On Mon, 10 Aug 2026 20:01:24 GMT, Andy Goryachev <[email protected]> wrote:
>> this will only rebuild the style helper that needs it. And only the first
>> ancestor. I can't see how this could be a problem - do you have a unit test
>> in mind?
>> I tested several scenarios and could not spot any problem. Note that this is
>> a very rare case that usually only happens for the scenarios I implemented
>> as tests
>
> ok, so here is the test that passes in master and fails spectacularly with
> this PR:
>
>
> @Test
> void checkQuadraticPerformace() {
> scene.getStylesheets().add(toDataURL(
> """
> .old {
> -fx-padding: 1.0;
> }
> .new {
> -fx-padding: 99.0;
> }
> """));
>
> AtomicInteger counter = new AtomicInteger();
>
> class TPane extends Pane {
> public TPane(String style) {
> getStyleClass().add("style");
> }
>
> @Override
> public Styleable getStyleableParent() {
> counter.incrementAndGet();
> return super.getStyleableParent();
> }
> }
>
> int number = 16;
> ArrayList<TPane> chain = new ArrayList<>();
>
> TPane top = new TPane("old");
> chain.add(top);
>
> TPane p = top;
> for (int i = 1; i < number; i++) {
> TPane ch = new TPane("old");
> p.getChildren().add(ch);
> chain.add(ch);
> p = ch;
> }
>
> scene.setRoot(top);
> top.applyCss();
>
> counter.set(0);
> // mark the chain dirty
> p.getChildren().add(new Pane());
> int baseline = counter.get();
>
> for (TPane pane : chain) {
> pane.getStyleClass().setAll("new");
> }
>
> counter.set(0);
> // should not result in quadratic performance
> p.getChildren().add(new Pane());
> int newCount = counter.get();
>
> assertTrue(newCount <= baseline * 4, () -> {
> return MessageFormat.format("Baseline={0}, observed={1}",
> baseline, newCount);
> });
> }
Thanks, very helpful! I thought about it for a while, and did come up with
another implementation that I think is a bit more simple and the other hand
more optimized for that scenario.
Now I will collect all nodes just once and reuse that list to initialize all
stale `styleHelper`. That should be much more optimized and I actually think it
improved the code as well a little bit.
I first thought this may get much more complex, but it isn't IMO.
-------------
PR Review Comment: https://git.openjdk.org/jfx/pull/2225#discussion_r3950038048
