RFR: 8327858: Improve spliterator and forEach for single-element immutable collections [v2]
Viktor Klang
vklang at openjdk.org
Thu Mar 21 20:12:22 UTC 2024
On Thu, 21 Mar 2024 18:01:38 GMT, Chen Liang <liach at openjdk.org> wrote:
>> Please review this patch that:
>> 1. Implemented `forEach` to optimize for 1 or 2 element collections.
>> 2. Implemented `spliterator` to optimize for a single element.
>>
>> The default implementations for multiple-element immutable collections are fine as-is, specializing implementation doesn't provide much benefit.
>
> Chen Liang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 13 commits:
>
> - Use the improved form in forEach
> - Merge branch 'master' of https://github.com/openjdk/jdk into feature/imm-coll-stream
> - Null checks should probably be in the beginning...
> - mark implicit null checks
> - Merge branch 'master' of https://github.com/openjdk/jdk into feature/imm-coll-stream
> - Copyright year, revert changes for non-few element collections
> - Merge branch 'master' of https://github.com/openjdk/jdk into feature/imm-coll-stream
> - Merge branch 'feature/imm-coll-stream' of https://github.com/liachmodded/jdk into feature/imm-coll-stream
> - Spliterator for 12, iterate/forEach benchmark
> - fix comments
> - ... and 3 more: https://git.openjdk.org/jdk/compare/d5b95a0e...69bd0e9c
src/java.base/share/classes/java/util/ImmutableCollections.java line 924:
> 922: action.accept(REVERSE ? (E)e1 : e0); // implicit null check
> 923: action.accept(REVERSE ? e0 : (E)e1);
> 924: }
Out of curiosity, how does the following fare performance-wise?
Suggestion:
action.accept((!REVERSE || e1 == EMPTY) ? e0 : (E)e1); // implicit null check
if (e1 != EMPTY)
action.accept(!REVERSE ? (E)e1 : e0);
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/15834#discussion_r1534612528
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