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/*
* 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);
}
}
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