Improve performance of callback handling #399

public class BenchmarkNatives
{
    [NativeMethod] 
    public virtual void CallRemoteFunction(string func, string format, params object[] args)
    {
        throw new NativeNotImplementedException();
    }
}

public class GameMode : BaseMode
{
    private (string, int, float)? _benchStore;

    protected override void OnInitialized(EventArgs e)
    {
        base.OnInitialized(e);

        // (...)

        Console.WriteLine("Bench start");
        RunCallbackBenchmark();
    }

    private void RunCallbackBenchmark()
    {
        var natives = NativeObjectProxyFactory.CreateInstance<BenchmarkNatives>();
        var args = new object[] { "stringValue", 4321, 23.665f };
        var sw = new Stopwatch();
        
        const int maxRuns = 10;
        const int runCallCount = 1_000_000;

        var totalElapsed = TimeSpan.Zero;
        for (var j = 0; j <= maxRuns; j++)
        {
            Console.WriteLine($"Bench run {j}/{maxRuns}");
            if (j == 0) Console.WriteLine("(warmup)");

            sw.Restart();

            for (var i = 0; i < runCallCount; i++)
            {
                natives.CallRemoteFunction("BenchmarkCallback", "sdf", args);

                // validate
                
                if (!_benchStore.HasValue || _benchStore.Value.Item1 != "stringValue" ||
                    _benchStore.Value.Item2 != 4321 || Math.Abs(_benchStore.Value.Item3 - 23.665f) > 0.001f)
                {
                    throw new InvalidOperationException("native call failed!");
                }

                _benchStore = null;
            }

            sw.Stop();

            if (j > 0)
                totalElapsed += sw.Elapsed;
            Console.WriteLine($"{runCallCount} calls took {sw.Elapsed}");
        }

        Console.WriteLine($"AVG of {totalElapsed / maxRuns}");
    }

    [Callback]
    public void BenchmarkCallback(string stringValue, int intValue, float floatValue)
    {
        _benchStore = (stringValue, intValue, floatValue);
    }
}