| /** |
| * 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.mapred.lib; |
| |
| import java.io.*; |
| import java.lang.reflect.*; |
| |
| import org.apache.hadoop.mapred.*; |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configuration; |
| |
| /** |
| * A generic RecordReader that can hand out different recordReaders |
| * for each chunk in a {@link CombineFileSplit}. |
| * A CombineFileSplit can combine data chunks from multiple files. |
| * This class allows using different RecordReaders for processing |
| * these data chunks from different files. |
| * @see CombineFileSplit |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public class CombineFileRecordReader<K, V> implements RecordReader<K, V> { |
| |
| static final Class [] constructorSignature = new Class [] |
| {CombineFileSplit.class, |
| Configuration.class, |
| Reporter.class, |
| Integer.class}; |
| |
| protected CombineFileSplit split; |
| protected JobConf jc; |
| protected Reporter reporter; |
| protected Constructor<RecordReader<K, V>> rrConstructor; |
| |
| protected int idx; |
| protected long progress; |
| protected RecordReader<K, V> curReader; |
| |
| public boolean next(K key, V value) throws IOException { |
| |
| while ((curReader == null) || !curReader.next(key, value)) { |
| if (!initNextRecordReader()) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| public K createKey() { |
| return curReader.createKey(); |
| } |
| |
| public V createValue() { |
| return curReader.createValue(); |
| } |
| |
| /** |
| * return the amount of data processed |
| */ |
| public long getPos() throws IOException { |
| return progress; |
| } |
| |
| public void close() throws IOException { |
| if (curReader != null) { |
| curReader.close(); |
| curReader = null; |
| } |
| } |
| |
| /** |
| * return progress based on the amount of data processed so far. |
| */ |
| public float getProgress() throws IOException { |
| return Math.min(1.0f, progress/(float)(split.getLength())); |
| } |
| |
| /** |
| * A generic RecordReader that can hand out different recordReaders |
| * for each chunk in the CombineFileSplit. |
| */ |
| public CombineFileRecordReader(JobConf job, CombineFileSplit split, |
| Reporter reporter, |
| Class<RecordReader<K, V>> rrClass) |
| throws IOException { |
| this.split = split; |
| this.jc = job; |
| this.reporter = reporter; |
| this.idx = 0; |
| this.curReader = null; |
| this.progress = 0; |
| |
| try { |
| rrConstructor = rrClass.getDeclaredConstructor(constructorSignature); |
| rrConstructor.setAccessible(true); |
| } catch (Exception e) { |
| throw new RuntimeException(rrClass.getName() + |
| " does not have valid constructor", e); |
| } |
| initNextRecordReader(); |
| } |
| |
| /** |
| * Get the record reader for the next chunk in this CombineFileSplit. |
| */ |
| protected boolean initNextRecordReader() throws IOException { |
| |
| if (curReader != null) { |
| curReader.close(); |
| curReader = null; |
| if (idx > 0) { |
| progress += split.getLength(idx-1); // done processing so far |
| } |
| } |
| |
| // if all chunks have been processed, nothing more to do. |
| if (idx == split.getNumPaths()) { |
| return false; |
| } |
| |
| reporter.progress(); |
| |
| // get a record reader for the idx-th chunk |
| try { |
| curReader = rrConstructor.newInstance(new Object [] |
| {split, jc, reporter, Integer.valueOf(idx)}); |
| |
| // setup some helper config variables. |
| jc.set(JobContext.MAP_INPUT_FILE, split.getPath(idx).toString()); |
| jc.setLong(JobContext.MAP_INPUT_START, split.getOffset(idx)); |
| jc.setLong(JobContext.MAP_INPUT_PATH, split.getLength(idx)); |
| } catch (Exception e) { |
| throw new RuntimeException (e); |
| } |
| idx++; |
| return true; |
| } |
| } |