RFR: 8062247: Allow WhiteBox test to access JVM offsets

[Mikhailo Seledtsov]

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
>>>
>>
>