RFR: 8312132: Add tracking of multiple address spaces in NMT [v54]

[Gerard Ziemski]

On Tue, 30 Apr 2024 16:54:30 GMT, Gerard Ziemski <gziemski at openjdk.org> wrote:

>> Neither VMATree nor VirtualMemoryAreaTree are correct. VMATree has the advantage of brevity and the fact that its already ingrained in our brains, so we had conversations about it and at least one [concept document](https://gist.github.com/tstuefe/d9682b7f11b3375da27faa100f45e621) exists.
>> 
>> VirtualMemoryAreaTree OTOH is incorrect and unclear on several levels.
>> 
>> The tree is not a "MemoryTree" in its current form, since it tracks offsets into a file. And it's not "Virtual" by any stretch of the word. It would join the zoo of confusingly named classes like VirtualMemorySpace, which is neither more nor less Virtual than its parent class ReservedSpace.
>> 
>> If we rename it at all, I vote for IntervalTree. Because that's precisely what it is. It tracks intervals with attributes. And if templatized, we can reuse it for any kind of numerical region tracking and any kind of index types that we want.
>
> Googling for `IntervalTree` returns useful links. I like it.

If the class is general enough, then perhaps it should be moved into `shared/utilities` so others can use it as well? A candidate for a follow up later?

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PR Review Comment: https://git.openjdk.org/jdk/pull/18289#discussion_r1585221888