C# Task异步同步机制

1.引入第三方工具包:Nito.AsyncEx;

AsyncLock:

using Microsoft.VisualBasic.Devices;
using Nito.AsyncEx;
using System.Diagnostics;

namespace WinFormsApp2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        AsyncLock mutex =new AsyncLock();
        private async void button1_Click(object sender, EventArgs e)
        {
            var tasks=Enumerable.Range(1,10).Select(x=>ComputerAsync(x, mutex)).ToList();
            var result = await Task.WhenAll(tasks);
            Debug.WriteLine(string.Join(",", result));
        }

        private async Task<int> ComputerAsync(int x, AsyncLock mutex)
        {
            using (await mutex.LockAsync())
            {
                await Task.Delay(200);
                return x * x;
            };
        }
    }
}

2.SemaphoreSlim

 SemaphoreSlim SemaphoreSlim= new SemaphoreSlim(1,2);

 private async void button1_Click(object sender, EventArgs e)
 {
     var start = Stopwatch.GetTimestamp();
     var tasks=Enumerable.Range(1,10).Select(x=>ComputerAsync(x, mutex)).ToList();
     var result = await Task.WhenAll(tasks);
     var time = Stopwatch.GetTimestamp() - start;
     Debug.WriteLine(string.Join(",", result)+ time);
 }

 private async Task<int> ComputerAsync(int x, AsyncLock mutex)
 {
     await SemaphoreSlim.WaitAsync();
           await Task.Delay(2000);
     SemaphoreSlim.Release();
         return x * x;
     
 }

3.AsyncAutoResetEvent,AsyncManualResetEvent

 AsyncAutoResetEvent AsyncAutoResetEvent=new AsyncAutoResetEvent(false);
 AsyncManualResetEvent AsyncManualResetEvent=new AsyncManualResetEvent(false);
 private async void button1_Click(object sender, EventArgs e)
 {
     AsyncAutoResetEvent.Set();
     var start = Stopwatch.GetTimestamp();
     var tasks=Enumerable.Range(1,10).Select(x=>ComputerAsync(x, mutex)).ToList();
     var result = await Task.WhenAll(tasks);
     var time =TimeSpan.FromMilliseconds( Stopwatch.GetTimestamp() - start);
     Debug.WriteLine(string.Join(",", result)+"  time:" +time);
 }
 private async Task<int> ComputerAsync(int x, AsyncLock mutex)
 {
     await AsyncAutoResetEvent.WaitAsync();
     await Task.Delay(500);
      AsyncAutoResetEvent.Set();
     return x * x;

 }

4.TaskCompletionSource

TaskCompletionSource<string> tcs = new();
private void button2_Click(object sender, EventArgs e)
{
    var task1 = Task.Run(() =>
    {
        Thread.Sleep(2000);
        tcs.SetResult("Hello");
    });

    var task2 = Task.Run(async () =>
    {
        var result=await tcs.Task;
        Debug.WriteLine($"第一个线程完了。。。。{result}");

    });
    Task.WhenAll(task1, task2);
}

5.Await本身也是异步同步的功能

 private void button2_Click(object sender, EventArgs e)
 {
     var task1 = Task.Run(() =>
     {
         Thread.Sleep(2000);
         tcs.SetResult("Hello");
     });

     var task2 = Task.Run(async () =>
     {
         await task1;
         Debug.WriteLine($"第一个线程完了。。。。");

     });
     Task.WhenAll(task1, task2);
 }