RFR: 6983726: Reimplement MethodHandleProxies.asInterfaceInstance [v16]

[Mandy Chung]

On Wed, 31 May 2023 00:48:18 GMT, Mandy Chung <mchung at openjdk.org> wrote:

>>> Is it more straight-forward to keep a `ClassValue<Boolean>` and each wrapper instance class has an entry of `TRUE` value; otherwise, `FALSE`?
>> 
>> Then we still need to obtain the implemented interface and original method handle information every time they are queried. Having these information (or the method handle providing access) computed early is more convenient.
>> 
>>> If we can avoid implementing sun.invoke.WrapperInstance, this package access check issue would go away. Do you think you can look into it?
>> 
>> Apparently, calling utility methods from `sun.invoke`, like the `ensureOriginalLookup` in this patch, also triggers this check. However, I still think removing the `WrapperInstance` supertype is better, as this makes the code cleaner in reflection.
>
>> Apparently, calling utility methods from sun.invoke, like the ensureOriginalLookup in this patch, also triggers this check. 
> 
> It should not trigger `checkPackageAccess` if it does not implement the interface AFAICT.
> 
> It would trigger module-access check.  `java.base` can export `sun.invoke` to the dynamic module (it may be worth considering putting the internal interface in a specific package for the dynamic module' use - `sun.invoke` is ok since it currently has one interface but hard to catch when someone adds a new class/interface in `sun.invoke` unintentionally and leak out sensitive API.

> Then we still need to obtain the implemented interface and original method handle information every time they are queried. Having these information (or the method handle providing access) computed early is more convenient.

I was thinking the wrapper instance class still implements some private methods to get the implemented interface and original method handle which can be accessed only `java.base` via deep reflection.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13197#discussion_r1210972245