c# - 在主线程继续任务

Question

我知道有一个类似的问题:ContinueWith a Task on the Main thread

但这个问题更多是针对 wpf 的，我似乎无法让它在控制台应用程序上运行。

我想在不同的线程上执行一个方法，当该方法完成后，我想继续在主线程上执行。我不想加入方法。无论如何，这就是我所拥有的:

class Program
{
    static void Main(string[] args)
    {
        Thread.CurrentThread.Name = "MAIN";

        DoWork(x =>
        {
            Console.Write("Method successfully executed. Executing callback method in thread:" +
                "\n" + Thread.CurrentThread.Name);
        });

        Console.Read();
    }

    static void DoWork(Action<bool> onCompleteCallback)
    {
        Console.Write(Thread.CurrentThread.Name); // show on what thred we are executing

        Task doWork = new Task(() =>
        {
            Console.Write(Thread.CurrentThread.Name); // show on what thred we are executing
            Thread.Sleep(4000);
        });

        Action<Task> onComplete = (task) =>
        {                
            onCompleteCallback(true);
        };

        doWork.Start(); 

        // this line gives an error!
        doWork.ContinueWith(onComplete, TaskScheduler.FromCurrentSynchronizationContext());                       
    }
}

如何在主线程上执行 onCompleteCallback 方法？

Answer 1

but that question is more toward wpf and I cannot seeem to make it work on a console application.

您无法在控制台应用程序中执行此操作(无需大量工作)。 TPL 中内置的用于将调用编码回线程的机制都依赖于安装了 SynchronizationContext 的线程。这通常由用户界面框架安装(即:Windows 窗体中的 Application.Run，或 WPF 的启动代码等)。

在大多数情况下，它工作因为主线程有一个消息循环，框架可以将消息发布到消息循环，然后获取并运行代码。对于控制台应用程序，它只是一个“原始”线程 - 没有可以放置消息的消息循环。

当然，您可以安装自己的上下文，但这会增加很多可能没有必要的开销。

---

在控制台应用程序中，通常不需要“返回”到控制台线程。通常，您只需等待任务，即:

class Program
{
    static void Main(string[] args)
    {
        Thread.CurrentThread.Name = "MAIN";

        Task workTask = DoWork();

        workTask.Wait(); // Just wait, and the thread will continue
                         //  when the work is complete

        Console.Write("Method successfully executed. Executing callback method in thread:" +
                "\n" + Thread.CurrentThread.Name);
        Console.Read();
    }

    static Task DoWork()
    {
        Console.Write(Thread.CurrentThread.Name); // show on what thred we are executing

        Task doWork = new Task(() =>
        {
            Console.Write(Thread.CurrentThread.Name); // show on what thred we are executing
            Thread.Sleep(4000);
        });

        doWork.Start(); 

        return doWork;
    }
}