Improve StringBuilder usage by BrennanConroy · Pull Request #44691 · dotnet/aspnetcore (original) (raw)

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FYI @martincostello and @javiercn in regards to the conversation at https://github.com/dotnet/aspnetcore/pull/36368/files#r706039158

This makes use of Interpolated string handlers, and StringBuilder has a custom one which allows formatting the interpolated string directly into it's internal buffer instead of instantiating a string then copying the string.

Benchmark code

[MemoryDiagnoser] public class AppendBenchmark { private byte[] _b = new byte[30];

[GlobalSetup]
public void Setup()
{
    RandomNumberGenerator.Fill(_b);
}

[Benchmark]
public string AppendToString()
{
    var sb = new StringBuilder();
    foreach (var b in _b)
    {
        sb.Append(b.ToString("x2", CultureInfo.InvariantCulture));
    }
    return sb.ToString();
}

[Benchmark]
public string AppendInterpolated()
{
    var sb = new StringBuilder();
    foreach (var b in _b)
    {
        sb.Append(CultureInfo.InvariantCulture, $"{b:x2}");
    }
    return sb.ToString();
}

}