On Fri, 24 Oct 2025 09:01:10 GMT, Per Minborg <[email protected]> wrote:
>> Implement JEP 526: Lazy Constants (Second Preview)
>>
>> The lazy list/map implementations are broken out from `ImmutableCollections`
>> to a separate class.
>>
>> The old benchmarks are not moved/renamed to allow comparison with previous
>> releases.
>>
>> `java.util.Optional` is updated so that its field is annotated with
>> `@Stable`. This is to allow `Optional` instances to be held in lazy
>> constants and still provide constant folding.
>
> Per Minborg has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Rework toString implementations
src/java.base/share/classes/java/lang/LazyConstant.java line 94:
> 92: * lazy constant remains uninitialized.
> 93: *
> 94: * <h2 id="composition">Composing lazy constants</h2>
This section has some interesting usage, but I don't believe it should be
included in the API specification. Behaviors described here can be derived from
the formal specifications.
src/java.base/share/classes/java/lang/LazyConstant.java line 209:
> 207:
> 208: /**
> 209: * {@return the contents of this lazy constant if initialized,
> otherwise,\
Suggestion:
* {@return the contents of this lazy constant if initialized, otherwise,
src/java.base/share/classes/java/util/AbstractMap.java line 34:
> 32:
> 33: import jdk.internal.vm.annotation.AOTSafeClassInitializer;
> 34: import jdk.internal.vm.annotation.Stable;
Suggestion:
src/java.base/share/classes/java/util/Currency.java line 146:
> 144: private static ConcurrentMap<String, Currency> instances = new
> ConcurrentHashMap<>(7);
> 145: private static final LazyConstant<HashSet<Currency>> available =
> 146: LazyConstant.of(new Supplier<HashSet<Currency>>() {
Why can't we retain the method reference here? This is not used in early
bootstrap.
src/java.base/share/classes/java/util/LazyCollections.java line 516:
> 514:
> 515: @ForceInline
> 516: private void disposeOfMutex(long offset) {
I recommend removing this unused and otherwise confusing method.
src/java.base/share/classes/java/util/LazyCollections.java line 559:
> 557: }
> 558:
> 559: public static <E> int lastIndexOf(List<LazyConstant<E>> list, Object
> o) {
This indexOf and lastIndexOf appear unused.
src/java.base/share/classes/java/util/Map.java line 1814:
> 1812: final Set<K> keyCopies = Set.copyOf(keys);
> 1813: Objects.requireNonNull(computingFunction);
> 1814: if (keys instanceof EnumSet<?> && !keys.isEmpty()) {
I wonder if it's premature for us to optimize like this - for example, this
would be wasteful if the key set contains one enum constant but there are 1000
enum constants in this enum.
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PR Review Comment: https://git.openjdk.org/jdk/pull/27605#discussion_r2496459406
PR Review Comment: https://git.openjdk.org/jdk/pull/27605#discussion_r2496468213
PR Review Comment: https://git.openjdk.org/jdk/pull/27605#discussion_r2496478562
PR Review Comment: https://git.openjdk.org/jdk/pull/27605#discussion_r2496479687
PR Review Comment: https://git.openjdk.org/jdk/pull/27605#discussion_r2496503928
PR Review Comment: https://git.openjdk.org/jdk/pull/27605#discussion_r2496514844
PR Review Comment: https://git.openjdk.org/jdk/pull/27605#discussion_r2496516750
