On Mon, 24 May 2021 19:51:04 GMT, Paul Sandoz <psan...@openjdk.org> wrote:
>> Tagir F. Valeev has updated the pull request incrementally with one
>> additional commit since the last revision:
>>
>> Trailing whitespace removed
>
> src/java.base/share/classes/java/util/stream/AbstractPipeline.java line 471:
>
>> 469: int flags = getStreamAndOpFlags();
>> 470: long size = StreamOpFlag.SIZED.isKnown(flags) ?
>> spliterator.getExactSizeIfKnown() : -1;
>> 471: if (size != -1 && StreamOpFlag.SIZE_ADJUSTING.isKnown(flags) &&
>> !isParallel()) {
>
> Very nice. It's a good compromise to support only for sequential streams,
> since we have no size adjusting intermediate stateless op. If that was the
> case we would need to step back through the pipeline until the depth was
> zero, then step forward. I think it worth a comment here to inform our future
> selves if we ever add such an operation.
>
> Strictly speaking we only need to call `exactOutputSize` if the stage is size
> adjusting. Not sure it really matters perf-wise. If we leave as is maybe add
> a comment.
It's hard to imagine SIZE_ADJUSTING stateless intermediate op (probably the op
that duplicates every stream element like `flatMap(x -> Stream.of(x, x))` as a
single op?). Nevertheless, I added the comment. Please check if it's clear
enough. Thanks!
-------------
PR: https://git.openjdk.java.net/jdk/pull/3427
