RFR: 8258252: Move PtrQueue enqueue to PtrQueueSet subclasses

[Kim Barrett]

On Tue, 15 Dec 2020 09:55:14 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> Please review this refactoring in the PtrQueue/PtrQueueSet hierarchy.
>> 
>> The functions PtrQueue::enqueue and PtrQueue::enqueue_known_active are
>> removed, along with the helper virtual function PtrQueue::handle_completed_buffer.
>> 
>> Instead we now have G1{Dirty,Redirty}CardQueueSet::enqueue and SATBMarkQueueSet::enqueue/enqueue_known_active, each tailored to the corresponding specific behavior. They use some shared helper routines from PtrQueueSet, and the PtrQueue buffer and index have been made accessible to clients.
>> 
>> Testing:
>> mach5 tier1-3, 5 (stress tests)
>> Local (linux-x64) tier1 with -XX:+UseShenandoahGC
>
> Lgtm.

Thanks @tschatzl and @rkennke for reviews, and @rkennke for additional Shenandoah testing.

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PR: https://git.openjdk.java.net/jdk/pull/1776