非同步(BeginInvoke,EndInvoke)

整個非同步呼叫過程中都是圍繞IAsyncResult來進行的,,BeginXXX 返回這個對象,EndXXX接收這個對象來結束當前非同步對象

public interface IAsyncResult
{
     WaitHandle AsyncWaitHandle { get; } //阻塞一個線程，直到一個或多個同步對象接收到訊號
     Boolean IsCompleted { get; } //判讀當前非同步是否完成
     Object AsyncState { get; } //擷取額外的參數值
     Boolean CompletedSynchronously { get; } //幾乎沒有使用
 }

 

 public class AsyncResult : IAsyncResult, IMessageSink
 {
       //IAsyncResult 的實現      
       public virtual WaitHandle AsyncWaitHandle { get; }
       public virtual bool IsCompleted { get; }
       public virtual object AsyncState { get; }
       public virtual bool CompletedSynchronously { get; }
 
       // 其他一些重要的屬性
       public bool EndInvokeCalled { get; set; } //檢驗是否調用了EndInvoke()
       public virtual object AsyncDelegate { get; } //擷取原始的委派物件
}

 

 

ar.AsyncWaitHandle.WaitOne() //阻礙當前線程,直到非同步呼叫結束. 

 

namespace ConsoleApplication15
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("[(#{1}){0}]:Asynchronous Start", DateTime.Now.ToString(), Thread.CurrentThread.ManagedThreadId);

            AsyncTest test = new AsyncTest();
            ConsoleApplication15.AsyncTest.SalaryEventHandler del = test.YearlySalary;
            //使用回呼函數
            AsyncCallback callback = new AsyncCallback(OnSalaryCallback);
            IAsyncResult ar = del.BeginInvoke(100000, 15, 100000, callback, 2000);

            DoAntherJob();
            Console.ReadLine(); // 讓黑屏等待,不會直接關閉..
        }

        //開始其他工作.
        static void DoAntherJob()
        {
            Thread.Sleep(1000);//需要1秒才能完成這個工作,注1
            Console.WriteLine("[(#{1}){0}]:Do Another Job", DateTime.Now.ToString(), Thread.CurrentThread.ManagedThreadId);
        }

        static void OnSalaryCallback(IAsyncResult asyncResult)
        {
            //通過AsyncState 擷取額外的參數.
            decimal para = (int)asyncResult.AsyncState;

            //通過AsyncDelegate 擷取原始的委派物件
            AsyncResult obj = (AsyncResult)asyncResult;
            ConsoleApplication15.AsyncTest.SalaryEventHandler del = (ConsoleApplication15.AsyncTest.SalaryEventHandler)obj.AsyncDelegate;

            if (asyncResult.IsCompleted)// 判讀是否已經調用完成
                Console.WriteLine("[(#{1}){0}]:Asynchronous Finished.", DateTime.Now.ToString(), Thread.CurrentThread.ManagedThreadId);

            decimal val = del.EndInvoke(asyncResult);

            Console.WriteLine("[(#{2}){0}]:Output Result:{1}", DateTime.Now.ToString(), val + para, Thread.CurrentThread.ManagedThreadId);
        }
    }

    public class AsyncTest
    {
        public delegate decimal SalaryEventHandler(decimal salary, int monthCount, decimal bonus); // 對應YearlySalary方法
        public decimal YearlySalary(decimal salary, int monthCount, decimal bonus)
        {
            //類比耗時/複雜的邏輯計算.
            Thread.Sleep(3000);//等待3秒,注2
            return salary * monthCount + bonus;
        }
    }
}