How can I force unhandled exceptions in a WCF thread to crash the process?

Question

So here's the scenario:

I have a WCF service that has a bunch of FaultContracts defined per operation. I would like to arrange it such that if an unhandled exception is thrown in a WCF service thread that does not match a valid FaultContract, it takes down the entire process rather than just the thread. (The reason being that I would like a crash dump that contains the information on the exception, since it didn't match the contract.)

Is there any way to do this cleanly? The main problem I have is that WCF wants to translate all my exceptions into a client-side fault in order to keep the service running; I actually want to take the entire process down, which essentially means circumventing WCF's normal behavior.

Answer 1

Application.Exit();

That might do it, but the user will lose anything they're working on at the time.

Answer 2

Environment.FailFast() will create a crash dump; it will not run any pending try-finally blocks nor will it run any finalizers.

Answer 3

You need to use IErrorHandler to customize WCF's error handling behavior. You "apply the behavior" before you call (ServiceHost).Open().

For example (look for the line that says "serviceHost.Description.Behaviors.Add(new FailBehavior());" in Main()):

class FailBehavior : IServiceBehavior
{
    public void AddBindingParameters(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase, System.Collections.ObjectModel.Collection<ServiceEndpoint> endpoints, BindingParameterCollection bindingParameters)
    {
        return;
    }

    public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
    {
        Console.WriteLine("The FailFast behavior has been applied.");
        var f = new FailOnError();
        foreach(ChannelDispatcher chanDisp in serviceHostBase.ChannelDispatchers)
        {
            chanDisp.ErrorHandlers.Add(f);      
        }
    }

    public void Validate(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
    {
        return;
    }
}

class FailOnError : IErrorHandler
{
    public bool HandleError(Exception error)
    {
        // this is called for every exception -- even ungraceful disconnects
        if( !(error is CommunicationException) )
            throw new TargetInvocationException( "WCF operation failed.", error );
        else
            throw new CommunicationException( "Unexpected communication problem. (see inner exception)", error );

        // Unreachable
        //return false; // other handlers should be called
    }

    public void ProvideFault(Exception error, MessageVersion version, ref Message fault)
    {
        // Can't throw from here (it will be swallowed), and using Environment.FailFast
        // will result in all crashes going to the same WER bucket. We could create
        // another thread and throw on that, but instead I think throwing from HandleError
        // should work.

        //Console.WriteLine( "Unhandled exception: {0}", error );
        //Environment.FailFast("Unhandled exception thrown -- killing server");            
    }
}

class Program
{
    static void Main( string[] args )
    {
        Console.WriteLine( "Greetings from the server." );

        Uri uri = new Uri( "net.tcp://localhost:5678/ServerThatShouldCrash" );
        using( ServiceHost serviceHost = new ServiceHost( typeof( Server ), uri ) )
        {
            Binding binding = _CreateBinding();

            serviceHost.AddServiceEndpoint( typeof( IServer ),
                                            binding,
                                            uri );
            serviceHost.Description.Behaviors.Add(new FailBehavior());
            serviceHost.Open();

            // The service can now be accessed.
            Console.WriteLine( "The service is ready." );
            Console.WriteLine( "\nPress <ENTER> to terminate service.\n" );
            Console.ReadLine();
        }
    }

    private static Binding _CreateBinding()
    {
        NetTcpBinding netTcp = new NetTcpBinding( SecurityMode.None );
        netTcp.ReceiveTimeout = TimeSpan.MaxValue;
        netTcp.ReliableSession.InactivityTimeout = TimeSpan.MaxValue;
        return netTcp;
    } // end _CreateBinding()
}