Github user gengliangwang commented on a diff in the pull request:
https://github.com/apache/spark/pull/21774#discussion_r203796377
--- Diff:
external/avro/src/main/scala/org/apache/spark/sql/avro/CatalystDataToAvro.scala
---
@@ -0,0 +1,67 @@
+/*
+ * 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
+
+import java.io.ByteArrayOutputStream
+
+import org.apache.avro.generic.GenericDatumWriter
+import org.apache.avro.io.{BinaryEncoder, EncoderFactory}
+
+import org.apache.spark.sql.avro.{AvroSerializer, SchemaConverters}
+import org.apache.spark.sql.catalyst.expressions.{Expression,
UnaryExpression}
+import org.apache.spark.sql.catalyst.expressions.codegen.{CodegenContext,
CodeGenerator, ExprCode}
+import org.apache.spark.sql.types.{BinaryType, DataType}
+
+case class CatalystDataToAvro(child: Expression) extends UnaryExpression {
+
+ override def dataType: DataType = BinaryType
+
+ @transient private lazy val avroType =
+ SchemaConverters.toAvroType(child.dataType, child.nullable)
+
+ @transient private lazy val serializer =
+ new AvroSerializer(child.dataType, avroType, child.nullable)
+
+ @transient private lazy val writer =
+ new GenericDatumWriter[Any](avroType)
+
+ @transient private var encoder: BinaryEncoder = _
+
+ @transient private lazy val out = new ByteArrayOutputStream
+
+ override def nullSafeEval(input: Any): Any = {
+ out.reset()
+ encoder = EncoderFactory.get().directBinaryEncoder(out, encoder)
+ val avroData = serializer.serialize(input)
+ writer.write(avroData, encoder)
+ encoder.flush()
+ out.toByteArray
+ }
+
+ override def simpleString: String = {
+ s"to_avro(${child.sql}, ${child.dataType.simpleString})"
+ }
+
+ override def sql: String = simpleString
+
+ override protected def doGenCode(ctx: CodegenContext, ev: ExprCode):
ExprCode = {
--- End diff --
I tried complicated code like
```
nullSafeCodeGen(ctx, ev, binary => {
val avroReader = ctx.addReferenceObj("reader", reader)
val avroDeserializer = ctx.addReferenceObj("deserializer",
deserializer)
val avroDecoder = ctx.addMutableState(classOf[BinaryDecoder].getName,
"avroDecoder")
val catalystResult = ctx.addMutableState(classOf[Any].getName,
"catalystResult")
val decoderFactory = classOf[DecoderFactory].getName
s"""
$avroDecoder = $decoderFactory.get().binaryDecoder($binary,
$avroDecoder);
try {
$catalystResult = $avroReader.read($catalystResult, $avroDecoder);
} catch (java.io.IOException e) {
org.apache.spark.unsafe.Platform.throwException(e);
}
${ev.value} = (${CodeGenerator.boxedType(dataType)})
$avroDeserializer.deserialize($catalystResult);
"""
})
```
But eventually find it hard to serialize some objects.
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