RFR: 8351565: Implement JEP 502: Stable Values (Preview) [v40]

[Per Minborg]

On Thu, 3 Apr 2025 14:20:42 GMT, Archie Cobbs <acobbs at openjdk.org> wrote:

>> Per Minborg has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Make the sqrt example different
>
> src/java.base/share/classes/java/lang/StableValue.java line 383:
> 
>> 381:  * (e.g. {@linkplain #trySet(Object) trySet()})
>> 382:  * {@linkplain java.util.concurrent##MemoryVisibility <em>happens-before</em>}
>> 383:  * any subsequent read operation (e.g. {@linkplain #orElseThrow()}) that is successful.
> 
> Is `isSet()` also considered to be a "read operation"? I would assume so, but that requires a bit of reading between the lines. Maybe `isSet()` could be added as another parenthetical example after `orElseThrow()` here to squash that particular ambiguity.

Very good observation. I will clarify this. Thanks!

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PR Review Comment: https://git.openjdk.org/jdk/pull/23972#discussion_r2028387857