public void fire(
DependentSubjectListener subject, Integer event, DependentSubjectListener listener) {
// update the listener
boolean incremented = listener.latestRevision < event.intValue();
listener.latestRevision = event.intValue();
// make sure the listener's dependencies were notified first
listener.assertDependenciesSatisfiedRecursively(listener);
// send the event forward
if (incremented) {
listener.increment(0);
}
}
/**
* Dependencies are satisfied if the latestRevision is at least the latestRevision of all
* upstream {@link DependentSubjectListener}s.
*/
public void assertDependenciesSatisfiedRecursively(DependentSubjectListener notified) {
final Iterator<DependentSubjectListener> iter = upstreamSubjects.iterator();
while (iter.hasNext()) {
final DependentSubjectListener upstream = iter.next();
upstream.assertDependenciesSatisfiedRecursively(notified);
if (latestRevision < upstream.latestRevision)
throw new IllegalStateException(
"Dependencies not satisfied for "
+ notified
+ ", dependency "
+ this
+ " not updated by "
+ upstream
+ "!");
}
}