org.apache.sqoop.mapreduce.mainframe.MainframeDatasetRecordReader.java Source code

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Here is the source code for org.apache.sqoop.mapreduce.mainframe.MainframeDatasetRecordReader.java

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/**
 * 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.sqoop.mapreduce.mainframe;

import java.io.IOException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.util.ReflectionUtils;

import org.apache.sqoop.mapreduce.DBWritable;

import org.apache.sqoop.mapreduce.db.DBConfiguration;

/**
 * A RecordReader that reads records from a mainframe dataset.
 * Emits LongWritables containing the record number as key and DBWritables as
 * value.
 */
public abstract class MainframeDatasetRecordReader<T extends DBWritable> extends RecordReader<LongWritable, T> {
    private Class<T> inputClass;
    private Configuration conf;
    private MainframeDatasetInputSplit split;
    private LongWritable key;
    private T datasetRecord;
    private long numberRecordRead;
    private int datasetProcessed;

    private static final Log LOG = LogFactory.getLog(MainframeDatasetRecordReader.class.getName());

    @Override
    public void initialize(InputSplit inputSplit, TaskAttemptContext taskAttemptContext)
            throws IOException, InterruptedException {

        split = (MainframeDatasetInputSplit) inputSplit;
        conf = taskAttemptContext.getConfiguration();
        inputClass = (Class<T>) (conf.getClass(DBConfiguration.INPUT_CLASS_PROPERTY, null));
        key = null;
        datasetRecord = null;
        numberRecordRead = 0;
        datasetProcessed = 0;
    }

    @Override
    public boolean nextKeyValue() throws IOException, InterruptedException {
        if (key == null) {
            key = new LongWritable();
        }
        if (datasetRecord == null) {
            datasetRecord = ReflectionUtils.newInstance(inputClass, conf);
        }
        if (getNextRecord(datasetRecord)) {
            numberRecordRead++;
            key.set(numberRecordRead);
            return true;
        }
        return false;
    }

    @Override
    public LongWritable getCurrentKey() throws IOException, InterruptedException {
        return key;
    }

    @Override
    public T getCurrentValue() throws IOException, InterruptedException {
        return datasetRecord;
    }

    @Override
    public float getProgress() throws IOException, InterruptedException {
        return datasetProcessed / (float) split.getLength();
    }

    protected String getNextDataset() {
        String datasetName = split.getNextDataset();
        if (datasetName != null) {
            datasetProcessed++;
            LOG.info("Starting transfer of " + datasetName);
        }
        return datasetName;
    }

    protected Configuration getConfiguration() {
        return conf;
    }

    protected abstract boolean getNextRecord(T datasetRecord) throws IOException;

}