| /** |
| * 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.mapreduce.lib.input; |
| |
| import java.io.IOException; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.mapreduce.InputSplit; |
| import org.apache.hadoop.mapreduce.MRJobConfig; |
| import org.apache.hadoop.mapreduce.RecordReader; |
| import org.apache.hadoop.mapreduce.TaskAttemptContext; |
| |
| /** |
| * A wrapper class for a record reader that handles a single file split. It |
| * delegates most of the methods to the wrapped instance. A concrete subclass |
| * needs to provide a constructor that calls this parent constructor with the |
| * appropriate input format. The subclass constructor must satisfy the specific |
| * constructor signature that is required by |
| * <code>CombineFileRecordReader</code>. |
| * |
| * Subclassing is needed to get a concrete record reader wrapper because of the |
| * constructor requirement. |
| * |
| * @see CombineFileRecordReader |
| * @see CombineFileInputFormat |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public abstract class CombineFileRecordReaderWrapper<K,V> |
| extends RecordReader<K,V> { |
| private final FileSplit fileSplit; |
| private final RecordReader<K,V> delegate; |
| |
| protected CombineFileRecordReaderWrapper(FileInputFormat<K,V> inputFormat, |
| CombineFileSplit split, TaskAttemptContext context, Integer idx) |
| throws IOException, InterruptedException { |
| fileSplit = new FileSplit(split.getPath(idx), |
| split.getOffset(idx), |
| split.getLength(idx), |
| split.getLocations()); |
| |
| delegate = inputFormat.createRecordReader(fileSplit, context); |
| } |
| |
| public void initialize(InputSplit split, TaskAttemptContext context) |
| throws IOException, InterruptedException { |
| // it really should be the same file split at the time the wrapper instance |
| // was created |
| assert fileSplitIsValid(context); |
| |
| delegate.initialize(fileSplit, context); |
| } |
| |
| private boolean fileSplitIsValid(TaskAttemptContext context) { |
| Configuration conf = context.getConfiguration(); |
| long offset = conf.getLong(MRJobConfig.MAP_INPUT_START, 0L); |
| if (fileSplit.getStart() != offset) { |
| return false; |
| } |
| long length = conf.getLong(MRJobConfig.MAP_INPUT_PATH, 0L); |
| if (fileSplit.getLength() != length) { |
| return false; |
| } |
| String path = conf.get(MRJobConfig.MAP_INPUT_FILE); |
| if (!fileSplit.getPath().toString().equals(path)) { |
| return false; |
| } |
| return true; |
| } |
| |
| public boolean nextKeyValue() throws IOException, InterruptedException { |
| return delegate.nextKeyValue(); |
| } |
| |
| public K getCurrentKey() throws IOException, InterruptedException { |
| return delegate.getCurrentKey(); |
| } |
| |
| public V getCurrentValue() throws IOException, InterruptedException { |
| return delegate.getCurrentValue(); |
| } |
| |
| public float getProgress() throws IOException, InterruptedException { |
| return delegate.getProgress(); |
| } |
| |
| public void close() throws IOException { |
| delegate.close(); |
| } |
| } |