RFR: 8062247: Allow WhiteBox test to access JVM offsets

[Yumin Qi]

We have vmStructs, which define the data types for SA, FileMapHeaderInfo 
is not in it or we can use that for return offset info.
So we can have WhiteBox.java

static private int getOffSet(String name);

Better is: getOffsetName(String typeName, String memberName);

I will try to get a new version.

Thanks
Yumin



On 10/28/2014 11:21 AM, Christian Tornqvist wrote:
> I agree with Coleen, we shouldn't create and pass a Java hash table back. There has to be a better solution using native data structures.
>
> Thanks.
> Christian
>
> -----Original Message-----
> From: hotspot-runtime-dev [mailto:hotspot-runtime-dev-bounces at openjdk.java.net] On Behalf Of Coleen Phillimore
> Sent: Tuesday, October 28, 2014 2:10 PM
> To: hotspot-runtime-dev at openjdk.java.net
> Subject: Re: RFR: 8062247: Allow WhiteBox test to access JVM offsets
>
>
> Hi Yumin,
>
> Can you not create Java hashtables from C++?  This is really convoluted.  I think there may be a more direct way to encode these offsets and get their values.  Eg.  Have a WB API to
> get_offset("value")  and have a table coded in the WB api to associate the value string with the offset.  At worst, use a C++ hashtable to perform this association.
>
> Because the WB api calls up to Java for each hashtable insert, it's not like calling back to WB api for the offset is going to be less efficient.
>
> I don't like this change.
>
> Thanks,
> Coleen
>
> On 10/28/2014 12:01 AM, 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
>