private void actOnExists(final String path, final Runnable action) {
// Watch for node existence.
final AtomicBoolean nodeExists = new AtomicBoolean(false);
Futures.addCallback(
zkClient.exists(
path,
new Watcher() {
@Override
public void process(WatchedEvent event) {
if (!shouldProcessZKEvent()) {
return;
}
// When node is created, call the action.
// Other event type would be handled by the action.
if (event.getType() == Event.EventType.NodeCreated
&& nodeExists.compareAndSet(false, true)) {
action.run();
}
}
}),
new FutureCallback<Stat>() {
@Override
public void onSuccess(Stat result) {
if (result != null && nodeExists.compareAndSet(false, true)) {
action.run();
}
}
@Override
public void onFailure(Throwable t) {
LOG.error("Failed in exists call to {}. Shutting down service.", path, t);
forceShutDown();
}
},
Threads.SAME_THREAD_EXECUTOR);
}
