AsyncCollector

AsyncCollector.cs

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

namespace Utils
{
    class AsyncCollector
    {
        public IReadOnlyList<Task> Tasks => _tasks.AsReadOnly();

        private readonly List<Task> _tasks = new List<Task>();

        public void Register(Func<Task> asyncDelegate) =>
            this.Register(asyncDelegate, out _);

        public void Register(Func<Task> asyncDelegate, out Task registeredTask)
        {
            registeredTask = asyncDelegate();
            _tasks.Add(registeredTask);
        }
        
        #region Overloads that don't require closures
        
        public void Register<TSubject>(TSubject subject, Func<TSubject, Task> asyncDelegate) =>
            this.Register(subject, asyncDelegate, out _);

        public void Register<TSubject>(TSubject subject, Func<TSubject, Task> asyncDelegate, out Task registeredTask)
        {
            registeredTask = asyncDelegate(subject);
            _tasks.Add(registeredTask);
        }
        
        #endregion

        public async Task WhenAll(bool clearAfterwards = true)
        {
            try
            {
                await Task.WhenAll(_tasks);
            }
            finally
            {
                if (clearAfterwards)
                    _tasks.Clear();
            }
        }

        public void Clear() => _tasks.Clear();
    }
}