Review request:Updated JDK-8004728 Implement core reflection API for parameter reflection

Joel Borggrén-Franck joel.franck at
Thu Dec 20 13:45:52 UTC 2012

Hi Peter, Eric and and others,

Thanks for your comments,

On 12/20/2012 09:09 AM, Peter Levart wrote:
> Hi Eric and others,
> I'd also like to rise an internal design concern regarding construction
> of Parameter objects. Currently raw reflection data for Executable
> objects is obtained from the VM atomically - the whole Method or
> Constructor is fully constructed with all necessary information in one
> go. That's true also for parameter types and parameter annotations. New
> Parameter API is now "pulling" lazily some additional information from
> the VM (parameter names and modifiers). How does this play together with
> class re-definitions/re-transformations? Is it possible that a class
> re-definition changes parameter names? Can it change parameter annotations?
> Imagine one has a reference to a Method, that has since it's
> construction already been re-defined in the VM (for example a parameter
> name and annotation has changed).  When asking for annotations on the
> re-defined parameter, you will get annotations that were actual at the
> time the Method was constructed, but when asked for the parameters and
> their names, you will get the already redefined names.
> I think that the more correct implementation would construct
> Method/Constructor objects in the VM with all the necessary information
> (parameter names and modifiers) already present in the Executable
> objects. This information could be conveniently packed and only unpacked
> and expanded on user's request - like annotations.

I would like to go the opposite way with Executable, Method, Field and 
Parameter, like the caches work on Class instances in your patch.

Reflective Objects should be created with non-initialized caches of 
metadata. When someone wants to look at the metatdata we should check 
the redefine count on Class, and update the caches if necessary. There 
is already infrastructure for this in the VM for the old annotations 
byte[] on Field, Method and Constructor.

I am unclear if the parameter name is part of the signature, this is 
significant because (IIRC) signaturs can not change in redefine, but 
parameter annotations should be able to change.


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