RFR(S): 8061443: Whitebox get*VMFlag() methods fail with develop flags in product builds

[Vladimir Kozlov]

getVMOption() specification does not say anything about product, locked 
or develop flags. "If a VM option of the given name does not exist" can 
interpreted different ways.

http://docs.oracle.com/javase/8/docs/jre/api/management/extension/com/sun/management/HotSpotDiagnosticMXBean.html

VMOption getVMOption(String name)

     Returns a VMOption object for a VM option of the given name.

     Returns:
         a VMOption object for a VM option of the given name.
     Throws:
         NullPointerException - if name is null.
         IllegalArgumentException - if a VM option of the given name 
does not exist.

Thanks,
Vladimir

On 10/22/14 6:46 AM, Tobias Hartmann wrote:
> Hi David,
>
> On 22.10.2014 14:33, David Holmes wrote:
>> On 22/10/2014 6:48 PM, Tobias Hartmann wrote:
>>> Hi David,
>>>
>>> On 22.10.2014 04:16, David Holmes wrote:
>>>> Hi Tobias,
>>>>
>>>> On 21/10/2014 11:08 PM, Tobias Hartmann wrote:
>>>>> Hi,
>>>>>
>>>>> please review the following patch.
>>>>>
>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8061443
>>>>> Webrev: http://cr.openjdk.java.net/~thartmann/8061443/webrev.00/
>>>>>
>>>>> Problem:
>>>>> The Whitebox API methods get*VMFlag() fail with develop/notproduct flags in
>>>>> product builds.
>>>>>
>>>>> Solution:
>>>>> The code is changed to invoke 'Flag::find_flag' with allow_locked=true and
>>>>> return_flag=true to return both locked and notproduct/develop flags. I also
>>>>> changed the JVM monitoring and management code 'jmm_GetVMGlobals()'.
>>>>
>>>> Why did you change the jmm code? You seemed to have changed its semantics -
>>>> which may require a CCC request.
>>>
>>> I changed the jmm code because the whitebox tests use a JMM call to verify the
>>> return value (see 'VmFlagTest<T>.getVMOptionAsString()').
>>>
>>> Do you think a CCC request is necessary here?
>>
>> Depends what the jmm code is supposed to return - I don't know the spec. But
>> changing the behaviour for the sake of a test without consideration of real
>> users is not something that should be done lightly.
>
> I agree. I filed a CCC request and attached the link to the bug.
>
> Thanks,
> Tobias
>
>>
>> David
>>
>>> Thanks,
>>> Tobias
>>>
>>>>
>>>> Thanks,
>>>> David
>>>>
>>>>> I adapted the existing tests to check for develop flags as well. I noticed that
>>>>> HotspotDiagnosticMXBean.getVMOption() fails with double flags and filed
>>>>> JDK-8061616 [1].
>>>>>
>>>>> Testing:
>>>>> - New testcases
>>>>> - JPRT
>>>>>
>>>>> Thanks,
>>>>> Tobias
>>>>>
>>>>>
>>>>> [1] https://bugs.openjdk.java.net/browse/JDK-8061616
>>>>>