package org.apache.helix.manager.zk;
/*
* 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.
*/
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import org.apache.helix.store.zk.ZNode;
import org.apache.helix.util.HelixUtil;
import org.apache.zookeeper.data.Stat;
public abstract class Cache<T> {
final ReadWriteLock _lock;
final ConcurrentHashMap<String, ZNode> _cache;
public Cache() {
_lock = new ReentrantReadWriteLock();
_cache = new ConcurrentHashMap<String, ZNode>();
}
public void addToParentChildSet(String parentPath, String childName) {
ZNode znode = _cache.get(parentPath);
if (znode != null) {
znode.addChild(childName);
}
}
public void addToParentChildSet(String parentPath, List<String> childNames) {
if (childNames != null && !childNames.isEmpty()) {
ZNode znode = _cache.get(parentPath);
if (znode != null) {
znode.addChildren(childNames);
}
}
}
public void removeFromParentChildSet(String parentPath, String name) {
ZNode zNode = _cache.get(parentPath);
if (zNode != null) {
zNode.removeChild(name);
}
}
public boolean exists(String path) {
return _cache.containsKey(path);
}
public ZNode get(String path) {
try {
_lock.readLock().lock();
return _cache.get(path);
} finally {
_lock.readLock().unlock();
}
}
public void lockWrite() {
_lock.writeLock().lock();
}
public void unlockWrite() {
_lock.writeLock().unlock();
}
public void lockRead() {
_lock.readLock().lock();
}
public void unlockRead() {
_lock.readLock().unlock();
}
public void purgeRecursive(String path) {
try {
_lock.writeLock().lock();
String parentPath = HelixUtil.getZkParentPath(path);
String name = HelixUtil.getZkName(path);
removeFromParentChildSet(parentPath, name);
ZNode znode = _cache.remove(path);
if (znode != null) {
// recursively remove children nodes
Set<String> childNames = znode.getChildSet();
for (String childName : childNames) {
String childPath = path + "/" + childName;
purgeRecursive(childPath);
}
}
} finally {
_lock.writeLock().unlock();
}
}
public void reset() {
try {
_lock.writeLock().lock();
_cache.clear();
} finally {
_lock.writeLock().unlock();
}
}
public abstract void update(String path, T data, Stat stat);
public abstract void updateRecursive(String path);
// debug
public Map<String, ZNode> getCache() {
return _cache;
}
}