@Override
public Subscription call(Observer<T> observer) {
if (started.compareAndSet(false, true)) {
AtomicObservableSubscription subscription = new AtomicObservableSubscription();
this.observer = new SynchronizedObserver<T>(observer, subscription);
/* start the Observers */
for (ZipObserver<T, ?> rw : observers) {
rw.startWatching();
}
return subscription.wrap(
new Subscription() {
@Override
public void unsubscribe() {
stop();
}
});
} else {
/* a Observer already has subscribed so blow up */
throw new IllegalStateException("Only one Observer can subscribe to this Observable.");
}
}
public void startWatching() {
if (subscribed.compareAndSet(false, true)) {
// only subscribe once even if called more than once
subscription.wrap(w.subscribe(this));
}
}