@Override
public void stopPublishing(String prop) {
trace(_log, "unregister: ", prop);
_zkChildWatcher.cancelWatch(prop);
_zkDataWatcher.cancelAllWatches();
}
@Override
public void startPublishing(String prop) {
trace(_log, "register: ", prop);
if (_eventBus == null) {
throw new IllegalStateException("_eventBus must not be null when publishing");
}
// Zookeeper callbacks (see the listener below) will be executed by the Zookeeper
// notification thread, in order. See:
// http://zookeeper.apache.org/doc/current/zookeeperProgrammers.html#Java+Binding
// This call occurs on a different thread, the PropertyEventBus callback thread.
//
// Publication to the event bus always occurs in the callback which is executed by the
// ZooKeeper notification thread. Since ZK guarantees the callbacks will be executed in
// the same order as the requests were made, we will never publish a stale value to the bus,
// even if there was a watch set on this property before this call to startPublishing().
_zkChildWatcher.addWatch(prop);
_zk.getChildren(getPath(prop), _zkChildWatcher, _zkChildWatcher, true);
}
