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

[Staffan Larsen]

I don’t agree that locked flags are the same as debug flags. Perhaps two queries? One for constant flags and one for locked flags?

/Staffan


On 23 okt 2014, at 12:02, Tobias Hartmann <Tobias.Hartmann at oracle.com> wrote:

> Hi Staffan,
> 
> On 23.10.2014 11:29, Staffan Larsen wrote:
>> This is better!
>> 
>> But won’t the new WB_IsDebugVMFlag() return true for flags that don’t exist at all? 
> 
> Of course, you are right. I fixed it and added a call to 'isDebugVMFlag' to
> 'VmFlagTest.testWriteNegative' to check that it always returns false for
> non-existing flags.
> 
> New webrev: http://cr.openjdk.java.net/~thartmann/8061443/webrev.02/
> 
> Thanks,
> Tobias
> 
>> 
>> /Staffan
>> 
>> 
>> On 23 okt 2014, at 10:57, Tobias Hartmann <Tobias.Hartmann at oracle.com
>> <mailto:Tobias.Hartmann at oracle.com>> wrote:
>> 
>>> Vladimir, David, Staffan,
>>> 
>>> thanks for the reviews.
>>> 
>>> On 23.10.2014 09:06, Staffan Larsen wrote:
>>>> 
>>>> On 23 okt 2014, at 04:35, David Holmes <david.holmes at oracle.com
>>>> <mailto:david.holmes at oracle.com>> wrote:
>>>> 
>>>>> On 23/10/2014 7:22 AM, Vladimir Kozlov wrote:
>>>>>> 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.
>>>>> 
>>>>> Perhaps, but conceptually develop flags are not part of a product build and
>>>>> by definition non-product flags are not part of a product build, so I think
>>>>> the existing jmm code is quite right to exclude them and the new code should
>>>>> do the same. It doesn't make sense to me to present someone with a list of
>>>>> flags that can't actually be used.
>>>> 
>>>> I agree with David here. Instead of changing the JMM API, you can add
>>>> functionality to the WhiteBox API to get the value of non-product flags.
>>> 
>>> I agree. I reverted the JMM changes and added a Whitebox API method
>>> 'isDebugVMFlag' to check whether a flag is debug/notproduct.
>>> 
>>> I changed the tests such that we only use JMM to verify the values returned by
>>> the Whitebox API if the flag is accessible (i.e. is not a debug/notproduct flag
>>> in a product build).
>>> 
>>> New webrev: http://cr.openjdk.java.net/~thartmann/8061443/webrev.01/
>>> 
>>> Thanks,
>>> Tobias
>>> 
>>>> /Staffan
>>>> 
>>>>> 
>>>>> Thanks,
>>>>> David
>>>>> 
>>>>>> 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
>>