以树形结构存储了zookeeper中给所有的数据信息
ConcurrentHashMap<String,DataNode> nodes<br>WatchManager dataWatches 数据变更通知<br>WatchManager childWatches节点变更通知<br>String rootZookeeper 根节点<br>Map<Long,HashSet<String>>ephemerals 临时节点信息
注册中心时数据如何存储<br>
nodes key:path,value DataNode<br>ephemerals key:session value:path的集合(通过session找到路径)<br>HashMap<String,HashSet<Watcher>>watchTable<br>HashMap<Watcher,HashSet<String>>watch2Paths<br>