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/** * 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.mapreduce; import org.apache.avro.Schema; import org.apache.avro.generic.GenericData; import org.apache.avro.hadoop.io.AvroKeyComparator; import org.apache.avro.hadoop.io.AvroSerialization; import org.apache.avro.mapred.AvroKey; import org.apache.avro.mapred.AvroValue; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.mapreduce.Job; /** * Utility methods for configuring jobs that work with Avro. * * <p>When using Avro data as MapReduce keys and values, data must be wrapped in a * suitable AvroWrapper implementation. MapReduce keys must be wrapped in an AvroKey * object, and MapReduce values must be wrapped in an AvroValue object.</p> * * <p>Suppose you would like to write a line count mapper that reads from a text file. If * instead of using a Text and IntWritable output value, you would like to use Avro data * with a schema of <i>"string"</i> and <i>"int"</i>, respectively, you may parameterize * your mapper with {@code AvroKey<CharSequence>} and {@code AvroValue<Integer>} * types. Then, use the <code>setMapOutputKeySchema()</code> and * <code>setMapOutputValueSchema()</code> methods to set writer schemas for the records * you will generate.</p> */ public final class AvroJob { /** Disable the constructor for this utility class. */ private AvroJob() { } /** Configuration key for the input key schema. */ private static final String CONF_INPUT_KEY_SCHEMA = "avro.schema.input.key"; /** Configuration key for the input value schema. */ private static final String CONF_INPUT_VALUE_SCHEMA = "avro.schema.input.value"; /** Configuration key for the output key schema. */ private static final String CONF_OUTPUT_KEY_SCHEMA = "avro.schema.output.key"; /** Configuration key for the output value schema. */ private static final String CONF_OUTPUT_VALUE_SCHEMA = "avro.schema.output.value"; /** The configuration key for a job's output compression codec. * This takes one of the strings registered in {@link org.apache.avro.file.CodecFactory} */ public static final String CONF_OUTPUT_CODEC = "avro.output.codec"; /** * Sets the job input key schema. * * @param job The job to configure. * @param schema The input key schema. */ public static void setInputKeySchema(Job job, Schema schema) { job.getConfiguration().set(CONF_INPUT_KEY_SCHEMA, schema.toString()); } /** * Sets the job input value schema. * * @param job The job to configure. * @param schema The input value schema. */ public static void setInputValueSchema(Job job, Schema schema) { job.getConfiguration().set(CONF_INPUT_VALUE_SCHEMA, schema.toString()); } /** * Sets the map output key schema. * * @param job The job to configure. * @param schema The map output key schema. */ public static void setMapOutputKeySchema(Job job, Schema schema) { job.setMapOutputKeyClass(AvroKey.class); job.setGroupingComparatorClass(AvroKeyComparator.class); job.setSortComparatorClass(AvroKeyComparator.class); AvroSerialization.setKeyWriterSchema(job.getConfiguration(), schema); AvroSerialization.setKeyReaderSchema(job.getConfiguration(), schema); AvroSerialization.addToConfiguration(job.getConfiguration()); } /** * Sets the map output value schema. * * @param job The job to configure. * @param schema The map output value schema. */ public static void setMapOutputValueSchema(Job job, Schema schema) { job.setMapOutputValueClass(AvroValue.class); AvroSerialization.setValueWriterSchema(job.getConfiguration(), schema); AvroSerialization.setValueReaderSchema(job.getConfiguration(), schema); AvroSerialization.addToConfiguration(job.getConfiguration()); } /** * Sets the job output key schema. * * @param job The job to configure. * @param schema The job output key schema. */ public static void setOutputKeySchema(Job job, Schema schema) { job.setOutputKeyClass(AvroKey.class); job.getConfiguration().set(CONF_OUTPUT_KEY_SCHEMA, schema.toString()); } /** * Sets the job output value schema. * * @param job The job to configure. * @param schema The job output value schema. */ public static void setOutputValueSchema(Job job, Schema schema) { job.setOutputValueClass(AvroValue.class); job.getConfiguration().set(CONF_OUTPUT_VALUE_SCHEMA, schema.toString()); } /** * Sets the job data model class. * * @param job The job to configure. * @param modelClass The job data model class. */ public static void setDataModelClass(Job job, Class<? extends GenericData> modelClass) { AvroSerialization.setDataModelClass(job.getConfiguration(), modelClass); } /** * Gets the job input key schema. * * @param conf The job configuration. * @return The job input key schema, or null if not set. */ public static Schema getInputKeySchema(Configuration conf) { String schemaString = conf.get(CONF_INPUT_KEY_SCHEMA); return schemaString != null ? Schema.parse(schemaString) : null; } /** * Gets the job input value schema. * * @param conf The job configuration. * @return The job input value schema, or null if not set. */ public static Schema getInputValueSchema(Configuration conf) { String schemaString = conf.get(CONF_INPUT_VALUE_SCHEMA); return schemaString != null ? Schema.parse(schemaString) : null; } /** * Gets the map output key schema. * * @param conf The job configuration. * @return The map output key schema, or null if not set. */ public static Schema getMapOutputKeySchema(Configuration conf) { return AvroSerialization.getKeyWriterSchema(conf); } /** * Gets the map output value schema. * * @param conf The job configuration. * @return The map output value schema, or null if not set. */ public static Schema getMapOutputValueSchema(Configuration conf) { return AvroSerialization.getValueWriterSchema(conf); } /** * Gets the job output key schema. * * @param conf The job configuration. * @return The job output key schema, or null if not set. */ public static Schema getOutputKeySchema(Configuration conf) { String schemaString = conf.get(CONF_OUTPUT_KEY_SCHEMA); return schemaString != null ? Schema.parse(schemaString) : null; } /** * Gets the job output value schema. * * @param conf The job configuration. * @return The job output value schema, or null if not set. */ public static Schema getOutputValueSchema(Configuration conf) { String schemaString = conf.get(CONF_OUTPUT_VALUE_SCHEMA); return schemaString != null ? Schema.parse(schemaString) : null; } }