Question

I made a simple test of the Castle Dynamic Proxy library:

public class Printer
{
    public virtual void Write(string msg)
    {
        Console.Write(msg); 
    }
}

public class CastleDynamicProxy
{
    public static void Test()
    {
        ProxyGenerator generator = new ProxyGenerator();

        Printer logger = generator.CreateClassProxy<Printer>(new TestInterceptor());

        logger.Write("Hello, World!"); 
    }
}

Now in my interceptor I want to time the function, but its causing a StackOverflowException because I am calling the target method inside the Intercept method, causing an infinite loop:

public class TestInterceptor : IInterceptor
{
    public void Intercept(IInvocation invocation)
    {
       var accessor = invocation.Proxy as IProxyTargetAccessor;

       MethodInfo target = accessor.DynProxyGetTarget().GetType().GetMethod("Write"); 

       var s = Stopwatch.StartNew(); 

       target.Invoke(invocation.InvocationTarget, invocation.Arguments);

       s.Stop(); 
    }
}

Is there anyway around this, either by 1) stopping the interceptions process altogether, or 2) removing my interceptor after I have used it for what I need, before getting into an infinite loop?

Answer 1

Are you sure that’s what you want to do? I’ve created a timing interceptor as well to see if a method call (such as a DB query) exceeds a threshold, and if so to log it.

Instead of manually invoking the target, just use invocation.Proceed() to tell it to go ahead with the intercepted call.

My code looks like this:

        public void Intercept(IInvocation invocation)
        {
            var timer = Stopwatch.StartNew();

            // i think you want this to proceed with the invocation...
            invocation.Proceed();

            timer.Stop();

            // check if threshold is exceeded
            if (timer.Elapsed > _threshold)
            {
                // log it to logger of choice
            }
        }