content: /*
   * 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
   *
   *     https://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 parametrize 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 ? new Schema.Parser().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 ? new Schema.Parser().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 ? new Schema.Parser().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 ? new Schema.Parser().parse(schemaString) : null;
    }
  }
  