contrib/registry/zookeeper: 服务多实例，会删除之前的注册信息

                        gsvc.SetRegistry(zookeeper.New(
				[]string{"127.0.0.1:2181"}, zookeeper.WithRootPath("/gogf"),
			))

			s := g.Server("hello.svc")

			s.BindHandler("/", func(r *ghttp.Request) {
				g.Log().Info(r.Context(), `request received`)
				r.Response.Write(`Hello world`)
			})

			s.Run()

// ensureName ensure node exists, if not exist, create and set data
func (r *Registry) ensureName(path string, data []byte, flags int32) error {
	exists, stat, err := r.conn.Exists(path)
	if err != nil {
		return gerror.Wrapf(err,
			"Error with check node exist which name is %s",
			path,
		)
	}
	// ephemeral nodes handling after restart
	// fixes a race condition if the server crashes without using CreateProtectedEphemeralSequential()
	if flags&zk.FlagEphemeral == zk.FlagEphemeral {
                // 此处会删除 原有server name对应的node节点
		err = r.conn.Delete(path, stat.Version)
		if err != nil && err != zk.ErrNoNode {
			return gerror.Wrapf(err,
				"Error with delete node which name is %s",
				path,
			)
		}
		exists = false
	}
	if !exists {
		if len(r.opts.user) > 0 && len(r.opts.password) > 0 {
			_, err = r.conn.Create(path, data, flags, zk.DigestACL(zk.PermAll, r.opts.user, r.opts.password))
		} else {
			_, err = r.conn.Create(path, data, flags, zk.WorldACL(zk.PermAll))
		}
		if err != nil {
			return gerror.Wrapf(err,
				"Error with create node which name is %s",
				path,
			)
		}
	}
	return nil
}