RFR: 8349525: RBTree: provide leftmost, rightmost, and a simple way to print trees

[Thomas Stuefe]

On Thu, 6 Feb 2025 13:56:23 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> For things I currently work on (compilation memory statistic), I need this functionality.
>> 
>> Changes:
>> 
>> - added leftmost() and rightmost() (pretty self-explanatory)
>> - added print_on(outputStream*) (likewise)
>> - const correctness
>> - other minor cleanups
>> - gtests for all added functions
>> 
>> Tests: GHA (all clean), manual tests on Linux x64
>
> src/hotspot/share/utilities/rbTree.inline.hpp line 561:
> 
>> 559: void print_T(outputStream* st, T x) {
>> 560:   st->print(PTR_FORMAT, p2i(x));
>> 561: }
> 
> I've done something like this before but ended up not integrating it. Seems like this is something we should have in a generic place, in the future. Just a note, nothing to fix.

I agree

> src/hotspot/share/utilities/rbTree.inline.hpp line 568:
> 
>> 566:   st->sp(1 + depth * 2);
>> 567:   st->print("@" PTR_FORMAT ": [", p2i(n));
>> 568:   print_T<K>(st, n->key());
> 
> Do you need to provide the template parameter because key and val returns references? I would've assumed that C++ can infer the type and pick the right function.

More for expressiveness

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PR Review Comment: https://git.openjdk.org/jdk/pull/23486#discussion_r1946044334
PR Review Comment: https://git.openjdk.org/jdk/pull/23486#discussion_r1946044635