聊聊多线程那一些事儿 之 五 async.await深度剖析聊聊多线程那一些事儿（task）之 三 异步取消和异步方法聊聊多线程那一些事儿 之 四 经典应用（取与舍、动态创建）

 static void Main(string[] args)
 {
     Console.WriteLine($"主线程开始，线程ID：{Thread.CurrentThread.ManagedThreadId}\n");

     // 同步实现 
     AddSync(1, 2);

     // 异步方法,没有 Await
     AddNoAwaitSyncHas(1, 2);

     // 异步方法,有 Await
     AddHasAwaitAsync(1, 2);

     Console.WriteLine($"主线程结束，线程ID：{Thread.CurrentThread.ManagedThreadId}\n");
     Console.ReadLine();
     return;
 }

 /// <summary>
 /// 同步计算两个数字之和
 /// </summary>
 /// <param name="num1">参数1</param>
 /// <param name="num2">参数2</param>
 /// <returns></returns>
 private static int AddSync(int num1, int num2)
 {
     Thread.Sleep(1000);
     Console.WriteLine($"同步方法，线程ID：{Thread.CurrentThread.ManagedThreadId}\n");
     return num1 + num2;
 }

 /// <summary>
 /// 对两个数字求和 (异步方法,没有 Await)
 /// </summary>
 /// <param name="num1">参数1</param>
 /// <param name="num2">参数2</param>
 /// <returns>结果</returns>
 private static async Task<int> AddNoAwaitSyncHas(int num1, int num2)
 {
     Console.WriteLine($"异步线程没有await前，线程ID：{Thread.CurrentThread.ManagedThreadId}\n");
     // 两个数字求和，假设其中会涉及到很耗时的逻辑
     Thread.Sleep(1000);
     Console.WriteLine($"异步线程没有await后，线程ID：{Thread.CurrentThread.ManagedThreadId}\n");
     return num1 + num2;
 }

 /// <summary>
 /// 对两个数字求和 (异步方法,有 Await)
 /// </summary>
 /// <param name="num1">参数1</param>
 /// <param name="num2">参数2</param>
 /// <returns>结果</returns>
 private static async Task<int> AddHasAwaitAsync(int num1, int num2)
 {
     Console.WriteLine($"异步线程await前，线程ID：{Thread.CurrentThread.ManagedThreadId}\n");
     // 两个数字求和，假设其中会涉及到很耗时的逻辑
     var add = Add(num1, num2);
     int result = await add;
     Console.WriteLine($"异步线程await后，线程ID：{Thread.CurrentThread.ManagedThreadId}\n");
     return result;
 }

 /// <summary>
 /// Task 对两个数字求和
 /// </summary>
 /// <param name="num1">参数1</param>
 /// <param name="num2">参数2</param>
 /// <returns>结果</returns>
 private static Task<int> Add(int num1, int num2)
 {
     // 假设该逻辑执行起来很耗时
     var task = Task.Run(() =>
     {
         Console.WriteLine($"我是Task内部执行开始：线程ID :{Thread.CurrentThread.ManagedThreadId}\n");
         Thread.Sleep(5000);
         Console.WriteLine($"我是Task内部执行结束：线程ID :{Thread.CurrentThread.ManagedThreadId}\n");
         return num1 + num2;
     });

     return task;
 }

public interface IAsyncStateMachine {       
 void MoveNext();       
 void SetStateMachine(IAsyncStateMachine stateMachine); 
}