Avoid resizing of fixed-size HashSet/LinkedHashSet variants
#32291
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| public static <E> LinkedHashSet<E> newLinkedHashSet(int expectedSize) { | ||
| return new LinkedHashSet<>(computeMapInitialCapacity(expectedSize), DEFAULT_LOAD_FACTOR); | ||
| } | ||
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| private static int computeMapInitialCapacity(int expectedSize) { |
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| private static int computeMapInitialCapacity(int expectedSize) { | |
| private static int computeInitialCapacity(int expectedSize) { |
Probably better to rename this method since it's now used for maps and sets.
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It sort of makes sense I guess since it ends up being backed by a Map.
True. I just thought the new name would require less cognitive overhead for anyone reading the code. Though, to be honest, it's an internal helper method. So it doesn't really matter.
In any case, thanks for making the change.
On a side note, I just learned that there's a new HashSet.newHashSet() factory method in Java 19. So thanks for that. 👍
Though we still have a Java 17 baseline.
sbrannen
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Add helpers to CollectionUtils for building HashSets and LinkedHashSets that can hold an expected number of elements without needing to resize / rehash.
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I also wanted to note that part of the reason for this PR is that I'd like to be able to rely on this helper in Spring projects that can't use the JDK19 helpers, and where we don't necessarily want to rely on Guava. |
| * @param expectedSize the expected number of elements (with a corresponding | ||
| * capacity to be derived so that no resize/rehash operations are needed) | ||
| * @see #newLinkedHashSet(int) | ||
| */ |
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In the future, please remember to add @since tags to newly introduced non-private` methods and to update the copyright headers of all affected files.
Though no need to do that for this PR: I'll take care of that when merging.
sbrannen
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HashSet/LinkedHashSet variants
Add helpers to CollectionUtils for building HashSets and LinkedHashSets that can hold an expected number of elements without needing to resize / rehash.
I also went ahead and updated places throughout the code base that appeared to be potentially sizing HashSet / LinkedHashSet incorrectly. This is by no means exhaustive.
See ff11467, where this was added for HashMap / LinkedHashMap.