RFR(S): 8194741: Refactor oops in constant pool from CDS to use the Access API

[Erik Österlund]

Hi Jiangli,

You are welcome. :)

/Erik

On 2018-01-10 20:54, Jiangli Zhou wrote:
> Hi Erik,
>
> Thanks a lot for the refactoring. I’m really glad that the G1 specific code for explicit enqueuing is no longer needed in shared code when an archived object becomes ‘in use’.
>
> Thanks,
> Jiangli
>
>> On Jan 10, 2018, at 6:29 AM, Erik Österlund <erik.osterlund at oracle.com> wrote:
>>
>> Hi,
>>
>> The constant pool may install resolved_references from CDS archives. This installation might happen during concurrent marking. Therefore, a new previously known graph is mounted onto the existing Java heap object graph. Naturally, this makes SATB invariants confused and therefore requires explicit enqueuing.
>>
>> This patch hooks this into the Access API. While there are different ways that this could be annotated, I chose to introduce a new decorator called IN_ARCHIVE_ROOT, which similar to IN_CONCURRENT_ROOT denotes a kind of special root that needs to be handled differently. In the G1 case, it results in a SATB enqueue when it is loaded. This approach made me scratch my head less than various other ideas I had.
>>
>> Webrev:
>> http://cr.openjdk.java.net/~eosterlund/8194741/webrev.00/
>>
>> Bug:
>> https://bugs.openjdk.java.net/browse/JDK-8194741
>>
>> /Erik