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 java.util.ArrayList;
36import java.util.Collection;
37import java.util.Comparator;
38import java.util.List;
39import java.util.Set;
40import java.util.concurrent.Callable;
41import java.util.concurrent.CompletionService;
42import java.util.concurrent.ExecutionException;
43import java.util.concurrent.Executor;
44import java.util.concurrent.ExecutorCompletionService;
45import java.util.concurrent.Future;
46
47import junit.framework.Test;
48import junit.framework.TestSuite;
49
50public class ExecutorCompletionService9Test extends JSR166TestCase {
51    public static void main(String[] args) {
52        main(suite(), args);
53    }
54    public static Test suite() {
55        return new TestSuite(ExecutorCompletionService9Test.class);
56    }
57
58    void solveAll(Executor e,
59                  Collection<Callable<Integer>> solvers)
60        throws InterruptedException, ExecutionException {
61        CompletionService<Integer> cs
62            = new ExecutorCompletionService<>(e);
63        solvers.forEach(cs::submit);
64        for (int i = solvers.size(); i > 0; i--) {
65            Integer r = cs.take().get();
66            if (r != null)
67                use(r);
68        }
69    }
70
71    void solveAny(Executor e,
72                  Collection<Callable<Integer>> solvers)
73        throws InterruptedException {
74        CompletionService<Integer> cs
75            = new ExecutorCompletionService<>(e);
76        int n = solvers.size();
77        List<Future<Integer>> futures = new ArrayList<>(n);
78        Integer result = null;
79        try {
80            solvers.forEach(solver -> futures.add(cs.submit(solver)));
81            for (int i = n; i > 0; i--) {
82                try {
83                    Integer r = cs.take().get();
84                    if (r != null) {
85                        result = r;
86                        break;
87                    }
88                } catch (ExecutionException ignore) {}
89            }
90        } finally {
91            futures.forEach(future -> future.cancel(true));
92        }
93
94        if (result != null)
95            use(result);
96    }
97
98    ArrayList<Integer> results;
99
100    void use(Integer x) {
101        if (results == null) results = new ArrayList<Integer>();
102        results.add(x);
103    }
104
105    /**
106     * The first "solvers" sample code in the class javadoc works.
107     */
108    public void testSolveAll()
109        throws InterruptedException, ExecutionException {
110        results = null;
111        Set<Callable<Integer>> solvers = Set.of(
112            () -> null,
113            () -> 1,
114            () -> 2,
115            () -> 3,
116            () -> null);
117        solveAll(cachedThreadPool, solvers);
118        results.sort(Comparator.naturalOrder());
119        assertEquals(List.of(1, 2, 3), results);
120    }
121
122    /**
123     * The second "solvers" sample code in the class javadoc works.
124     */
125    public void testSolveAny()
126        throws InterruptedException {
127        results = null;
128        Set<Callable<Integer>> solvers = Set.of(
129            () -> { throw new ArithmeticException(); },
130            () -> null,
131            () -> 1,
132            () -> 2);
133        solveAny(cachedThreadPool, solvers);
134        assertEquals(1, results.size());
135        Integer elt = results.get(0);
136        assertTrue(elt.equals(1) || elt.equals(2));
137    }
138
139}
140