如何把一个任务睡觉（或延迟）在C＃4.0？(How to put a task to sleep (

有Task.Delay在.NET 4.5

我怎样才能做到在.NET 4.0中一样吗？

Answer 1:

您可以使用Timer来创建Delay在4.0的方法：

public static Task Delay(double milliseconds)
{
    var tcs = new TaskCompletionSource<bool>();
    System.Timers.Timer timer = new System.Timers.Timer();
    timer.Elapsed+=(obj, args) =>
    {
        tcs.TrySetResult(true);
    };
    timer.Interval = milliseconds;
    timer.AutoReset = false;
    timer.Start();
    return tcs.Task;
}

Answer 2:

使用Microsoft.Bcl.Async从NuGet包，它有TaskEx.Delay 。

Answer 3:

using System;
using System.Threading;
using System.Threading.Tasks;

class Program
{
    static void Main()
    {
        Delay(2000).ContinueWith(_ => Console.WriteLine("Done"));
        Console.Read();
    }

    static Task Delay(int milliseconds)
    {
        var tcs = new TaskCompletionSource<object>();
        new Timer(_ => tcs.SetResult(null)).Change(milliseconds, -1);
        return tcs.Task;
    }
}

从部分如何实现4.0 Task.Delay

Answer 4:

下面是一个撤销Task.Delay实现的代码和样本线束。 您是在可能感兴趣的Delay方法：

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

namespace DelayImplementation
{
    class Program
    {
        static void Main(string[] args)
        {
            System.Threading.CancellationTokenSource tcs = new System.Threading.CancellationTokenSource();

            int id = 1;
            Console.WriteLine(string.Format("Starting new delay task {0}. This one will be cancelled.", id));
            Task delayTask = Delay(8000, tcs.Token);
            HandleTask(delayTask, id);

            System.Threading.Thread.Sleep(2000);
            tcs.Cancel();

            id = 2;
            System.Threading.CancellationTokenSource tcs2 = new System.Threading.CancellationTokenSource();
            Console.WriteLine(string.Format("Starting delay task {0}. This one will NOT be cancelled.", id));
            var delayTask2 = Delay(4000, tcs2.Token);
            HandleTask(delayTask2, id);

            System.Console.ReadLine();
        }

        private static void HandleTask(Task delayTask, int id)
        {
            delayTask.ContinueWith(p => Console.WriteLine(string.Format("Task {0} was cancelled.", id)), TaskContinuationOptions.OnlyOnCanceled);
            delayTask.ContinueWith(p => Console.WriteLine(string.Format("Task {0} was completed.", id)), TaskContinuationOptions.OnlyOnRanToCompletion);
        }

        static Task Delay(int delayTime, System.Threading.CancellationToken token)
        {
            TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();

            if (delayTime < 0) throw new ArgumentOutOfRangeException("Delay time cannot be under 0");

            System.Threading.Timer timer = null;
            timer = new System.Threading.Timer(p =>
            {
                timer.Dispose(); //stop the timer
                tcs.TrySetResult(null); //timer expired, attempt to move task to the completed state.
            }, null, delayTime, System.Threading.Timeout.Infinite);

            token.Register(() =>
                {
                    timer.Dispose(); //stop the timer
                    tcs.TrySetCanceled(); //attempt to mode task to canceled state
                });

            return tcs.Task;
        }
    }
}

Answer 5:

扩展从这一想法的答案 ：

new AutoResetEvent(false).WaitOne(1000);

Answer 6:

在很多情况下，一个纯粹的AutoResetEvent比的Thread.Sleep更好的（）...

AutoResetEvent pause = new AutoResetEvent(false);
Task timeout = Task.Factory.StartNew(()=>{
pause.WaitOne(1000, true);
});

希望它可以帮助

Answer 7:

您也可以下载的Visual Studio异步CTP和使用TaskEx.Delay

Answer 8:

    public static void DelayExecute(double delay, Action actionToExecute)
    {
        if (actionToExecute != null)
        {
            var timer = new DispatcherTimer
            {
                Interval = TimeSpan.FromMilliseconds(delay)
            };
            timer.Tick += (delegate
            {
                timer.Stop();
                actionToExecute();
            });
            timer.Start();
        }
    }

Answer 9:

下面是用适当的清理一个简洁的，基于定时器的实现：

var wait = new TaskCompletionSource<bool>();
using (new Timer(_ => wait.SetResult(false), null, delay, Timeout.Infinite))
    await wait.Task;

要在.NET 4.0中使用此代码，您需要Microsoft.Bcl.Async NuGet包。

文章来源: How to put a task to sleep (or delay) in C# 4.0?