org.lable.oss.dynamicconfig.zookeeper.ZooKeeperHelper Maven / Gradle / Ivy
/*
* Copyright (C) 2015 Lable ([email protected])
*
* Licensed 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.lable.oss.dynamicconfig.zookeeper;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;
import java.util.ArrayList;
import java.util.List;
/**
* A collection of short hand static methods for common ZooKeeper operations.
*/
public class ZooKeeperHelper {
/**
* Recursively create empty znodes (if missing) analogous to {@code mkdir -p}.
*
* @param zookeeper ZooKeeper instance to work with.
* @param znode Path to create.
* @throws org.apache.zookeeper.KeeperException
* @throws InterruptedException
*/
static void mkdirp(ZooKeeper zookeeper, String znode) throws KeeperException, InterruptedException {
boolean createPath = false;
for (String path : pathParts(znode)) {
if (!createPath) {
Stat stat = zookeeper.exists(path, false);
if (stat == null) {
createPath = true;
}
}
if (createPath) {
create(zookeeper, path);
}
}
}
/**
* Create an empty normal (persistent) Znode.
*
* @param zookeeper ZooKeeper instance to work with.
* @param znode Znode to create.
* @throws KeeperException
* @throws InterruptedException
*/
static void create(ZooKeeper zookeeper, String znode) throws KeeperException, InterruptedException {
zookeeper.create(znode, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
/**
* Create a normal (persistent) Znode.
*
* @param zookeeper ZooKeeper instance to work with.
* @param znode Znode to create.
* @param value Znode contents.
* @throws KeeperException
* @throws InterruptedException
*/
static void create(ZooKeeper zookeeper, String znode, byte[] value) throws KeeperException, InterruptedException {
zookeeper.create(znode, value, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
/**
* Create an empty normal (persistent) Znode. If the znode already exists, do nothing.
*
* @param zookeeper ZooKeeper instance to work with.
* @param znode Znode to create.
* @throws KeeperException
* @throws InterruptedException
*/
static void createIfNotThere(ZooKeeper zookeeper, String znode) throws KeeperException, InterruptedException {
try {
create(zookeeper, znode);
} catch (KeeperException e) {
if (e.code() != KeeperException.Code.NODEEXISTS) {
// Rethrow all exceptions, except "node exists",
// because if the node exists, this method reached its goal.
throw e;
}
}
}
/**
* Parse a znode path, and return a list containing the full paths to its constituent directories.
*
* @param path Path to parse.
* @return List of paths.
*/
static List pathParts(String path) {
String[] pathParts = path.split("/");
List parts = new ArrayList<>(pathParts.length);
String pathSoFar = "";
for (String pathPart : pathParts) {
if (!pathPart.equals("")) {
pathSoFar += "/" + pathPart;
parts.add(pathSoFar);
}
}
return parts;
}
}