Replace Dangerous Characters Benchmark

Program.cs

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;
using System.Buffers;
using System.Text;

BenchmarkRunner.Run<HeaderDecoder>();

public class HeaderDecoder
{
    private static readonly SearchValues<char> s_dangerousCharacters = SearchValues.Create('\0', '\r', '\n');
    private static readonly SearchValues<byte> s_dangerousCharacterBytes = SearchValues.Create((byte)'\0', (byte)'\r', (byte)'\n');
    private static readonly string NoSpecialCharsTest  = "qwertzuiopö ASDFGHJKLü yxcvbnmé 123456789 qwertzuiop ASDFGHJKL yxcvbnm 123456789 qwertzuiop ASDFGHJKL yxcvbnm 123456789";
    private static readonly string HasSpecialCharsTest = "qwertzuiopö\0ASDFGHJKLü\nyxcvbnmé\r123456789 qwertzuiop\0ASDFGHJKL\nyxcvbnm\r123456789 qwertzuiop\0ASDFGHJKL\nyxcvbnm\r123456789";

    [Params(true, false)]
    public bool Dangerous { get; set; }

    [Params(true, false)]
    public bool UseUtf8 { get; set; }

    private Encoding _encoding;
    private byte[] _input;

    [GlobalSetup]
    public void Setup()
    {
        string str = Dangerous ? HasSpecialCharsTest : NoSpecialCharsTest;
        _input = Encoding.ASCII.GetBytes(str);
        _encoding = UseUtf8 ? Encoding.UTF8 : Encoding.Latin1;
    }

    [Benchmark]
    public string GetString()
    {
        ReadOnlySpan<byte> input = _input;
        return _encoding.GetString(input);
    }

    [Benchmark]
    public string StringCreate()
    {
        ReadOnlySpan<byte> input = _input;
        int length = _encoding.GetCharCount(input);
        return string.Create(length, new CreateHeaderState(input, _encoding), static (chars, s) =>
        {
            s.Encoding.GetChars(s.Bytes, chars);
        });
    }

    [Benchmark]
    public string StringCreate_ReplaceDangerous()
    {
        ReadOnlySpan<byte> input = _input;
        int length = _encoding.GetCharCount(input);
        return string.Create(length, new CreateHeaderState(input, _encoding), static (chars, s) =>
        {
            s.Encoding.GetChars(s.Bytes, chars);
            chars.ReplaceAny(s_dangerousCharacters, ' ');
        });
    }

    [Benchmark]
    public string StringCreate_ReplaceDangerous_IfAny()
    {
        ReadOnlySpan<byte> input = _input;
        bool replaceDangerous = input.IndexOfAny(s_dangerousCharacterBytes) >= 0;

        int length = _encoding.GetCharCount(input);
        return string.Create(length, new CreateHeaderState(input, _encoding, replaceDangerous), static (chars, s) =>
        {
            s.Encoding.GetChars(s.Bytes, chars);
            if (s.ReplaceDangerous) chars.ReplaceAny(s_dangerousCharacters, ' ');
        });
    }

    private readonly ref struct CreateHeaderState
    {
        public readonly ReadOnlySpan<byte> Bytes;
        public readonly Encoding Encoding;
        public readonly bool ReplaceDangerous;

        public CreateHeaderState(ReadOnlySpan<byte> bytes, Encoding encoding, bool replaceDangerous = false)
        {
            Bytes = bytes;
            Encoding = encoding;
            ReplaceDangerous = replaceDangerous;
        }
    }
}

public static class Extensions
{
    public static void ReplaceAny<T>(this Span<T> span, SearchValues<T> values, T newValue) where T : IEquatable<T>?
    {
        int pos;
        while ((pos = span.IndexOfAny(values)) >= 0)
        {
            span[pos] = newValue;
            span = span.Slice(pos + 1);
        }
    }
}

results.md

Method	Dangerous	UseUtf8	Mean	Error	StdDev
GetString	False	False	21.06 ns	0.463 ns	0.433 ns
StringCreate	False	False	19.47 ns	0.433 ns	0.362 ns
StringCreate_ReplaceDangerous	False	False	28.47 ns	0.603 ns	0.865 ns
StringCreate_ReplaceDangerous_IfAny	False	False	25.24 ns	0.484 ns	0.452 ns
GetString	False	True	29.44 ns	0.638 ns	0.682 ns
StringCreate	False	True	29.16 ns	0.504 ns	0.421 ns
StringCreate_ReplaceDangerous	False	True	38.52 ns	0.783 ns	0.654 ns
StringCreate_ReplaceDangerous_IfAny	False	True	33.03 ns	0.590 ns	0.523 ns
GetString	True	False	20.33 ns	0.311 ns	0.276 ns
StringCreate	True	False	19.06 ns	0.269 ns	0.239 ns
StringCreate_ReplaceDangerous	True	False	75.23 ns	1.555 ns	2.022 ns
StringCreate_ReplaceDangerous_IfAny	True	False	77.28 ns	1.552 ns	1.787 ns
GetString	True	True	29.27 ns	0.612 ns	0.573 ns
StringCreate	True	True	27.59 ns	0.594 ns	0.993 ns
StringCreate_ReplaceDangerous	True	True	81.58 ns	1.627 ns	1.670 ns
StringCreate_ReplaceDangerous_IfAny	True	True	84.19 ns	1.720 ns	1.980 ns