426 lines
17 KiB
Java
426 lines
17 KiB
Java
/*
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* Copyright (c) 2012, 2013, 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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import org.testng.annotations.Test;
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import java.lang.reflect.Constructor;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.Iterator;
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import java.util.List;
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import java.util.ListIterator;
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import java.util.NoSuchElementException;
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import static org.testng.Assert.assertEquals;
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import static org.testng.Assert.assertFalse;
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import static org.testng.Assert.assertTrue;
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import static org.testng.Assert.fail;
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/**
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* @test
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* @run testng IteratorDefaults
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* @summary test extension methods on Iterator
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*/
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@Test
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public class IteratorDefaults {
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private static interface Callback {
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void call(List<Integer> list);
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}
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// call the callback for each recursive subList
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private void trimmedSubList(final List<Integer> list, final Callback callback) {
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int size = list.size();
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if (size > 1) {
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// trim 1 element from both ends
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final List<Integer> subList = list.subList(1, size - 1);
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callback.call(subList);
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trimmedSubList(subList, callback);
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}
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}
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public void testRemoveUnsupported() {
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final Iterator iterator = new Iterator() {
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@Override
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public boolean hasNext() {
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return false;
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}
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@Override
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public Object next() {
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return null;
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}
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};
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try {
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iterator.remove();
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fail("expected UnsupportedOperationException from remove not thrown");
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} catch (UnsupportedOperationException ignore) {
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}
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}
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public void testRemoveOverride() {
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final IteratorWithRemove iterator = new IteratorWithRemove();
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iterator.remove();
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assertTrue(iterator.removed);
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}
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public void testForEach() throws Exception {
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final Integer[] data = new Integer[1000];
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for (int i=0; i < data.length; i++) {
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data[i] = i;
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}
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final List<Integer> source = Arrays.asList(data);
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final String[] iterableCollectionClasses = {
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"java.util.ArrayDeque",
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"java.util.ArrayList",
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"java.util.HashSet",
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"java.util.LinkedHashSet",
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"java.util.LinkedList",
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"java.util.PriorityQueue",
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"java.util.TreeSet",
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"java.util.Vector",
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"java.util.concurrent.ConcurrentLinkedDeque",
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"java.util.concurrent.ConcurrentLinkedQueue",
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"java.util.concurrent.ConcurrentSkipListSet",
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"java.util.concurrent.CopyOnWriteArrayList",
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"java.util.concurrent.CopyOnWriteArraySet",
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"java.util.concurrent.LinkedBlockingDeque",
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"java.util.concurrent.LinkedBlockingQueue",
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"java.util.concurrent.LinkedTransferQueue",
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"java.util.concurrent.PriorityBlockingQueue"
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};
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for (final String iterableClass : iterableCollectionClasses) {
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final Iterable<Integer> iterable =
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(Iterable<Integer>) Class.forName(iterableClass).newInstance();
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((Collection<Integer>) iterable).addAll(source);
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final Iterator<Integer> iterator = iterable.iterator();
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final List<Integer> target = new ArrayList<>(source.size());
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iterator.forEachRemaining(target::add);
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if ("java.util.HashSet".equals(iterableClass)) {
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target.sort((x, y) -> x - y);
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assertEquals(target, source);
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} else {
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assertEquals(target, source);
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}
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// verify that for an iterator that has been advanced via next(),
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// forEach starts from the current location, not zero
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final int OFFSET = 5;
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final List<Integer> reference2 = new ArrayList<>(source).subList(OFFSET, source.size());
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final List<Integer> removed2 = new ArrayList<>(OFFSET);
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final Iterator<Integer> iterator2 = iterable.iterator();
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for (int i=0; i < OFFSET; i++) {
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// advance the iterator by OFFSET, saving iterated elements
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removed2.add(iterator2.next());
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}
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final List<Integer> target2 = new ArrayList<>(reference2.size());
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iterator2.forEachRemaining(target2::add);
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if ("java.util.HashSet".equals(iterableClass)) {
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assertEquals(target2.size(), reference2.size());
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target2.addAll(removed2);
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target2.sort((x, y) -> x - y);
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assertEquals(target2, source);
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assertEquals(target2.subList(OFFSET, source.size()), reference2);
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} else {
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assertEquals(target2, reference2);
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}
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}
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}
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public void testForEachSubList() throws Exception {
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final Integer[] data = new Integer[100];
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for (int i = 0; i < data.length; i++) {
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data[i] = i;
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}
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final List<Integer> source = Arrays.asList(data);
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final String[] listClasses = {
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"java.util.ArrayList",
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"java.util.LinkedList",
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"java.util.Vector",
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"java.util.concurrent.CopyOnWriteArrayList"
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};
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for (final String listClass : listClasses) {
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final List<Integer> list =
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(List<Integer>) Class.forName(listClass).newInstance();
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list.addAll(source);
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trimmedSubList(list, new Callback() {
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@Override
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public void call(final List<Integer> list) {
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if (list.size() < 1) {
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return;
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}
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final List<Integer> target = new ArrayList<>(list.size());
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final ListIterator<Integer> iterator = list.listIterator();
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assertTrue(iterator.hasNext());
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assertFalse(iterator.hasPrevious());
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assertEquals(iterator.nextIndex(), 0);
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assertEquals(iterator.previousIndex(), -1);
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iterator.forEachRemaining(target::add);
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assertEquals(target, list);
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assertFalse(iterator.hasNext());
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assertTrue(iterator.hasPrevious());
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assertEquals(iterator.nextIndex(), list.size());
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assertEquals(iterator.previousIndex(), list.size() - 1);
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try {
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iterator.next();
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fail(listClass + " iterator advanced beyond end");
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} catch (NoSuchElementException ignore) {
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}
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}
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});
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}
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}
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public void testOptimizedForEach() throws Exception {
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final Integer[] data = new Integer[1000 * 1000];
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for (int i=0; i < data.length; i++) {
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data[i] = i;
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}
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final List<Integer> source = Arrays.asList(data);
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final String[] listClasses = {
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"java.util.ArrayList",
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"java.util.LinkedList",
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"java.util.Vector",
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"java.util.concurrent.CopyOnWriteArrayList"
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};
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final int OFFSET = 3;
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final List<Integer> target = new ArrayList<>(source);
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for (final String listClass : listClasses) {
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final List<Integer> list =
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(List<Integer>) Class.forName(listClass).newInstance();
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list.addAll(source);
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final ListIterator<Integer> iterator = list.listIterator();
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assertFalse(iterator.hasPrevious());
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for (int i=0; i < OFFSET; i++) {
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iterator.next();
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}
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assertTrue(iterator.hasNext());
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assertTrue(iterator.hasPrevious());
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assertEquals(iterator.nextIndex(), OFFSET);
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assertEquals(iterator.previousIndex(), OFFSET - 1);
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iterator.forEachRemaining(e -> {
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target.set(e, e + 1);
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});
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for (int i=OFFSET; i < data.length; i++) {
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assertEquals(target.get(i).intValue(), source.get(i)+1);
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}
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assertFalse(iterator.hasNext());
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assertTrue(iterator.hasPrevious());
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assertEquals(iterator.nextIndex(), data.length);
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assertEquals(iterator.previousIndex(), data.length - 1);
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// CopyOnWriteArrayList.listIterator().remove() is unsupported
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if (!"java.util.concurrent.CopyOnWriteArrayList".equals(listClass)) {
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for (int i = data.length - 1; i >= 0; i--) {
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iterator.remove(); // must not throw
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if (i > 0) {
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iterator.previous();
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}
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}
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assertTrue(list.isEmpty());
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}
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try {
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iterator.next();
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fail(listClass + " iterator advanced beyond end");
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} catch (NoSuchElementException ignore) {
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}
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}
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}
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@Test(enabled = false)
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public void compareForEachPerformance() throws Exception {
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final Integer[] data = new Integer[1000 * 100];
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for (int i=0; i < data.length; i++) {
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data[i] = i;
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}
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final List<Integer> source = Arrays.asList(data);
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final String[] iterableCollectionClasses = {
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"java.util.ArrayList", // warmup, results discarded
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"java.util.ArrayDeque",
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"java.util.ArrayList",
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"java.util.HashSet",
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"java.util.LinkedHashSet",
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"java.util.LinkedList",
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"java.util.PriorityQueue",
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"java.util.TreeSet",
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"java.util.Vector",
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"java.util.concurrent.ConcurrentLinkedDeque",
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"java.util.concurrent.ConcurrentLinkedQueue",
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"java.util.concurrent.ConcurrentSkipListSet",
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"java.util.concurrent.CopyOnWriteArrayList",
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"java.util.concurrent.CopyOnWriteArraySet",
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"java.util.concurrent.LinkedBlockingDeque",
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"java.util.concurrent.LinkedBlockingQueue",
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"java.util.concurrent.LinkedTransferQueue",
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"java.util.concurrent.PriorityBlockingQueue"
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};
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boolean warmup = true;
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final int ITERATIONS = 10;
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final Integer[] target = new Integer[source.size()];
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for (final String iterableClass : iterableCollectionClasses) {
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final Class<? extends Collection<Integer>> type =
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(Class<? extends Collection<Integer>>) Class.forName(iterableClass);
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final Constructor<? extends Collection<Integer>> copyConstructor =
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type.getConstructor(Collection.class);
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final Iterable<Integer> iterable = copyConstructor.newInstance(source);
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final Iterable<Integer> reference =
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Collections.unmodifiableCollection((Collection<Integer>) iterable);
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for (int i=0; i < ITERATIONS; i++) {
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final Iterator<Integer> iterator = reference.iterator();
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final long forEachStart = System.nanoTime();
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iterator.forEachRemaining(x -> {target[x.intValue()] = x;});
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final long forEachEnd = System.nanoTime();
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final Iterator<Integer> iterator2 = reference.iterator();
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Integer x;
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final long iteratorStart = System.nanoTime();
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while (iterator2.hasNext()) {
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x = iterator2.next();
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target[x.intValue()] = x;
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}
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final long iteratorEnd = System.nanoTime();
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if (warmup) { continue; } // warmup, discard results
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final long forEachTime = forEachEnd - forEachStart;
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final long iteratorTime = iteratorEnd - iteratorStart;
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final long speedup = iteratorTime - forEachTime;
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System.out.print(iterableClass);
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System.out.print(" iterator: ");
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System.out.print(iteratorTime);
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System.out.print(", forEach: ");
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System.out.print(forEachTime);
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System.out.print(", speedup: ");
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System.out.print(speedup);
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System.out.print(" (");
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System.out.print((speedup * 100) / iteratorTime);
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System.out.print("%)\n");
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}
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if (warmup) { warmup = false; }
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System.out.println();
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}
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}
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@Test(enabled = false)
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public void compareSubListForEachPerformance() throws Exception {
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final Integer[] data = new Integer[1000 * 100];
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for (int i = 0; i < data.length; i++) {
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data[i] = i;
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}
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final List<Integer> source = Arrays.asList(data);
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final String[] listClasses = {
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"java.util.ArrayList", // warmup, results discarded
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"java.util.ArrayList",
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"java.util.LinkedList",
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"java.util.Vector",
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"java.util.concurrent.CopyOnWriteArrayList"
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};
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boolean warmup = true;
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final int ITERATIONS = 10;
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final Integer[] target = new Integer[source.size()];
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for (final String listClass : listClasses) {
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final Class<? extends List<Integer >> type =
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(Class<? extends List<Integer>>) Class.forName(listClass);
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final Constructor<? extends List<Integer >> copyConstructor =
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type.getConstructor(Collection.class);
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final List<Integer> iterable = copyConstructor.newInstance(source);
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final List<Integer> reference = Collections.unmodifiableList(iterable);
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for (int i = 0; i < ITERATIONS; i++) {
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final Iterator<Integer> iterator = reference.subList(42, reference.size() - 37).iterator();
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final long forEachStart = System.nanoTime();
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iterator.forEachRemaining(x -> {
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target[x.intValue()] = x;
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});
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final long forEachEnd = System.nanoTime();
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final Iterator<Integer> iterator2 = reference.iterator();
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Integer x;
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final long iteratorStart = System.nanoTime();
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while (iterator2.hasNext()) {
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x = iterator2.next();
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target[x.intValue()] = x;
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}
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final long iteratorEnd = System.nanoTime();
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if (warmup) { continue; } // warmup, discard results
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final long forEachTime = forEachEnd - forEachStart;
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final long iteratorTime = iteratorEnd - iteratorStart;
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final long speedup = iteratorTime - forEachTime;
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System.out.print(listClass);
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System.out.print(" iterator: ");
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System.out.print(iteratorTime);
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System.out.print(", forEach: ");
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System.out.print(forEachTime);
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System.out.print(", speedup: ");
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System.out.print(speedup);
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System.out.print(" (");
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System.out.print((speedup * 100) / iteratorTime);
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System.out.print("%)\n");
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}
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if (warmup) { warmup = false; }
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System.out.println();
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}
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}
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static class IteratorWithRemove implements Iterator {
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public boolean removed;
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IteratorWithRemove() {
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removed = false;
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}
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@Override
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public boolean hasNext() {
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return false;
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}
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@Override
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public Object next() {
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return null;
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}
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@Override
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public void remove() {
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removed = true;
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}
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}
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}
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