using System;

using System.Collections.Generic;

using System.Threading;

using System.Threading.Tasks;

public class Program

{

    static CancellationTokenSource cts = new CancellationTokenSource();

    static Random random = new Random(); 

    static async Task Main(string[] args)

    {

        var token = cts.Token;

        await Foo(token);

    }

    static async Task Foo(CancellationToken token)

    {

        try

        {

            Console.WriteLine("Starting Foo");

            await DoAsyncStuff1(token);

            await DoAsyncStuff2(token);

            await DoAsyncStuff3(token);

            Console.WriteLine("Foo Completed");

        }

        catch(Exception e)

        {

            Console.WriteLine($"Exception was caught {e}");

            await Task.Delay(TimeSpan.FromSeconds(1), token);

            Console.WriteLine($"Wait to restart");

            await Foo(token);

        }

    }

    static async Task DoAsyncStuff1(CancellationToken token)

    {

        Console.WriteLine("Start doing async task 1");

        await Task.Delay(500);

        Console.WriteLine("Completed doing async task 1");

    }

    static async Task DoAsyncStuff2(CancellationToken token)

    {

        Console.WriteLine("Start doing async task 2");

        await Task.Delay(500);

        Console.WriteLine("Completed doing async task 2");

    }

    static async Task DoAsyncStuff3(CancellationToken token)

    {

        Console.WriteLine("Start doing async task 3");

        var number = random.Next(5);

        Console.WriteLine($"Random number is {number}");

        if(number<2)

        {

            cts.Cancel();

        }

        await Task.Delay(500);

        token.ThrowIfCancellationRequested();   

        Console.WriteLine("Completed doing async task 3");

    }

}