RFR: 8351565: Implement JEP 502: Stable Values (Preview) [v56]

[Chen Liang]

On Fri, 18 Apr 2025 12:33:49 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Per Minborg has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Address comments on original vs underlying
>
> src/java.base/share/classes/java/lang/StableValue.java line 363:
> 
>> 361:  * The content of a stable value is guaranteed to be set at most once. If competing
>> 362:  * threads are racing to set a stable value, only one update succeeds, while other updates
>> 363:  * are blocked until the stable value becomes set.
> 
> I think it would be good to say here that the blocked updates will be discarded, or something to that effect. The current sentence can be interpreted as the blocked updates still taking place after the SV becomes set.

Indeed, something like "other updates will block and then observe the stable value is set"

> src/java.base/share/classes/java/lang/StableValue.java line 396:
> 
>> 394:  * stable value itself is stored in a {@code static final} field). Stable functions and
>> 395:  * collections are built on top of StableValue. As such, they are also treated as
>> 396:  * constants by the JVM.
> 
> This doesn't seem quite correct. stable collections aren't necessarily treated as constant, you need a constant reference, e.g. stored in a static final field. The contents can be treated as constant though.
> 
> Suggestion:
> 
>  * collections are built on top of StableValue. As such, their contents is also treated as
>  * constant by the JVM.

"their contents are"

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/23972#discussion_r2050775415
PR Review Comment: https://git.openjdk.org/jdk/pull/23972#discussion_r2050775808