c#语言简介_简单介绍自己

task Scheduler根据定义

The task Scheduler by the definition blurb.

“Is the class where the usage context is within the task libraries. “

它的作用像是WPF/Winform时代的SynchronizationContext.

It is like the Synchronization context in the cross WPF/Win forms era.

像SynchronizationContext.一样，TaskScheduler也有可能依赖特定的UI SynchronizationContext.

As with the Synchronization context, we may have requirement for like the UI context synchronization.

代码如下:

Give the code as below.

C#代码  

1. /// <summary>  
2. /// This service is designed to return a TaskScheduler for application’s main, UI thread.  
3. /// This service MUST be instantiated on UI thread.  
4. /// </summary>  
5. [DebuggerNonUserCode]  
6. public class UITaskSchedulerService : IUITaskSchedulerService  
7. {  
8.     private static readonly UITaskSchedulerService InstanceField = new UITaskSchedulerService();  
9.     private static readonly TaskScheduler TaskSchedulerUI;  
10.     private static readonly Thread GuiThread;  
11.   
12.     static UITaskSchedulerService()  
13.     {  
14.         GuiThread = Thread.CurrentThread;  
15.         TaskSchedulerUI = TaskScheduler.FromCurrentSynchronizationContext();  
16.     }  
17.   
18.     /// <summary>  
19.     /// Gets the instance.  
20.     /// </summary>  
21.     public static UITaskSchedulerService Instance  
22.     {  
23.         get  
24.         {  
25.             return InstanceField;  
26.         }  
27.     }  
28.   
29.     /// <summary>  
30.     /// Get TaskScheduler to schedule Tasks on UI thread.  
31.     /// </summary>  
32.     /// <returns>TaskScheduler to schedule Tasks on UI thread.</returns>  
33.     public TaskScheduler GetUITaskScheduler()  
34.     {  
35.         return TaskSchedulerUI;  
36.     }  
37.   
38.     /// <summary>  
39.     /// Check whether current tread is UI tread  
40.     /// </summary>  
41.     /// <returns><c>true</c>if current tread is UI tread.</returns>  
42.     public bool IsOnUIThread()  
43.     {  
44.         return GuiThread == Thread.CurrentThread;  
45.     }  
46. }  

该class的要求是必须在UI thread初始化。

The requirement for the UITaskShcedulerService is that you should construct the singleton instance to start from a UI threads.

因为他内部使用的是TaskScheduler.FromCurrentSynchronizationContext，根据MSDN的TaskScheduler Class 定义 ，它拿到的是当前thread的synchronization context

Because it  internally use the TaskScheduler.FromCurrentSynchronizationContext. and from the TaskScheduler Class from MSDN, it retrieve the current thread’s synchronization context.

C#代码  

1. Task.Factory  
2.                 .StartNew(  
3.                     () =>  
4.                     _riskProvider.GetRiskPnL(),  
5.                     CancellationToken.None,  
6.                     TaskCreationOptions.None,  
7.                     TaskScheduler.Default)  
8.                   .ContinueWith(  
9.                     (task) => ProcessResults(task.Result),  
10.                     UITaskSchedulerService.Instance.GetUITaskScheduler()  
11.                     )  
12.                 //.ContinueWith(  
13.                 // (task) => ProcessResults(task.Result),  
14.                 // TaskScheduler.FromCurrentSynchronizationContext())  
15.                 .LogTaskExceptionIfAny(Log)  
16.                 .ContinueWith(x => DataUpdater());  

 处理结果需要dispatch到UI thread上，这样才能正确的显示。

We need to dispatch the process result back to the UI thread so that display can be properly handled.

References:

TaskScheduler Class