[langtools] RFR (L): 8010319: Implementation of JEP 181: Nest-Based Access Control

[Maurizio Cimadamore]

Hi David,
the webrev looks good.

You did an excellent job in staying on top of all these different areas 
- kudos!

The only thing I can't decide is whether we will need an escape hatch 
flag for when you compile using -target 11 and, for some weird reason 
you need to disable nestmates (e.g. you want javac to emit accessors). 
But with all the testing you did, I'm confident that what we have is 
good - we can always add such a flag at a later stage - it's so trivial.

Cheers
Maurizio


On 15/05/18 01:52, David Holmes wrote:
> This review is being spread across four groups: langtools, core-libs, 
> hotspot and serviceability. This is the specific review thread for 
> langtools - webrev:
>
> http://cr.openjdk.java.net/~dholmes/8010319-JEP181/webrev.langtools.v1/
>
> See below for full details - including annotated full webrev guiding 
> the review.
>
> The intent is to have JEP-181 targeted and integrated by the end of 
> this month.
>
> Thanks,
> David
> -----
>
> The nestmates project (JEP-181) introduces new classfile attributes to 
> identify classes and interfaces in the same nest, so that the VM can 
> perform access control based on those attributes and so allow direct 
> private access between nestmates without requiring javac to generate 
> synthetic accessor methods. These access control changes also extend 
> to core reflection and the MethodHandle.Lookup contexts.
>
> Direct private calls between nestmates requires a more general calling 
> context than is permitted by invokespecial, and so the JVMS is updated 
> to allow, and javac updated to use, invokevirtual and invokeinterface 
> for private class and interface method calls respectively. These 
> changed semantics also extend to MethodHandle findXXX operations.
>
> At this time we are only concerned with static nest definitions, which 
> map to a top-level class/interface as the nest-host and all its nested 
> types as nest-members.
>
> Please see the JEP for further details.
>
> JEP: https://bugs.openjdk.java.net/browse/JDK-8046171
> Bug: https://bugs.openjdk.java.net/browse/JDK-8010319
> CSR: https://bugs.openjdk.java.net/browse/JDK-8197445
>
> All of the specification changes have been previously been worked out 
> by the Valhalla Project Expert Group, and the implementation reviewed 
> by the various contributors and discussed on the valhalla-dev mailing 
> list.
>
> Acknowledgments and contributions: Alex Buckley, Maurizio Cimadamore, 
> Mandy Chung, Tobias Hartmann, Vladimir Ivanov, Karen Kinnear, Vladimir 
> Kozlov, John Rose, Dan Smith, Serguei Spitsyn, Kumar Srinivasan
>
> Master webrev of all changes:
>
> http://cr.openjdk.java.net/~dholmes/8010319-JEP181/webrev.full.v1/
>
> Annotated master webrev index:
>
> http://cr.openjdk.java.net/~dholmes/8010319-JEP181/jep181-webrev.html
>
> Performance: this is expected to be performance neutral in a general 
> sense. Benchmarking and performance runs are about to start.
>
> Testing Discussion:
> ------------------
>
> The testing for nestmates can be broken into four main groups:
>
> -  New tests specifically related to nestmates and currently in the 
> runtime/Nestmates directory
>
> - New tests to complement existing tests by adding in testcases not 
> previously expressible.
>   -  For example java/lang/invoke/SpecialInterfaceCall.java tests use 
> of invokespecial for private interface methods and performing receiver 
> typechecks, so we add java/lang/invoke/PrivateInterfaceCall.java to do 
> similar tests for invokeinterface.
>
> -  New JVM TI tests to verify the spec changes related to nest 
> attributes.
>
> -  Existing tests significantly affected by the nestmates changes, 
> primarily:
>    -  runtime/SelectionResolution
>
>    In most cases the nestmate changes makes certain invocations that 
> were illegal, legal (e.g. not requiring invokespecial to invoke 
> private interface methods; allowing access to private members via 
> reflection/Methodhandles that were previously not allowed).
>
> - Existing tests incidentally affected by the nestmate changes
>
>   This includes tests of things utilising class 
> redefinition/retransformation to alter nested types but which 
> unintentionally alter nest relationships (which is not permitted).
>
> There are still a number of tests problem-listed with issues filed 
> against them to have them adapted to work with nestmates. Some of 
> these are intended to be addressed in the short-term, while some (such 
> as the runtime/SelectionResolution test changes) may not eventuate.
>
> - https://bugs.openjdk.java.net/browse/JDK-8203033
> - https://bugs.openjdk.java.net/browse/JDK-8199450
> - https://bugs.openjdk.java.net/browse/JDK-8196855
> - https://bugs.openjdk.java.net/browse/JDK-8194857
> - https://bugs.openjdk.java.net/browse/JDK-8187655
>
> There is also further test work still to be completed (the JNI and JDI 
> invocation tests):
> - https://bugs.openjdk.java.net/browse/JDK-8191117
> which will continue in parallel with the main RFR.
>
> Pre-integration Testing:
>  - General:
>     - Mach5: hs/jdk tier1,2
>     - Mach5: hs-nightly (tiers 1 -3)
>  - Targetted
>    - nashorn (for asm changes)
>    - hotspot: runtime/*
>               serviceability/*
>               compiler/*
>               vmTestbase/*
>    - jdk: java/lang/invoke/*
>           java/lang/reflect/*
>           java/lang/instrument/*
>           java/lang/Class/*
>           java/lang/management/*
>   - langtools: tools/javac
>                tools/javap
>