@Override
                public void run() throws Exception {
                    // reinstall watch
                    exists(path, true);
                    try {
                        Object data = readData(path, null, true);
                        listener.handleDataChange(path, data);
                    } catch (ZkNoNodeException e) {
                        listener.handleDataDeleted(path);
                    }
                }
Counts number of children for the given path.

@param path
@return number of children or 0 if path does not exist.
shared/common/src/main/java/com/alibaba/otter/shared/common/utils/zookeeper/ZkClientx.java