RFR: 8273626: G1: Factor out concurrent segmented array from G1CardSetAllocator [v4]

[Hamlin Li]

On Sat, 9 Oct 2021 03:53:35 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> To finish https://bugs.openjdk.java.net/browse/JDK-8254739, we need a segmented array to store a growing regions index array, in the initial version of that patch, a newly home made segmented array was used, but the memory efficiency is not as good as expected, G1CardSetAllocator is a potential candidate to fullfill the requirement, but need some enhancement.
>> 
>> This is a try to enhance G1CardSetAllocator(and G1CardSetBuffer, G1CardSetBufferList) to support element size less pointer size, and strip this basic function as a more generic segmented array (G1SegmentedArray).
>
> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
> 
>   refine code

Thanks Thomas for the detailed review, I have modified as suggested and file issues to track the later work.
https://bugs.openjdk.java.net/browse/JDK-8274988
https://bugs.openjdk.java.net/browse/JDK-8274987
https://bugs.openjdk.java.net/browse/JDK-8254739?focusedCommentId=14451862&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14451862

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PR: https://git.openjdk.java.net/jdk/pull/5478