76 lines
2.9 KiB
Java
76 lines
2.9 KiB
Java
/*
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* Copyright (c) 2004, 2008, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* @test
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* @bug 4992438 6633113
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* @summary Checks that fairness setting is respected.
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*/
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import java.util.concurrent.BlockingQueue;
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import java.util.concurrent.SynchronousQueue;
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import java.util.concurrent.locks.Condition;
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import java.util.concurrent.locks.ReentrantLock;
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public class Fairness {
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private static void testFairness(boolean fair,
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final BlockingQueue<Integer> q)
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throws Throwable
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{
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final ReentrantLock lock = new ReentrantLock();
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final Condition ready = lock.newCondition();
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final int threadCount = 10;
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final Throwable[] badness = new Throwable[1];
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lock.lock();
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for (int i = 0; i < threadCount; i++) {
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final Integer I = i;
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Thread t = new Thread() { public void run() {
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try {
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lock.lock();
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ready.signal();
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lock.unlock();
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q.put(I);
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} catch (Throwable t) { badness[0] = t; }}};
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t.start();
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ready.await();
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// Probably unnecessary, but should be bullet-proof
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while (t.getState() == Thread.State.RUNNABLE)
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Thread.yield();
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}
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for (int i = 0; i < threadCount; i++) {
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int j = q.take();
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// Non-fair queues are lifo in our implementation
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if (fair ? j != i : j != threadCount - 1 - i)
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throw new Error(String.format("fair=%b i=%d j=%d%n",
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fair, i, j));
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}
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if (badness[0] != null) throw new Error(badness[0]);
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}
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public static void main(String[] args) throws Throwable {
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testFairness(false, new SynchronousQueue<Integer>());
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testFairness(false, new SynchronousQueue<Integer>(false));
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testFairness(true, new SynchronousQueue<Integer>(true));
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}
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}
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