Async Task.WhenAll with timeout

Question

Is there a way in the new async dotnet 4.5 library to set a timeout on the Task.WhenAll method. I want to fetch several sources and stop after say 5 seconds and

Answer 1

I think a clearer, more robust option that also does exception handling right would be to use Task.WhenAny on each task together with a timeout task, go through all the completed tasks and filter out the timeout ones, and use await Task.WhenAll() instead of Task.Result to gather all the results.

Here's a complete working solution:

static async Task WhenAll(IEnumerable> tasks, TimeSpan timeout)
{
    var timeoutTask = Task.Delay(timeout).ContinueWith(_ => default(TResult));
    var completedTasks = 
        (await Task.WhenAll(tasks.Select(task => Task.WhenAny(task, timeoutTask)))).
        Where(task => task != timeoutTask);
    return await Task.WhenAll(completedTasks);
}