| /* |
| * Copyright (c) 2004, 2008, Oracle and/or its affiliates. All rights reserved. |
| * 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. |
| */ |
| |
| /* |
| * @test |
| * @bug 4992438 6633113 |
| * @summary Checks that fairness setting is respected. |
| */ |
| |
| import java.util.concurrent.*; |
| import java.util.concurrent.locks.*; |
| |
| public class Fairness { |
| private static void testFairness(boolean fair, |
| final BlockingQueue<Integer> q) |
| throws Throwable |
| { |
| final ReentrantLock lock = new ReentrantLock(); |
| final Condition ready = lock.newCondition(); |
| final int threadCount = 10; |
| final Throwable[] badness = new Throwable[1]; |
| lock.lock(); |
| for (int i = 0; i < threadCount; i++) { |
| final Integer I = i; |
| Thread t = new Thread() { public void run() { |
| try { |
| lock.lock(); |
| ready.signal(); |
| lock.unlock(); |
| q.put(I); |
| } catch (Throwable t) { badness[0] = t; }}}; |
| t.start(); |
| ready.await(); |
| // Probably unnecessary, but should be bullet-proof |
| while (t.getState() == Thread.State.RUNNABLE) |
| Thread.yield(); |
| } |
| for (int i = 0; i < threadCount; i++) { |
| int j = q.take(); |
| // Non-fair queues are lifo in our implementation |
| if (fair ? j != i : j != threadCount - 1 - i) |
| throw new Error(String.format("fair=%b i=%d j=%d%n", |
| fair, i, j)); |
| } |
| if (badness[0] != null) throw new Error(badness[0]); |
| } |
| |
| public static void main(String[] args) throws Throwable { |
| testFairness(false, new SynchronousQueue<Integer>()); |
| testFairness(false, new SynchronousQueue<Integer>(false)); |
| testFairness(true, new SynchronousQueue<Integer>(true)); |
| } |
| } |