RFR: 8152641: Plugin to generate BMH$Species classes ahead-of-time

[Mandy Chung]

> On Mar 25, 2016, at 7:58 AM, Claes Redestad <claes.redestad at oracle.com> wrote:
> 
> Hi,
> 
> On 2016-03-25 11:11, Peter Levart wrote:
>> Hi Claes, Mandy,
>> 
>> On 03/25/2016 02:51 AM, Mandy Chung wrote:
>>> Hi Claes,
>>> 
>>> This is a good interesting work to generate BoundMethodHandle$Species_* classes at link time.  This will save the class generation time.  Instead of Class.forName, you may want to have a class (similar to SystemModules [1]) that will be updated at link time so that BoundMethodHandle can reference it statically to determine what species are generated at link time and even return statically Class<?> of the generated class.
>> 
>> You may still want to load this classes lazily when needed. Otherwise the BMH.CLASS_CACHE could simply be pre-populated with name -> Class<?> entries at appropriate early time.
> 
> I think laziness is a good property here, since it won't penalize modular applications that choose to instruct jlink to pregenerate a lot of BMH classes.
> 
> Perhaps we can allow for static resolve + lazy classload by emitting a switch equivalent to:
> 
> switch (types) {
>  case "LL":
>    return Species_LL.class;
>  case "L3":
>    return Species_L3.class;
>  ..
>  default:
>    return generateBMHSpeciesClass(types);
> }
> 

This is exactly what I was thinking.

Mandy