Review Request: JDK-8157464: StackWalker.getCallerClass() is not

[Mandy Chung]

Hi Coleen,

Thanks for the review. 


> On Sep 13, 2016, at 2:32 PM, Coleen Phillimore <coleen.phillimore at oracle.com> wrote:
> 
> 
> 
> On 9/13/16 2:54 PM, Daniel Fuchs wrote:
>> Hi Mandy,
>> 
>> This looks good to me.
>> But I wonder about these 5 lines - isn't this introducing a change
>> of behavior if the caller is an anonymous class?
>> 
>> 149       InstanceKlass* ik = method->method_holder();
>> 150       if (ik->is_anonymous()) {
>> 151         // use the host class as the caller class
>> 152         ik = ik->host_klass();
>> 153       }
>> 
>> What is the reason for returning the host class instead?

> 
> Somehow I think you want to see all the lambda classes in the stack trace, or skip them but the host class might be confusing because it's something like  java/lang/invoke/LambdaForm a lot of the time.   At least you'd get java.lang.invoke.LambdaForm$BMH/1170794006 which has a little more information.
> 

StackWalker::walk wants to see all lambda classes in the stack trrace (if SHOW_HIDDEN_FRAMES is set).  StackWalker::getCallerClass does not since it wants to find the true caller. I have revised the patch to skip the hidden frames instead:
   http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8157464/webrev.02/ 


> http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8157464/webrev.01/hotspot/src/share/vm/prims/stackwalk.cpp.udiff.html
> 
> + THROW_MSG_0(vmSymbols::java_lang_UnsupportedOperationException(),
> 
> I think you need ResourceMark rm(THREAD); above this line.
> 

Fixed.  Thanks for catching it.

> I can't review the test because I'm not sure what it's doing.  Does it create a module just for the test?
> 

It creates a module called “csm” where CallerSensitiveTest class is in and then invoke CallerSensitiveTest with and without security manager.  This test can run in an unnamed module but I chose it as an example to build a module.

This test invokes StackWalker::getCallerClass via static reference, reflection, MethodHandle, lambda.  Also verify that StackWalker::getCallerClass can't be called from @CallerSensitive method.

Mandy