@Test
public void testEnsureTaskIsSubmittedIfPreReqsCompleteWhileDependencyQueued() throws Exception {
m_coordinator.setLoopDelay(1000);
/**
* This is a test case that tests a very specific race condition. The loopDelay is used to make
* the race condition work
*/
// use latches so the finishing can be managed
CountDownLatch aBlocker = new CountDownLatch(1);
CountDownLatch bBlocker = new CountDownLatch(1);
CountDownLatch cBlocker = new CountDownLatch(0); // we don't care when c finishes
// create the tasks and a simple prerequisite and schedule
Task a = createTask(waiter("A", aBlocker));
Task b = createTask(waiter("B", bBlocker));
Task c = createTask(waiter("C", cBlocker));
c.addPrerequisite(a);
b.schedule();
a.schedule();
c.schedule();
// wait for the coordinator thread to process all of the above
Thread.sleep(3500);
/* we are not trying to set up the following situation
* c has 1 'pendingPrereq'
* the coordinator threads Q has 'a.complete, b.complete, c.addPrereq(b)'
*
* In this situation then the completing tasks will not be able to submit
* 'c' because it has a pending prerequisite.
*
* By the time the prerequisite is added they are all complete.
*
* In this case we need to ensure the c is submitted
*/
// Because of the loopDelay.. this following will all sit on the queue
// call countDown will allow these to complete
bBlocker.countDown();
aBlocker.countDown();
// we wait just to a litlte to make sure the two completes get added
Thread.sleep(100);
// not we add the prerequisite
c.addPrerequisite(b);
c.waitFor(10000, TimeUnit.MILLISECONDS);
assertTrue("Task C never completed", c.isFinished());
/*
* If the queue call look this AFTER the call to c.addPrerequisite(b) increment pendingPrereqs
* Q: a.complete, (pendingPrereq non zero) b.complete (pendingPrereq non zero) c.prereq(b) (decrementPrereqs) .....
*/
}
final void doAddPrerequisite(final Task prereq) {
if (!prereq.isFinished()) {
m_prerequisites.add(prereq);
notifyPrerequisteAdded(prereq);
}
}