com.pivotal.hawq.mapreduce.ao.HAWQAORecordReader.java Source code

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Here is the source code for com.pivotal.hawq.mapreduce.ao.HAWQAORecordReader.java

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package com.pivotal.hawq.mapreduce.ao;

/*
 * 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.
 */

import com.pivotal.hawq.mapreduce.conf.HAWQConfiguration;
import com.pivotal.hawq.mapreduce.HAWQException;
import com.pivotal.hawq.mapreduce.HAWQRecord;
import com.pivotal.hawq.mapreduce.ao.io.HAWQAOFileReader;
import com.pivotal.hawq.mapreduce.ao.io.HAWQAORecord;

import com.pivotal.hawq.mapreduce.schema.HAWQSchema;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;

import java.io.IOException;

/**
 * The record reader breaks the data into key/value pairs for input to mapper.
 */
public class HAWQAORecordReader extends RecordReader<Void, HAWQRecord> {

    private HAWQRecord value = null;
    private HAWQAOFileReader filereader = null;
    private boolean more = true;

    /**
     * Close the record reader.
     */
    @Override
    public void close() throws IOException {
        filereader.close();
    }

    /**
     * Get the current key
     * 
     * @return the current key or null if there is no current key
     * @throws IOException
     * @throws InterruptedException
     */
    @Override
    public Void getCurrentKey() throws IOException, InterruptedException {
        // Always null
        return null;
    }

    /**
     * Get the current value.
     * 
     * @return the object that was read
     * @throws IOException
     * @throws InterruptedException
     */
    @Override
    public HAWQRecord getCurrentValue() throws IOException, InterruptedException {
        return value;
    }

    /**
     * The current progress of the record reader through its data.
     * 
     * @return a number between 0.0 and 1.0 that is the fraction of the data
     *         read
     * @throws IOException
     * @throws InterruptedException
     */
    @Override
    public float getProgress() throws IOException, InterruptedException {
        return more ? 0f : 100f;
    }

    /**
     * Called once at initialization.
     * 
     * @param split
     *            the split that defines the range of records to read
     * @param context
     *            the information about the task
     * @throws IOException
     * @throws InterruptedException
     */
    @Override
    public void initialize(InputSplit split, TaskAttemptContext context) throws IOException, InterruptedException {

        // initialize the value
        Configuration conf = context.getConfiguration();

        // Extract the parameters needed by HAWQAOFileReader and HAWQAORecord
        String encoding = HAWQConfiguration.getInputTableEncoding(conf);
        HAWQSchema schema = HAWQConfiguration.getInputTableSchema(conf);
        /*
         * GPSQL-1047
         * 
         * Get version from configuration and init HAWQAORecord with it
         */
        String version = HAWQConfiguration.getDatabaseVersion(conf);

        filereader = new HAWQAOFileReader(conf, split);

        try {
            value = new HAWQAORecord(schema, encoding, version);
        } catch (HAWQException hawqE) {
            throw new IOException(hawqE.getMessage());
        }
    }

    /**
     * Read the next key, value pair.
     * 
     * @return true if a key/value pair was read
     * @throws IOException
     * @throws InterruptedException
     */
    @Override
    public boolean nextKeyValue() throws IOException, InterruptedException {
        try {
            if (filereader.readRecord((HAWQAORecord) value)) {
                return true;
            }
        } catch (HAWQException hawqE) {
            throw new IOException(hawqE.getMessage());
        }
        more = false;
        return false;
    }
}