series of switchpoints or better

[Jochen Theodorou]

Hi all,

I am constructing a new meta class system for Groovy (ok, I say that for 
several years already, but bear with me) and I was wondering about the 
actual performance of switchpoints.

In my current scenario I would need a way to say a certain group of meta 
classes got updated and the method for this callsite needs potentially 
be reselected.

So if I have class A, class B and then I have a meta class for Object 
and one for A.

If the meta class for A is changed, all handles operating on instances 
of A may have to reselect. the handles for B and Object need not to be 
affected. If the meta class for Object changes, I need to invalidate all 
the handles for A, B and Object.

Doing this with switchpoints means probably one switchpoint per 
metaclass and a small number of meta classes per class (in total 3 in my 
example). This would mean my MethodHandle would have to get through a 
bunch of switchpoints, before it can do the actual method invocation. 
And while switchpoints might be fast it does not sound good to me.

Or I can do one switchpoint for all methodhandles in the system, which 
makes me wonder if after a meta class change the callsite ever gets 
Jitted again. The later performance penalty is actually also not very 
attractive to me.

So what is the way to go here? Or is there an even better way?

bye Jochen