From: Peter Bodik <bodikp.archive@...>
Date: 2006-03-18T05:03:48+09:00
Subject: aspectr and rails

Has anybody successfully used AspectR with Rails?

I would like to profile some parts of my Rails app such as accesses to
DB, helper methods, and rendering of views. I'd like to do this in the
live production version of the site and I'd like to turn this
monitoring on and off at run-time.

I know I could instrument all of these methods manually and collect the
data I want, but ideally I'd like to make no changes to the actual
application.

So I tried using AspectR for this and it works for some methods, but
most of the methods return this error:

#<NoMethodError: You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occured while evaluating nil.[]>

in this method (part of aspectr) when it tries to access
@__aop_advice_methods:

      def __aop_advice_list(joinpoint, method)
		method = method.to_s
		unless (method_hash = @__aop_advice_methods[joinpoint])
	  			method_hash = @__aop_advice_methods[joinpoint] = {}
		end
		unless (advice_list = method_hash[method])
	  		advice_list =  method_hash[method] = []
		end
		advice_list
      end

It seems like @__aop_advice_methods disappears or something.

Anybody has an idea how to fix this?

Or a different way how to do the monitoring I described above?

Thanks,
Peter