| /* |
| * Copyright 2016 Google, Inc. 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 |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| /* |
| * @test |
| * @bug 8146568 |
| * @summary brittle white box test of internal array management |
| * @modules java.base/java.util:open |
| * @run testng ArrayManagement |
| */ |
| |
| import java.lang.reflect.Field; |
| import java.util.AbstractList; |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.List; |
| import java.util.SplittableRandom; |
| |
| import org.testng.annotations.Test; |
| import static org.testng.Assert.*; |
| |
| public class ArrayManagement { |
| static final int DEFAULT_CAPACITY = 10; |
| static final Field ELEMENT_DATA; |
| static final Field MODCOUNT; |
| static final SplittableRandom rnd = new SplittableRandom(); |
| |
| static { |
| try { |
| ELEMENT_DATA = ArrayList.class.getDeclaredField("elementData"); |
| ELEMENT_DATA.setAccessible(true); |
| MODCOUNT = AbstractList.class.getDeclaredField("modCount"); |
| MODCOUNT.setAccessible(true); |
| } catch (ReflectiveOperationException huh) { |
| throw new AssertionError(huh); |
| } |
| } |
| |
| static Object[] elementData(ArrayList<?> list) { |
| try { |
| return (Object[]) ELEMENT_DATA.get(list); |
| } catch (ReflectiveOperationException huh) { |
| throw new AssertionError(huh); |
| } |
| } |
| |
| static int modCount(ArrayList<?> list) { |
| try { |
| return MODCOUNT.getInt(list); |
| } catch (ReflectiveOperationException huh) { |
| throw new AssertionError(huh); |
| } |
| } |
| |
| static int capacity(ArrayList<?> list) { |
| return elementData(list).length; |
| } |
| |
| static int newCapacity(int oldCapacity) { |
| return oldCapacity + (oldCapacity >> 1); |
| } |
| |
| static void ensureCapacity(ArrayList<Object> list, int capacity) { |
| int oldCapacity = capacity(list); |
| int oldModCount = modCount(list); |
| list.ensureCapacity(capacity); |
| assertTrue(capacity(list) >= capacity || capacity(list) == 0); |
| assertEquals(modCount(list), |
| (capacity(list) == oldCapacity) |
| ? oldModCount |
| : oldModCount + 1); |
| } |
| |
| static List<Object> singletonList() { |
| return Collections.singletonList(Boolean.TRUE); |
| } |
| |
| /** Opportunistically randomly test various add operations. */ |
| static void addOneElement(ArrayList<Object> list) { |
| int size = list.size(); |
| int modCount = modCount(list); |
| switch (rnd.nextInt(4)) { |
| case 0: assertTrue(list.add(Boolean.TRUE)); break; |
| case 1: list.add(size, Boolean.TRUE); break; |
| case 2: assertTrue(list.addAll(singletonList())); break; |
| case 3: assertTrue(list.addAll(size, singletonList())); break; |
| default: throw new AssertionError(); |
| } |
| assertEquals(modCount(list), modCount + 1); |
| assertEquals(list.size(), size + 1); |
| } |
| |
| @Test public void defaultCapacity() { |
| ArrayList<Object> list = new ArrayList<>(); |
| assertEquals(capacity(new ArrayList<Object>()), 0); |
| for (int i = 0; i < DEFAULT_CAPACITY; i++) { |
| addOneElement(list); |
| assertEquals(capacity(list), DEFAULT_CAPACITY); |
| } |
| addOneElement(list); |
| assertEquals(capacity(list), newCapacity(DEFAULT_CAPACITY)); |
| } |
| |
| @Test public void defaultCapacityEnsureCapacity() { |
| ArrayList<Object> list = new ArrayList<>(); |
| for (int i = 0; i <= DEFAULT_CAPACITY; i++) { |
| ensureCapacity(list, i); // no-op! |
| assertEquals(capacity(list), 0); |
| } |
| for (int i = 0; i < DEFAULT_CAPACITY; i++) { |
| addOneElement(list); |
| assertEquals(capacity(list), DEFAULT_CAPACITY); |
| } |
| addOneElement(list); |
| assertEquals(capacity(list), newCapacity(DEFAULT_CAPACITY)); |
| { |
| int capacity = capacity(list); |
| ensureCapacity(list, capacity + 1); |
| assertEquals(capacity(list), newCapacity(capacity)); |
| } |
| { |
| int capacity = capacity(list); |
| ensureCapacity(list, 3 * capacity); |
| assertEquals(capacity(list), 3 * capacity); |
| } |
| } |
| |
| @Test public void ensureCapacityBeyondDefaultCapacity() { |
| ArrayList<Object> list = new ArrayList<>(); |
| list.ensureCapacity(DEFAULT_CAPACITY + 1); |
| assertEquals(capacity(list), DEFAULT_CAPACITY + 1); |
| for (int i = 0; i < DEFAULT_CAPACITY + 1; i++) { |
| addOneElement(list); |
| assertEquals(capacity(list), DEFAULT_CAPACITY + 1); |
| } |
| addOneElement(list); |
| assertEquals(capacity(list), newCapacity(DEFAULT_CAPACITY + 1)); |
| } |
| |
| @Test public void explicitZeroCapacity() { |
| ArrayList<Object> list = new ArrayList<>(0); |
| assertEquals(capacity(list), 0); |
| addOneElement(list); |
| assertEquals(capacity(list), 1); |
| addOneElement(list); |
| assertEquals(capacity(list), 2); |
| addOneElement(list); |
| assertEquals(capacity(list), 3); |
| addOneElement(list); |
| assertEquals(capacity(list), 4); |
| addOneElement(list); |
| assertEquals(capacity(list), 6); |
| addOneElement(list); |
| assertEquals(capacity(list), 6); |
| addOneElement(list); |
| assertEquals(capacity(list), 9); |
| list.clear(); |
| assertEquals(capacity(list), 9); |
| } |
| |
| @Test public void explicitLargeCapacity() { |
| int n = DEFAULT_CAPACITY * 3; |
| ArrayList<Object> list = new ArrayList<>(n); |
| assertEquals(capacity(list), n); |
| ensureCapacity(list, 0); |
| ensureCapacity(list, n); |
| for (int i = 0; i < n; i++) addOneElement(list); |
| assertEquals(capacity(list), n); |
| |
| addOneElement(list); |
| assertEquals(capacity(list), newCapacity(n)); |
| } |
| |
| @Test public void emptyArraysAreShared() { |
| assertSame(elementData(new ArrayList<Object>()), |
| elementData(new ArrayList<Object>())); |
| assertSame(elementData(new ArrayList<Object>(0)), |
| elementData(new ArrayList<Object>(0))); |
| } |
| |
| @Test public void emptyArraysDifferBetweenDefaultAndExplicit() { |
| assertNotSame(elementData(new ArrayList<Object>()), |
| elementData(new ArrayList<Object>(0))); |
| } |
| |
| @Test public void negativeCapacity() { |
| for (int capacity : new int[] { -1, Integer.MIN_VALUE }) { |
| try { |
| new ArrayList<Object>(capacity); |
| fail("should throw"); |
| } catch (IllegalArgumentException success) {} |
| } |
| } |
| } |