/*
* 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.giraph.graph;
import org.apache.giraph.edge.Edge;
import org.apache.giraph.utils.UnsafeByteArrayInputStream;
import org.apache.giraph.utils.UnsafeByteArrayOutputStream;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparable;
import java.io.DataInput;
import java.io.IOException;
/**
* Special version of vertex that holds the value in raw byte form to save
* memory.
*
* @param <I> Vertex id
* @param <V> Vertex data
* @param <E> Edge data
*/
public class ByteValueVertex<I extends WritableComparable,
V extends Writable, E extends Writable>
extends DefaultVertex<I, V, E> {
/** Vertex value stored as raw bytes */
private byte[] valueBytes;
/** Value as an cached object that is only valid during the vertex update */
private V cachedValue = null;
@Override
public V getValue() {
if (cachedValue != null) {
return cachedValue; // Return always same instance
}
DataInput dis = new UnsafeByteArrayInputStream(valueBytes);
cachedValue = getConf().createVertexValue();
try {
cachedValue.readFields(dis);
} catch (IOException ioe) {
throw new RuntimeException("Could not deserialize vertex value", ioe);
}
// Forget the serialized data, because we have cached the object
valueBytes = null;
return cachedValue;
}
/**
* Serializes the value to bytes, stored in field valueBytes
* @param value new vertex value
*/
private void setSerializedValue(V value) {
UnsafeByteArrayOutputStream bos = new UnsafeByteArrayOutputStream();
try {
value.write(bos);
bos.close();
} catch (IOException ioe) {
throw new RuntimeException("Could not serialize vertex value", ioe);
}
this.valueBytes = bos.toByteArray();
cachedValue = null;
}
@Override
public void setValue(V value) {
if (cachedValue != null) {
cachedValue = value;
} else {
setSerializedValue(value);
}
}
@Override
public void initialize(I id, V value, Iterable<Edge<I, E>> edges) {
// Set the parent's value to null, and instead use our own setter
super.initialize(id, null, edges);
setValue(value);
}
@Override
public void initialize(I id, V value) {
super.initialize(id, null);
setValue(value);
}
@Override
public void unwrapMutableEdges() {
// This method is called always after compute(vertex), so
// we use this to commit the vertex value.
if (cachedValue != null) {
// This means the value has been requested from vertex
// and possible mutated -- so we need to update the byte array
setSerializedValue(cachedValue);
cachedValue = null; // Uncache the value
}
super.unwrapMutableEdges();
}
}