| /* |
| * 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. |
| */ |
| |
| /* |
| * This file is available under and governed by the GNU General Public |
| * License version 2 only, as published by the Free Software Foundation. |
| * However, the following notice accompanied the original version of this |
| * file: |
| * |
| * Written by Doug Lea with assistance from members of JCP JSR-166 |
| * Expert Group and released to the public domain, as explained at |
| * http://creativecommons.org/publicdomain/zero/1.0/ |
| */ |
| |
| import java.util.concurrent.Executors; |
| import java.util.concurrent.ExecutorService; |
| import java.util.concurrent.Phaser; |
| import java.util.concurrent.ThreadLocalRandom; |
| import java.util.concurrent.atomic.LongAccumulator; |
| |
| import junit.framework.Test; |
| import junit.framework.TestSuite; |
| |
| public class LongAccumulatorTest extends JSR166TestCase { |
| public static void main(String[] args) { |
| main(suite(), args); |
| } |
| public static Test suite() { |
| return new TestSuite(LongAccumulatorTest.class); |
| } |
| |
| /** |
| * new instance initialized to supplied identity |
| */ |
| public void testConstructor() { |
| for (long identity : new long[] { Long.MIN_VALUE, 0, Long.MAX_VALUE }) |
| assertEquals(identity, |
| new LongAccumulator(Long::max, identity).get()); |
| } |
| |
| /** |
| * accumulate accumulates given value to current, and get returns current value |
| */ |
| public void testAccumulateAndGet() { |
| LongAccumulator acc = new LongAccumulator(Long::max, 0L); |
| acc.accumulate(2); |
| assertEquals(2, acc.get()); |
| acc.accumulate(-4); |
| assertEquals(2, acc.get()); |
| acc.accumulate(4); |
| assertEquals(4, acc.get()); |
| } |
| |
| /** |
| * reset() causes subsequent get() to return zero |
| */ |
| public void testReset() { |
| LongAccumulator acc = new LongAccumulator(Long::max, 0L); |
| acc.accumulate(2); |
| assertEquals(2, acc.get()); |
| acc.reset(); |
| assertEquals(0, acc.get()); |
| } |
| |
| /** |
| * getThenReset() returns current value; subsequent get() returns zero |
| */ |
| public void testGetThenReset() { |
| LongAccumulator acc = new LongAccumulator(Long::max, 0L); |
| acc.accumulate(2); |
| assertEquals(2, acc.get()); |
| assertEquals(2, acc.getThenReset()); |
| assertEquals(0, acc.get()); |
| } |
| |
| /** |
| * toString returns current value. |
| */ |
| public void testToString() { |
| LongAccumulator acc = new LongAccumulator(Long::max, 0L); |
| assertEquals("0", acc.toString()); |
| acc.accumulate(1); |
| assertEquals(Long.toString(1), acc.toString()); |
| } |
| |
| /** |
| * intValue returns current value. |
| */ |
| public void testIntValue() { |
| LongAccumulator acc = new LongAccumulator(Long::max, 0L); |
| assertEquals(0, acc.intValue()); |
| acc.accumulate(1); |
| assertEquals(1, acc.intValue()); |
| } |
| |
| /** |
| * longValue returns current value. |
| */ |
| public void testLongValue() { |
| LongAccumulator acc = new LongAccumulator(Long::max, 0L); |
| assertEquals(0, acc.longValue()); |
| acc.accumulate(1); |
| assertEquals(1, acc.longValue()); |
| } |
| |
| /** |
| * floatValue returns current value. |
| */ |
| public void testFloatValue() { |
| LongAccumulator acc = new LongAccumulator(Long::max, 0L); |
| assertEquals(0.0f, acc.floatValue()); |
| acc.accumulate(1); |
| assertEquals(1.0f, acc.floatValue()); |
| } |
| |
| /** |
| * doubleValue returns current value. |
| */ |
| public void testDoubleValue() { |
| LongAccumulator acc = new LongAccumulator(Long::max, 0L); |
| assertEquals(0.0, acc.doubleValue()); |
| acc.accumulate(1); |
| assertEquals(1.0, acc.doubleValue()); |
| } |
| |
| /** |
| * accumulates by multiple threads produce correct result |
| */ |
| public void testAccumulateAndGetMT() { |
| final LongAccumulator acc |
| = new LongAccumulator((x, y) -> x + y, 0L); |
| final int nThreads = ThreadLocalRandom.current().nextInt(1, 5); |
| final Phaser phaser = new Phaser(nThreads + 1); |
| final int incs = 1_000_000; |
| final long total = nThreads * incs/2L * (incs - 1); // Gauss |
| final Runnable task = () -> { |
| phaser.arriveAndAwaitAdvance(); |
| for (int i = 0; i < incs; i++) { |
| acc.accumulate((long) i); |
| assertTrue(acc.get() <= total); |
| } |
| phaser.arrive(); |
| }; |
| final ExecutorService p = Executors.newCachedThreadPool(); |
| try (PoolCleaner cleaner = cleaner(p)) { |
| for (int i = nThreads; i-->0; ) |
| p.execute(task); |
| phaser.arriveAndAwaitAdvance(); |
| phaser.arriveAndAwaitAdvance(); |
| assertEquals(total, acc.get()); |
| } |
| } |
| |
| } |