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/**
* 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.inspector.manager;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;
import org.apache.zookeeper.inspector.logger.LoggerFactory;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
public class NodesCache {
public static final int CACHE_SIZE = 40000;
public static final int EXPIRATION_TIME = 100;
private final LoadingCache<String, List<String>> nodes;
private ZooKeeper zooKeeper;
public NodesCache(ZooKeeper zooKeeper) {
this.zooKeeper = zooKeeper;
this.nodes = CacheBuilder.newBuilder()
.maximumSize(CACHE_SIZE)
.expireAfterWrite(EXPIRATION_TIME, TimeUnit.MILLISECONDS)
.build(
new CacheLoader<String, List<String>>() {
@Override
public List<String> load(String nodePath) throws Exception {
return getChildren(nodePath);
}
}
);
}
public List<String> getChildren(String nodePath) {
try {
Stat s = zooKeeper.exists(nodePath, false);
if (s != null) {
List<String> children = this.zooKeeper.getChildren(nodePath, false);
Collections.sort(children);
return children;
}
} catch (Exception e) {
LoggerFactory.getLogger().error(
"Error occurred retrieving child of node: " + nodePath, e
);
}
return null;
}
public String getNodeChild(String nodePath, int index) {
List<String> childNodes = null;
try {
childNodes = nodes.get(nodePath);
return childNodes.get(index);
} catch (ExecutionException e) {
LoggerFactory.getLogger().error(
"Error occurred retrieving child " + index + "of node: " + nodePath, e
);
}
return null;
}
}
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