/*
* org.openmicroscopy.shoola.util.concur.TestProducerLoopSync2
*
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* Copyright (C) 2006 University of Dundee. All rights reserved.
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package org.openmicroscopy.shoola.util.concur;
//Java imports
//Third-party libraries
import junit.framework.TestCase;
//Application-internal dependencies
/**
* Verifies the safety of {@link ProducerLoop}.
* We test that <code>doStep</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 TestProducerLoopSync2
extends TestCase
{
private static final int BUF_SZ = 10; //Both buffer size and payload.
private ProducerLoop target; //Object under test.
private int bytesWritten; //Transfers 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() { bytesWritten = target.getBytesWritten(); }
});
//NOTE: getBytesWritten() is sync. So if it is called while doStep 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 the sync methods of ProducerLoop.
AsyncByteBuffer buffer = new AsyncByteBuffer(BUF_SZ, BUF_SZ);
FakeByteBufferFiller producer =
new FakeByteBufferFiller(BUF_SZ, (byte) 1);
target = new ProducerLoop(buffer, producer);
target.register(new ControlFlowObserver() {
public void update(int checkPointID)
{ //Called w/in main thread.
if (checkPointID == ProducerLoop.LOCK_ACQUIRED) {
//doStep in progress. Spawn alt thread to retrieve
//target's bytesWritten field.
threads.startAltFlow(); //getBytesWritten() will be called.
threads.pauseMainFlow();
//NOTE: Even though pausing the main flow doesn't guarantee
//that getBytesWritten() will be invoked in the mean time,
//the 2-second delay used should in practice make this
//extremely likely to happen.
}
}
});
//NOTE: If getBytesWritten() gets executed b/f doStep() modifies the
//target's bytesWritten field, then we would also get the wrong value
//for our bytesWritten field. 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 getBytesWritten()
//is actually invoked while doStep() 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 testDoStep()
throws Exception
{
//Target's state is FILLING.
//This will call observer, which will spawn alt flow and pause
//main flow. As the main flow is paused, the alt flow will
//retrieve the target's bytesWritten field.
target.doStep();
//Wait for alt flow to join back so that its memory will be flushed
//and the state value it read will be available to the main flow.
threads.awaitAltFlow();
assertEquals("Concurrent access to target's state.",
BUF_SZ, bytesWritten);
}
}