我需要一个定制的同步上下文,它具有以下特点:
在编写自己的代码之前,我希望有人能指导我使用简单(且小型)的实现。
- 拥有一个单独的线程来运行“发布”和“发送”委托
- 按照发送的顺序进行发送
- 不需要其他方法
在编写自己的代码之前,我希望有人能指导我使用简单(且小型)的实现。
这是我一段时间以前写的,没有版权问题,也没有保证(系统没有进入生产):
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();
}
}
}
idesign.net(在页面上搜索“自定义同步上下文”)有一个SynchronizationContext可以完成此任务,但它比我需要的更复杂。
我有一个类似的需求——对服务器组件进行单元测试,以确认其回调委托调用是否被编排到适当的同步上下文,并想出了以下代码(基于Stephen Toub的博客文章http://blogs.msdn.com/b/pfxteam/archive/2012/01/20/10259049.aspx),我认为它更简单和通用,因为它使用自己内部的线程来处理Post()
/Send()
请求,而不是依赖于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) { }
}
}
SynchronizationContext
实例,而其他一些则没有(例如MSTest)。AsyncContext
,它安装了一个单线程的SynchronizationContext
并在该单个线程上处理消息队列。使用非常简单:public Task MyTestMethod() => AsyncContext.Run(async () =>
{
// asynchronous code here.
});
AsyncContext
旨在用于单元测试和控制台应用程序,并且对一些更加特殊的情况有适当的处理,例如:
async void
方法,并且Run
方法将不会返回,直到它们完成。AsyncContext.Run
允许返回结果值,如果您想在异步代码之外进行断言,则非常有用。Run
的委托传播异常或者从async void
方法中传播任何异常,则该异常将从AsyncContext.Run
传播出去(不带异常包装并保留异常调用堆栈)。然而,AsyncContext
仅是一个SynchronizationContext
(带有"runner"),并且没有UI特定的线程同步机制(例如,Dispatcher
,Control.Invoke
)。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
或WindowsFormsContext
,这是最初的Async CTP中的辅助类型。
我已经修改了Bond的答案,以便不再依赖WPF(Dispatcher),而是改为依赖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);
}
}
}