c# – 如何为各种代码块创建通用超时对象？

以下是如何使用我创建的Timebox类.

public void MyMethod( ... ) {

    // some stuff

    // instead of this
    // using(...){ /* your code here */ }

    // you can use this
    var timebox = new Timebox(TimeSpan.FromSeconds(1));
    timebox.Execute(() =>
    {
        /* your code here */
    });

    // some more stuff

}

以下是Timebox的工作原理.

>使用给定的Timespan创建Timebox对象
>调用Execute时,Timebox会创建一个子AppDomain来保存TimeboxRuntime对象引用,并向其返回一个代理
>子AppDomain中的TimeboxRuntime对象将Action作为输入在子域中执行
> Timebox然后创建一个任务来调用TimeboxRuntime代理
>任务已启动(并且操作执行开始),并且“main”线程等待给定的TimeSpan
>在给定的TimeSpan之后(或任务完成时),无论Action是否完成,都会卸载子AppDomain.
>如果操作超时,则抛出TimeoutException,否则如果操作抛出异常,则由子AppDomain捕获并返回以调用AppDomain

缺点是您的程序需要足够高的权限才能创建AppDomain.

这是一个示例程序,演示它是如何工作的(我相信如果包含正确的用法,你可以复制粘贴它).如果你有兴趣,我也创建了this gist.

public class Program
{
    public static void Main()
    {
        try
        {
            var timebox = new Timebox(TimeSpan.FromSeconds(1));
            timebox.Execute(() =>
            {
                // do your thing
                for (var i = 0; i < 1000; i++)
                {
                    Console.WriteLine(i);
                }
            });

            Console.WriteLine("Didn't Time Out");
        }
        catch (TimeoutException e)
        {
            Console.WriteLine("Timed Out");
            // handle it
        }
        catch(Exception e)
        {
            Console.WriteLine("Another exception was thrown in your timeboxed function");
            // handle it
        }
        Console.WriteLine("Program Finished");
        Console.ReadLine();
    }
}

public class Timebox
{
    private readonly TimeSpan _ts;

    public Timebox(TimeSpan ts)
    {
        _ts = ts;
    }

    public void Execute(Action func)
    {
        AppDomain childDomain = null;
        try
        {
            // Construct and initialize settings for a second AppDomain.  Perhaps some of
            // this is unnecessary but perhaps not.
            var domainSetup = new AppDomainSetup()
            {
                ApplicationBase = AppDomain.CurrentDomain.SetupInformation.ApplicationBase,ConfigurationFile = AppDomain.CurrentDomain.SetupInformation.ConfigurationFile,ApplicationName = AppDomain.CurrentDomain.SetupInformation.ApplicationName,LoaderOptimization = LoaderOptimization.MultiDomainHost
            };

            // Create the child AppDomain
            childDomain = AppDomain.CreateDomain("Timebox Domain",null,domainSetup);

            // Create an instance of the timebox runtime child AppDomain
            var timeboxRuntime = (ITimeboxRuntime)childDomain.CreateInstanceAndUnwrap(
                typeof(TimeboxRuntime).Assembly.FullName,typeof(TimeboxRuntime).FullName);

            // Start the runtime,by passing it the function we're timboxing
            Exception ex = null;
            var timeoutOccurred = true;
            var task = new Task(() =>
            {
                ex = timeboxRuntime.Run(func);
                timeoutOccurred = false;
            });

            // start task,and wait for the alloted timespan.  If the method doesn't finish
            // by then,then we kill the childDomain and throw a TimeoutException
            task.Start();
            task.Wait(_ts);

            // if the timeout occurred then we throw the exception for the caller to handle.
            if(timeoutOccurred)
            {
                throw new TimeoutException("The child domain timed out");
            }

            // If no timeout occurred,then throw whatever exception was thrown
            // by our child AppDomain,so that calling code "sees" the exception
            // thrown by the code that it passes in.
            if(ex != null)
            {
                throw ex;
            }
        }
        finally
        {
            // kill the child domain whether or not the function has completed
            if(childDomain != null) AppDomain.Unload(childDomain);
        }
    }

    // don't strictly need this,but I prefer having an interface point to the proxy
    private interface ITimeboxRuntime
    {
        Exception Run(Action action);
    }

    // Need to derive from MarshalByRefObject... proxy is returned across AppDomain boundary.
    private class TimeboxRuntime : MarshalByRefObject,ITimeboxRuntime
    {
        public Exception Run(Action action)
        {
            try
            {
                // Nike: just do it!
                action();
            }
            catch(Exception e)
            {
                // return the exception to be thrown in the calling AppDomain
                return e;
            }
            return null;
        }
    }
}

编辑：

之所以我使用AppDomain而不是仅使用线程或任务,是因为没有用于终止任意代码的线程或任务的防弹方式[2] [3].根据您的要求,AppDomain对我来说似乎是最好的方法.