Benchmark multiple Guid-to-Base64Url and Base64Url-to-Guid methods

BenchmarkGuidToBase64Url.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFrameworks>net10.0;net9.0</TargetFrameworks>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="BenchmarkDotNet" Version="0.15.8" />
  </ItemGroup>

</Project>

Program.cs

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

// dotnet run -c Release -f net9.0 --filter "*" --runtimes net9.0 net10.0
BenchmarkRunner.Run<GuidToBase64Url>(args: args);

[GroupBenchmarksBy(BenchmarkLogicalGroupRule.ByCategory)]
[MemoryDiagnoser]
[HideColumns("Job", "Error", "StdDev", "Gen0")]
public class GuidToBase64Url
{
    public Guid _guid = new("c05d4d42-e4e7-4f2e-9b1f-f896a86ed633");
    public string _str = "Qk1dwOfkLk-bH_iWqG7WMw";

    [BenchmarkCategory("to"), Benchmark(Baseline = true)]
    public string ToShortString_Original()
    {
        return Convert.ToBase64String(_guid.ToByteArray())[..^2]
            .Replace('+', '-')
            .Replace('/', '_');
    }

    [BenchmarkCategory("to"), Benchmark]
    public string ToShortString_Custom()
    {
        Span<byte> bytes = stackalloc byte[16];
        _guid.TryWriteBytes(bytes);

        Span<char> chars = stackalloc char[24];
        Convert.TryToBase64Chars(bytes, chars, out _);

        chars = chars[..22];
        chars.Replace('+', '-');
        chars.Replace('/', '_');
        return chars.ToString();
    }

    [BenchmarkCategory("to"), Benchmark]
    public string ToShortString_Base64Url()
    {
        Span<byte> bytes = stackalloc byte[16];
        _guid.TryWriteBytes(bytes);
        return Base64Url.EncodeToString(bytes);
    }

    [BenchmarkCategory("from"), Benchmark(Baseline = true)]
    public Guid FromShortString_Original()
    {
        return new Guid(Convert.FromBase64String(
            _str.Replace('_', '/').Replace('-', '+') + "=="));
    }

    [BenchmarkCategory("from"), Benchmark]
    public Guid FromShortString_Custom()
    {
        Span<char> chars = stackalloc char[24];
        _str.CopyTo(chars);
        chars.Replace('_', '/');
        chars.Replace('-', '+');
        "==".CopyTo(chars[22..]);

        Span<byte> bytes = stackalloc byte[16];
        Convert.TryFromBase64Chars(chars, bytes, out _);

        return new Guid(bytes);
    }

    [BenchmarkCategory("from"), Benchmark]
    public Guid FromShortString_Base64Url()
    {
        Span<byte> bytes = stackalloc byte[16];
        Base64Url.DecodeFromChars(_str.AsSpan(), bytes);
        return new Guid(bytes);
    }
}