[Nestmates] RFR: JVM TI and related updates
david.holmes at oracle.com
Tue Mar 20 05:59:15 UTC 2018
This RFR is for the JVM TI specification and implementation changes, and
related JDWP, instrumentation and JDI changes. The bulk of this work was
done by Serguei - which was very much appreciated. I have written the
test based on initial examples that Serguei provided.
The actual spec changes are done under sub-task:
This has been discussed/reviewed on the EG list and here as part of the
CSR review. The changes are being putback now so that we can also
putback the implementation changes - as the specs, in part, generate
some of the code. If you have comments on the actual specification
changes please respond to the CSR review thread - thanks.
The implementation changes, and accompanying tests have been done under:
The basic change is simple: redefinition/retransformation may not modify
either the NestHost or NestMembers attributes of a class: no additions,
no removals, no changes. As the order of classes in the NestMembers
attribute is not specified (and can easily vary across compilers, or
even within one compiler under different conditions) we cannot consider
a change in order to be a change, so we have to allow for that.
The testing is simple in principle, but in practice quite complicated to
set up the necessary conditions and manage all the different "versions"
of the "same class". The testing approach is explained in great detail
in the main test: TestNestmateAttr.java
We are still awaiting a standalone JDI test to be written, but that will
be coming shortly and I want to clear the decks so will follow up on
In addition some existing redefinition tests started to fail because
they were inadvertently changing the NestHost attribute. This arose
because the tests were using nested classes to be redefined, but the way
the InMemoryJavaCompiler was used actually produces a top-level class
(no NestHost attribute) that happens to have a $ in the name (A$B is
actaully a legal class name for a top-level class). These tests will be
updated shortly but for now are ProblemListed.
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