RFR: 8345314: Add a red–black tree as a utility data structure

[Casper Norrbin]

On Mon, 25 Nov 2024 13:11:52 GMT, Casper Norrbin <cnorrbin at openjdk.org> wrote:

> Hi everyone,
> 
> This effort began as an exploration of replacing the current NMT treap with a red-black tree. Along the way, I discovered that others were also interested in having a general-purpose tree structure available within HotSpot.
> 
> The red-black tree is designed to serve as a drop-in replacement for the existing NMT treap, keeping a nearly identical interface. However, I’ve also added a few additional requested features, such as an iterator.
> 
> Testing builds off the treap tests, adding a few extra that inserts/removes and checks that the tree is correct. Testing uses the function `verify_self`, which iterates over the tree and checks att all red-black tree properties hold. Additionally, the tree has been tested in vmatree instead of the treap without any errors.
> 
> For those who may want to revisit the fundamentals of red-black trees, [Wikipedia](https://en.wikipedia.org/wiki/Red%E2%80%93black_tree) offers a great summary with tables covering the various balancing cases. Alternatively, your favorite data structure book could provide even more insight.

Thanks for the feedback 🙂 I've made the changes requested

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PR Comment: https://git.openjdk.org/jdk/pull/22360#issuecomment-2511872300