Github user cloud-fan commented on a diff in the pull request: https://github.com/apache/spark/pull/21762#discussion_r202502456 --- Diff: external/avro/src/main/scala/org/apache/spark/sql/avro/AvroDeserializer.scala --- @@ -0,0 +1,348 @@ +/* + * 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.spark.sql.avro + +import java.nio.ByteBuffer + +import scala.collection.JavaConverters._ +import scala.collection.mutable.ArrayBuffer + +import org.apache.avro.{Schema, SchemaBuilder} +import org.apache.avro.Schema.Type._ +import org.apache.avro.generic._ +import org.apache.avro.util.Utf8 + +import org.apache.spark.sql.catalyst.InternalRow +import org.apache.spark.sql.catalyst.expressions.{SpecificInternalRow, UnsafeArrayData} +import org.apache.spark.sql.catalyst.util.{ArrayBasedMapData, ArrayData, DateTimeUtils, GenericArrayData} +import org.apache.spark.sql.types._ +import org.apache.spark.unsafe.types.UTF8String + +/** + * A deserializer to deserialize data in avro format to data in catalyst format. + */ +class AvroDeserializer(rootAvroType: Schema, rootCatalystType: DataType) { + private val converter: Any => Any = rootCatalystType match { + // A shortcut for empty schema. + case st: StructType if st.isEmpty => + (data: Any) => InternalRow.empty + + case st: StructType => + val resultRow = new SpecificInternalRow(st.map(_.dataType)) + val fieldUpdater = new RowUpdater(resultRow) + val writer = getRecordWriter(rootAvroType, st, Nil) + (data: Any) => { + val record = data.asInstanceOf[GenericRecord] + writer(fieldUpdater, record) + resultRow + } + + case _ => + val tmpRow = new SpecificInternalRow(Seq(rootCatalystType)) + val fieldUpdater = new RowUpdater(tmpRow) + val writer = newWriter(rootAvroType, rootCatalystType, Nil) + (data: Any) => { + writer(fieldUpdater, 0, data) + tmpRow.get(0, rootCatalystType) + } + } + + def deserialize(data: Any): Any = converter(data) + + /** + * Creates a writer to writer avro values to Catalyst values at the given ordinal with the given --- End diff -- nit `a writer to write`
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