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WCF后续之旅(11): 关于并发、回调的线程关联性（Thread Affinity）
一、从基于Windows Application客户端的WCF回调失败谈起
在"我的WCF之旅"系列文章中,有一篇（WinForm Application中调用Duplex Service出现TimeoutException的原因和解决方案）专门介绍在一个Windows Application客户端应用, 通过WCF 的Duplex通信方式进行回调失败的文章.我们今天以此作为出发点介绍WCF在Thread Affinity下的表现和解决方案.
1: namespace Artech.ThreadAffinity.Contracts
2: {
3: [ServiceContract(CallbackContract = typeof(ICalculateCallback))]
4: public interface ICalculate
5: {
6: [OperationContract]
7: void Add(double op1, double op2);
8: }
9: }
1: namespace Artech.ThreadAffinity.Contracts
2: {
3: public interface ICalculateCallback
4: {
5: [OperationContract]
6: void DisplayResult(double result);
7: }
8: }
1: namespace Artech.ThreadAffinity.Services
2: {
3: [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Reentrant)]
4: public class CalculateService:ICalculate
5: {
6: public static ListBox DisplayPanel
7: { get; set; }
8:
9: #region ICalculate Members
10:
11: public void Add(double op1, double op2)
12: {
13: double result = op1 + op2;
14: ICalculateCallback callback = OperationContext.Current.GetCallbackChannel<ICalculateCallback>();
15:
16: DisplayPanel.Items.Add(string.Format("{0} + {1} = {2}", op1, op2, result));
17:
18: callback.DisplayResult(result);
19: }
20:
21: #endregion
22: }
23: }
由于需要进行callback, 我们把ConcurrencyMode
设为Reentrant。当得到运算的结果后，通过OperationContext.Current.GetCallbackChannel得到callback对象，并调用之。还有一点需要提的是，该service是通过一个Windows
Form application进行host的。并且有一个ListBox列出所有service执行的结果，就像这样：
3、Hosting
1: private void HostForm_Load(object sender, EventArgs e)
2: {
3: this._serviceHost = new ServiceHost(typeof(CalculateService));
4: CalculateService.DisplayPanel = this.listBoxResult;
5: CalculateService.SynchronizationContext = SynchronizationContext.Current;
6: this._serviceHost.Opened += delegate
7: {
8: this.Text = "The calculate service has been started up!";
9: };
10:
11: this._serviceHost.Open();
12: }
1: <configuration>
2: <system.serviceModel>
3: <services>
4: <service name="Artech.ThreadAffinity.Services.CalculateService">
5: <endpoint binding="netTcpBinding" bindingConfiguration="" contract="Artech.ThreadAffinity.Contracts.ICalculate" />
6: <host>
7: <baseAddresses>
8: <add baseAddress="net.tcp://127.0.0.1:8888/calculateservice" />
9: </baseAddresses>
10: </host>
11: </service>
12: </services>
13: </system.serviceModel>
14: </configuration>
4、Client
1: namespace Clients
2: {
3: public class CalculateCallback : ICalculateCallback
4: {
5: public static TextBox ResultPanel;
6:
7: #region ICalculateCallback Members
8:
9: public void DisplayResult(double result)
10: {
11: ResultPanel.Text = result.ToString();
12: }
13:
14: #endregion
15: }
16: }
1: <configuration>
2: <system.serviceModel>
3: <client>
4: <endpoint address="net.tcp://127.0.0.1:8888/calculateservice"
5: binding="netTcpBinding" bindingConfiguration="" contract="Artech.ThreadAffinity.Contracts.ICalculate"
6: name="calculateservice" />
7: </client>
8: </system.serviceModel>
9: </configuration>
1: private void buttonCalculate_Click(object sender, EventArgs e)
2: {
3: CalculateCallback.ResultPanel = this.textBoxResult;
4: DuplexChannelFactory<ICalculate> channelFactory = new DuplexChannelFactory<ICalculate>(new CalculateCallback(), "calculateservice");
5: ICalculate calculator = channelFactory.CreateChannel();
6: calculator.Add(double.Parse(this.textBoxOp1.Text), double.Parse(this.textBoxOp2.Text));
7: }
二、是什么导致TimeoutException？
三、解决方案一：通过异步调用或者One-way回调
1: public void Add(double op1, double op2)
2: {
3: double result = op1 + op2;
4: ICalculateCallback callback = OperationContext.Current.GetCallbackChannel<ICalculateCallback>();
5:
6: ThreadPool.QueueUserWorkItem(delegate{ callback.DisplayResult(result); }, null);
7: }
1: namespace Artech.ThreadAffinity.Contracts
2: {
3: [ServiceContract(CallbackContract = typeof(ICalculateCallback))]
4: public interface ICalculate
5: {
6: [OperationContract(IsOneWay = true)]
7: void Add(double op1, double op2);
8: }
9: }
四、方案二、通过解除Callback操作和UI线程的关联性
1: public virtual void Post(SendOrPostCallback d, object state)
2: public virtual void Send(SendOrPostCallback d, object state)
1: namespace Artech.ThreadAffinity.Clients
2: {
3: [CallbackBehavior(UseSynchronizationContext = false)]
4: public class CalculateCallback : ICalculateCallback
5: {
6: public static TextBox ResultPanel;
7:
8: #region ICalculateCallback Members
9:
10: public void DisplayResult(double result)
11: {
12: ResultPanel.Text = result.ToString();
13:
14: }
15:
16: #endregion
17: }
18: }
19:
原因很简单，由于我们将callbaclk的设置成false，那么callback的操作将不会再UI线程下执行。但是我们需要运算的结果输入到UI的TextBox上，对UI上控件的操作需要在UI线程上执行，显然会抛出异常了。
1: namespace Artech.ThreadAffinity.Clients
2: {
3: [CallbackBehavior(UseSynchronizationContext = false)]
4: public class CalculateCallback : ICalculateCallback
5: {
6: public static TextBox ResultPanel;
7: public static SynchronizationContext SynchronizationContext;
8:
9: #region ICalculateCallback Members
10:
11: public void DisplayResult(double result)
12: {
13: SynchronizationContext.Post(delegate { ResultPanel.Text = result.ToString(); }, null);
14: }
15:
16: #endregion
17: }
18: }
1: private void buttonCalculate_Click(object sender, EventArgs e)
2: {
3: CalculateCallback.ResultPanel = this.textBoxResult;
4: CalculateCallback.SynchronizationContext = SynchronizationContext.Current;
5:
6: DuplexChannelFactory<ICalculate> channelFactory = new DuplexChannelFactory<ICalculate>(new CalculateCallback(), "calculateservice");
7: ICalculate calculator = channelFactory.CreateChannel();
8: calculator.Add(double.Parse(this.textBoxOp1.Text), double.Parse(this.textBoxOp2.Text));
9: }
五、另一种可选方案：通过ISynchronizeInvoke的Invoke/BeginInvoke
1: public interface ISynchronizeInvoke
2: {
3: // Methods
4: [HostProtection(SecurityAction.LinkDemand, Synchronization=true, ExternalThreading=true)]
5: IAsyncResult BeginInvoke(Delegate method, object[] args);
6: object EndInvoke(IAsyncResult result);
7: object Invoke(Delegate method, object[] args);
8:
9: // Properties
10: bool InvokeRequired { get; }
11: }
12:
1: namespace Artech.ThreadAffinity.Clients
2: {
3: [CallbackBehavior(UseSynchronizationContext = false)]
4: public class CalculateCallback : ICalculateCallback
5: {
6: public static TextBox ResultPanel;
7: public delegate void DisplayResultDelegate(TextBox resultPanel, double result);
8:
9: #region ICalculateCallback Members
10:
11: public void DisplayResult(double result)
12: {
13: DisplayResultDelegate displayResultDelegate = new DisplayResultDelegate(DisplayResult);
14: ResultPanel.BeginInvoke(displayResultDelegate, new object[] { ResultPanel, result });
15: }
16:
17: private void DisplayResult(TextBox resultPanel, double result)
18: {
19: resultPanel.Text = result.ToString();
20: }
21:
22: #endregion
23: }
24: }
25:
六、Service Hosting的线程关联性
1: namespace Artech.ThreadAffinity.Services
2: {
3: [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Reentrant,UseSynchronizationContext = false)]
4: public class CalculateService:ICalculate
5: {
6: public static ListBox DisplayPanel
7: { get; set; }
8:
9: #region ICalculate Members
10:
11: public void Add(double op1, double op2)
12: {
13: double result = op1 + op2;
14: ICalculateCallback callback = OperationContext.Current.GetCallbackChannel<ICalculateCallback>();
15:
16: DisplayPanel.Items.Add(string.Format("{0} + {1} = {2}", op1, op2, result));
17:
18: callback.DisplayResult(result);
19: }
20:
21: #endregion
22: }
23: }
24:
1: namespace Artech.ThreadAffinity.Services
2: {
3: [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Reentrant,UseSynchronizationContext = false)]
4: public class CalculateService:ICalculate
5: {
6: public static ListBox DisplayPanel
7: { get; set; }
8:
9: public static SynchronizationContext SynchronizationContext
10: { get; set; }
11:
12: #region ICalculate Members
13:
14: public void Add(double op1, double op2)
15: {
16: double result = op1 + op2;
17: ICalculateCallback callback = OperationContext.Current.GetCallbackChannel<ICalculateCallback>();
18: SynchronizationContext.Post(delegate
19: {
20: DisplayPanel.Items.Add(string.Format("{0} + {1} = {2}", op1, op2, result));
21: }, null);
22:
23: callback.DisplayResult(result);
24: }
25:
26: #endregion
27: }
28: }
29:
1: private void HostForm_Load(object sender, EventArgs e)
2: {
3: this._serviceHost = new ServiceHost(typeof(CalculateService));
4: CalculateService.DisplayPanel = this.listBoxResult;
5: CalculateService.SynchronizationContext = SynchronizationContext.Current;
6: this._serviceHost.Opened += delegate
7: {
8: this.Text = "The calculate service has been started up!";
9: };
10:
11: this._serviceHost.Open();
12: }
13:
WCF后续之旅：
WCF后续之旅(1): WCF是如何通过Binding进行通信的
WCF后续之旅(2): 如何对Channel Layer进行扩展——创建自定义Channel
WCF后续之旅(3): WCF Service Mode Layer 的中枢—Dispatcher
WCF后续之旅(4)：WCF Extension Point 概览
WCF后续之旅(5): 通过WCF Extension实现Localization
WCF后续之旅(6): 通过WCF Extension实现Context信息的传递
WCF后续之旅(7)：通过WCF Extension实现和Enterprise Library Unity Container的集成
WCF后续之旅(8)：通过WCF Extension 实现与MS Enterprise Library Policy Injection Application Block 的集成
WCF后续之旅(9)：通过WCF的双向通信实现Session管理[Part I]
WCF后续之旅(9): 通过WCF双向通信实现Session管理[Part II]
WCF后续之旅(10): 通过WCF Extension实现以对象池的方式创建Service Instance
WCF后续之旅(11): 关于并发、回调的线程关联性（Thread Affinity）
WCF后续之旅(12): 线程关联性（Thread Affinity）对WCF并发访问的影响
WCF后续之旅(13): 创建一个简单的WCF SOAP Message拦截、转发工具[上篇]
WCF后续之旅(13)：创建一个简单的SOAP Message拦截、转发工具[下篇]
WCF后续之旅(14)：TCP端口共享
WCF后续之旅(15): 逻辑地址和物理地址
WCF后续之旅(16): 消息是如何分发到Endpoint的--消息筛选(Message Filter)
WCF后续之旅(17)：通过tcpTracer进行消息的路由
作者：蒋金楠
微信公众账号：大内老A
微博：www.weibo.com/artech
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本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。
微信公众账号：大内老A
微博：www.weibo.com/artech
如果你想及时得到个人撰写文章以及着作的消息推送，或者想看看个人推荐的技术资料，可以扫描左边二维码（或者长按识别二维码）关注个人公众号（原来公众帐号蒋金楠的自媒体将会停用）。
本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。
最后更新：2017-10-30 17:04:23