RFR: 8258255: Move PtrQueue active flag to SATBMarkQueue [v2]

[Stefan Johansson]

On Thu, 17 Dec 2020 16:50:13 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Please review this change to the PtrQueue hierarchy, moving the support for
>> "active" queues and qset to SATBMarkQueue[Set], which is the only user of
>> this feature.  Other classes derived from PtrQueue[Set] currently work
>> around or ignore this feature.  This change removes it from consideration
>> entirely for those other classes.
>> 
>> Testing:
>> mach5 tier1
>> local (linux-x64) hotspot:tier1 with -XX:+UseShenandoahGC
>> 
>> In the process of doing this refactoring I noticed that some of the
>> vmStructs support around PtrQueue[Set] didn't get moved from G1 to shared,
>> and the G1 parts are incomplete.  Filed JDK-8258581 to address that.
>
> Kim Barrett has updated the pull request incrementally with one additional commit since the last revision:
> 
>   tschatzl review

Nice cleanup, look good.

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Marked as reviewed by sjohanss (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1820