Aynchronously numerate Task results with timeout and cancellation.

TaskHelper.cs

public static class TaskHelper
{
    public static async Task<IEnumerable<TResult>> EnumerateTaskResults<TResult>(IEnumerable<Func<TResult>> source, TimeSpan timeout, CancellationToken cancellationToken)
    {
        var enumerateTasks = source
            .Select(x => Task.Run(() => x.Invoke()))
            .ToArray();

        var timeoutTask = Task.Delay(timeout, cancellationToken);

        await Task.WhenAny(Task.WhenAll(enumerateTasks), timeoutTask);
        cancellationToken.ThrowIfCancellationRequested();

        return enumerateTasks
            .Where(x => x.Status == TaskStatus.RanToCompletion)
            .Select(x => x.Result);
    }
}