src/main/java/org/apache/giraph/graph/IntIntNullIntVertex.java

/*
 * 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 com.google.common.collect.Iterables;
import org.apache.giraph.utils.UnmodifiableIntArrayIterator;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.NullWritable;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Iterator;
import java.util.Map;

/**
 * Simple implementation of {@link BasicVertex} using an int as id, value and message.
 * Edges are immutable and unweighted. This class aims to be as memory efficient as possible.
 */
public abstract class IntIntNullIntVertex extends
        BasicVertex<IntWritable, IntWritable, NullWritable,IntWritable> {

    private int id;
    private int value;

    private int[] neighbors;
    private int[] messages;

    @Override
    public void initialize(IntWritable vertexId, IntWritable vertexValue,
            Map<IntWritable, NullWritable> edges,
            Iterable<IntWritable> messages) {
        id = vertexId.get();
        value = vertexValue.get();
        this.neighbors = new int[edges.size()];
        int n = 0;
        for (IntWritable neighbor : edges.keySet()) {
            this.neighbors[n++] = neighbor.get();
        }
        this.messages = new int[Iterables.size(messages)];
        n = 0;
        for (IntWritable message : messages) {
            this.messages[n++] = message.get();
        }
    }

    @Override
    public IntWritable getVertexId() {
        return new IntWritable(id);
    }

    @Override
    public IntWritable getVertexValue() {
        return new IntWritable(value);
    }

    @Override
    public void setVertexValue(IntWritable vertexValue) {
        value = vertexValue.get();
    }

    @Override
    public Iterator<IntWritable> iterator() {
        return new UnmodifiableIntArrayIterator(neighbors);
    }

    @Override
    public NullWritable getEdgeValue(IntWritable targetVertexId) {
        return NullWritable.get();
    }

    @Override
    public boolean hasEdge(IntWritable targetVertexId) {
        for (int neighbor : neighbors) {
            if (neighbor == targetVertexId.get()) {
                return true;
            }
        }
        return false;
    }

    @Override
    public int getNumOutEdges() {
        return neighbors.length;
    }

    @Override
    public void sendMsgToAllEdges(final IntWritable message) {
        for (int neighbor : neighbors) {
            sendMsg(new IntWritable(neighbor), message);
        }
    }

    @Override
    public Iterable<IntWritable> getMessages() {
        return new Iterable<IntWritable>() {
            @Override
            public Iterator<IntWritable> iterator() {
                return new UnmodifiableIntArrayIterator(messages);
            }
        };
    }

    @Override
    public void putMessages(Iterable<IntWritable> newMessages) {
        messages = new int[Iterables.size(newMessages)];
        int n = 0;
        for (IntWritable message : newMessages) {
            messages[n++] = message.get();
        }
    }

    @Override
    void releaseResources() {
        messages = new int[0];
    }

    @Override
    public void write(final DataOutput out) throws IOException {
        out.writeInt(id);
        out.writeInt(value);
        out.writeInt(neighbors.length);
        for (int n = 0; n < neighbors.length; n++) {
            out.writeInt(neighbors[n]);
        }
        out.writeInt(messages.length);
        for (int n = 0; n < messages.length; n++) {
            out.writeInt(messages[n]);
        }
    }

    @Override
    public void readFields(DataInput in) throws IOException {
        id = in.readInt();
        value = in.readInt();
        int numEdges = in.readInt();
        neighbors = new int[numEdges];
        for (int n = 0; n < numEdges; n++) {
            neighbors[n] = in.readInt();
        }
        int numMessages = in.readInt();
        messages = new int[numMessages];
        for (int n = 0; n < numMessages; n++) {
            messages[n] = in.readInt();
        }
    }

}