Timebox Class

Timebox.cs

using System;
using System.Threading.Tasks;

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;
        }
    }
}