fmt.Sprint(i)

		buf := bytes.NewBuffer(nil)

		for j := 0; j < zeroes-len(s); j++ {
			buf.WriteString("0")
		}

		result = buf.String() + s
	}

	padResult = result
}

func BenchmarkPadWithBufferByte(b *testing.B) {
	var result string

	for i := 0; i < b.N; i++ {
		s := fmt.Sprint(i)

		buf := bytes.NewBuffer(nil)

		for j := 0; j < zeroes-len(s); j++ {
			buf.Write([]byte{'0'})
		}

		result = buf.String() + s
	}

	padResult = result
}

func BenchmarkPadWithStringBuffer(b *testing.B) {
	var result string

	for i := 0; i < b.N; i++ {
		s := fmt.Sprint(i)

		buf := &strings.Builder{}

		for j := 0; j < zeroes-len(s); j++ {
			buf.WriteString("0")
		}

		result = buf.String() + s
	}

	padResult = result
}

func BenchmarkPadWithStringBufferByte(b *testing.B) {
	var result string

	for i := 0; i < b.N; i++ {
		s := fmt.Sprint(i)

		buf := &strings.Builder{}

		for j := 0; j < zeroes-len(s); j++ {
			buf.Write([]byte{'0'})
		}

		result = buf.String() + s
	}

	padResult = result
}

func BenchmarkPadWithRepeat(b *testing.B) {
	var result string
	for i := 0; i < b.N; i++ {
		result = strings.Repeat("0", zeroes)
	}

	padResult = result
}

results.md

With zeroes = 2:

Running tool: /usr/local/bin/go test -benchmem -run=^$ github.com/ajm188/playground/bench/strings -bench ^(BenchmarkPadWithSprintf|BenchmarkPadWithMinimalSprint|BenchmarkPadWithBuffer|BenchmarkPadWithBufferByte|BenchmarkPadWithStringBuffer|BenchmarkPadWithStringBufferByte|BenchmarkPadWithRepeat)$

goos: darwin
goarch: amd64
pkg: github.com/ajm188/playground/bench/strings
BenchmarkPadWithSprintf-8            	 6237045	       193 ns/op	      23 B/op	       2 allocs/op
BenchmarkPadWithMinimalSprint-8      	 6153098	       219 ns/op	      23 B/op	       2 allocs/op
BenchmarkPadWithBuffer-8             	14622043	        81.7 ns/op	      16 B/op	       1 allocs/op
BenchmarkPadWithBufferByte-8         	15127011	        82.5 ns/op	      16 B/op	       1 allocs/op
BenchmarkPadWithStringBuffer-8       	14942125	        80.1 ns/op	      16 B/op	       1 allocs/op
BenchmarkPadWithStringBufferByte-8   	14615377	       106 ns/op	      16 B/op	       1 allocs/op
BenchmarkPadWithRepeat-8             	45234685	        26.8 ns/op	       2 B/op	       1 allocs/op
PASS
ok  	github.com/ajm188/playground/bench/strings	10.964s

With zeroes = 200:

Running tool: /usr/local/bin/go test -benchmem -run=^$ github.com/ajm188/playground/bench/strings -bench ^(BenchmarkPadWithSprintf|BenchmarkPadWithMinimalSprint|BenchmarkPadWithBuffer|BenchmarkPadWithBufferByte|BenchmarkPadWithStringBuffer|BenchmarkPadWithStringBufferByte|BenchmarkPadWithRepeat)$

goos: darwin
goarch: amd64
pkg: github.com/ajm188/playground/bench/strings
BenchmarkPadWithSprintf-8            	 2155336	       562 ns/op	     432 B/op	       4 allocs/op
BenchmarkPadWithMinimalSprint-8      	 1985774	       646 ns/op	     440 B/op	       5 allocs/op
BenchmarkPadWithBuffer-8             	  897444	      1324 ns/op	     928 B/op	       7 allocs/op
BenchmarkPadWithBufferByte-8         	  901957	      1401 ns/op	     928 B/op	       7 allocs/op
BenchmarkPadWithStringBuffer-8       	 1828899	       655 ns/op	     728 B/op	       9 allocs/op
BenchmarkPadWithStringBufferByte-8   	 1769736	       670 ns/op	     728 B/op	       9 allocs/op
BenchmarkPadWithRepeat-8             	14318334	        83.3 ns/op	     208 B/op	       1 allocs/op
PASS
ok  	github.com/ajm188/playground/bench/strings	11.518s

With zeroes = 2000:

Running tool: /usr/local/bin/go test -benchmem -run=^$ github.com/ajm188/playground/bench/strings -bench ^(BenchmarkPadWithSprintf|BenchmarkPadWithMinimalSprint|BenchmarkPadWithBuffer|BenchmarkPadWithBufferByte|BenchmarkPadWithStringBuffer|BenchmarkPadWithStringBufferByte|BenchmarkPadWithRepeat)$

goos: darwin
goarch: amd64
pkg: github.com/ajm188/playground/bench/strings
BenchmarkPadWithSprintf-8            	  348314	      3307 ns/op	    4121 B/op	       5 allocs/op
BenchmarkPadWithMinimalSprint-8      	  367332	      3276 ns/op	    4129 B/op	       6 allocs/op
BenchmarkPadWithBuffer-8             	  108021	     10953 ns/op	    8642 B/op	      10 allocs/op
BenchmarkPadWithBufferByte-8         	  106500	     11408 ns/op	    8642 B/op	      10 allocs/op
BenchmarkPadWithStringBuffer-8       	  292899	      4133 ns/op	    9483 B/op	      14 allocs/op
BenchmarkPadWithStringBufferByte-8   	  263287	      4705 ns/op	    9483 B/op	      14 allocs/op
BenchmarkPadWithRepeat-8             	 3714966	       312 ns/op	    2048 B/op	       1 allocs/op
PASS
ok  	github.com/ajm188/playground/bench/strings	9.520s

The Sprintf approaches start to overtake in terms of time around 25 zeroes, and in terms of memory allocations at 7 zeroes.