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From: David Hawthorne <dhawth@3crowd.com>
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Subject: map.input.file in 20.1
Date: Mon, 12 Jul 2010 14:56:16 -0700
Message-Id: <F53EADC8-270E-4FC6-9E3B-2FD75216B77F@3crowd.com>
To: common-user@hadoop.apache.org
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I'm trying to get the name of the file that the map job is operating on =
out of the Context passed to the setup function.  It's proving harder =
than seems proper.

I've found several links via google on this topic, but I've seen no =
responses to previous questions.

We have this from July 17, 2009:

http://www.mail-archive.com/common-user@hadoop.apache.org/msg00535.html

I attempted that solution and javac complained about using a deprecated =
API.

It's very clearly spelled out in this doc:

http://hadoop.apache.org/common/docs/r0.20.1/mapred_tutorial.html

and yet the example source code for 20.1 is still using the mapred.* =
(deprecated) API that the prior link used as well.

For the record, here's what I've tried, in the hopes that someone will =
just paste back a working solution:

import java.io.IOException;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.reduce.IntSumReducer;
import org.apache.hadoop.mapred.FileSplit;

public class Foo {
        public static class FooMapper extends Mapper<Object, Text, Text, =
IntWritable> {

                private org.apache.hadoop.io.Text input_file;

                public void setup (Context context) {
                        Configuration conf =3D =
context.getConfiguration();
=20
			//
			// fails to compile due to use of deprecated =
mapred API:
			//
                        FileSplit fileSplit =3D =
(FileSplit)context.getInputSplit();
                        String input_fname =3D =
fileSplit.getPath().toString();
                        input_file.set(input_fname);

			//
			// results in null pointer exception because =
conf.get returns null:
			//
                        // input_file.set(conf.get("map.input.file"));
                }
	}
}