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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.hadoop.io; import java.lang.reflect.Constructor; import java.util.Collection; import org.apache.avro.Schema; import org.apache.avro.generic.GenericData; import org.apache.avro.io.DatumReader; import org.apache.avro.io.DatumWriter; import org.apache.avro.mapred.AvroKey; import org.apache.avro.mapred.AvroValue; import org.apache.avro.mapred.AvroWrapper; import org.apache.avro.reflect.ReflectData; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.conf.Configured; import org.apache.hadoop.io.serializer.Deserializer; import org.apache.hadoop.io.serializer.Serialization; import org.apache.hadoop.io.serializer.Serializer; import org.apache.hadoop.util.ReflectionUtils; /** * The {@link org.apache.hadoop.io.serializer.Serialization} used by jobs configured with * {@link org.apache.avro.mapreduce.AvroJob}. * * @param <T> The Java type of the Avro data to serialize. */ public class AvroSerialization<T> extends Configured implements Serialization<AvroWrapper<T>> { /** Conf key for the writer schema of the AvroKey datum being serialized/deserialized. */ private static final String CONF_KEY_WRITER_SCHEMA = "avro.serialization.key.writer.schema"; /** Conf key for the reader schema of the AvroKey datum being serialized/deserialized. */ private static final String CONF_KEY_READER_SCHEMA = "avro.serialization.key.reader.schema"; /** Conf key for the writer schema of the AvroValue datum being serialized/deserialized. */ private static final String CONF_VALUE_WRITER_SCHEMA = "avro.serialization.value.writer.schema"; /** Conf key for the reader schema of the AvroValue datum being serialized/deserialized. */ private static final String CONF_VALUE_READER_SCHEMA = "avro.serialization.value.reader.schema"; /** Conf key for the data model implementation class. */ private static final String CONF_DATA_MODEL = "avro.serialization.data.model"; /** {@inheritDoc} */ @Override public boolean accept(Class<?> c) { return AvroKey.class.isAssignableFrom(c) || AvroValue.class.isAssignableFrom(c); } /** * Gets an object capable of deserializing the output from a Mapper. * * @param c The class to get a deserializer for. * @return A deserializer for objects of class <code>c</code>. */ @Override public Deserializer<AvroWrapper<T>> getDeserializer(Class<AvroWrapper<T>> c) { Configuration conf = getConf(); GenericData dataModel = createDataModel(conf); if (AvroKey.class.isAssignableFrom(c)) { Schema writerSchema = getKeyWriterSchema(conf); Schema readerSchema = getKeyReaderSchema(conf); DatumReader<T> datumReader = (readerSchema != null) ? dataModel.createDatumReader(writerSchema, readerSchema) : dataModel.createDatumReader(writerSchema); return new AvroKeyDeserializer<T>(writerSchema, readerSchema, datumReader); } else if (AvroValue.class.isAssignableFrom(c)) { Schema writerSchema = getValueWriterSchema(conf); Schema readerSchema = getValueReaderSchema(conf); DatumReader<T> datumReader = (readerSchema != null) ? dataModel.createDatumReader(writerSchema, readerSchema) : dataModel.createDatumReader(writerSchema); return new AvroValueDeserializer<T>(writerSchema, readerSchema, datumReader); } else { throw new IllegalStateException("Only AvroKey and AvroValue are supported."); } } /** * Gets an object capable of serializing output from a Mapper. * * @param c The class to get a serializer for. * @return A serializer for objects of class <code>c</code>. */ @Override public Serializer<AvroWrapper<T>> getSerializer(Class<AvroWrapper<T>> c) { Configuration conf = getConf(); Schema schema; if (AvroKey.class.isAssignableFrom(c)) { schema = getKeyWriterSchema(conf); } else if (AvroValue.class.isAssignableFrom(c)) { schema = getValueWriterSchema(conf); } else { throw new IllegalStateException("Only AvroKey and AvroValue are supported."); } GenericData dataModel = createDataModel(conf); DatumWriter<T> datumWriter = dataModel.createDatumWriter(schema); return new AvroSerializer<T>(schema, datumWriter); } /** * Adds the AvroSerialization scheme to the configuration, so SerializationFactory * instances constructed from the given configuration will be aware of it. * * @param conf The configuration to add AvroSerialization to. */ public static void addToConfiguration(Configuration conf) { Collection<String> serializations = conf.getStringCollection("io.serializations"); if (!serializations.contains(AvroSerialization.class.getName())) { serializations.add(AvroSerialization.class.getName()); conf.setStrings("io.serializations", serializations.toArray(new String[serializations.size()])); } } /** * Sets the writer schema of the AvroKey datum that is being serialized/deserialized. * * @param conf The configuration. * @param schema The Avro key schema. */ public static void setKeyWriterSchema(Configuration conf, Schema schema) { if (null == schema) { throw new IllegalArgumentException("Writer schema may not be null"); } conf.set(CONF_KEY_WRITER_SCHEMA, schema.toString()); } /** * Sets the reader schema of the AvroKey datum that is being serialized/deserialized. * * @param conf The configuration. * @param schema The Avro key schema. */ public static void setKeyReaderSchema(Configuration conf, Schema schema) { conf.set(CONF_KEY_READER_SCHEMA, schema.toString()); } /** * Sets the writer schema of the AvroValue datum that is being serialized/deserialized. * * @param conf The configuration. * @param schema The Avro value schema. */ public static void setValueWriterSchema(Configuration conf, Schema schema) { if (null == schema) { throw new IllegalArgumentException("Writer schema may not be null"); } conf.set(CONF_VALUE_WRITER_SCHEMA, schema.toString()); } /** * Sets the reader schema of the AvroValue datum that is being serialized/deserialized. * * @param conf The configuration. * @param schema The Avro value schema. */ public static void setValueReaderSchema(Configuration conf, Schema schema) { conf.set(CONF_VALUE_READER_SCHEMA, schema.toString()); } /** * Sets the data model class for de/seralization. * * @param conf The configuration. * @param modelClass The data model class. */ public static void setDataModelClass(Configuration conf, Class<? extends GenericData> modelClass) { conf.setClass(CONF_DATA_MODEL, modelClass, GenericData.class); } /** * Gets the writer schema of the AvroKey datum that is being serialized/deserialized. * * @param conf The configuration. * @return The Avro key writer schema, or null if none was set. */ public static Schema getKeyWriterSchema(Configuration conf) { String json = conf.get(CONF_KEY_WRITER_SCHEMA); return null == json ? null : Schema.parse(json); } /** * Gets the reader schema of the AvroKey datum that is being serialized/deserialized. * * @param conf The configuration. * @return The Avro key reader schema, or null if none was set. */ public static Schema getKeyReaderSchema(Configuration conf) { String json = conf.get(CONF_KEY_READER_SCHEMA); return null == json ? null : Schema.parse(json); } /** * Gets the writer schema of the AvroValue datum that is being serialized/deserialized. * * @param conf The configuration. * @return The Avro value writer schema, or null if none was set. */ public static Schema getValueWriterSchema(Configuration conf) { String json = conf.get(CONF_VALUE_WRITER_SCHEMA); return null == json ? null : Schema.parse(json); } /** * Gets the reader schema of the AvroValue datum that is being serialized/deserialized. * * @param conf The configuration. * @return The Avro value reader schema, or null if none was set. */ public static Schema getValueReaderSchema(Configuration conf) { String json = conf.get(CONF_VALUE_READER_SCHEMA); return null == json ? null : Schema.parse(json); } /** * Gets the data model class for de/seralization. * * @param conf The configuration. */ public static Class<? extends GenericData> getDataModelClass(Configuration conf) { return conf.getClass(CONF_DATA_MODEL, ReflectData.class, GenericData.class); } private static GenericData newDataModelInstance(Class<? extends GenericData> modelClass, Configuration conf) { GenericData dataModel; try { Constructor<? extends GenericData> ctor = modelClass.getDeclaredConstructor(ClassLoader.class); ctor.setAccessible(true); dataModel = ctor.newInstance(conf.getClassLoader()); } catch (Exception e) { throw new RuntimeException(e); } ReflectionUtils.setConf(dataModel, conf); return dataModel; } /** * Gets an instance of data model implementation, defaulting to * {@link ReflectData} if not explicitly specified. * * @param conf The job configuration. * @return Instance of the job data model implementation. */ public static GenericData createDataModel(Configuration conf) { Class<? extends GenericData> modelClass = getDataModelClass(conf); return newDataModelInstance(modelClass, conf); } }