104 lines
3.8 KiB
Java
104 lines
3.8 KiB
Java
/*
|
|
* 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
|
|
* @modules java.base/java.util.concurrent:open
|
|
* @bug 4992438 6633113
|
|
* @summary Checks that fairness setting is respected.
|
|
*/
|
|
|
|
import java.lang.invoke.MethodHandles;
|
|
import java.lang.invoke.VarHandle;
|
|
import java.util.concurrent.BlockingQueue;
|
|
import java.util.concurrent.LinkedTransferQueue;
|
|
import java.util.concurrent.SynchronousQueue;
|
|
import java.util.concurrent.locks.Condition;
|
|
import java.util.concurrent.locks.ReentrantLock;
|
|
|
|
public class Fairness {
|
|
private final static VarHandle underlyingTransferQueueAccess;
|
|
|
|
static {
|
|
try {
|
|
underlyingTransferQueueAccess =
|
|
MethodHandles.privateLookupIn(
|
|
SynchronousQueue.class,
|
|
MethodHandles.lookup()
|
|
).findVarHandle(
|
|
SynchronousQueue.class,
|
|
"transferer",
|
|
Class.forName(SynchronousQueue.class.getName() + "$Transferer")
|
|
);
|
|
} catch (Exception ex) {
|
|
throw new ExceptionInInitializerError(ex);
|
|
}
|
|
}
|
|
|
|
|
|
private static void testFairness(boolean fair, final SynchronousQueue<Integer> q)
|
|
throws Throwable
|
|
{
|
|
final LinkedTransferQueue<Integer> underlying =
|
|
(LinkedTransferQueue<Integer>)underlyingTransferQueueAccess.get(q);
|
|
|
|
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();
|
|
// Wait until previous put:ing thread is provably parked
|
|
while (underlying.size() < (i + 1))
|
|
Thread.yield();
|
|
|
|
if (underlying.size() > (i + 1))
|
|
throw new Error("Unexpected number of waiting producers: " + i);
|
|
}
|
|
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<>());
|
|
testFairness(false, new SynchronousQueue<>(false));
|
|
testFairness(true, new SynchronousQueue<>(true));
|
|
}
|
|
}
|