| /** |
| * 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.lib.output; |
| |
| import java.io.IOException; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.mapreduce.Job; |
| import org.apache.hadoop.mapreduce.JobContext; |
| import org.apache.hadoop.mapreduce.OutputCommitter; |
| import org.apache.hadoop.mapreduce.OutputFormat; |
| import org.apache.hadoop.mapreduce.RecordWriter; |
| import org.apache.hadoop.mapreduce.TaskAttemptContext; |
| import org.apache.hadoop.util.ReflectionUtils; |
| |
| /** |
| * A Convenience class that creates output lazily. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public class LazyOutputFormat <K,V> extends FilterOutputFormat<K, V> { |
| public static String OUTPUT_FORMAT = |
| "mapreduce.output.lazyoutputformat.outputformat"; |
| /** |
| * Set the underlying output format for LazyOutputFormat. |
| * @param job the {@link Job} to modify |
| * @param theClass the underlying class |
| */ |
| @SuppressWarnings("unchecked") |
| public static void setOutputFormatClass(Job job, |
| Class<? extends OutputFormat> theClass) { |
| job.setOutputFormatClass(LazyOutputFormat.class); |
| job.getConfiguration().setClass(OUTPUT_FORMAT, |
| theClass, OutputFormat.class); |
| } |
| |
| @SuppressWarnings("unchecked") |
| private void getBaseOutputFormat(Configuration conf) |
| throws IOException { |
| baseOut = ((OutputFormat<K, V>) ReflectionUtils.newInstance( |
| conf.getClass(OUTPUT_FORMAT, null), conf)); |
| if (baseOut == null) { |
| throw new IOException("Output Format not set for LazyOutputFormat"); |
| } |
| } |
| |
| @Override |
| public RecordWriter<K, V> getRecordWriter(TaskAttemptContext context) |
| throws IOException, InterruptedException { |
| if (baseOut == null) { |
| getBaseOutputFormat(context.getConfiguration()); |
| } |
| return new LazyRecordWriter<K, V>(baseOut, context); |
| } |
| |
| @Override |
| public void checkOutputSpecs(JobContext context) |
| throws IOException, InterruptedException { |
| if (baseOut == null) { |
| getBaseOutputFormat(context.getConfiguration()); |
| } |
| super.checkOutputSpecs(context); |
| } |
| |
| @Override |
| public OutputCommitter getOutputCommitter(TaskAttemptContext context) |
| throws IOException, InterruptedException { |
| if (baseOut == null) { |
| getBaseOutputFormat(context.getConfiguration()); |
| } |
| return super.getOutputCommitter(context); |
| } |
| |
| /** |
| * A convenience class to be used with LazyOutputFormat |
| */ |
| private static class LazyRecordWriter<K,V> extends FilterRecordWriter<K,V> { |
| |
| final OutputFormat<K,V> outputFormat; |
| final TaskAttemptContext taskContext; |
| |
| public LazyRecordWriter(OutputFormat<K,V> out, |
| TaskAttemptContext taskContext) |
| throws IOException, InterruptedException { |
| this.outputFormat = out; |
| this.taskContext = taskContext; |
| } |
| |
| @Override |
| public void write(K key, V value) throws IOException, InterruptedException { |
| if (rawWriter == null) { |
| rawWriter = outputFormat.getRecordWriter(taskContext); |
| } |
| rawWriter.write(key, value); |
| } |
| |
| @Override |
| public void close(TaskAttemptContext context) |
| throws IOException, InterruptedException { |
| if (rawWriter != null) { |
| rawWriter.close(context); |
| } |
| } |
| |
| } |
| } |