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/*
* Copyright (c) 2014, 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.
*
*/
package rtm;
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
/**
* To force transactional execution abort due to memory conflict
* one thread should access memory region from transactional region
* while another thread should modify the same memory region.
* Since this scenario is based on the race condition between threads
* you should not expect some particular amount of aborts.
*/
class MemoryConflictProvoker extends AbortProvoker {
// Following field have to be static in order to avoid escape analysis.
@SuppressWarnings("UnsuedDeclaration")
private static int field = 0;
private static final int INNER_ITERATIONS = 10000;
private final CyclicBarrier barrier;
/**
* This thread will access and modify memory region
* from outside of the transaction.
*/
private final Runnable conflictingThread;
public MemoryConflictProvoker() {
this(new Object());
}
public MemoryConflictProvoker(Object monitor) {
super(monitor);
barrier = new CyclicBarrier(2);
conflictingThread = () -> {
try {
barrier.await();
} catch (Exception e) {
throw new RuntimeException(e);
}
for (int i = 0; i < MemoryConflictProvoker.INNER_ITERATIONS; i++) {
MemoryConflictProvoker.field++;
}
};
}
/**
* Accesses and modifies memory region from within the transaction.
*/
public void transactionalRegion() {
for (int i = 0; i < MemoryConflictProvoker.INNER_ITERATIONS; i++) {
synchronized(monitor) {
MemoryConflictProvoker.field--;
}
}
}
@Override
public void forceAbort() {
try {
Thread t = new Thread(conflictingThread);
t.start();
try {
barrier.await();
} catch (InterruptedException | BrokenBarrierException e) {
throw new RuntimeException(e);
}
transactionalRegion();
t.join();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
@Override
public String getMethodWithLockName() {
return this.getClass().getName() + "::transactionalRegion";
}
}
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