callback every x instruction

[walid]

Hello, 
Are there any plans to include the type of code suggested in the last few mails in the following conversation?http://mail.openjdk.java.net/pipermail/nashorn-dev/2014-March/002861.html
Aside from sandboxing and using classloader shutters, it would be really useful (and in my case, mandatory) to get a callback every x instruction, allowing me to check for execution time and other resource limitation. 
This would be the equivalent of the Rhino feature which has an instruction count callback. The callback isn't (as mentioned in some conversation i found online) only available in interpreted mode: the generated code is also instrumented to add frequent calls back, allowing this callback to be triggered even in compiled mode.
Any reason why this isn't implemented in nashorn? Are there any major reasons why it wouldn't be? if it is only a matter of priority, i would appreciate some notes on where you suggest i could start so that i implement it myself for my own project.

thank you, 
-walid