RFR: 8293920: G1: Add index based heap region iteration

[Kim Barrett]

On Fri, 16 Sep 2022 09:58:33 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> I was hoping that somehow there could be a solution with somewhat less code duplication (but also not overdoing with lots of additional boilerplate to make that possible), but I have no good idea either. Lgtm.

I thought about some ways to reduce the code duplication.  But maybe the solution in the long run is to transform uses of HeapRegionClosure into uses of HeapRegionIndexClosure?  There needs to be some convenient way to do the index->region lookup by the closures though.  Making each of them reimplement would not be good.  We can clean this up once we have a better idea of how many of each use-case we really have.

-------------

PR: https://git.openjdk.org/jdk/pull/10301