Hi Dan and David,
On 5/21/19 15:58, David Holmes wrote:
Hi Dan,
On 22/05/2019 2:34 am, Daniel D. Daugherty wrote:
On 5/21/19 2:19 AM, serguei.spit...@oracle.com wrote:
Hi guys,
I've found one more fragment in the IsModifiableClass spec which has
to be fixed.
Updated webrev v2:
http://cr.openjdk.java.net/~sspitsyn/webrevs/2019/8046018-jvmti-cap-spec.2/
src/hotspot/share/prims/jvmti.xml
No comments.
Looks like there was a specific update to the spec to allow
can_redefine_any_class
to include retransform (in addition to redefine):
1.1.82
13 February 2006 Doc fixes: update can_redefine_any_class to
include retransform. Clarify that exception events cover all
Throwables. In GetStackTrace, no test is done for start_depth too big
if start_depth is zero, Clarify fields reported in Primitive Field
Callback -- static vs instance. Repair confusing names of heap types,
including callback names. Require consistent usage of stack depth in
the face of thread launch methods. Note incompatibility of JVM TI
memory management with other systems.
I can't tell if you've chased down that change and why you no longer
think that change is necessary.
I'm okay with the change, but I think you have more research to do here.
I already chased that down and mentioned it in the CSR. It was done
under:
https://bugs.openjdk.java.net/browse/JDK-6328530
Unfortunately I misread the original bug description. In relation to
can_redefine_any_class it states:
A more precise definition would be:
Can retransform or redefine any non-primitive non-array class.
It appears to me that they did consider can_redefine_any_class to be a
"super" capability that could be added on top of can_redefine_classes
to extend it to "any" class; or on top of can_retransform_classes to
extend it to "any" class. If so the name choice was unfortunate.
Further it seems the implementation never checked this anyway.
Right.
The approach taken for JDK-6328530 is non-symmetrical and confusing.
But, I think, I understand why this decision was made. :)
If we ever decide to make some (non-primitive and non-array) classes to
be non-modifiable then
I do not see problems to implement it in a way that
can_redefine_any_class will be checked on
RedefineClasses only and can_retransform_any_class will be checked on
RetransformClasses only.
We will get a symmetry (and so, a simplification as well) in two dimensions:
- between redefine and retransform capabilities
- between can_redefine_classes and can_redefine_any_class capabilities
Thanks,
Serguei
David
Dan
Specdiff:
http://cr.openjdk.java.net/~sspitsyn/webrevs/2019/8046018-jvmti-cap-spec.2/jvmti-specdiff/
Enhancement:
https://bugs.openjdk.java.net/browse/JDK-8046018
Related CSR:
https://bugs.openjdk.java.net/browse/JDK-8223915
Thanks,
Serguei
On 5/20/19 21:43, serguei.spit...@oracle.com wrote:
Hi David,
Thank you for looking at this!
On 5/20/19 20:53, David Holmes wrote:
Hi Serguei,
On 21/05/2019 4:07 am, serguei.spit...@oracle.com wrote:
Please, review a fix for enhancement:
https://bugs.openjdk.java.net/browse/JDK-8046018
Related CSR:
https://bugs.openjdk.java.net/browse/JDK-8223915
I have some comments on the CSR and about this change overall as
to me it is not a simple clarification at all, but potentially a
significant change in the meaning of the capability.
I've answered your question in the CSR with my comment.
Webrev:
http://cr.openjdk.java.net/~sspitsyn/webrevs/2019/8046018-jvmti-cap-spec.1/
You introduced a typo: modifialble
Assuming this proceeds a similar change is needed earlier:
7444 <capability id="can_redefine_any_class">
7445 If possessed then all classes (except primitive,
array, and some implementation defined
7446 classes) are modifiable (redefine or retransform).
Good catch, thanks!
I've updated the webrev in place.
Thanks,
Serguei
Thanks,
David
-----
Summary:
The fix is to make the JVMTI can_redefine_any_class capability
spec more inconsistent.
It is just about a couple of lines.
Thanks,
Serguei
