fullstack/pregelix/pregelix-api/src/main/java/edu/uci/ics/pregelix/api/io/text/TextVertexOutputFormat.java

/*
 * Copyright 2009-2010 by The Regents of the University of California
 * 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 from
 * 
 *     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 edu.uci.ics.pregelix.api.io.text;

import java.io.IOException;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.OutputCommitter;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;

import edu.uci.ics.pregelix.api.io.VertexOutputFormat;
import edu.uci.ics.pregelix.api.io.VertexWriter;

/**
 * Abstract class that users should subclass to use their own text based vertex
 * output format.
 * 
 * @param <I>
 *            Vertex index value
 * @param <V>
 *            Vertex value
 * @param <E>
 *            Edge value
 */
@SuppressWarnings("rawtypes")
public abstract class TextVertexOutputFormat<I extends WritableComparable, V extends Writable, E extends Writable>
        extends VertexOutputFormat<I, V, E> {
    /** Uses the TextOutputFormat to do everything */
    protected TextOutputFormat<Text, Text> textOutputFormat = new TextOutputFormat<Text, Text>();

    /**
     * Abstract class to be implemented by the user based on their specific
     * vertex output. Easiest to ignore the key value separator and only use key
     * instead.
     * 
     * @param <I>
     *            Vertex index value
     * @param <V>
     *            Vertex value
     * @param <E>
     *            Edge value
     */
    public static abstract class TextVertexWriter<I extends WritableComparable, V extends Writable, E extends Writable>
            implements VertexWriter<I, V, E> {
        /** Context passed to initialize */
        private TaskAttemptContext context;
        /** Internal line record writer */
        private final RecordWriter<Text, Text> lineRecordWriter;

        /**
         * Initialize with the LineRecordWriter.
         * 
         * @param lineRecordWriter
         *            Line record writer from TextOutputFormat
         */
        public TextVertexWriter(RecordWriter<Text, Text> lineRecordWriter) {
            this.lineRecordWriter = lineRecordWriter;
        }

        @Override
        public void initialize(TaskAttemptContext context) throws IOException {
            this.context = context;
        }

        @Override
        public void close(TaskAttemptContext context) throws IOException, InterruptedException {
            lineRecordWriter.close(context);
        }

        /**
         * Get the line record writer.
         * 
         * @return Record writer to be used for writing.
         */
        public RecordWriter<Text, Text> getRecordWriter() {
            return lineRecordWriter;
        }

        /**
         * Get the context.
         * 
         * @return Context passed to initialize.
         */
        public TaskAttemptContext getContext() {
            return context;
        }
    }

    @Override
    public void checkOutputSpecs(JobContext context) throws IOException, InterruptedException {
        textOutputFormat.checkOutputSpecs(context);
    }

    @Override
    public OutputCommitter getOutputCommitter(TaskAttemptContext context) throws IOException, InterruptedException {
        return textOutputFormat.getOutputCommitter(context);
    }
}