org.apache.hadoop.mapred.MapRunnable Maven / Gradle / Ivy
/**
* 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;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
/**
* Expert: Generic interface for {@link Mapper}s.
*
* Custom implementations of MapRunnable can exert greater
* control on map processing e.g. multi-threaded, asynchronous mappers etc.
*
* @see Mapper
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
public interface MapRunnable
extends JobConfigurable {
/**
* Start mapping input <key, value> pairs.
*
* Mapping of input records to output records is complete when this method
* returns.
*
* @param input the {@link RecordReader} to read the input records.
* @param output the {@link OutputCollector} to collect the outputrecords.
* @param reporter {@link Reporter} to report progress, status-updates etc.
* @throws IOException
*/
void run(RecordReader input, OutputCollector output,
Reporter reporter)
throws IOException;
}