8155600: Performance optimization of Arrays.asList().iterator()
Reviewed-by: redestad, shade, plevart, attila
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jdk
@ -1,5 +1,5 @@
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/*
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* Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
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* Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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@ -4403,6 +4403,35 @@ public class Arrays {
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public void sort(Comparator<? super E> c) {
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Arrays.sort(a, c);
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}
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@Override
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public Iterator<E> iterator() {
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return new ArrayItr<>(a);
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}
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}
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private static class ArrayItr<E> implements Iterator<E> {
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private int cursor;
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private final E[] a;
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ArrayItr(E[] a) {
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this.a = a;
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}
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@Override
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public boolean hasNext() {
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return cursor < a.length;
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}
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@Override
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public E next() {
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int i = cursor;
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if (i >= a.length) {
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throw new NoSuchElementException();
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}
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cursor = i + 1;
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return a[i];
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}
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}
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/**
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93
jdk/test/java/util/Arrays/AsList.java
Normal file
93
jdk/test/java/util/Arrays/AsList.java
Normal file
@ -0,0 +1,93 @@
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/*
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* Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/**
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* @test
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* @bug 8155600
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* @summary Tests for Arrays.asList()
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* @run testng AsList
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*/
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import java.util.Arrays;
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import java.util.Iterator;
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import java.util.NoSuchElementException;
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import java.util.stream.IntStream;
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import org.testng.annotations.Test;
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import org.testng.annotations.DataProvider;
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import static org.testng.Assert.assertSame;
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import static org.testng.Assert.assertTrue;
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import static org.testng.Assert.assertFalse;
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import static org.testng.Assert.fail;
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public class AsList {
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/*
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* Iterator contract test
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*/
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@Test(dataProvider = "Arrays")
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public void testIterator(Object[] array) {
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Iterator<Object> itr = Arrays.asList(array).iterator();
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for (int i = 0; i < array.length; i++) {
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assertTrue(itr.hasNext());
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assertTrue(itr.hasNext()); // must be idempotent
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assertSame(array[i], itr.next());
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try {
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itr.remove();
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fail("Remove must throw");
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} catch (UnsupportedOperationException ex) {
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// expected
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}
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}
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assertFalse(itr.hasNext());
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for (int i = 0; i < 3; i++) {
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assertFalse(itr.hasNext());
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try {
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itr.next();
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fail("Next succeed when there's no data left");
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} catch (NoSuchElementException ex) {
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// expected
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}
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}
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}
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@DataProvider(name = "Arrays")
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public static Object[][] arrays() {
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Object[][] arrays = {
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{ new Object[] { } },
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{ new Object[] { 1 } },
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{ new Object[] { null } },
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{ new Object[] { null, 1 } },
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{ new Object[] { 1, null } },
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{ new Object[] { null, null } },
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{ new Object[] { null, 1, 2 } },
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{ new Object[] { 1, null, 2 } },
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{ new Object[] { 1, 2, null } },
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{ new Object[] { null, null, null } },
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{ new Object[] { 1, 2, 3, null, 4 } },
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{ new Object[] { "a", "a", "a", "a" } },
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{ IntStream.range(0, 100).boxed().toArray() }
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};
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return arrays;
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}
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}
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