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WCF後續之旅(11): 關於並發、回調的線程關聯性（Thread Affinity）
一、從基於Windows Application客戶端的WCF回調失敗談起
在"我的WCF之旅"係列文章中,有一篇（WinForm Application中調用Duplex Service出現TimeoutException的原因和解決方案）專門介紹在一個Windows Application客戶端應用, 通過WCF 的Duplex通信方式進行回調失敗的文章.我們今天以此作為出發點介紹WCF在Thread Affinity下的表現和解決方案.
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: }
由於需要進行callback, 我們把ConcurrencyMode
設為Reentrant。當得到運算的結果後，通過OperationContext.Current.GetCallbackChannel得到callback對象，並調用之。還有一點需要提的是，該service是通過一個Windows
Form application進行host的。並且有一個ListBox列出所有service執行的結果，就像這樣：
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、是什麼導致TimeoutException？
三、解決方案一：通過異步調用或者One-way回調
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、通過解除Callback操作和UI線程的關聯性
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:
原因很簡單，由於我們將callbaclk的設置成false，那麼callback的操作將不會再UI線程下執行。但是我們需要運算的結果輸入到UI的TextBox上，對UI上控件的操作需要在UI線程上執行，顯然會拋出異常了。
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、另一種可選方案：通過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的線程關聯性
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後續之旅：
WCF後續之旅(1): WCF是如何通過Binding進行通信的
WCF後續之旅(2): 如何對Channel Layer進行擴展——創建自定義Channel
WCF後續之旅(3): WCF Service Mode Layer 的中樞—Dispatcher
WCF後續之旅(4)：WCF Extension Point 概覽
WCF後續之旅(5): 通過WCF Extension實現Localization
WCF後續之旅(6): 通過WCF Extension實現Context信息的傳遞
WCF後續之旅(7)：通過WCF Extension實現和Enterprise Library Unity Container的集成
WCF後續之旅(8)：通過WCF Extension 實現與MS Enterprise Library Policy Injection Application Block 的集成
WCF後續之旅(9)：通過WCF的雙向通信實現Session管理[Part I]
WCF後續之旅(9): 通過WCF雙向通信實現Session管理[Part II]
WCF後續之旅(10): 通過WCF Extension實現以對象池的方式創建Service Instance
WCF後續之旅(11): 關於並發、回調的線程關聯性（Thread Affinity）
WCF後續之旅(12): 線程關聯性（Thread Affinity）對WCF並發訪問的影響
WCF後續之旅(13): 創建一個簡單的WCF SOAP Message攔截、轉發工具[上篇]
WCF後續之旅(13)：創建一個簡單的SOAP Message攔截、轉發工具[下篇]
WCF後續之旅(14)：TCP端口共享
WCF後續之旅(15): 邏輯地址和物理地址
WCF後續之旅(16): 消息是如何分發到Endpoint的--消息篩選(Message Filter)
WCF後續之旅(17)：通過tcpTracer進行消息的路由
作者：蔣金楠
微信公眾賬號：大內老A
微博：www.weibo.com/artech
如果你想及時得到個人撰寫文章以及著作的消息推送，或者想看看個人推薦的技術資料，可以掃描左邊二維碼（或者長按識別二維碼）關注個人公眾號（原來公眾帳號蔣金楠的自媒體將會停用）。
本文版權歸作者和博客園共有，歡迎轉載，但未經作者同意必須保留此段聲明，且在文章頁麵明顯位置給出原文連接，否則保留追究法律責任的權利。
微信公眾賬號：大內老A
微博：www.weibo.com/artech
如果你想及時得到個人撰寫文章以及著作的消息推送，或者想看看個人推薦的技術資料，可以掃描左邊二維碼（或者長按識別二維碼）關注個人公眾號（原來公眾帳號蔣金楠的自媒體將會停用）。
本文版權歸作者和博客園共有，歡迎轉載，但未經作者同意必須保留此段聲明，且在文章頁麵明顯位置給出原文連接，否則保留追究法律責任的權利。
最後更新：2017-10-30 17:04:23