C# - 简单介绍TaskScheduler

标题: C# - 简单介绍TaskScheduler
Title: C# - A Brief bump to the 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.

///
    /// This service is designed to return a TaskScheduler for application's main, UI thread.
    /// This service MUST be instantiated on UI thread.
    ///
    [DebuggerNonUserCode]
    public class UITaskSchedulerService : IUITaskSchedulerService
    {
        private static readonly UITaskSchedulerService InstanceField = new UITaskSchedulerService();
        private static readonly TaskScheduler TaskSchedulerUI;
        private static readonly Thread GuiThread;

        static UITaskSchedulerService()
        {
            GuiThread = Thread.CurrentThread;
            TaskSchedulerUI = TaskScheduler.FromCurrentSynchronizationContext();
        }

        ///
        /// Gets the instance.
        ///
        public static UITaskSchedulerService Instance
        {
            get
            {
                return InstanceField;
            }
        }

        ///
        /// Get TaskScheduler to schedule Tasks on UI thread.
        ///
        /// TaskScheduler to schedule Tasks on UI thread.
        public TaskScheduler GetUITaskScheduler()
        {
            return TaskSchedulerUI;
        }

        ///
        /// Check whether current tread is UI tread
        ///
        /// trueif current tread is UI tread.
        public bool IsOnUIThread()
        {
            return GuiThread == Thread.CurrentThread;
        }
    }

 

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 定义 ，它拿到的是当前thread的synchronization context

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

Task.Factory
                .StartNew(
                    () =>
                    _riskProvider.GetRiskPnL(),
                    CancellationToken.None,
                    TaskCreationOptions.None,
                    TaskScheduler.Default)
                  .ContinueWith(
                    (task) => ProcessResults(task.Result),
                    UITaskSchedulerService.Instance.GetUITaskScheduler()
                    )
                //.ContinueWith(
                //    (task) => ProcessResults(task.Result),
                //    TaskScheduler.FromCurrentSynchronizationContext())
                .LogTaskExceptionIfAny(Log)
                .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: