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/*
* 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.BlockingQueue;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
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));
}
}
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