/*
* 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.pig.piggybank.storage.avro;
import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.avro.Schema;
import org.apache.avro.Schema.Field;
import org.apache.avro.Schema.Type;
/**
* This class creates two maps out of a given Avro schema. And it supports
* looking up avro schemas using either type name or field name.
*
* 1. map[type name] = > avro schema
* 2. map[field name] => avro schema
*
*/
public class AvroSchemaManager {
/**map[field name] => schema */
Map<String, Schema> name2Schema = null;
/**map[type name]=> schema*/
Map<String, Schema> typeName2Schema = null;
/**
* Construct with a given schema
*/
public AvroSchemaManager(Schema schema) throws IOException {
name2Schema = new HashMap<String, Schema>();
typeName2Schema = new HashMap<String, Schema>();
if (AvroStorageUtils.containsRecursiveRecord(schema)) {
throw new IOException ("Schema containing recursive records cannot be referred to"
+ " by 'data' and 'schema_file'. Please instead use 'same' with a path that"
+ " points to an avro file encoded by the same schema as what you want to use,"
+ " or use 'schema' with a json string representation." );
}
init(null, schema, false);
}
private boolean isNamedSchema(Schema schema) {
Type type = schema.getType();
return type.equals(Type.RECORD) || type.equals(Type.ENUM) || type.equals(Type.FIXED);
}
/**
* Initialize given a schema
*/
protected void init(String namespace, Schema schema,
boolean ignoreNameMap) {
/* put to map[type name]=>schema */
if (isNamedSchema(schema)) {
String typeName = schema.getName();
if (typeName2Schema.containsKey(typeName))
AvroStorageLog.warn("Duplicate schemas defined for type:"
+ typeName
+ ". will ignore the second one:"
+ schema);
else {
AvroStorageLog.details("add " + schema.getName() + "=" + schema
+ " to type2Schema");
typeName2Schema.put(schema.getName(), schema);
}
}
/* put field schema to map[field name]=>schema*/
if (schema.getType().equals(Type.RECORD)) {
List<Field> fields = schema.getFields();
for (Field field : fields) {
Schema fieldSchema = field.schema();
String name = (namespace == null) ? field.name() : namespace + "." + field.name();
if (!ignoreNameMap) {
if (name2Schema.containsKey(name))
AvroStorageLog.warn("Duplicate schemas defined for alias:" + name
+ ". Will ignore the second one:"+ fieldSchema);
else {
AvroStorageLog.details("add " + name + "=" + fieldSchema + " to name2Schema");
name2Schema.put(name, fieldSchema);
}
}
init(name, fieldSchema, ignoreNameMap);
}
} else if (schema.getType().equals(Type.UNION)) {
if (AvroStorageUtils.isAcceptableUnion(schema)) {
Schema realSchema = AvroStorageUtils.getAcceptedType(schema);
init(namespace, realSchema, ignoreNameMap);
} else {
List<Schema> list = schema.getTypes();
for (Schema s : list) {
init(namespace, s, true);
}
}
} else if (schema.getType().equals(Type.ARRAY)) {
Schema elemSchema = schema.getElementType();
init(namespace, elemSchema, true);
} else if (schema.getType().equals(Type.MAP)) {
Schema valueSchema = schema.getValueType();
init(namespace, valueSchema, true);
}
}
/**
* Look up schema using type name or field name
*/
public Schema getSchema(String name) {
Schema schema = typeName2Schema.get(name);
schema = (schema == null) ? name2Schema.get(name) : schema;
return schema;
}
}