RFR: 8311978: Create abstraction over heap metrics for heuristics [v8]

[Aleksey Shipilev]

On Thu, 20 Jul 2023 20:40:57 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> This change introduces a new interface `ShenandoahHeapStats`. Presently, the interface is implemented by `ShenandoahHeap`. The generational mode for Shenandoah will provide a new implementation of this interface `ShenandoahGeneration`.
>
> William Kemper has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove redundant include

The idea looks good.

But let me bikeshed a little: since this new class would be later implemented by `ShenandoahGeneration`, should it really be called `Shenandoah*Heap*Stats`? Looks more like `ShenandoahSpaceStats` or something like that?

Also, please change the synopsis for the bug to clearly state this is about Shenandoah: `8311978: Shenandoah: Create abstraction over heap metrics for heuristics`

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PR Review: https://git.openjdk.org/jdk/pull/14856#pullrequestreview-1540874912
PR Comment: https://git.openjdk.org/jdk/pull/14856#issuecomment-1645335691