On Thu, 16 Mar 2023 15:20:27 GMT, Chen Liang <li...@openjdk.org> wrote:
>> Possible extensions of `ClassHierarchyResolver` factories, or maybe even >> extensions of the default resolver are on the table and I just planned to >> open this discussion. >> >> Here is specific case where original code passes `ClassLoader` down to to >> the ASM engine for class hierarchy resolution based on class loading. >> >> Classfile API has more flexibility in that area and can resolve class >> hierarchy based on provided minimal information. Default class hierarchy >> resolution is fast-scanning of classfiles provided by ClassLoader as >> resources. It is not necessary to resolve all dependencies nor load the >> classes. However this is one of the cases where I'm not sure the default >> does it right. The above code turns default class hierarchy resolution back >> to the original class-loading approach. >> >> In `InnerClassLambdaMetafactory` I didn't observed any `ClassLoader` beeing >> passed down to ASM, so it rely on the defaults. >> >> The right solution may be to extend the default class hierarchy resolution >> to fall back to class-loading when the resource form of the class is not >> available. A factory method can just replicate the same behavior with >> provided different `ClassLoader`. >> >> I'm open to any comments and suggestions. > > I was thinking of implementing a class resolution via Reflection API with the > `MethodHandles.Lookup` passed into `LambdaMetafactory` for correctness. Could > it be that Lambda bytecode is too simple (as it's just calling a method > handle in an instance method and a constructor, in a class extending Object > and implementing a few interfaces) so the class hierarchy resolution wasn't > critical? > In InnerClassLambdaMetafactory I didn't observed any ClassLoader beeing > passed down to ASM, so it rely on the defaults. This is right. A lambda proxy is defined with the same class loader of the caller's class. For dynamic proxies, it is generated using the class loader specified via `newProxyInstance(ClassLoader loader, Class<?>[] interfaces, InvocationHandler h)` which should be used for class resolution. ------------- PR: https://git.openjdk.org/jdk/pull/10991
