gistfile1.txt

using System;
using System.Diagnostics;

namespace BoxingTest
{
	public interface ICriticalNotifyCompletion
	{
		void UnsafeOnCompleted(Action a);
		void UnsafeOnCompleted2(Action a);
	}

	public interface IAsyncStateMachine
	{
		void MoveNext();
	}

	struct Awaiter : ICriticalNotifyCompletion
	{
		public void UnsafeOnCompleted(Action a)
		{
			a();
		}

		public void UnsafeOnCompleted2(Action a)
		{
			for (int i = 0; i < 1000000; ++i)
				a();
		}
	}

	public struct AsyncVoidMethodBuilder
	{
		public void AwaitUnsafeOnCompleted<TAwaiter, TStateMachine>(ref TAwaiter awaiter, ref TStateMachine stateMachine)
			where TAwaiter : ICriticalNotifyCompletion
			where TStateMachine : IAsyncStateMachine
		{
			var action = new Action(stateMachine.MoveNext);
			awaiter.UnsafeOnCompleted(action);
		}


		public void AwaitUnsafeOnCompleted2<TAwaiter, TStateMachine>(ref TAwaiter awaiter, ref TStateMachine stateMachine)
			where TAwaiter : ICriticalNotifyCompletion
			where TStateMachine : IAsyncStateMachine
		{
			var action = new Action(stateMachine.MoveNext);
			awaiter.UnsafeOnCompleted2(action);
		}
	}

	struct Test : IAsyncStateMachine
	{
		public static int counter;

		public void MoveNext()
		{
			++counter;
		}

		public void Entry ()
		{
			var s = new AsyncVoidMethodBuilder();
			var awaiter = new Awaiter();
			s.AwaitUnsafeOnCompleted(ref awaiter, ref this);
		}

		public void Entry2 ()
		{
			var s = new AsyncVoidMethodBuilder();
			var awaiter = new Awaiter();
			s.AwaitUnsafeOnCompleted2(ref awaiter, ref this);
		}

	}

	class Program
	{
		static void Main(string[] args)
		{
			var sw = new Stopwatch();
			sw.Start();
			for (int i = 0; i < 1000000; ++i)
			{
				new Test().Entry();
			}

			sw.Stop();
			Console.WriteLine(sw.ElapsedMilliseconds);
			Console.WriteLine("---");

			sw = new Stopwatch();
			sw.Start();
			new Test().Entry2();
			sw.Stop();
			Console.WriteLine(sw.ElapsedMilliseconds);
			Console.WriteLine("---");
		}

	}
}