io.cdap.cdap.internal.app.runtime.batch.dataset.input.MultipleInputs Maven / Gradle / Ivy
/*
* Copyright © 2016 Cask Data, Inc.
*
* Licensed 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 io.cdap.cdap.internal.app.runtime.batch.dataset.input;
import com.google.common.reflect.TypeToken;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapreduce.InputFormat;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import java.lang.reflect.Type;
import java.util.HashMap;
import java.util.Map;
/**
* This utility class supports MapReduce jobs that have multiple inputs with
* a different {@link InputFormat} and {@link Mapper} for each path
*/
public final class MultipleInputs {
private static final String INPUT_CONFIGS = "mapreduce.input.multipleinputs.inputs";
private static final Gson GSON = new GsonBuilder().enableComplexMapKeySerialization().create();
private static final Type STRING_MAPPER_INPUT_MAP_TYPE = new TypeToken>() { }.getType();
private MultipleInputs() {
}
/**
* Add a {@link Path} with a custom {@link InputFormat} and
* {@link Mapper} to the list of inputs for the map-reduce job.
*
* @param job The {@link Job}
* @param namedInput name of the input
* @param inputFormatClass the name of the InputFormat class to be used for this input
* @param inputConfigs the configurations to be used for this input
* @param mapperClass {@link Mapper} class to use for this path
*/
@SuppressWarnings("unchecked")
public static void addInput(Job job, String namedInput, String inputFormatClass, Map inputConfigs,
Class mapperClass) {
Configuration conf = job.getConfiguration();
Map map = getInputMap(conf);
// this shouldn't happen, because it is already protected against in BasicMapReduceContext#addInput
if (map.containsKey(namedInput)) {
throw new IllegalArgumentException("Input already configured: " + namedInput);
}
map.put(namedInput, new MapperInput(inputFormatClass, inputConfigs, mapperClass));
conf.set(INPUT_CONFIGS, GSON.toJson(map));
job.setInputFormatClass(MultiInputFormat.class);
}
/**
* @param conf the Configuration from which to deserialize the input configurations
* @return a mapping from input name to the MapperInput for that input
*/
public static Map getInputMap(Configuration conf) {
String mapString = conf.get(INPUT_CONFIGS);
if (mapString == null) {
return new HashMap<>();
}
return GSON.fromJson(mapString, STRING_MAPPER_INPUT_MAP_TYPE);
}
/**
* A simple POJO for encapsulating information for an input. We don't use
* {@link io.cdap.cdap.internal.app.runtime.batch.dataset.input.MapperInput}, because that consists of an Interface,
* which doesn't serialize well.
*/
public static final class MapperInput {
private final String inputFormatClassName;
private final Map inputFormatConfiguration;
private final String mapperClassName;
public MapperInput(String inputFormatClassName, Map inputFormatConfiguration,
Class mapper) {
this.inputFormatClassName = inputFormatClassName;
this.inputFormatConfiguration = inputFormatConfiguration;
this.mapperClassName = mapper.getName();
}
public String getInputFormatClassName() {
return inputFormatClassName;
}
public Map getInputFormatConfiguration() {
return inputFormatConfiguration;
}
public String getMapperClassName() {
return mapperClassName;
}
}
}