/*
* 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.comm.messages;
import it.unimi.dsi.fastutil.longs.LongArrayList;
import it.unimi.dsi.fastutil.longs.LongListIterator;
import org.apache.giraph.factories.MessageValueFactory;
import org.apache.giraph.utils.ExtendedByteArrayOutputBuffer;
import org.apache.giraph.utils.ExtendedDataOutput;
import org.apache.giraph.utils.UnsafeReusableByteArrayInput;
import org.apache.hadoop.io.Writable;
import java.io.IOException;
import java.util.Iterator;
/**
* Create an iterable for messages based on a pointer list
*
* @param <M> messageType
*/
public class PointerListMessagesIterable<M extends Writable>
implements Iterable<M> {
/** Message class */
private final MessageValueFactory<M> messageValueFactory;
/** List of pointers to messages in byte array */
private final LongArrayList pointers;
/** Holds the byte arrays of serialized messages */
private final ExtendedByteArrayOutputBuffer msgBuffer;
/** Reader to read data from byte buffer */
private final UnsafeReusableByteArrayInput messageReader;
/**
*
* @param messageValueFactory message value factory
* @param pointers pointers to messages in buffer
* @param msgBuffer holds the byte arrays of serialized messages
*/
public PointerListMessagesIterable(MessageValueFactory<M> messageValueFactory,
LongArrayList pointers, ExtendedByteArrayOutputBuffer msgBuffer) {
this.messageValueFactory = messageValueFactory;
this.pointers = pointers;
this.msgBuffer = msgBuffer;
// TODO - if needed implement same for Safe as well
messageReader = new UnsafeReusableByteArrayInput();
}
/**
* Create message from factory
*
* @return message instance
*/
protected M createMessage() {
return messageValueFactory.newInstance();
}
@Override
public Iterator<M> iterator() {
return new Iterator<M>() {
private final LongListIterator iterator = pointers.iterator();
private final M reusableMsg =
PointerListMessagesIterable.this.createMessage();
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public M next() {
long pointer = iterator.next();
try {
int index = (int) (pointer >>> 32);
int offset = (int) pointer;
ExtendedDataOutput buffer = msgBuffer.getDataOutput(index);
messageReader.initialize(buffer.getByteArray(), offset,
buffer.getPos());
reusableMsg.readFields(messageReader);
} catch (IOException e) {
throw new IllegalStateException("Got exception : " + e);
}
return reusableMsg;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
};
}
}