/*
* org.openmicroscopy.shoola.util.concur.tasks.TestFutureSync
*
*------------------------------------------------------------------------------
* Copyright (C) 2006 University of Dundee. All rights reserved.
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* This program 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 for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
*------------------------------------------------------------------------------
*/
package org.openmicroscopy.shoola.util.concur.tasks;
//Java imports
//Third-party libraries
import junit.framework.TestCase;
//Application-internal dependencies
import org.openmicroscopy.shoola.util.concur.ControlFlowObserver;
import org.openmicroscopy.shoola.util.concur.ThreadSupport;
/**
* Verifies the safety of {@link Future}.
* We test that <code>getResult</code>, <code>setResult</code>, and
* <code>setException</code> calls are serialized in the presence of multiple
* threads acting on the object.
*
* @see org.openmicroscopy.shoola.util.concur.ThreadSupport
* @author Jean-Marie Burel
* <a href="mailto:j.burel@dundee.ac.uk">j.burel@dundee.ac.uk</a>
* @author <br>Andrea Falconi
* <a href="mailto:a.falconi@dundee.ac.uk">
* a.falconi@dundee.ac.uk</a>
* @version 2.2
* <small>
* (<b>Internal version:</b> $Revision$ $Date$)
* </small>
* @since OME2.2
*/
public class TestFutureSync
extends TestCase
{
private Future future; //Object to test.
private int fState; //To transfer value from alternate flow.
private ThreadSupport threads; //To manage main/alt flows.
public void setUp()
{
threads = new ThreadSupport(new Runnable() { //Alternate flow.
public void run() { fState = future.getState(); }
});
//NOTE: getState() is sync. So if it is called while get/set is being
//executed in the main thread, then the alternate thread will have
//to wait until the lock is released. This is enough to test safety,
//there's no need to use more than two threads and verify all
//possible combinations of getResult/setResult/setException.
future = new Future(); //Not in a legal state yet (two-step init).
future.setCommand(new MockExecCommand()); //OK, init completed now.
future.register(new ControlFlowObserver() {
public void update(int checkPointID)
{ //Called w/in main thread.
if (checkPointID == Future.LOCK_ACQUIRED) {
//get/set in progress. Spawn alt thread to retrieve state.
threads.startAltFlow(); //future.getState() will be called.
threads.pauseMainFlow();
//NOTE: Even though pausing the main flow doesn't guarantee
//that getState() will be invoked in the mean time, the
//2-second delay used should in practice make this extremely
//likely to happen.
}
}
});
//NOTE: If getState() gets executed b/f get/set modifies the state,
//then we would also get the wrong value for fState. In this case,
//we can deduce that locks were screwed up and thus fail the test.
//The test would be optimal if we could make sure that getState() is
//actually invoked while get/set is being executed (in practice this is
//quite sure though). In any case, pausing the main thread is the best
//we can do as there's no way to tell whether a thread is waiting to
//acquire a lock.
}
public void testSetResult()
{
future.setResult(null);
threads.awaitAltFlow();
assertEquals("Concurrent access to future state.",
Future.HAS_RESULT, fState);
}
public void testSetException()
{
future.setException(null);
threads.awaitAltFlow();
assertEquals("Concurrent access to future state.",
Future.HAS_EXCEPTION, fState);
}
public void testGetResult()
throws ExecException
{
//Keeps track of how many times update (see below) gets called.
//In fact, we have the following nested sequence: future.getResult ->
//observer.update -> future.setResult -> observer.update
final int[] updateCount = {0};
future.register(new ControlFlowObserver() {
public void update(int checkPointID)
{ //Called w/in main thread.
if (updateCount[0]++ != 0) return; //setResult, see below.
if (checkPointID == Future.LOCK_ACQUIRED) {
//getResult in progress. Spawn alt thread to retrieve state.
threads.startAltFlow(); //future.getState() will be called.
threads.pauseMainFlow();
//NOTE: Even though pausing the main flow doesn't guarantee
//that getState() will be invoked in the mean time, the
//2-second delay used should in practice make this extremely
//likely to happen.
future.setResult(null); //Change state.
}
}
});
try {
future.getResult();
} catch (InterruptedException ie) {
//OK, expected.
}
threads.awaitAltFlow();
assertEquals("Concurrent access to future state.",
Future.HAS_RESULT, fState);
}
}