/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.zookeeper;
import java.util.
ArrayList;
import java.util.
Deque;
import java.util.
LinkedList;
import java.util.
List;
import org.apache.zookeeper.
AsyncCallback.
VoidCallback;
import org.apache.zookeeper.common.
PathUtils;
import org.slf4j.
Logger;
import org.slf4j.
LoggerFactory;
public class
ZKUtil {
private static final
Logger LOG =
LoggerFactory.
getLogger(
ZKUtil.class);
/**
* Recursively delete the node with the given path.
* <p>
* Important: All versions, of all nodes, under the given node are deleted.
* <p>
* If there is an error with deleting one of the sub-nodes in the tree,
* this operation would abort and would be the responsibility of the app to handle the same.
*
* See {@link #delete(String, int)} for more details.
*
* @throws IllegalArgumentException if an invalid path is specified
*/
public static void
deleteRecursive(
ZooKeeper zk, final
String pathRoot)
throws
InterruptedException,
KeeperException
{
PathUtils.
validatePath(
pathRoot);
List<
String>
tree =
listSubTreeBFS(
zk,
pathRoot);
LOG.
debug("Deleting " +
tree);
LOG.
debug("Deleting " +
tree.
size() + " subnodes ");
for (int
i =
tree.
size() - 1;
i >= 0 ; --
i) {
//Delete the leaves first and eventually get rid of the root
zk.
delete(
tree.
get(
i), -1); //Delete all versions of the node with -1.
}
}
/**
* Recursively delete the node with the given path. (async version).
*
* <p>
* Important: All versions, of all nodes, under the given node are deleted.
* <p>
* If there is an error with deleting one of the sub-nodes in the tree,
* this operation would abort and would be the responsibility of the app to handle the same.
* <p>
* @param zk the zookeeper handle
* @param pathRoot the path to be deleted
* @param cb call back method
* @param ctx the context the callback method is called with
* @throws IllegalArgumentException if an invalid path is specified
*/
public static void
deleteRecursive(
ZooKeeper zk, final
String pathRoot,
VoidCallback cb,
Object ctx)
throws
InterruptedException,
KeeperException
{
PathUtils.
validatePath(
pathRoot);
List<
String>
tree =
listSubTreeBFS(
zk,
pathRoot);
LOG.
debug("Deleting " +
tree);
LOG.
debug("Deleting " +
tree.
size() + " subnodes ");
for (int
i =
tree.
size() - 1;
i >= 0 ; --
i) {
//Delete the leaves first and eventually get rid of the root
zk.
delete(
tree.
get(
i), -1,
cb,
ctx); //Delete all versions of the node with -1.
}
}
/**
* BFS Traversal of the system under pathRoot, with the entries in the list, in the
* same order as that of the traversal.
* <p>
* <b>Important:</b> This is <i>not an atomic snapshot</i> of the tree ever, but the
* state as it exists across multiple RPCs from zkClient to the ensemble.
* For practical purposes, it is suggested to bring the clients to the ensemble
* down (i.e. prevent writes to pathRoot) to 'simulate' a snapshot behavior.
*
* @param zk the zookeeper handle
* @param pathRoot The znode path, for which the entire subtree needs to be listed.
* @throws InterruptedException
* @throws KeeperException
*/
public static
List<
String>
listSubTreeBFS(
ZooKeeper zk, final
String pathRoot) throws
KeeperException,
InterruptedException {
Deque<
String>
queue = new
LinkedList<
String>();
List<
String>
tree = new
ArrayList<
String>();
queue.
add(
pathRoot);
tree.
add(
pathRoot);
while (true) {
String node =
queue.
pollFirst();
if (
node == null) {
break;
}
List<
String>
children =
zk.
getChildren(
node, false);
for (final
String child :
children) {
final
String childPath =
node + "/" +
child;
queue.
add(
childPath);
tree.
add(
childPath);
}
}
return
tree;
}
}