parallel process on awake

main

using System;
using System.Threading;
using System.Threading.Tasks;

namespace AwaitExperiments
{
    class Program
    {
        private static CancellationTokenSource _tokenSource;
        private static int _i;

        static async Task Main(string[] args)
        {
            _tokenSource = new CancellationTokenSource();
            var token = _tokenSource.Token;

            try
            {
                await MainTaskAsync(token);
            }
            catch (OperationCanceledException _)
            {
                Console.WriteLine($"Was canceled i: {_i}");
            }
            finally
            {
                Console.WriteLine($"Finally call i: {_i}");
            }

            /*Console.WriteLine("[Another job] Start");
            await Task.Delay(3000);
            Console.WriteLine("[Another job] Complete");
            Console.WriteLine($"Complete normaly i: {_i}");*/
        }

        private static async Task MainTaskAsync(CancellationToken ct)
        {
            _i = 0;
            var someWorkOneTask = SomeWorkOneAsync(ct);
            ++_i;
            await Task.Delay(1200, ct);
            ++_i;
            var someWorkTwoTask = SomeWorkTwoAsync(someWorkOneTask, ct);
            /*++_i;
            await someWorkTwoTask;*/
            ++_i;
            await someWorkTwoTask;

            ct.ThrowIfCancellationRequested(); 
            ++_i;
            ct.ThrowIfCancellationRequested();
            ++_i;
            ct.ThrowIfCancellationRequested();
            ++_i;

            if (ct.IsCancellationRequested)
            {
                Console.WriteLine($"[MainTaskAsync] cancelation reuqested i: {_i}");
                ct.ThrowIfCancellationRequested();
            }
            await LastWorkAsync(ct);

            ++_i;
        }

        private static async Task LastWorkAsync(CancellationToken ct)
        {
            Console.WriteLine($"[LastWorkAsync] start i: {_i}");
            if (ct.IsCancellationRequested)
            {
                Console.WriteLine($"[LastWorkAsync] cancelation reuqested i: {_i}");
                ct.ThrowIfCancellationRequested();
            }
            await Task.Delay(1000, ct);
            Console.WriteLine($"[LastWorkAsync] complete i: {_i}");
        }

        private static async Task SomeWorkOneAsync(CancellationToken ct)
        {
            Console.WriteLine($"[SomeWorkOneAsync] start i: {_i}");
            Console.WriteLine($"[SomeWorkOneAsync] await Task.Delay(1000, ct) start i: {_i}");
            await Task.Delay(1000, ct);
            Console.WriteLine($"[SomeWorkOneAsync] await Task.Delay(1000, ct) complete i: {_i}");
            LateTaskAsync(ct);
            Console.WriteLine($"[SomeWorkOneAsync] await Task.Delay(100, ct) start i: {_i}");
            await Task.Delay(100, ct);
            Console.WriteLine($"[SomeWorkOneAsync] await Task.Delay(100, ct) complete i: {_i}");
            Console.WriteLine($"[SomeWorkOneAsync] complete i: {_i}");
        }

        private static async Task LateTaskAsync(CancellationToken ct)
        {
            Console.WriteLine($"[LateTaskAsync] start i: {_i}");
            await Task.Delay(301, ct);//301 хорошо иллюстрирует баг. 100 иллюстрирует разницу между точкой создания таска и ожидания
            _tokenSource.Cancel();
            Console.WriteLine($"[LateTaskAsync] complete i: {_i}");
        }

        private static async Task SomeWorkTwoAsync(Task someWorkOneTask, CancellationToken ct)
        {
            Console.WriteLine($"[SomeWorkTwoAsync] start i: {_i}");
            ct.ThrowIfCancellationRequested();
            await someWorkOneTask;
            Console.WriteLine($"[SomeWorkTwoAsync] await someWorkOneTask complete i: {_i}");

            await FakeRequestAsync(ct);
            Console.WriteLine($"[SomeWorkTwoAsync] complete i: {_i}");
        }

        private static async Task FakeRequestAsync(CancellationToken ct)
        {
            if (ct.IsCancellationRequested)
            {
                Console.WriteLine($"[FakeRequestAsync] cancelation requested i: {_i}");
                ct.ThrowIfCancellationRequested();
            }

            await Task.Delay(100);
        }
    }
}