C# - 简单介绍TaskScheduler

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. static UITaskSchedulerService()


12. {


13. GuiThread = Thread.CurrentThread;


14. TaskSchedulerUI = TaskScheduler.FromCurrentSynchronizationContext();


15. }
16. /// <summary>


17. /// Gets the instance.


18. /// </summary>


19. public static UITaskSchedulerService Instance


20. {


21. get


22. {


23. return InstanceField;


24. }


25. }
26. /// <summary>


27. /// Get TaskScheduler to schedule Tasks on UI thread.


28. /// </summary>


29. /// <returns>TaskScheduler to schedule Tasks on UI thread.</returns>


30. public TaskScheduler GetUITaskScheduler()


31. {


32. return TaskSchedulerUI;


33. }
34. /// <summary>


35. /// Check whether current tread is UI tread


36. /// </summary>


37. /// <returns><c>true</c>if current tread is UI tread.</returns>


38. public bool IsOnUIThread()


39. {


40. return GuiThread == Thread.CurrentThread;


41. }


42. }

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