RFR: 8062247: Allow WhiteBox test to access JVM offsets

[Mikhailo Seledtsov]

Yumin,

  OK, I see you chose to pass the name of the struct implicitly instead 
of using an explicit parameter. I have no strong objection to that.
Please make sure to clarify this in the comments.

Thank you,
Misha

On 11/3/2014 1:15 PM, Yumin Qi wrote:
> If you check the name passed to this function, it already told (I just 
> changed to getOffsetForName and in testing):
>
> wb.getOffsetForName("FileMapHeader::_crc")
>
> Do not need to give type info(that will need build a list for type 
> info like in vmStructs). This is a simple code fore testing purpose, I 
> think we should keep it simple. I added that if the offsetname not 
> supported, throw exception instead. Will post webrev today after jprt 
> finished.
>
> Thanks
> Yumin
>
> On 11/3/2014 12:05 PM, Mikhailo Seledtsov wrote:
>> Hi Yumin,
>>
>>  If this API is intended to get offsets for various data structures, 
>> I would expect a data  structure type identified to be passed as a 
>> parameter. For instance,
>>
>> public native int getOffset(String dataStructureId, String fieldName)
>>     where
>>         dataStructureId would be some kind of ID for data structure, 
>> either data structure name or internal alias
>>         fieldName - the name of the field for which the offset value 
>> is returned
>>       A specific error code could be returned for unsupported 
>> dataStructureId
>>
>> Alternatively, this could be an API specific to a given 
>> data-structure. E.g. getMySpecifiedDatastructOffset(String fieldName)
>>
>> Thank you,
>> Misha
>>
>>
>> On 11/2/2014 9:52 PM, Yumin Qi wrote:
>>> Misha,
>>>
>>>   It is a generic name, now it only targets on FileMapHeader, it can 
>>> add other data structure of vm if needed in future. Maybe a name 
>>> like getOffsetForName(String name) is better?
>>>
>>> Thanks
>>> Yumin
>>>
>>> On 10/31/2014 11:56 AM, Mikhailo Seledtsov wrote:
>>>> Hi Yumin,
>>>>
>>>>  The name getOffsets() seems too generic. Perhaps, we could rename 
>>>> it to be more specific to the task.
>>>>
>>>> Thank you,
>>>> Misha
>>>>
>>>> On 10/29/2014 5:46 PM, Yumin Qi wrote:
>>>>> Please review the new changeset at same location.
>>>>> New API supply an interface to get data member offset by it's name.
>>>>> http://cr.openjdk.java.net/~minqi/8062247/webrev00/
>>>>>
>>>>> Thanks
>>>>> Yumin
>>>>>
>>>>> On 10/27/2014 9:01 PM, Yumin Qi wrote:
>>>>>> Please review
>>>>>>
>>>>>> bug: https://bugs.openjdk.java.net/browse/JDK-8062247
>>>>>> webrev: http://cr.openjdk.java.net/~minqi/8062247/webrev00/
>>>>>>
>>>>>> Summary: Internal test failed since the variable offsets changed 
>>>>>> in hotspot. The way to get offset in the test is hard-coded. To 
>>>>>> reduce the risk of future changes of hotspot offsets, the fix add 
>>>>>> a WhiteBox API function to get a map for FileMapHeaderInfo, which 
>>>>>> return the members' offsets in a Hashtable.
>>>>>>
>>>>>> Tests: JPRT, jtreg.
>>>>>>
>>>>>> Thanks
>>>>>> Yumin
>>>>>
>>>>
>>>
>>
>