class Program
    {
        static void Main(string[] args)
        {
            Func<int, int> mySum1 = SumNumbers;
            Func<int, int> mySum2 = SumNumbers;
            Func<int, int> mySum3 = SumNumbers;

            AsyncCallback callback = c => Console.WriteLine("线程ID:{0},回调函数执行:{1}",Thread.CurrentThread.ManagedThreadId,c.AsyncState);


            IAsyncResult result1= mySum1.BeginInvoke(10000, callback, "第一个异步");
            IAsyncResult result2= mySum2.BeginInvoke(10000, callback, "第二个异步");
            IAsyncResult result3= mySum3.BeginInvoke(10000, callback, "第三个异步");


            //异步等待方式1：使用EndInvoke
            int asyc1 = mySum1.EndInvoke(result1);
            Console.WriteLine("第一个异步已经执行完成，结果:{0}",asyc1);

            //异步等待方式2：使用AsyncWaitHandle.WaitOne，参数-1表示一直等待到执行完成
            if (result2.AsyncWaitHandle.WaitOne(-1))
            {
                Console.WriteLine("第二个异步执行完成");
            }

            //异步等待方式3：使用IsCompleted判断
            while (!result3.IsCompleted)
            {
                Console.WriteLine("第三个异步还在执行中....");
                Thread.Sleep(300);
            }
            Console.WriteLine("第三个异步执行完成");

            Console.ReadKey();
        }

        public static int SumNumbers(int count)
        {
            int sum = 0;
            for (int i = 0; i < count; i++)
            {
                sum += i;
            }

            Thread.Sleep(3000);
            return sum;
        }
    }