RFR: 8345314: Add a red–black tree as a utility data structure [v10]

[Johan Sjölen]

On Thu, 9 Jan 2025 14:11:59 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 that 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.
>
> Casper Norrbin has updated the pull request incrementally with one additional commit since the last revision:
> 
>   chaged assert to EXPECTs in node tests

Could you add a comment saying that nodes are address stable?

src/hotspot/share/utilities/rbTree.hpp line 40:

> 38: // ALLOCATOR must check for oom and exit, as RBTree currently does not handle the
> 39: // allocation failing.
> 40: // Key needs to be of a type that is trivially destructable

destruct**i**ble

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PR Review: https://git.openjdk.org/jdk/pull/22360#pullrequestreview-2540125280
PR Review Comment: https://git.openjdk.org/jdk/pull/22360#discussion_r1908940840