Performance over different approaches to get a mask format from a HTTP status code (e.g. 201=2xx, 204=2xx, 405=4xx, 500=5xx)

status_test.go

package util_test

import (
	"fmt"
	"math"
	"regexp"
	"strconv"
	"testing"
)

var re = regexp.MustCompile(`\d{2}$`)

// Get a masked value from a http status code (e.g. 201=2xx, 204=2xx, 405=4xx, 500=5xx)
func BenchmarkStatusBucket(b *testing.B) {
	statusCode := 201

	b.Run("if-statements", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			s := getStatusIfStatemets(statusCode)
			_ = s
		}
	})

	b.Run("Itoa+concat", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			s := getStatusItoaWithConcat(statusCode)
			_ = s
		}
	})

	b.Run("Itoa+[]byte", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			s := getStatusItoaWithByteArray(statusCode)
			_ = s
		}
	})

	b.Run("Itoa+Sprintf", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			s := getStatusItoaWithSprintf(statusCode)
			_ = s
		}
	})

	b.Run("regex+concat", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			s := getStatusRegexWithConcat(statusCode)
			_ = s
		}
	})

	b.Run("math+Sprintf", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			s := getStatusMathWithSprintf(statusCode)
			_ = s
		}
	})
}

var (
	status1xx = "1xx"
	status2xx = "2xx"
	status3xx = "3xx"
	status4xx = "4xx"
	status5xx = "5xx"
)

func getStatusIfStatemets(statusCode int) string {
	if statusCode >= 100 && statusCode < 200 {
		return status1xx
	} else if statusCode < 300 {
		return status2xx
	} else if statusCode < 400 {
		return status3xx
	} else if statusCode < 500 {
		return status4xx
	}

	return status5xx
}

func getStatusItoaWithConcat(statusCode int) string {
	return string(strconv.Itoa(statusCode)[0]) + "xx"
}

func getStatusItoaWithByteArray(statusCode int) string {
	b := make([]byte, 3)
	b[0] = strconv.Itoa(statusCode)[0]
	b[1] = 'x'
	b[2] = 'x'
	return string(b[:])
}
func getStatusItoaWithSprintf(statusCode int) string {
	return fmt.Sprintf("%dxx", strconv.Itoa(statusCode)[0])
}
func getStatusRegexWithConcat(statusCode int) string {
	return re.ReplaceAllString(strconv.FormatInt(int64(statusCode), 10), `XX`)
}
func getStatusMathWithSprintf(statusCode int) string {
	return fmt.Sprintf("%.0fxx", math.Floor(float64(statusCode/100)))
}

go version go1.12 darwin/amd64

Benchmark test

go test -bench=.  -memprofile=mem.out -benchmem -benchtime=5s
goos: darwin
goarch: amd64
BenchmarkStatusBucket/if-statements-8           10000000000              0.67 ns/op            0 B/op        0 allocs/op
BenchmarkStatusBucket/Itoa+concat-8             100000000               52.5 ns/op             3 B/op        1 allocs/op
BenchmarkStatusBucket/Itoa+[]byte-8             100000000               53.7 ns/op             6 B/op        2 allocs/op
BenchmarkStatusBucket/Itoa+Sprintf-8            50000000               135 ns/op               8 B/op        2 allocs/op
BenchmarkStatusBucket/regex+concat-8            20000000               426 ns/op              32 B/op        4 allocs/op
BenchmarkStatusBucket/math+Sprintf-8            20000000               323 ns/op              16 B/op        2 allocs/op

Memory profiling alloc_space

go tool pprof util.test mem.out
File: util.test
Type: alloc_space
Time: Mar 9, 2019 at 9:40am (-03)
Entering interactive mode (type "help" for commands, "o" for options)
(pprof) top 20
Showing nodes accounting for 2311.54MB, 99.49% of 2323.32MB total
Dropped 8 nodes (cum <= 11.62MB)
      flat  flat%   sum%        cum   cum%
  755.01MB 32.50% 32.50%   755.01MB 32.50%  strconv.formatBits
  518.01MB 22.30% 54.79%   519.01MB 22.34%  fmt.Sprintf
  498.51MB 21.46% 76.25%   509.30MB 21.92%  regexp.(*Regexp).replaceAll
     312MB 13.43% 89.68%   622.01MB 26.77%  github.com/InVisionApp/api/util_test.getStatusItoaWithByteArray
  146.50MB  6.31% 95.98%   655.80MB 28.23%  regexp.(*Regexp).ReplaceAllString
   81.50MB  3.51% 99.49%      316MB 13.60%  github.com/InVisionApp/api/util_test.getStatusMathWithSprintf
         0     0% 99.49%      323MB 13.90%  github.com/InVisionApp/api/util_test.BenchmarkStatusBucket.func2
         0     0% 99.49%   622.01MB 26.77%  github.com/InVisionApp/api/util_test.BenchmarkStatusBucket.func3
         0     0% 99.49%   406.51MB 17.50%  github.com/InVisionApp/api/util_test.BenchmarkStatusBucket.func4
         0     0% 99.49%   655.80MB 28.23%  github.com/InVisionApp/api/util_test.BenchmarkStatusBucket.func5
         0     0% 99.49%      316MB 13.60%  github.com/InVisionApp/api/util_test.BenchmarkStatusBucket.func6
         0     0% 99.49%      323MB 13.90%  github.com/InVisionApp/api/util_test.getStatusItoaWithConcat
         0     0% 99.49%   406.51MB 17.50%  github.com/InVisionApp/api/util_test.getStatusItoaWithSprintf
         0     0% 99.49%   655.80MB 28.23%  github.com/InVisionApp/api/util_test.getStatusRegexWithConcat
         0     0% 99.49%   755.01MB 32.50%  strconv.FormatInt
         0     0% 99.49%   755.01MB 32.50%  strconv.Itoa
         0     0% 99.49%  2323.32MB   100%  testing.(*B).launch
         0     0% 99.49%  2323.32MB   100%  testing.(*B).runN

This report shows the if statement is the fastest and with less allocations and the regex approach is the opposite of that.