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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.server;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import java.io.IOException;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import org.apache.jute.InputArchive;
import org.apache.jute.OutputArchive;
import org.apache.jute.Record;
import org.apache.zookeeper.data.Stat;
import org.apache.zookeeper.data.StatPersisted;
/**
* This class contains the data for a node in the data tree.
* <p>
* A data node contains a reference to its parent, a byte array as its data, an
* array of ACLs, a stat object, and a set of its children's paths.
*
*/
@SuppressFBWarnings({"EI_EXPOSE_REP", "EI_EXPOSE_REP2"})
public class DataNode implements Record {
// the digest value of this node, calculated from path, data and stat
private volatile long digest;
// indicate if the digest of this node is up to date or not, used to
// optimize the performance.
volatile boolean digestCached;
/** the data for this datanode */
byte[] data;
/**
* the acl map long for this datanode. the datatree has the map
*/
Long acl;
/**
* the stat for this node that is persisted to disk.
*/
public StatPersisted stat;
/**
* the list of children for this node. note that the list of children string
* does not contain the parent path -- just the last part of the path. This
* should be synchronized on except deserializing (for speed up issues).
*/
private Set<String> children = null;
private static final Set<String> EMPTY_SET = Collections.emptySet();
/**
* default constructor for the datanode
*/
DataNode() {
// default constructor
}
/**
* create a DataNode with parent, data, acls and stat
*
* @param data
* the data to be set
* @param acl
* the acls for this node
* @param stat
* the stat for this node.
*/
public DataNode(byte[] data, Long acl, StatPersisted stat) {
this.data = data;
this.acl = acl;
this.stat = stat;
}
/**
* Method that inserts a child into the children set
*
* @param child
* to be inserted
* @return true if this set did not already contain the specified element
*/
public synchronized boolean addChild(String child) {
if (children == null) {
// let's be conservative on the typical number of children
children = new HashSet<String>(8);
}
return children.add(child);
}
/**
* Method that removes a child from the children set
*
* @param child
* @return true if this set contained the specified element
*/
public synchronized boolean removeChild(String child) {
if (children == null) {
return false;
}
return children.remove(child);
}
/**
* convenience method for setting the children for this datanode
*
* @param children
*/
public synchronized void setChildren(HashSet<String> children) {
this.children = children;
}
/**
* convenience methods to get the children
*
* @return the children of this datanode. If the datanode has no children, empty
* set is returned
*/
public synchronized Set<String> getChildren() {
if (children == null) {
return EMPTY_SET;
}
return Collections.unmodifiableSet(children);
}
public synchronized void copyStat(Stat to) {
to.setAversion(stat.getAversion());
to.setCtime(stat.getCtime());
to.setCzxid(stat.getCzxid());
to.setMtime(stat.getMtime());
to.setMzxid(stat.getMzxid());
to.setPzxid(stat.getPzxid());
to.setVersion(stat.getVersion());
to.setEphemeralOwner(getClientEphemeralOwner(stat));
to.setDataLength(data == null ? 0 : data.length);
int numChildren = 0;
if (this.children != null) {
numChildren = children.size();
}
// when we do the Cversion we need to translate from the count of the creates
// to the count of the changes (v3 semantics)
// for every create there is a delete except for the children still present
to.setCversion(stat.getCversion() * 2 - numChildren);
to.setNumChildren(numChildren);
}
private static long getClientEphemeralOwner(StatPersisted stat) {
EphemeralType ephemeralType = EphemeralType.get(stat.getEphemeralOwner());
if (ephemeralType != EphemeralType.NORMAL) {
return 0;
}
return stat.getEphemeralOwner();
}
public synchronized void deserialize(InputArchive archive, String tag) throws IOException {
archive.startRecord("node");
data = archive.readBuffer("data");
acl = archive.readLong("acl");
stat = new StatPersisted();
stat.deserialize(archive, "statpersisted");
archive.endRecord("node");
}
public synchronized void serialize(OutputArchive archive, String tag) throws IOException {
archive.startRecord(this, "node");
archive.writeBuffer(data, "data");
archive.writeLong(acl, "acl");
stat.serialize(archive, "statpersisted");
archive.endRecord(this, "node");
}
public boolean isDigestCached() {
return digestCached;
}
public void setDigestCached(boolean digestCached) {
this.digestCached = digestCached;
}
public long getDigest() {
return digest;
}
public void setDigest(long digest) {
this.digest = digest;
}
public synchronized byte[] getData() {
return data;
}
}
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