0

如果我有以下代码

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

namespace ConsoleApplication3
{
    class Program
    {
        static Task<int> GetSuperLargeNumber()
        {
            var main = Task.Factory.StartNew(() =>
                                                 {
                                                     Thread.Sleep(1000);
                                                     return 100;
                                                 });
            var second = main.ContinueWith(x => Console.WriteLine("Second: " + x.Result), TaskContinuationOptions.AttachedToParent);
            var third = main.ContinueWith(x => Console.WriteLine("Third: " + x.Result), TaskContinuationOptions.AttachedToParent);

            return main.ContinueWith(x  =>
                                             {
                                                 Task.WaitAll(second, third);
                                                 return x.Result;
                                             });
        }

        static void Main(string[] args)
        {
            GetSuperLargeNumber().ContinueWith(x => Console.WriteLine("Complete"));

            Console.ReadKey();
        }
    }
}

我希望 main 首先启动，然后 2 个依赖项可以在第一个和第二个并行启动之后启动。然后我想返回一个带有值的未来，供调用者添加一个延续。但是我想确保第二个和第三个先运行。下面的代码是实现这一目标的最佳方法吗？看起来有点笨重

4

2 回答 2

3

我对TPL不太熟悉，但这不ContinueWhenAll就是为了吗？

static Task<int> GetSuperLargeNumber()
{
    var main = Task.Factory.StartNew(() =>
                                         {
                                             Thread.Sleep(1000);
                                             return 100;
                                         });
    var second = main.ContinueWith(
        x => Console.WriteLine("Second: " + x.Result),
        TaskContinuationOptions.AttachedToParent);
    var third = main.ContinueWith(
        x => Console.WriteLine("Third: " + x.Result),
        TaskContinuationOptions.AttachedToParent);

    return Task.Factory.ContinueWhenAll(
        new[] { second, third },
        (twotasks) => /* not sure how to get the original result here */);
    }

我不知道如何从完成的和（包含在）中获取main's 结果，但也许您可以修改它们以传递结果。secondthirdtwotasks

编辑：或者，正如亚历克斯指出的那样，使用

Task.Factory.ContinueWhenAll(new[] { main, second, third }, (threetasks) => ...

并从中读取结果threetasks[0]。

于 2013-01-17T08:58:57.847 回答
0

这就足够了：

static Task<int> GetSuperLargeNumber()
{
    var main = Task.Factory.StartNew<int>(() =>
    {
        Thread.Sleep(1000);
        return 100;
    });
    var second = main.ContinueWith(x => Console.WriteLine("Second: " + x.Result), TaskContinuationOptions.AttachedToParent);
    var third = main.ContinueWith(x => Console.WriteLine("Third: " + x.Result), TaskContinuationOptions.AttachedToParent);

    Task.WaitAll(second, third);

    return main;
}
于 2013-01-17T09:05:14.543 回答