ZooKeeper watcher without loosing events

ZooInstall.java

	private void getConfigsFromZookeeper() throws IOException {
        logger.debug("Connected to Zookeeper");
        synchronized(lock) {
            try {
                configs = trackChildren(configs);
            } catch (Exception e) {
                logger.error("Error tracking Zookeeper config", e);
            }
        }
	}

	/*
	 * Tracks any new configs that has been added to ZooKeeper since the last start of this bundle. 
	 * The returned Map will contain these new configs in addition to the configs that are already being tracked.
	 */
	private Map<String,String> trackChildren(Map<String,String> oldConfigs) throws KeeperException, InterruptedException, IOException {
		Map<String,String> newConfigs = Collections.synchronizedMap( new HashMap<String,String>(oldConfigs) );
		List<String> children = children = zk.getChildren("/configs", true);
		for( String child : children ) {
			// if it is a new child node
			if( !newConfigs.containsKey(child) ) { 
				trackChild(newConfigs, "/configs/"+child );
			}
		}
		return newConfigs;
	}
	
	/*
	 * upon datachange event, get the new data & set watcher again
	 * upon nodedelete event, process has already deleted it from state, but watch it again in case it has been recreated before trackChildren set the watch again
	 * if the child node had been been processed, trackChildren will call this method to process it and watch it
	 */
	private void trackChild(Map<String,String> newConfigs, String path) throws KeeperException, InterruptedException, IOException {
		if( path == null ) return;
		try {
			byte[] data = zk.getData(path, true, null);
		        // do something
                        logger.debug("watching " + path );
		}catch(NoNodeException e){
			
		}
	}

	public void process(WatchedEvent event) {
			logger.debug( "ZK process event: " + event.getType() + " " + event.getPath() );
            if( event.getType() == Event.EventType.None ) {
                if( event.getState().ordinal() == 3 ) {
                    try {
                        getConfigsFromZookeeper();
                    } catch (IOException e) {
                        logger.error( "Failed download configurations from zookeeper", e );
                    }
                }
            }
			if( event.getType() == Event.EventType.NodeChildrenChanged ) {
				synchronized(lock) {
					try {
						logger.debug("about to track children");
						configs = trackChildren(configs);
						logger.debug("processed all children");
					} catch (Exception e) { }
				}
			}
			if( event.getType() == Event.EventType.NodeDataChanged ){
				synchronized(lock) {
					try {
						logger.debug("data change detected for " + event.getPath());
						trackChild(configs,event.getPath());
					} catch (Exception e) {
					}
				}
			}
			if( event.getType() == Event.EventType.NodeDeleted ) {
				String child = (event.getPath()==null) ? null : (new File(event.getPath())).getName();
				synchronized(lock) {
					try {
						logger.debug("node " + event.getPath() + " deleted");
						String pid = configs.remove(child);
						Configuration config = configAdmin.getConfiguration(pid);
						config.delete();
						trackChild(configs,event.getPath());
					} catch (Exception e) {
					}
				}
			}
	}