Fix Spliterator implementations for sorted collections #6188
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amalloy
added
package=collect
status=triaged
type=performance
kevinb9n
reviewed
Oct 18, 2022
| @@ -96,7 +96,7 @@ public int characteristics() { | |||
| @CheckForNull | |||
| public Comparator<? super T> getComparator() { | |||
| if (hasCharacteristics(Spliterator.SORTED)) { | |||
| return comparator; | |||
| return Ordering.natural().equals(comparator) ? null : comparator; | |||
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We should special-case Comparator.naturalOrder() too.
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Okay I've updated it to handle Comparator.naturalOrder() as well.
Spliterators returned by CollectSpliterators.indexed and ImmutableSortedSet.spliterator violated the Spliterator API by not returning null in getComparator when the source items are naturally sorted. The effect was that sort operations on Streams backed by these Spliterators were not optimized away, resulting in additional unnecessary sorting. Fixes google#6187.
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Spliterators returned by CollectSpliterators.indexed and ImmutableSortedSet.spliterator violated the Spliterator API by not returning null in getComparator when the source items are naturally sorted. The effect was that sort operations on Streams backed by these Spliterators were not optimized away, resulting in additional unnecessary sorting.
Fixes #6187.