寻找自定义SynchronizationContext的示例（单元测试需要）

时间：2009-12-10 17:01:36

标签： c# .net multithreading unit-testing

我需要一个自定义SynchronizationContext：

  • 拥有一个运行“帖子”和“发送”代表的单个帖子
  • 按照发送顺序发送
  • 不需要其他方法

我需要这个，所以我可以单独测试一些线程代码，这些代码将在真实应用程序中与WinForm对话。

在我自己编写之前，我希望有人能指出我的简单（和小）实现。

5 个答案:

答案 0 :(得分：10)

这个是我前段时间写的，没有版权问题，也没有保证（系统没有投入生产）：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Windows.Threading;

namespace ManagedHelpers.Threads
{
    public class STASynchronizationContext : SynchronizationContext, IDisposable
    {
        private readonly Dispatcher dispatcher;
        private object dispObj;
        private readonly Thread mainThread;

        public STASynchronizationContext()
        {
            mainThread = new Thread(MainThread) { Name = "STASynchronizationContextMainThread", IsBackground = false };
            mainThread.SetApartmentState(ApartmentState.STA);
            mainThread.Start();

            //wait to get the main thread's dispatcher
            while (Thread.VolatileRead(ref dispObj) == null)
                Thread.Yield();

            dispatcher = dispObj as Dispatcher;
        }

        public override void Post(SendOrPostCallback d, object state)
        {
            dispatcher.BeginInvoke(d, new object[] { state });
        }

        public override void Send(SendOrPostCallback d, object state)
        {
            dispatcher.Invoke(d, new object[] { state });
        }

        private void MainThread(object param)
        {
            Thread.VolatileWrite(ref dispObj, Dispatcher.CurrentDispatcher);
            Console.WriteLine("Main Thread is setup ! Id = {0}", Thread.CurrentThread.ManagedThreadId);
            Dispatcher.Run();
        }

        public void Dispose()
        {
            if (!dispatcher.HasShutdownStarted && !dispatcher.HasShutdownFinished)
                dispatcher.BeginInvokeShutdown(DispatcherPriority.Normal);

            GC.SuppressFinalize(this);
        }

        ~STASynchronizationContext()
        {
            Dispose();
        }
    }
}

答案 1 :(得分：8)

idesign.net（在页面上搜索自定义同步上下文）有一个可以完成工作的SynchronizationContext，但是我需要它们更复杂。

答案 2 :(得分：2)

有一个类似的要求 - 单元测试服务器组件以确认它的回调委托调用被编组到适当的SynchronizationContext上并提出以下代码（基于Stephen Toub的博客文章http://blogs.msdn.com/b/pfxteam/archive/2012/01/20/10259049.aspx）我认可的是更简单，更通用，因为它使用自己的内部线程来处理Post() / Send()请求，而不是依赖WPF / Winforms / ..来执行调度。

    // A simple SynchronizationContext that encapsulates it's own dedicated task queue and processing
    // thread for servicing Send() & Post() calls.  
    // Based upon http://blogs.msdn.com/b/pfxteam/archive/2012/01/20/10259049.aspx but uses it's own thread
    // rather than running on the thread that it's instanciated on
    public sealed class DedicatedThreadSynchronisationContext : SynchronizationContext, IDisposable
    {
        public DedicatedThreadSynchronisationContext()
        {
            m_thread = new Thread(ThreadWorkerDelegate);
            m_thread.Start(this);
        }

        public void Dispose()
        {
            m_queue.CompleteAdding();
        }

        /// <summary>Dispatches an asynchronous message to the synchronization context.</summary>
        /// <param name="d">The System.Threading.SendOrPostCallback delegate to call.</param>
        /// <param name="state">The object passed to the delegate.</param>
        public override void Post(SendOrPostCallback d, object state)
        {
            if (d == null) throw new ArgumentNullException("d");
            m_queue.Add(new KeyValuePair<SendOrPostCallback, object>(d, state));
        }

        /// <summary> As 
        public override void Send(SendOrPostCallback d, object state)
        {
            using (var handledEvent = new ManualResetEvent(false))
            {
                Post(SendOrPostCallback_BlockingWrapper, Tuple.Create(d, state, handledEvent));
                handledEvent.WaitOne();
            }
        }

        public int WorkerThreadId { get { return m_thread.ManagedThreadId; } }
        //=========================================================================================

        private static void SendOrPostCallback_BlockingWrapper(object state)
        {
            var innerCallback = (state as Tuple<SendOrPostCallback, object, ManualResetEvent>);
            try
            {
                innerCallback.Item1(innerCallback.Item2);
            }
            finally
            {
                innerCallback.Item3.Set();
            }
        }

        /// <summary>The queue of work items.</summary>
        private readonly BlockingCollection<KeyValuePair<SendOrPostCallback, object>> m_queue =
            new BlockingCollection<KeyValuePair<SendOrPostCallback, object>>();

        private readonly Thread m_thread = null;

        /// <summary>Runs an loop to process all queued work items.</summary>
        private void ThreadWorkerDelegate(object obj)
        {
            SynchronizationContext.SetSynchronizationContext(obj as SynchronizationContext);

            try
            {
                foreach (var workItem in m_queue.GetConsumingEnumerable())
                    workItem.Key(workItem.Value);
            }
            catch (ObjectDisposedException) { }
        }
    }

答案 3 :(得分：1)

一些现代单元测试库（例如 xUnit）默认已经包含单线程 void Update() { Vector3 mousePosition = Camera.main.ScreenToWorldPoint(Input.mousePosition); Vector3 direction = mousePosition - transform.position; float angle = Mathf.Atan2(direction.y, direction.x) * Mathf.Rad2Deg; transform.rotation = Quaternion.Euler(0, 0, angle); // Debug.Log(angle); } 实例。其他人没有（例如，MSTest）。

我的 AsyncEx library 有一个 SynchronizationContext，它安装了一个单线程 AsyncContext 并且只处理该单线程上的消息队列。用法很简单：

SynchronizationContext

public Task MyTestMethod() => AsyncContext.Run(async () => { // asynchronous code here. }); 是为单元测试和控制台应用程序设计的，并且可以正确处理一些更奇特的场景，例如：

  • AsyncContext 方法被检测到，async void 方法在它们完成之前不会返回。
  • Run 允许返回结果值，如果您想在异步代码之外进行断言，这将非常有用。
  • 如果传递给 AsyncContext.Run 的委托传播异常或如果任何异常传播出 Run 方法，则该异常传播出 async void （没有异常包装器并保留异常调用堆栈）。

然而，AsyncContext.Run 只是一个AsyncContext（带有一个“runner”），并且没有特定于 UI 的线程同步机制的概念（例如，{{1 }}, SynchronizationContext)。如果您需要测试使用调度程序或控件的代码，则需要使用 WpfContext or WindowsFormsContext，它们是原始 Async CTP 中的辅助类型。

答案 4 :(得分：0)

我已经通过Bond调整了答案，以消除对WPF（Dispatcher）的依赖，并依赖于WinForms：

namespace ManagedHelpers.Threads
   {
   using System;
   using System.Collections.Generic;
   using System.Diagnostics;
   using System.Linq;
   using System.Text;
   using System.Threading;
   using System.Threading.Tasks;
   using System.Windows.Forms;
   using NUnit.Framework;

   public class STASynchronizationContext : SynchronizationContext, IDisposable
      {
      private readonly Control control;
      private readonly int mainThreadId;

      public STASynchronizationContext()
         {
         this.control = new Control();

         this.control.CreateControl();

         this.mainThreadId = Thread.CurrentThread.ManagedThreadId;

         if (Thread.CurrentThread.Name == null)
            {
            Thread.CurrentThread.Name = "AsynchronousTestRunner Main Thread";
            }
         }

      public override void Post(SendOrPostCallback d, object state)
         {
         control.BeginInvoke(d, new object[] { state });
         }

      public override void Send(SendOrPostCallback d, object state)
         {
         control.Invoke(d, new object[] { state });
         }

      public void Dispose()
         {
         Assert.AreEqual(this.mainThreadId, Thread.CurrentThread.ManagedThreadId);

         this.Dispose(true);
         GC.SuppressFinalize(this);
         }

      protected virtual void Dispose(bool disposing)
         {
         Assert.AreEqual(this.mainThreadId, Thread.CurrentThread.ManagedThreadId);

         if (disposing)
            {
            if (control != null)
               {
               control.Dispose();
               }
            }
         }

      ~STASynchronizationContext()
         {
         this.Dispose(false);
         }
      }
   }
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