| /** |
| * 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.mapreduce; |
| |
| import java.io.IOException; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| /** |
| * A context object that allows input and output from the task. It is only |
| * supplied to the {@link Mapper} or {@link Reducer}. |
| * @param <KEYIN> the input key type for the task |
| * @param <VALUEIN> the input value type for the task |
| * @param <KEYOUT> the output key type for the task |
| * @param <VALUEOUT> the output value type for the task |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Evolving |
| public interface TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT> |
| extends TaskAttemptContext { |
| |
| /** |
| * Advance to the next key, value pair, returning null if at end. |
| * @return the key object that was read into, or null if no more |
| */ |
| public boolean nextKeyValue() throws IOException, InterruptedException; |
| |
| /** |
| * Get the current key. |
| * @return the current key object or null if there isn't one |
| * @throws IOException |
| * @throws InterruptedException |
| */ |
| public KEYIN getCurrentKey() throws IOException, InterruptedException; |
| |
| /** |
| * Get the current value. |
| * @return the value object that was read into |
| * @throws IOException |
| * @throws InterruptedException |
| */ |
| public VALUEIN getCurrentValue() throws IOException, InterruptedException; |
| |
| /** |
| * Generate an output key/value pair. |
| */ |
| public void write(KEYOUT key, VALUEOUT value) |
| throws IOException, InterruptedException; |
| |
| /** |
| * Get the {@link OutputCommitter} for the task-attempt. |
| * @return the <code>OutputCommitter</code> for the task-attempt |
| */ |
| public OutputCommitter getOutputCommitter(); |
| } |