/**
* 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.avro.mapred;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import org.apache.avro.Schema;
import org.apache.avro.SchemaParseException;
import org.apache.commons.codec.binary.Base64;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapred.JobConf;
/**
* This class supports Avro-MapReduce jobs that have multiple input paths with
* a different {@link Schema} and {@link AvroMapper} for each path.
*
* <p>
* Usage:
* </p>
* <p>
* <strong>Case 1: (ReflectData based inputs)</strong>
* </p>
* <pre>
* // Enable ReflectData usage across job.
* AvroJob.setReflect(job);
*
* Schema type1Schema = ReflectData.get().getSchema(Type1Record.class)
* AvroMultipleInputs.addInputPath(job, inputPath1, type1Schema, Type1AvroMapper.class);
* </pre>
*
* Where Type1AvroMapper would be implemented as
* <pre>
* class Type1AvroMapper extends AvroMapper<Type1Record, Pair<ComparingKeyRecord, CommonValueRecord>>
* </pre>
*
* <pre>
* Schema type2Schema = ReflectData.get().getSchema(Type2Record.class)
* AvroMultipleInputs.addInputPath(job, inputPath2, type2Schema, Type2AvroMapper.class);
* </pre>
*
* Where Type2AvroMapper would be implemented as
* <pre>
* class Type2AvroMapper extends AvroMapper<Type2Record, Pair<ComparingKeyRecord, CommonValueRecord>>
* </pre>
*
* <p>
* <strong>Case 2: (SpecificData based inputs)</strong>
* </p>
*
* <pre>
* Schema type1Schema = Type1Record.SCHEMA$;
* AvroMultipleInputs.addInputPath(job, inputPath1, type1Schema, Type1AvroMapper.class);
* </pre>
*
* Where Type1AvroMapper would be implemented as
* <pre>
* class Type1AvroMapper extends AvroMapper<Type1Record, Pair<ComparingKeyRecord, CommonValueRecord>>
* </pre>
*
* <pre>
* Schema type2Schema = Type2Record.SCHEMA$;
* AvroMultipleInputs.addInputPath(job, inputPath2, type2Schema, Type2AvroMapper.class);
* </pre>
*
* Where Type2AvroMapper would be implemented as
* <pre>
* class Type2AvroMapper extends AvroMapper<Type2Record, Pair<ComparingKeyRecord, CommonValueRecord>>
* </pre>
*
* <p>
* <strong>Note on InputFormat:</strong>
* The InputFormat used will always be {@link AvroInputFormat} when using this class.
* </p>
* <p>
* <strong>Note on collector outputs:</strong>
* When using this class, you will need to ensure that the mapper implementations
* involved must all emit the same Key type and Value
* record types, as set by {@link AvroJob#setOutputSchema(JobConf, Schema)}
* or {@link AvroJob#setMapOutputSchema(JobConf, Schema)}.
* </p>
*/
public class AvroMultipleInputs {
private static String schemaKey =
"avro.mapreduce.input.multipleinputs.dir.schemas";
private static String mappersKey =
"avro.mapreduce.input.multipleinputs.dir.mappers";
/**
* Add a {@link Path} with a custom {@link Schema} to the list of
* inputs for the map-reduce job.
*
* @param conf The configuration of the job
* @param path {@link Path} to be added to the list of inputs for the job
* @param inputSchema {@link Schema} class to use for this path
*/
private static void addInputPath(JobConf conf, Path path,
Schema inputSchema) {
String schemaMapping = path.toString() + ";"
+ toBase64(inputSchema.toString());
String schemas = conf.get(schemaKey);
conf.set(schemaKey,
schemas == null ? schemaMapping : schemas + ","
+ schemaMapping);
conf.setInputFormat(DelegatingInputFormat.class);
}
/**
* Add a {@link Path} with a custom {@link Schema} and
* {@link AvroMapper} to the list of inputs for the map-reduce job.
*
* @param conf The configuration of the job
* @param path {@link Path} to be added to the list of inputs for the job
* @param inputSchema {@link Schema} to use for this path
* @param mapperClass {@link AvroMapper} class to use for this path
*/
public static void addInputPath(JobConf conf, Path path,
Class<? extends AvroMapper> mapperClass,
Schema inputSchema) {
addInputPath(conf, path, inputSchema);
String mapperMapping = path.toString() + ";" + mapperClass.getName();
System.out.println(mapperMapping);
String mappers = conf.get(mappersKey);
conf.set(mappersKey, mappers == null ? mapperMapping
: mappers + "," + mapperMapping);
conf.setMapperClass(DelegatingMapper.class);
}
/**
* Retrieves a map of {@link Path}s to the {@link AvroMapper} class that
* should be used for them.
*
* @param conf The configuration of the job
* @see #addInputPath(JobConf, Path, Class, Schema)
* @return A map of paths-to-mappers for the job
*/
@SuppressWarnings("unchecked")
static Map<Path, Class<? extends AvroMapper>> getMapperTypeMap(JobConf conf) {
if (conf.get(mappersKey) == null) {
return Collections.emptyMap();
}
Map<Path, Class<? extends AvroMapper>> m = new HashMap<Path, Class<? extends AvroMapper>>();
String[] pathMappings = conf.get(mappersKey).split(",");
for (String pathMapping : pathMappings) {
String[] split = pathMapping.split(";");
Class<? extends AvroMapper> mapClass;
try {
mapClass = (Class<? extends AvroMapper>) conf.getClassByName(split[1]);
} catch (ClassNotFoundException e) {
throw new RuntimeException(e);
}
m.put(new Path(split[0]), mapClass);
}
return m;
}
/**
* Retrieves a map of {@link Path}s to the {@link Schema} that
* should be used for them.
*
* @param conf The configuration of the job
* @see #addInputPath(JobConf, Path, Class, Schema)
* @return A map of paths to schemas for the job
*/
static Map<Path, Schema> getInputSchemaMap(JobConf conf) {
if (conf.get(schemaKey) == null) {
return Collections.emptyMap();
}
Map<Path, Schema> m = new HashMap<Path, Schema>();
String[] schemaMappings =
conf.get(schemaKey).split(",");
Schema.Parser schemaParser = new Schema.Parser();
for (String schemaMapping : schemaMappings) {
String[] split = schemaMapping.split(";");
String schemaString = fromBase64(split[1]);
Schema inputSchema;
try {
inputSchema = schemaParser.parse(schemaString);
} catch (SchemaParseException e) {
throw new RuntimeException(e);
}
m.put(new Path(split[0]), inputSchema);
}
return m;
}
private static String toBase64(String rawString) {
Base64 base64decoder = new Base64();
return new String(base64decoder.encode(rawString.getBytes()));
}
private static String fromBase64(String base64String) {
Base64 base64decoder = new Base64();
return new String(base64decoder.decode(base64String.getBytes()));
}
}