第十三章 异步编程

Foundations

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Threading;

namespace Foundations
{
  class Program
  {
    static void Main()
    {
      var ctx = new DispatcherSynchronizationContext();

      // SynchronizationContext.SetSynchronizationContext(ctx);
      // CallerWithAsync();
      // CallerWithContinuationTask();
      // CallerWithAwaiter();
      // MultipleAsyncMethods();
      // MultipleAsyncMethodsWithCombinators1();
      //   MultipleAsyncMethodsWithCombinators2();
      ConvertingAsyncPattern();
      Console.ReadLine();


    }

    private static async void ConvertingAsyncPattern()
    {
      string r = await Task<string>.Factory.FromAsync<string>(BeginGreeting, EndGreeting, "Angela", null);
      Console.WriteLine(r);
    }


    private async static void MultipleAsyncMethods()
    {
      string s1 = await GreetingAsync("Stephanie");
      string s2 = await GreetingAsync("Matthias");
      Console.WriteLine("Finished both methods.
 Result 1: {0}
 Result 2: {1}", s1, s2);
    }

    private async static void MultipleAsyncMethodsWithCombinators1()
    {
      Task<string> t1 = GreetingAsync("Stephanie");
      Task<string> t2 = GreetingAsync("Matthias");
      await Task.WhenAll(t1, t2);
      Console.WriteLine("Finished both methods.
 Result 1: {0}
 Result 2: {1}", t1.Result, t2.Result);
    }

    private async static void MultipleAsyncMethodsWithCombinators2()
    {
      Task<string> t1 = GreetingAsync("Stephanie");
      Task<string> t2 = GreetingAsync("Matthias");
      string[] result = await Task.WhenAll(t1, t2);
      Console.WriteLine("Finished both methods.
 Result 1: {0}
 Result 2: {1}", result[0], result[1]);
    }

    private static void CallerWithContinuationTask()
    {
      Console.WriteLine("started CallerWithContinuationTask in thread {0} and task {1}", Thread.CurrentThread.ManagedThreadId, Task.CurrentId);

      var t1 = GreetingAsync("Stephanie");


      t1.ContinueWith(t =>
        {
          string result = t.Result;
          Console.WriteLine(result);
          Console.WriteLine("finished CallerWithContinuationTask in thread {0} and task {1}", Thread.CurrentThread.ManagedThreadId, Task.CurrentId);
        });

    }

    private static void CallerWithAwaiter()
    {
      Console.WriteLine(Thread.CurrentThread.ManagedThreadId);
      string result = GreetingAsync("Matthias").GetAwaiter().GetResult();
      Console.WriteLine(result);
      Console.WriteLine(Thread.CurrentThread.ManagedThreadId);
    }

    private async static void CallerWithAsync()
    {
      Console.WriteLine("started CallerWithAsync in thread {0} and task {1}", Thread.CurrentThread.ManagedThreadId, Task.CurrentId);
      string result = await GreetingAsync("Stephanie");
      Console.WriteLine(result);
      Console.WriteLine("finished GreetingAsync in thread {0} and task {1}", Thread.CurrentThread.ManagedThreadId, Task.CurrentId);
    }

    private async static void CallerWithAsync2()
    {
      Console.WriteLine("started CallerWithAsync in thread {0} and task {1}", Thread.CurrentThread.ManagedThreadId, Task.CurrentId);
      Console.WriteLine(await GreetingAsync("Stephanie"));
      Console.WriteLine("finished GreetingAsync in thread {0} and task {1}", Thread.CurrentThread.ManagedThreadId, Task.CurrentId);
    }

    static Task<string> GreetingAsync(string name)
    {
      return Task.Run<string>(() =>
        {
          Console.WriteLine("running greetingasync in thread {0} and task {1}", Thread.CurrentThread.ManagedThreadId, Task.CurrentId);
          return Greeting(name);
        });
    }

    static string Greeting(string name)
    {
      Console.WriteLine("running greeting in thread {0} and task {1}", Thread.CurrentThread.ManagedThreadId, Task.CurrentId);

      Thread.Sleep(3000);
      return string.Format("Hello, {0}", name);
    }

    private static Func<string, string> greetingInvoker = Greeting;

    static IAsyncResult BeginGreeting(string name, AsyncCallback callback, object state)
    {
      return greetingInvoker.BeginInvoke(name, callback, state);
    }

    static string EndGreeting(IAsyncResult ar)
    {
      return greetingInvoker.EndInvoke(ar);
    }

  }
}