org.acaro.graffiti.processing.GraffitiReader.java Source code

Introduction

Here is the source code for org.acaro.graffiti.processing.GraffitiReader.java

Source

/*  Copyright 2011 Claudio Martella
 *
 *  Licensed 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.acaro.graffiti.processing;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.acaro.graffiti.Graffiti;
import org.acaro.graffiti.query.ParseError;
import org.acaro.graffiti.query.Query;
import org.acaro.graffiti.query.QueryParser;
import org.antlr.runtime.RecognitionException;
import org.apache.giraph.graph.BasicVertex;
import org.apache.giraph.lib.TextVertexInputFormat.TextVertexReader;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.json.JSONArray;
import org.json.JSONException;

public class GraffitiReader extends TextVertexReader<Text, IntWritable, Text, Message> {

    private List<Message> msgList;

    public GraffitiReader(RecordReader<LongWritable, Text> recordReader) {
        super(recordReader);
    }

    @Override
    public BasicVertex<Text, IntWritable, Text, Message> getCurrentVertex()
            throws IOException, InterruptedException {

        Vertex vertex = new Vertex();
        Text line = getRecordReader().getCurrentValue();

        try {

            JSONArray jsonVertex = new JSONArray(line.toString());
            vertex.setVertexId(new Text(jsonVertex.getString(0)));
            vertex.setMsgList(msgList);
            JSONArray jsonEdgeArray = jsonVertex.getJSONArray(1);

            for (int i = 0; i < jsonEdgeArray.length(); ++i) {
                JSONArray jsonEdge = jsonEdgeArray.getJSONArray(i);
                vertex.addEdge(new Text(jsonEdge.getString(1)), new Text(jsonEdge.getString(0)));
            }
        } catch (JSONException e) {
            throw new IllegalArgumentException("next: Couldn't get vertex from line " + line, e);
        }

        return vertex;
    }

    @Override
    public boolean nextVertex() throws IOException, InterruptedException {
        return getRecordReader().nextKeyValue();
    }

    @Override
    public void initialize(InputSplit inputSplit, TaskAttemptContext context)
            throws IOException, InterruptedException {
        super.initialize(inputSplit, context);

        try {

            String queryString = context.getConfiguration().get(Graffiti.QUERY);
            Query query = new QueryParser(queryString).parse();
            msgList = new ArrayList<Message>(1);
            msgList.add(new Message(query, new ResultSet()));

        } catch (RecognitionException e) {
            e.printStackTrace();
            throw new ParseError("cannot parse query ");
        }
    }
}