/tags/release-0.0.0-rc0/hive/external/ql/src/java/org/apache/hadoop/hive/ql/io/CombineHiveRecordReader.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.hadoop.hive.ql.io;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hive.ql.exec.ExecMapper;
import org.apache.hadoop.hive.ql.io.CombineHiveInputFormat.CombineHiveInputSplit;
import org.apache.hadoop.hive.shims.HadoopShims.InputSplitShim;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapred.FileSplit;
import org.apache.hadoop.mapred.InputFormat;
import org.apache.hadoop.mapred.InputSplit;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.RecordReader;
import org.apache.hadoop.mapred.Reporter;

/**
 * CombineHiveRecordReader.
 *
 * @param <K>
 * @param <V>
 */
public class CombineHiveRecordReader<K extends WritableComparable, V extends Writable>
    extends HiveContextAwareRecordReader<K, V> {

  private final RecordReader recordReader;

  public CombineHiveRecordReader(InputSplit split, Configuration conf,
      Reporter reporter, Integer partition) throws IOException {
    JobConf job = (JobConf) conf;
    CombineHiveInputSplit hsplit = new CombineHiveInputSplit(job,
        (InputSplitShim) split);
    String inputFormatClassName = hsplit.inputFormatClassName();
    Class inputFormatClass = null;
    try {
      inputFormatClass = Class.forName(inputFormatClassName);
    } catch (ClassNotFoundException e) {
      throw new IOException("CombineHiveRecordReader: class not found "
          + inputFormatClassName);
    }
    InputFormat inputFormat = HiveInputFormat.getInputFormatFromCache(
        inputFormatClass, job);

    // create a split for the given partition
    FileSplit fsplit = new FileSplit(hsplit.getPaths()[partition], hsplit
        .getStartOffsets()[partition], hsplit.getLengths()[partition], hsplit
        .getLocations());

    this.recordReader = inputFormat.getRecordReader(fsplit, job, reporter);
    this.initIOContext(fsplit, job, inputFormatClass, this.recordReader);
  }

  @Override
  public void doClose() throws IOException {
    recordReader.close();
  }

  public K createKey() {
    return (K) recordReader.createKey();
  }

  public V createValue() {
    return (V) recordReader.createValue();
  }

  public long getPos() throws IOException {
    return recordReader.getPos();
  }

  public float getProgress() throws IOException {
    return recordReader.getProgress();
  }

  @Override
  public boolean doNext(K key, V value) throws IOException {
    if (ExecMapper.getDone()) {
      return false;
    }
    return recordReader.next(key, value);
  }
}