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8327858: Improve spliterator and forEach for single-element immutable collections

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Reviewed-by: smarks, vklang
This commit is contained in:
Chen Liang 2025-04-04 00:59:02 +00:00
parent a449aeef28
commit 1c2a5533f4
3 changed files with 126 additions and 2 deletions
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45
src/java.base/share/classes/java/util/ImmutableCollections.java
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@ -32,7 +32,9 @@ import java.io.ObjectOutputStream;
import java.io.ObjectStreamException;
import java.io.Serializable;
import java.lang.reflect.Array;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.UnaryOperator;
@ -656,6 +658,24 @@ class ImmutableCollections {
}
return array;
}
@Override
@SuppressWarnings("unchecked")
public void forEach(Consumer<? super E> action) {
action.accept(e0); // implicit null check
if (e1 != EMPTY) {
action.accept((E) e1);
}
}
@Override
public Spliterator<E> spliterator() {
if (e1 == EMPTY) {
return Collections.singletonSpliterator(e0);
} else {
return super.spliterator();
}
}
}
@jdk.internal.ValueBased
@ -895,6 +915,26 @@ class ImmutableCollections {
}
return array;
}
@Override
@SuppressWarnings("unchecked")
public void forEach(Consumer<? super E> action) {
if (e1 == EMPTY) {
action.accept(e0); // implicit null check
} else {
action.accept(REVERSE ? (E)e1 : e0); // implicit null check
action.accept(REVERSE ? e0 : (E)e1);
}
}
@Override
public Spliterator<E> spliterator() {
if (e1 == EMPTY) {
return Collections.singletonSpliterator(e0);
} else {
return super.spliterator();
}
}
}
@ -1158,6 +1198,11 @@ class ImmutableCollections {
public int hashCode() {
return k0.hashCode() ^ v0.hashCode();
}
@Override
public void forEach(BiConsumer<? super K, ? super V> action) {
action.accept(k0, v0); // implicit null check
}
}
/**

37
test/jdk/java/util/Collection/MOAT.java
View File

@ -26,7 +26,7 @@
* @bug 6207984 6272521 6192552 6269713 6197726 6260652 5073546 4137464
* 4155650 4216399 4294891 6282555 6318622 6355327 6383475 6420753
* 6431845 4802633 6570566 6570575 6570631 6570924 6691185 6691215
* 4802647 7123424 8024709 8193128
* 4802647 7123424 8024709 8193128 8327858
* @summary Run many tests on many Collection and Map implementations
* @author Martin Buchholz
* @modules java.base/java.util:open
@ -479,6 +479,8 @@ public class MOAT {
() -> c.removeAll(singleton(first)),
() -> c.retainAll(emptyList()));
}
testForEachMatch(c);
testSpliteratorMatch(c);
}
private static <T> void testImmutableSeqColl(final SequencedCollection<T> c, T t) {
@ -540,6 +542,39 @@ public class MOAT {
() -> c.retainAll(c));
}
// Ensures forEach supplies in the same order as the iterator
private static <T> void testForEachMatch(Collection<T> c) {
var itr = c.iterator();
int[] index = {0};
c.forEach(item -> {
T itrNext = null;
if (!itr.hasNext() || !Objects.equals(itrNext = itr.next(), item)) {
fail("forEach and iterator mismatch at " + index[0] + " forEach: " + item + ", itr: " + itrNext);
}
index[0]++;
});
if (itr.hasNext()) {
fail("forEach and iterator mismatch at tail, extras in itr");
}
}
// Ensures spliterator returns in the same order as the iterator
private static <T> void testSpliteratorMatch(Collection<T> c) {
var itr = c.iterator();
var split = c.spliterator();
int[] index = {0};
split.forEachRemaining(item -> {
T itrNext = null;
if (!itr.hasNext() || !Objects.equals(itrNext = itr.next(), item)) {
fail("iterator and spliterator mismatch at " + index[0] + " spliterator: " + item + ", itr: " + itrNext);
}
index[0]++;
});
if (itr.hasNext()) {
fail("iterator and spliterator mismatch at tail, extra item in itr");
}
}
/**
* Test that calling a mutator always throws UOE, even if the mutator
* wouldn't actually do anything on an empty collection.

46
test/micro/org/openjdk/bench/java/util/ImmutableColls.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2019, 2020, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2019, 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -297,6 +297,50 @@ public class ImmutableColls {
}
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public void forEachOverSet(Blackhole bh) {
forEachSet(bh, fs4);
forEachSet(bh, s1);
forEachSet(bh, s3);
forEachSet(bh, fs2);
forEachSet(bh, s0);
}
public void forEachSet(Blackhole bh, Set<String> coll) {
coll.forEach(bh::consume);
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public void iterateOverList(Blackhole bh) {
iterateList(bh, fl4);
iterateList(bh, fl1);
iterateList(bh, l3);
iterateList(bh, l0);
iterateList(bh, fl2);
}
public void iterateList(Blackhole bh, List<String> coll) {
for (String s : coll) {
bh.consume(s);
}
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public void forEachOverList(Blackhole bh) {
forEachList(bh, fl4);
forEachList(bh, fl1);
forEachList(bh, l3);
forEachList(bh, l0);
forEachList(bh, fl2);
}
public void forEachList(Blackhole bh, List<String> coll) {
coll.forEach(bh::consume);
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public void toArrayFromMap(Blackhole bh) {