Await list of async predicates, but drop out on first false

Question

Imagine the following class:

public class Checker
{
   public async Task Check() { ... }
}

Now, imagine a list of instances of

Answer 1

Here's a fully functional test program, following in steps of dcastro:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AsyncCheckerTest
{
    public class Checker
    {
        public int Seconds { get; private set; }

        public Checker(int seconds)
        {
            Seconds = seconds;
        }

        public async Task CheckAsync()
        {
            await Task.Delay(Seconds * 1000);
            return Seconds != 3;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var task = RunAsync();
            task.Wait();

            Console.WriteLine("Overall result: " + task.Result);
            Console.ReadLine();
        }

        public static async Task RunAsync()
        {
            var checkers = new List();
            checkers
                .AddRange(Enumerable.Range(1, 5)
                .Select(i => new Checker(i)));

            return await checkers
                            .Select(c => c.CheckAsync())
                            .AllAsync();
        }
    }

    public static class ExtensionMethods
    {
        public static async Task AllAsync(this IEnumerable> source)
        {
            var tasks = source.ToList();

            while (tasks.Count != 0)
            {
                Task finishedTask = await Task.WhenAny(tasks);

                bool checkResult = finishedTask.Result;

                if (!checkResult)
                {
                    Console.WriteLine("Completed at " + DateTimeOffset.Now + "...false");
                    return false;
                }

                Console.WriteLine("Working... " + DateTimeOffset.Now);
                tasks.Remove(finishedTask);
            }

            return true;
        }
    }
}

Here's sample output:

Working... 6/27/2014 1:47:35 AM -05:00
Working... 6/27/2014 1:47:36 AM -05:00
Completed at 6/27/2014 1:47:37 AM -05:00...false
Overall result: False

Note that entire eval ended when exit condition was reached, without waiting for the rest to finish.