RavenDB - An Introduction

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

namespace Raven.Client.Shard.ShardStrategy.ShardAccess
{
	internal static class ParallelExtensions
	{
		public static void WaitAll(this IEnumerable<Task> tasks)
		{
			try
			{
				Task.WaitAll(tasks.ToArray());
			}
			catch (Exception ex)
			{
				//when task takes exception it wraps in aggregate exception, if in continuation
				//then could be double wrapped, etc. This should always get us the original
				while (true)
				{
					if (ex.InnerException == null || !(ex is AggregateException))
					{
						throw PreserveStackTrace(ex);
					}
					ex = ex.InnerException;
				}
			}
		}

		private static Exception PreserveStackTrace(Exception exception)
		{
			typeof (Exception).InvokeMember("InternalPreserveStackTrace", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.InvokeMethod, null,
			                                exception, null);
			return exception;
		}
	}
}