On 22/06/2016 11:16, Michael Rasmussen wrote:
Hi
With the addition of GetModuleByPackageName added to JVMTI ([1], [2]),
are there any plans to add similar functionality to the
Instrumentation API (or somewhere else)?
From ClassFileTransformer we now get the Module for the class that is
currently being transformed, but a very common scenario when
transforming a class that is being loaded, is the need to get
information about other classes used by that class; classes which
might not have been loaded yet, meaning we need to get the bytes
somehow.
A common approach to this pre-jigsaw, was simply to translate the
classname to a filename and ClassLoader::getResourceAsStream; but with
named modules, this is no longer the case, we now have to know which
Module that class is in in order to get the bytes
(#ClassFilesAsResources, #ResourceEncapsulation etc).
Adding a GetModuleByPackageName equivalent method would go some way to
help with this issue.
GetModuleByPackageName is being added to JVM TI because
ClassFileLoadHook cannot be changed to add a new parameter and it would
too messy to introduce a different callback. It's much cleaner in the
java.lang.instrument API as the Module is passed to the
ClassFileTransformer.
As to whether yet more APIs are needed then I think it would be better
to wait until the #ClassFilesAsResources/#ResourceEncapsulation issues
are discussed.
-Alan
