bucket-name-validation.go

func BenchmarkValidation(b *testing.B) {
	buckets := [][]byte{
		[]byte("five5"),
		[]byte("abcd-abcd-abcd-abcd-abcd-abcd"),
		[]byte("abcd-abcd-abcd-abcd-abcd-abcd-abcd-abcd-abcd-abcd-abcd-abcd"),
	}
	for _, bucket := range buckets {
		b.Run("simple-size-"+strconv.Itoa(len(bucket)), func(b *testing.B) {
			for n := 0; n < b.N; n++ {
				labels := bytes.Split(bucket, []byte("."))
				for _, label := range labels {
					_ = validateBucketLabel(label)
				}
			}
		})

		regexp := regexp.MustCompile(`^([a-z0-9]+([a-z0-9\-][a-z0-9])*)+(.[a-z0-9]+([a-z0-9\-][a-z0-9])*)*$`)
		b.Run("regexp-size-"+strconv.Itoa(len(bucket)), func(b *testing.B) {
			for n := 0; n < b.N; n++ {
				regexp.MatchString(string(bucket))
			}
		})
	}
}

func validateBucketLabel(label []byte) error {
	if len(label) == 0 {
		return errs.New("bucket label cannot be empty")
	}

	if !isLowerLetter(label[0]) && !isDigit(label[0]) {
		return errs.New("bucket label must start with a lowercase letter or number")
	}

	if label[0] == '-' || label[len(label)-1] == '-' {
		return errs.New("bucket label cannot start or end with a hyphen")
	}

	for i := 1; i < len(label)-1; i++ {
		if !isLowerLetter(label[i]) && !isDigit(label[i]) && (label[i] != '-') && (label[i] != '.') {
			return errs.New("bucket name must contain only lowercase letters, numbers or hyphens")
		}
	}

	return nil
}

func isLowerLetter(r byte) bool {
	return r >= 'a' && r <= 'z'
}

func isDigit(r byte) bool {
	return r >= '0' && r <= '9'
}

Results:

BenchmarkValidation/simple-size-5-8         	30000000	        51.7 ns/op	      32 B/op	       1 allocs/op
BenchmarkValidation/regexp-size-5-8         	 5000000	       252 ns/op	       5 B/op	       1 allocs/op
BenchmarkValidation/simple-size-29-8        	20000000	       100 ns/op	      32 B/op	       1 allocs/op
BenchmarkValidation/regexp-size-29-8        	 2000000	       991 ns/op	      32 B/op	       1 allocs/op
BenchmarkValidation/simple-size-59-8        	20000000	       121 ns/op	      32 B/op	       1 allocs/op
BenchmarkValidation/regexp-size-59-8        	 1000000	      1857 ns/op	      65 B/op	       1 allocs/op
PASS
ok  	storj.io/storj/satellite/metainfo	12.664s