C# .Net并行(多核)编程 4 - Task的基本用法(复合的CancellationToken)

文章转自:http://ggicci.blog.163.com/blog/static/21036409620127204318184/

Title :

• Pro .NET 4 Parallel Programming in C# (Adam Freeman) Task的基本用法
• 复合的 Cancellation Token

 

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Quote :

You can create a token that is composed from several CancellationTokens that will be cancelled if any of the underlying tokens is cancelled. [From “Pro .Net 4 Parallel Programming in C#”]

你可以把一些 CancellationToken 组合在一起形成一个复合的 CancellationToken，只要其中任何一个 CancellationToken 被取消，那么这个复合的就会被取消。

至于如何复合，只需调用 System.Threading.CancallationTokenSource.CreateLinkedTokenSource() 方法即可。

 

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Code :

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

namespace Parallel_TaskProgramming
{
    class Program
    {
        public static void Main(string[] args)
        {
            CancellationTokenSource tokenSource1 = new CancellationTokenSource();
            CancellationTokenSource tokenSource2 = new CancellationTokenSource();
            CancellationTokenSource tokenSource3 = new CancellationTokenSource();
            //用多个CancallationToken复合
            CancellationTokenSource compositeTokenSource =
                CancellationTokenSource.CreateLinkedTokenSource(
                tokenSource1.Token, tokenSource2.Token, tokenSource3.Token);

            Task task = new Task(() =>
            {
                int i = 0;
                while (true)
                {
                    if (compositeTokenSource.Token.IsCancellationRequested)
                    {
                        throw new OperationCanceledException(compositeTokenSource.Token);
                    }
                    else
                    {
                        Console.WriteLine(i++);
                    }
                }
            }, compositeTokenSource.Token);

            task.Start();
            Thread.Sleep(5);
            //只要其中一个子token被取消，任务就会被取消
            tokenSource1.Cancel();

            Console.WriteLine("Press enter to finish.");
            Console.ReadLine();
        }
    }
}

Result :

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Press enter to finish.