using System;

using System.Threading.Tasks;

​

public class Program

{

    static DateTime _nextRefresh = DateTime.MaxValue;

    public static void Main()

    {

        MainAsync().GetAwaiter().GetResult();

    }

    public static async Task MainAsync()

    {

        for (int i=0; i<10; i++)

        {

            Update();

            await Task.Delay(20);

        }

        Console.WriteLine("Done updating!");

        await Task.Delay(3000);

        Console.WriteLine("Done!");

    }

​

    static private async void Update() 

    {

        Console.WriteLine("Update!");

        await RefreshInOneSecond();

    }

​

    static private async Task RefreshInOneSecond()

    {

        _nextRefresh = DateTime.Now.AddSeconds(1);

        await Task.Delay(1000);

        if (_nextRefresh < DateTime.Now)

        {

            _nextRefresh = DateTime.MaxValue;

            Refresh();

        }

    }

    static public void Refresh()

    {

        Console.WriteLine("Refresh!");

    }

}

​

​