/**
* Dependencies are satisfied if the latestRevision is at least the latestRevision of all
* upstream {@link DependentSubjectListener}s.
*/
public void assertDependenciesSatisfiedRecursively(DetachedSubject notified) {
final Iterator<DetachedSubject> iter = upstreamSubjects.iterator();
while (iter.hasNext()) {
final DetachedSubject upstream = iter.next();
upstream.assertDependenciesSatisfiedRecursively(notified);
if (latestRevision < upstream.latestRevision) {
throw new IllegalStateException(
"Dependencies not satisfied for "
+ notified
+ ", dependency "
+ this
+ " not updated by "
+ upstream
+ "!");
}
}
}
public void fire(DetachedSubject subject, Integer event, DetachedSubject.Listener listener) {
boolean changed = listener.subject.latestRevision < event.intValue();
// update the listener
listener.subject.latestRevision = event.intValue();
// make sure the listener's dependencies were notified first
listener.subject.assertDependenciesSatisfiedRecursively(listener.subject);
// send the event forward
if (changed) listener.subject.increment(0);
}
/**
* Test that listeners and subjects do not have to use the same identity so long as {@link
* ListEventPublisher#setRelatedSubject} is used.
*/
public void testRelatedSubjects() {
SequenceDependenciesEventPublisher publisher = new SequenceDependenciesEventPublisher();
DetachedSubject a = new DetachedSubject("A", publisher);
DetachedSubject b = new DetachedSubject("B", publisher);
DetachedSubject c = new DetachedSubject("C", publisher);
DetachedSubject d = new DetachedSubject("D", publisher);
DetachedSubject e = new DetachedSubject("E", publisher);
b.addListener(e);
a.addListener(b);
c.addListener(e);
a.addListener(c);
d.addListener(e);
a.addListener(d);
// changing a should impact e, but only after b, c, and d
a.increment(10);
assertEquals(10, a.latestRevision);
assertEquals(10, b.latestRevision);
assertEquals(10, c.latestRevision);
assertEquals(10, d.latestRevision);
assertEquals(10, e.latestRevision);
}