c# - 异步函数中的 TaskCompletionSource

Question

我有这样一个功能:

public async Task<bool> DoSomething()
{
   var tcs = new TaskCompletionSource<bool>();

   // Here is the problem. I need to keep this line because I wait on something asynchronously, but the function must return bool and I can't just return tcs.Task
   while(something)
      await Task.Delay(100);

   someobject.somevent += () => {
      // do some sht
      tcs.SetResult(true);
   }

   // it doesn't work
   return tcs.Task;
}

这只是一个假代码，但我在真实情况下需要它。我想让 DoSomething 保持异步，但我也想在其中保留 Task.Delay/Sleep。我如何在仅返回任务的非异步函数中执行此操作？

更新:

这有效:

class Program
    {
        static TaskCompletionSource<bool> tcs = new TaskCompletionSource<bool>();


        static Task<bool> Test()
        {
           // tcs = new TaskCompletionSource<bool>();
            Task.Factory.StartNew(() =>
            {
                Console.WriteLine("Waiting...");
                Thread.Sleep(5000);
                Console.WriteLine("Setting result");
                if(tcs.TrySetResult(true))
                    Console.WriteLine("Result has been set");


            });

            return tcs.Task;
        }

        static async Task Test2()
        {
            Console.WriteLine("Starting awaiting");
            var result = await Test();
            Console.WriteLine(result.ToString());
        }

        static void Main(string[] args)
        {


            Test2();

            Console.ReadKey(false);

        }
    }

这不是

static async Task<bool> Test()
{
   // tcs = new TaskCompletionSource<bool>();
    Task.Factory.StartNew(() =>
    {
        Console.WriteLine("Waiting...");
        Thread.Sleep(5000);
        Console.WriteLine("Setting result");
        if(tcs.TrySetResult(true))
            Console.WriteLine("Result has been set");


    });


    return await tcs.Task;
}

更糟糕的是，我已经在我的 Windows 窗体应用程序中测试了它并等待 tcs.Task 导致来自 System.Threading....dll 的奇怪崩溃

Answer 1

如果我理解正确(这很棘手，因为你的问题不是那么容易理解)你可以重述如下:

public async Task<bool> DoSomething()
{
   var tcs = new TaskCompletionSource<bool>();
   someobject.somevent += () => {
      // do some sht
      tcs.SetResult(true);
   }

   return await tcs.Task;
}