fixed compilation problems in akka-cluster
This commit is contained in:
Jonas Bonér
parent
fb008632cb
commit
2b1332e220
27 changed files with 490 additions and 2936 deletions
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/**
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package akka.cluster.zookeeper;
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import java.util.List;
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import java.util.NoSuchElementException;
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import java.util.TreeMap;
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import java.util.concurrent.CountDownLatch;
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import org.apache.log4j.Logger;
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import org.apache.zookeeper.CreateMode;
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import org.apache.zookeeper.KeeperException;
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import org.apache.zookeeper.WatchedEvent;
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import org.apache.zookeeper.Watcher;
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import org.apache.zookeeper.ZooDefs;
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import org.apache.zookeeper.ZooKeeper;
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import org.apache.zookeeper.data.ACL;
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import org.apache.zookeeper.data.Stat;
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/**
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*
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* A <a href="package.html">protocol to implement a distributed queue</a>.
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*
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*/
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public class DistributedQueue {
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private static final Logger LOG = Logger.getLogger(DistributedQueue.class);
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private final String dir;
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private ZooKeeper zookeeper;
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private List<ACL> acl = ZooDefs.Ids.OPEN_ACL_UNSAFE;
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private final String prefix = "qn-";
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public DistributedQueue(ZooKeeper zookeeper, String dir, List<ACL> acl){
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this.dir = dir;
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if(acl != null){
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this.acl = acl;
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}
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this.zookeeper = zookeeper;
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}
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/**
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* Returns a Map of the children, ordered by id.
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* @param watcher optional watcher on getChildren() operation.
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* @return map from id to child name for all children
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*/
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private TreeMap<Long,String> orderedChildren(Watcher watcher) throws KeeperException, InterruptedException {
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TreeMap<Long,String> orderedChildren = new TreeMap<Long,String>();
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List<String> childNames = null;
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try{
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childNames = zookeeper.getChildren(dir, watcher);
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}catch (KeeperException.NoNodeException e){
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throw e;
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}
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for(String childName : childNames){
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try{
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//Check format
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if(!childName.regionMatches(0, prefix, 0, prefix.length())){
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LOG.warn("Found child node with improper name: " + childName);
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continue;
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}
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String suffix = childName.substring(prefix.length());
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Long childId = new Long(suffix);
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orderedChildren.put(childId,childName);
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}catch(NumberFormatException e){
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LOG.warn("Found child node with improper format : " + childName + " " + e,e);
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}
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}
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return orderedChildren;
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}
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/**
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* Find the smallest child node.
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* @return The name of the smallest child node.
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*/
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private String smallestChildName() throws KeeperException, InterruptedException {
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long minId = Long.MAX_VALUE;
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String minName = "";
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List<String> childNames = null;
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try{
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childNames = zookeeper.getChildren(dir, false);
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}catch(KeeperException.NoNodeException e){
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LOG.warn("Caught: " +e,e);
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return null;
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}
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for(String childName : childNames){
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try{
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//Check format
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if(!childName.regionMatches(0, prefix, 0, prefix.length())){
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LOG.warn("Found child node with improper name: " + childName);
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continue;
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}
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String suffix = childName.substring(prefix.length());
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long childId = Long.parseLong(suffix);
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if(childId < minId){
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minId = childId;
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minName = childName;
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}
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}catch(NumberFormatException e){
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LOG.warn("Found child node with improper format : " + childName + " " + e,e);
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}
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}
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if(minId < Long.MAX_VALUE){
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return minName;
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}else{
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return null;
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}
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}
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/**
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* Return the head of the queue without modifying the queue.
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* @return the data at the head of the queue.
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* @throws NoSuchElementException
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* @throws KeeperException
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* @throws InterruptedException
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*/
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public byte[] element() throws NoSuchElementException, KeeperException, InterruptedException {
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TreeMap<Long,String> orderedChildren;
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// element, take, and remove follow the same pattern.
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// We want to return the child node with the smallest sequence number.
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// Since other clients are remove()ing and take()ing nodes concurrently,
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// the child with the smallest sequence number in orderedChildren might be gone by the time we check.
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// We don't call getChildren again until we have tried the rest of the nodes in sequence order.
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while(true){
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try{
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orderedChildren = orderedChildren(null);
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}catch(KeeperException.NoNodeException e){
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throw new NoSuchElementException();
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}
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if(orderedChildren.size() == 0 ) throw new NoSuchElementException();
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for(String headNode : orderedChildren.values()){
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if(headNode != null){
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try{
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return zookeeper.getData(dir+"/"+headNode, false, null);
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}catch(KeeperException.NoNodeException e){
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//Another client removed the node first, try next
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}
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}
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}
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}
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}
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/**
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* Attempts to remove the head of the queue and return it.
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* @return The former head of the queue
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* @throws NoSuchElementException
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* @throws KeeperException
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* @throws InterruptedException
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*/
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public byte[] remove() throws NoSuchElementException, KeeperException, InterruptedException {
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TreeMap<Long,String> orderedChildren;
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// Same as for element. Should refactor this.
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while(true){
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try{
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orderedChildren = orderedChildren(null);
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}catch(KeeperException.NoNodeException e){
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throw new NoSuchElementException();
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}
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if(orderedChildren.size() == 0) throw new NoSuchElementException();
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for(String headNode : orderedChildren.values()){
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String path = dir +"/"+headNode;
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try{
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byte[] data = zookeeper.getData(path, false, null);
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zookeeper.delete(path, -1);
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return data;
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}catch(KeeperException.NoNodeException e){
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// Another client deleted the node first.
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}
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}
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}
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}
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private class LatchChildWatcher implements Watcher {
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CountDownLatch latch;
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public LatchChildWatcher(){
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latch = new CountDownLatch(1);
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}
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public void process(WatchedEvent event){
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LOG.debug("Watcher fired on path: " + event.getPath() + " state: " +
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event.getState() + " type " + event.getType());
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latch.countDown();
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}
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public void await() throws InterruptedException {
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latch.await();
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}
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}
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/**
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* Removes the head of the queue and returns it, blocks until it succeeds.
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* @return The former head of the queue
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* @throws NoSuchElementException
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* @throws KeeperException
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* @throws InterruptedException
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*/
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public byte[] take() throws KeeperException, InterruptedException {
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TreeMap<Long,String> orderedChildren;
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// Same as for element. Should refactor this.
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while(true){
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LatchChildWatcher childWatcher = new LatchChildWatcher();
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try{
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orderedChildren = orderedChildren(childWatcher);
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}catch(KeeperException.NoNodeException e){
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zookeeper.create(dir, new byte[0], acl, CreateMode.PERSISTENT);
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continue;
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}
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if(orderedChildren.size() == 0){
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childWatcher.await();
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continue;
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}
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for(String headNode : orderedChildren.values()){
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String path = dir +"/"+headNode;
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try{
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byte[] data = zookeeper.getData(path, false, null);
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zookeeper.delete(path, -1);
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return data;
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}catch(KeeperException.NoNodeException e){
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// Another client deleted the node first.
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}
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}
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}
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}
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/**
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* Inserts data into queue.
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* @param data
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* @return true if data was successfully added
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*/
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public boolean offer(byte[] data) throws KeeperException, InterruptedException{
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for(;;){
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try{
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zookeeper.create(dir+"/"+prefix, data, acl, CreateMode.PERSISTENT_SEQUENTIAL);
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return true;
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}catch(KeeperException.NoNodeException e){
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zookeeper.create(dir, new byte[0], acl, CreateMode.PERSISTENT);
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}
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}
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}
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/**
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* Returns the data at the first element of the queue, or null if the queue is empty.
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* @return data at the first element of the queue, or null.
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* @throws KeeperException
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* @throws InterruptedException
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*/
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public byte[] peek() throws KeeperException, InterruptedException{
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try{
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return element();
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}catch(NoSuchElementException e){
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return null;
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}
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}
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/**
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* Attempts to remove the head of the queue and return it. Returns null if the queue is empty.
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* @return Head of the queue or null.
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* @throws KeeperException
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* @throws InterruptedException
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*/
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public byte[] poll() throws KeeperException, InterruptedException {
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try{
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return remove();
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}catch(NoSuchElementException e){
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return null;
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}
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}
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}
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