| /** |
| * 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.IOException; |
| import java.util.ArrayList; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.fs.FileStatus; |
| import org.apache.hadoop.io.LongWritable; |
| import org.apache.hadoop.io.Text; |
| import org.apache.hadoop.mapred.FileInputFormat; |
| import org.apache.hadoop.mapred.FileSplit; |
| import org.apache.hadoop.mapred.InputSplit; |
| import org.apache.hadoop.mapred.JobConf; |
| import org.apache.hadoop.mapred.JobConfigurable; |
| import org.apache.hadoop.mapred.LineRecordReader; |
| import org.apache.hadoop.mapred.RecordReader; |
| import org.apache.hadoop.mapred.Reporter; |
| |
| /** |
| * NLineInputFormat which splits N lines of input as one split. |
| * |
| * In many "pleasantly" parallel applications, each process/mapper |
| * processes the same input file (s), but with computations are |
| * controlled by different parameters.(Referred to as "parameter sweeps"). |
| * One way to achieve this, is to specify a set of parameters |
| * (one set per line) as input in a control file |
| * (which is the input path to the map-reduce application, |
| * where as the input dataset is specified |
| * via a config variable in JobConf.). |
| * |
| * The NLineInputFormat can be used in such applications, that splits |
| * the input file such that by default, one line is fed as |
| * a value to one map task, and key is the offset. |
| * i.e. (k,v) is (LongWritable, Text). |
| * The location hints will span the whole mapred cluster. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public class NLineInputFormat extends FileInputFormat<LongWritable, Text> |
| implements JobConfigurable { |
| private int N = 1; |
| |
| public RecordReader<LongWritable, Text> getRecordReader( |
| InputSplit genericSplit, |
| JobConf job, |
| Reporter reporter) |
| throws IOException { |
| reporter.setStatus(genericSplit.toString()); |
| return new LineRecordReader(job, (FileSplit) genericSplit); |
| } |
| |
| /** |
| * Logically splits the set of input files for the job, splits N lines |
| * of the input as one split. |
| * |
| * @see org.apache.hadoop.mapred.FileInputFormat#getSplits(JobConf, int) |
| */ |
| public InputSplit[] getSplits(JobConf job, int numSplits) |
| throws IOException { |
| ArrayList<FileSplit> splits = new ArrayList<FileSplit>(); |
| for (FileStatus status : listStatus(job)) { |
| for (org.apache.hadoop.mapreduce.lib.input.FileSplit split : |
| org.apache.hadoop.mapreduce.lib.input. |
| NLineInputFormat.getSplitsForFile(status, job, N)) { |
| splits.add(new FileSplit(split)); |
| } |
| } |
| return splits.toArray(new FileSplit[splits.size()]); |
| } |
| |
| public void configure(JobConf conf) { |
| N = conf.getInt("mapreduce.input.lineinputformat.linespermap", 1); |
| } |
| } |