1/*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 */
22
23/*
24 * This file is available under and governed by the GNU General Public
25 * License version 2 only, as published by the Free Software Foundation.
26 * However, the following notice accompanied the original version of this
27 * file:
28 *
29 * Written by Doug Lea and Martin Buchholz with assistance from
30 * members of JCP JSR-166 Expert Group and released to the public
31 * domain, as explained at
32 * http://creativecommons.org/publicdomain/zero/1.0/
33 */
34
35import static java.util.concurrent.TimeUnit.MILLISECONDS;
36import static java.util.concurrent.TimeUnit.SECONDS;
37
38import java.util.concurrent.CountedCompleter;
39import java.util.concurrent.ThreadLocalRandom;
40import java.util.concurrent.atomic.AtomicInteger;
41import java.util.function.BiConsumer;
42import java.util.function.Consumer;
43
44import junit.framework.Test;
45import junit.framework.TestSuite;
46
47public class CountedCompleter8Test extends JSR166TestCase {
48
49    public static void main(String[] args) {
50        main(suite(), args);
51    }
52
53    public static Test suite() {
54        return new TestSuite(CountedCompleter8Test.class);
55    }
56
57    /** CountedCompleter class javadoc code sample, version 1. */
58    public static <E> void forEach1(E[] array, Consumer<E> action) {
59        class Task extends CountedCompleter<Void> {
60            final int lo, hi;
61            Task(Task parent, int lo, int hi) {
62                super(parent); this.lo = lo; this.hi = hi;
63            }
64
65            public void compute() {
66                if (hi - lo >= 2) {
67                    int mid = (lo + hi) >>> 1;
68                    // must set pending count before fork
69                    setPendingCount(2);
70                    new Task(this, mid, hi).fork(); // right child
71                    new Task(this, lo, mid).fork(); // left child
72                }
73                else if (hi > lo)
74                    action.accept(array[lo]);
75                tryComplete();
76            }
77        }
78        new Task(null, 0, array.length).invoke();
79    }
80
81    /** CountedCompleter class javadoc code sample, version 2. */
82    public static <E> void forEach2(E[] array, Consumer<E> action) {
83        class Task extends CountedCompleter<Void> {
84            final int lo, hi;
85            Task(Task parent, int lo, int hi) {
86                super(parent); this.lo = lo; this.hi = hi;
87            }
88
89            public void compute() {
90                if (hi - lo >= 2) {
91                    int mid = (lo + hi) >>> 1;
92                    setPendingCount(1); // looks off by one, but correct!
93                    new Task(this, mid, hi).fork(); // right child
94                    new Task(this, lo, mid).compute(); // direct invoke
95                } else {
96                    if (hi > lo)
97                        action.accept(array[lo]);
98                    tryComplete();
99                }
100            }
101        }
102        new Task(null, 0, array.length).invoke();
103    }
104
105    /** CountedCompleter class javadoc code sample, version 3. */
106    public static <E> void forEach3(E[] array, Consumer<E> action) {
107        class Task extends CountedCompleter<Void> {
108            final int lo, hi;
109            Task(Task parent, int lo, int hi) {
110                super(parent); this.lo = lo; this.hi = hi;
111            }
112
113            public void compute() {
114                int n = hi - lo;
115                for (; n >= 2; n /= 2) {
116                    addToPendingCount(1);
117                    new Task(this, lo + n/2, lo + n).fork();
118                }
119                if (n > 0)
120                    action.accept(array[lo]);
121                propagateCompletion();
122            }
123        }
124        new Task(null, 0, array.length).invoke();
125    }
126
127    /** CountedCompleter class javadoc code sample, version 4. */
128    public static <E> void forEach4(E[] array, Consumer<E> action) {
129        class Task extends CountedCompleter<Void> {
130            final int lo, hi;
131            Task(Task parent, int lo, int hi) {
132                super(parent, 31 - Integer.numberOfLeadingZeros(hi - lo));
133                this.lo = lo; this.hi = hi;
134            }
135
136            public void compute() {
137                for (int n = hi - lo; n >= 2; n /= 2)
138                    new Task(this, lo + n/2, lo + n).fork();
139                action.accept(array[lo]);
140                propagateCompletion();
141            }
142        }
143        if (array.length > 0)
144            new Task(null, 0, array.length).invoke();
145    }
146
147    void testRecursiveDecomposition(
148        BiConsumer<Integer[], Consumer<Integer>> action) {
149        int n = ThreadLocalRandom.current().nextInt(8);
150        Integer[] a = new Integer[n];
151        for (int i = 0; i < n; i++) a[i] = i + 1;
152        AtomicInteger ai = new AtomicInteger(0);
153        action.accept(a, ai::addAndGet);
154        assertEquals(n * (n + 1) / 2, ai.get());
155    }
156
157    /**
158     * Variants of divide-by-two recursive decomposition into leaf tasks,
159     * as described in the CountedCompleter class javadoc code samples
160     */
161    public void testRecursiveDecomposition() {
162        testRecursiveDecomposition(CountedCompleter8Test::forEach1);
163        testRecursiveDecomposition(CountedCompleter8Test::forEach2);
164        testRecursiveDecomposition(CountedCompleter8Test::forEach3);
165        testRecursiveDecomposition(CountedCompleter8Test::forEach4);
166    }
167
168}
169