示例: .NET Framework提供的标准取消操作模式

using System;
using System.Threading;

namespace CancellationTokenSourceTest
{
    class Program
    {
        static void Main(string[] args)
        {
            //协作式取消和超时
            CancellationTokenSource cts = new CancellationTokenSource();
            //注册取消后的回调,会按倒序执行
            cts.Token.Register(() => { Console.WriteLine("token cts canceled callback1"); });
            cts.Token.Register(() => { Console.WriteLine("token cts canceled callback2"); });

            ThreadPool.QueueUserWorkItem(o=>Count(cts.Token, 1000));

            Console.WriteLine("Press <Enter> to cancel the operation.");
            Console.ReadLine();
            cts.Cancel();//如果Count方法已返回，Cancel没有任何效果
            Console.ReadLine();
        }

        private static void Count(CancellationToken token, Int32 countTo)
        {
            for (int count = 0; count < countTo; count++)
            {
                if (token.IsCancellationRequested)
                {
                    Console.WriteLine("Count is cancelled");
                    break;//退出循环以停止操作
                }
                Console.WriteLine(count);
                Thread.Sleep(200);
            }
            Console.WriteLine("Count is done");
        }
    }
}

运行测试