如何包装带有超时的流氓函数？

Question

我在一个 3rd 方库中有一个函数，它偶尔会变得流氓并且永远不会返回。像这样：

    // This is 3rd party function so I can't make it take a cancellation token.
    public void RogueFunction()
    {

        while (true)
        {
            _logger.LogInformation("sleeping...");
            Thread.Sleep(100);
        }
    }

我想将它包装在一个带有超时的任务中，这很容易使用“task.Wait(mills)”来完成。虽然这会在超时后将控制权交还给我，但它实际上并没有终止任务。

在下面的代码中，rogue 函数在超时后继续记录。

    [Fact]
    public void Test()
    {
        var task = Task.Factory.StartNew(RogueFunction);
        var complete = task.Wait(500);
        if (!complete)
        {
            // how do I kill the task so that it quits logging?
            Thread.Sleep(5000);

            task.Dispose();  // Throws exception: A task may only be disposed if it is in a completion state (RanToCompletion, Faulted or Canceled).
        }
    }

我如何完全终止这个任务，这样我就可以重试它，而不会导致一堆它们在我的后台线程池中无限运行。

Answer 1

看来Thread.Abort 是您唯一的选择。如果您担心这样做可能会使应用程序处于损坏状态（打开文件句柄等），那么最安全的选择是在不同的进程中运行线程，然后kill the process。另一个可行的解决方案是在不同的 AppDomain 中运行线程，然后中止线程并unload the AppDomain。

Answer 2

更新：

让一个有这样的功能：

static class Rogue
{
    // This is 3rd party function so I can't make it take a cancellation token.
    public static void RogueFunction()
    {
        while (true)
        {
            Console.WriteLine("RogueFunction works");
            Thread.Sleep(1000);
        }
    }
}

可能的解决方案是用这样的类包装它：

public class InfiniteAction
{
    private readonly Action action;
    private CancellationTokenSource cts;
    private Thread thread;

    public InfiniteAction(Action action) => this.action = action;

    public void Join() => thread?.Join();

    public void Start()
    {
        if (cts == null)
        {
            cts = new CancellationTokenSource();
            thread = new Thread(() => action());
            thread.IsBackground = true;
            thread.Start();
            cts.Token.Register(thread.Abort);
        }
    }

    public void Stop()
    {
        if (cts != null)
        {
            cts.Cancel();
            cts.Dispose();
            cts = null;
        }
    }
}

现在可以像InfiniteAction.Start() 一样开始无限动作并像InfiniteAction.Stop() 那样停止它。

可以手动完成：

void ManualCancelation()
{
    var infiniteAction = new InfiniteAction(Rogue.RogueFunction);
    Console.WriteLine("RogueFunction is executing.");
    infiniteAction.Start();

    Console.WriteLine("Press any key to stop it.");
    Console.ReadKey();
    Console.WriteLine();
    infiniteAction.Stop();

    Console.WriteLine("Make sure it has stopped and press any key to exit.");
    Console.ReadKey();
    Console.WriteLine();
}

或按计时器：

void ByTimerCancelation()
{
    var interval = 3000;
    var infiniteAction = new InfiniteAction(Rogue.RogueFunction);
    Console.WriteLine($"RogueFunction is executing and will be stopped in {interval} ms.");
    Console.WriteLine("Make sure it has stopped and press any key to exit.");
    infiniteAction.Start();
    var timer = new Timer(StopInfiniteAction, infiniteAction, interval, -1);
    Console.ReadKey();
    Console.WriteLine();
}

private void StopInfiniteAction(object action)
{
    var infiniteAction = action as InfiniteAction;
    if (infiniteAction != null)
        infiniteAction.Stop();
    else
        throw new ArgumentException($"Invalid argument {nameof(action)}");
}