4
我正在尝试.NET 4.0中的任务支持 - 特别是延续支持。我感到困惑的是,我无法弄清楚如何获得设置为执行的TaskContinuationOptions.OnlyOnCanceled
标志的延续。如果我在我的工作程序中执行ThrowIfCancellationRequested
,它似乎只是作为错误而不是取消操作传播出去。例如,给定这样的代码:任务并行库 - 如何通过TaskContinuationOptions.OnlyOnCanceled进行继续操作?
using System;
using System.Threading;
using System.Threading.Tasks;
namespace TaskExp1
{
class Program
{
static void Main()
{
var n = 10000;
DumpThreadId("main method");
var cts = new CancellationTokenSource();
var task = Task.Factory.StartNew<int>(_ => Sum(cts.Token, n),
cts.Token);
task.ContinueWith(t =>
{
DumpThreadId("ContinueWith Completed, ", newline:false);
Console.WriteLine("The result is " + t.Result);
}, TaskContinuationOptions.OnlyOnRanToCompletion);
task.ContinueWith(t =>
{
DumpThreadId("ContinueWith Faulted, ", newline: false);
Console.WriteLine(t.Exception.InnerExceptions[0].Message);
}, TaskContinuationOptions.OnlyOnFaulted);
task.ContinueWith(_ =>
{
DumpThreadId("ContinueWith Cancelled, ");
}, TaskContinuationOptions.OnlyOnCanceled);
Console.WriteLine("Computing sum of " + n + " ...");
Thread.SpinWait(100000);
cts.Cancel();
Console.WriteLine("Done.");
Console.ReadLine();
}
static int Sum(CancellationToken cancelToken, int n)
{
DumpThreadId("from Sum method");
int sum = 0;
for (; n > 0; n--)
{
Thread.SpinWait(500000);
if (n == 10000) cancelToken.ThrowIfCancellationRequested();
checked { sum += n; }
}
return sum;
}
static void DumpThreadId(string msg = "", bool newline = true)
{
var formattedMsg = String.Format("ThreadId: {0} {1}",
Thread.CurrentThread.ManagedThreadId, msg);
if (newline) formattedMsg += "\n";
Console.Write(formattedMsg);
}
}
}
此输出:
ThreadId: 9 main method
Computing sum of 10000 ...
Done.
ThreadId: 10 from Sum method
ThreadId: 10 ContinueWith Faulted, The operation was canceled.
如何退出我的工人(和)方式使得OnlyOnCanceled
继续被解雇?
哇,这似乎很微妙,但有道理 - 使用_!=使用()。谢谢! – 2010-11-17 00:02:21