1 /*
2 * This file is part of *** M y C o R e ***
3 * See http://www.mycore.de/ for details.
4 *
5 * MyCoRe is free software: you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, either version 3 of the License, or
8 * (at your option) any later version.
9 *
10 * MyCoRe is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with MyCoRe. If not, see <http://www.gnu.org/licenses/>.
17 */
18
19 package org.mycore.util.concurrent;
20
21 import java.util.Comparator;
22 import java.util.concurrent.CompletableFuture;
23 import java.util.concurrent.PriorityBlockingQueue;
24 import java.util.concurrent.ThreadPoolExecutor;
25 import java.util.function.Supplier;
26
27 /**
28 * A {@link CompletableFuture} encapsulates a {@link Supplier} with an <code>AsyncSupply</code>.
29 * This make a {@link ThreadPoolExecutor} with a {@link PriorityBlockingQueue} useless. To
30 * regain the {@link Comparable} feature we have to unwrap the <code>AsyncSupply</code> and
31 * compare the original {@link Runnable}.
32 *
33 * <a href="http://stackoverflow.com/questions/34866757/how-do-i-use-completablefuture-supplyasync-together-with-priorityblockingqueue">stackoverflow</a>
34 *
35 * Note: this comparator imposes orderings that are inconsistent with equals.
36 *
37 * @author Matthias Eichner
38 */
39 public class MCRRunnableComperator implements Comparator<Runnable> {
40
41 @SuppressWarnings({ "unchecked", "rawtypes" })
42 @Override
43 public int compare(Runnable o1, Runnable o2) {
44 if (isComparable(o1, o2)) {
45 return ((Comparable) o1).compareTo(o2);
46 }
47 return -1;
48 }
49
50 private boolean isComparable(Runnable o1, Runnable o2) {
51 return o1 instanceof Comparable && o2 instanceof Comparable;
52 }
53
54 }