C#异步迭代IAsyncEnumerable应用实现

private  void Button_Click(object sender, RoutedEventArgs e)
        {
            var dateStart = DateTime.Now;  //记录用时的起始时间
            DebugText = string.Empty;
            List<string> fpList = new List<string>() { "a", "b", "c", "d" };

            foreach (var item in MockIO)
            {
                var dateEnd = DateTime.Now;
                var timeSpan = dateEnd - dateStart;//记录开票用时
                DebugText += item + " " + timeSpan.TotalSeconds + "\r\n";

            }
        }

     /// <summary>
        /// 批量开票方法
        /// </summary>
        /// <param name="ls"></param>
        /// <returns></returns>
        public static IEnumerable<string> MockIO(List<string> ls)
        {

            foreach (var item in ls)
            {
                Task.Delay(1000).Wait();
                yield return item;
                Debug.WriteLine(Thread.GetCurrentProcessorId());
            }
        }

public static async IAsyncEnumerable<string> MockIOAsync(List<string> ls)
        {
            foreach (var item in ls)
            {
                Task<Task<string>> task = Task<Task<string>>.Factory.StartNew(async () =>
               {
                   await Task.Delay(1000);
                   return item;

               });

                yield return await task.Result;
            }
        }

public static async Task<IEnumerable<string>> MockIOPerformanceAsync(List<string> ls)
        {
            List<string> lss = new List<string>();
            List<Task> tasks = new List<Task>();
            foreach (var item in ls)
            {

                Task task = new Task(() =>
              {
                  Task.Delay(1000).Wait();
                  Debug.WriteLine(Thread.GetCurrentProcessorId());
                  lss.Add(item);
              });
                tasks.Add(task);
                task.Start();

            }
            foreach (var item in tasks)
            {
                await item;
            }
            return lss;
        }