| /* |
| * 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 and Martin Buchholz 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.CountedCompleter; |
| import java.util.concurrent.ThreadLocalRandom; |
| import java.util.concurrent.atomic.AtomicInteger; |
| import java.util.function.BiConsumer; |
| import java.util.function.Consumer; |
| |
| import junit.framework.Test; |
| import junit.framework.TestSuite; |
| |
| public class CountedCompleter8Test extends JSR166TestCase { |
| |
| public static void main(String[] args) { |
| main(suite(), args); |
| } |
| |
| public static Test suite() { |
| return new TestSuite(CountedCompleter8Test.class); |
| } |
| |
| /** CountedCompleter class javadoc code sample, version 1. */ |
| public static <E> void forEach1(E[] array, Consumer<E> action) { |
| class Task extends CountedCompleter<Void> { |
| final int lo, hi; |
| Task(Task parent, int lo, int hi) { |
| super(parent); this.lo = lo; this.hi = hi; |
| } |
| |
| public void compute() { |
| if (hi - lo >= 2) { |
| int mid = (lo + hi) >>> 1; |
| // must set pending count before fork |
| setPendingCount(2); |
| new Task(this, mid, hi).fork(); // right child |
| new Task(this, lo, mid).fork(); // left child |
| } |
| else if (hi > lo) |
| action.accept(array[lo]); |
| tryComplete(); |
| } |
| } |
| new Task(null, 0, array.length).invoke(); |
| } |
| |
| /** CountedCompleter class javadoc code sample, version 2. */ |
| public static <E> void forEach2(E[] array, Consumer<E> action) { |
| class Task extends CountedCompleter<Void> { |
| final int lo, hi; |
| Task(Task parent, int lo, int hi) { |
| super(parent); this.lo = lo; this.hi = hi; |
| } |
| |
| public void compute() { |
| if (hi - lo >= 2) { |
| int mid = (lo + hi) >>> 1; |
| setPendingCount(1); // looks off by one, but correct! |
| new Task(this, mid, hi).fork(); // right child |
| new Task(this, lo, mid).compute(); // direct invoke |
| } else { |
| if (hi > lo) |
| action.accept(array[lo]); |
| tryComplete(); |
| } |
| } |
| } |
| new Task(null, 0, array.length).invoke(); |
| } |
| |
| /** CountedCompleter class javadoc code sample, version 3. */ |
| public static <E> void forEach3(E[] array, Consumer<E> action) { |
| class Task extends CountedCompleter<Void> { |
| final int lo, hi; |
| Task(Task parent, int lo, int hi) { |
| super(parent); this.lo = lo; this.hi = hi; |
| } |
| |
| public void compute() { |
| int n = hi - lo; |
| for (; n >= 2; n /= 2) { |
| addToPendingCount(1); |
| new Task(this, lo + n/2, lo + n).fork(); |
| } |
| if (n > 0) |
| action.accept(array[lo]); |
| propagateCompletion(); |
| } |
| } |
| new Task(null, 0, array.length).invoke(); |
| } |
| |
| /** CountedCompleter class javadoc code sample, version 4. */ |
| public static <E> void forEach4(E[] array, Consumer<E> action) { |
| class Task extends CountedCompleter<Void> { |
| final int lo, hi; |
| Task(Task parent, int lo, int hi) { |
| super(parent, 31 - Integer.numberOfLeadingZeros(hi - lo)); |
| this.lo = lo; this.hi = hi; |
| } |
| |
| public void compute() { |
| for (int n = hi - lo; n >= 2; n /= 2) |
| new Task(this, lo + n/2, lo + n).fork(); |
| action.accept(array[lo]); |
| propagateCompletion(); |
| } |
| } |
| if (array.length > 0) |
| new Task(null, 0, array.length).invoke(); |
| } |
| |
| void testRecursiveDecomposition( |
| BiConsumer<Integer[], Consumer<Integer>> action) { |
| int n = ThreadLocalRandom.current().nextInt(8); |
| Integer[] a = new Integer[n]; |
| for (int i = 0; i < n; i++) a[i] = i + 1; |
| AtomicInteger ai = new AtomicInteger(0); |
| action.accept(a, ai::addAndGet); |
| assertEquals(n * (n + 1) / 2, ai.get()); |
| } |
| |
| /** |
| * Variants of divide-by-two recursive decomposition into leaf tasks, |
| * as described in the CountedCompleter class javadoc code samples |
| */ |
| public void testRecursiveDecomposition() { |
| testRecursiveDecomposition(CountedCompleter8Test::forEach1); |
| testRecursiveDecomposition(CountedCompleter8Test::forEach2); |
| testRecursiveDecomposition(CountedCompleter8Test::forEach3); |
| testRecursiveDecomposition(CountedCompleter8Test::forEach4); |
| } |
| |
| } |