RFR: 8342782: AWTEventMulticaster throws StackOverflowError using AquaButtonUI [v5]

[Laurent Bourgès]

On Sun, 24 Nov 2024 08:51:59 GMT, Laurent Bourgès <lbourges at openjdk.org> wrote:

>> @prrace : I added { .. }
>> 
>> @bourgesl : I'm struggling to define this as a constant in a helpful way. Is there an example of a similar constant somewhere in the codebase you could refer me to for comparison?
>> 
>> I think part of my challenge here is the AWTEventMulticaster doesn't promise to be any particular kind of tree. (For example: if it promised it was a self-balancing tree, then we'd know what our obligations were to meet that expectation.)
>> 
>> This PR's implementation is intended to be a fast heuristic/educated guess, but it does not scan the entire height of the left or right node. This makes it ... hard for me to name.
>> 
>> (Relatedly: the value 500 is arbitrary, and I'm happy to change it if someone would rather it be closer to 50 or 1000.)
>
> Here is a constant declaration (hotspot friendly):
> https://github.com/bourgesl/jdk-official/blob/d0b770c938be6b5b3a0176148265ef33184a9b8b/src/java.desktop/share/classes/sun/java2d/marlin/Renderer.java#L38
> 
> private static final int ALL_BUT_LSB = 0xFFFFFFFE;

'500 iterations' looks high, maybe 100?
It is a recursion ? You could try max recursion depth + 3 samples (first, middle, last) ?

Or this magic threshold could be tunable ac runtime using special static getter using a System property + default value, used by constant declaration (final static is mandatory):

https://github.com/bourgesl/jdk-official/blob/d0b770c938be6b5b3a0176148265ef33184a9b8b/src/java.desktop/share/classes/sun/java2d/marlin/MarlinProperties.java#L50

https://github.com/bourgesl/jdk-official/blob/d0b770c938be6b5b3a0176148265ef33184a9b8b/src/java.desktop/share/classes/sun/java2d/marlin/MarlinProperties.java#L303

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PR Review Comment: https://git.openjdk.org/jdk/pull/21962#discussion_r1855398578