Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3663#discussion_r113243381
--- Diff:
flink-connectors/flink-connector-kafka-base/src/main/java/org/apache/flink/streaming/util/serialization/AvroRowDeserializationSchema.java
---
@@ -0,0 +1,157 @@
+/*
+ * 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.flink.streaming.util.serialization;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.util.List;
+import org.apache.avro.Schema;
+import org.apache.avro.generic.GenericData;
+import org.apache.avro.generic.GenericRecord;
+import org.apache.avro.io.DatumReader;
+import org.apache.avro.io.Decoder;
+import org.apache.avro.io.DecoderFactory;
+import org.apache.avro.reflect.ReflectDatumReader;
+import org.apache.avro.specific.SpecificData;
+import org.apache.avro.specific.SpecificRecord;
+import org.apache.avro.util.Utf8;
+import org.apache.flink.types.Row;
+import org.apache.flink.util.Preconditions;
+
+/**
+ * Deserialization schema from Avro bytes over {@link SpecificRecord} to
{@link Row}.
+ *
+ * Deserializes the <code>byte[]</code> messages into (nested) Flink Rows.
+ *
+ * {@link Utf8} is converted to regular Java Strings.
+ */
+public class AvroRowDeserializationSchema extends
AbstractDeserializationSchema<Row> {
+
+ /**
+ * Schema for deterministic field order.
+ */
+ private final Schema schema;
+
+ /**
+ * Reader that deserializes byte array into a record.
+ */
+ private final DatumReader<GenericRecord> datumReader;
+
+ /**
+ * Input stream to read message from.
+ */
+ private final MutableByteArrayInputStream inputStream;
+
+ /**
+ * Avro decoder that decodes binary data
+ */
+ private final Decoder decoder;
+
+ /**
+ * Record to deserialize byte array to.
+ */
+ private GenericRecord record;
+
+ /**
+ * Creates a Avro deserialization schema for the given record.
+ *
+ * @param recordClazz Avro record class used to deserialize Avro's
record to Flink's row
+ */
+ @SuppressWarnings("unchecked")
+ public AvroRowDeserializationSchema(Class<? extends SpecificRecord>
recordClazz) {
+ Preconditions.checkNotNull(recordClazz, "Avro record class must
not be null.");
+ this.schema = SpecificData.get().getSchema(recordClazz);
+ this.datumReader = new ReflectDatumReader<>(schema);
+ this.record = new GenericData.Record(schema);
+ this.inputStream = new MutableByteArrayInputStream();
+ this.decoder = DecoderFactory.get().binaryDecoder(inputStream,
null);
+ }
+
+ @Override
+ public Row deserialize(byte[] message) throws IOException {
+ // read record
+ try {
+ inputStream.setBuffer(message);
+ this.record = datumReader.read(record, decoder);
+ } catch (IOException e) {
+ throw new RuntimeException("Failed to deserialize
Row.", e);
+ }
+
+ // convert to row
+ final Object row = convertToRow(schema, record);
+ return (Row) row;
+ }
+
+ /**
+ * Converts a (nested) Avro {@link SpecificRecord} into Flink's Row
type.
+ * Avro's {@link Utf8} fields are converted into regular Java strings.
+ */
+ private static Object convertToRow(Schema schema, Object recordObj) {
+ if (recordObj instanceof GenericRecord) {
+ // records can be wrapped in a union
+ if (schema.getType() == Schema.Type.UNION) {
+ final List<Schema> types = schema.getTypes();
+ if (types.size() == 2 && types.get(0).getType()
== Schema.Type.NULL && types.get(1).getType() == Schema.Type.RECORD) {
+ schema = types.get(1);
+ }
+ else {
+ throw new RuntimeException("Currently
we only support schemas of the following form: UNION[null, RECORD]. Given: " +
schema);
+ }
+ } else if (schema.getType() != Schema.Type.RECORD) {
+ throw new RuntimeException("Record type for row
type expected. But is: " + schema);
+ }
+ final List<Schema.Field> fields = schema.getFields();
+ final Row row = new Row(fields.size());
+ for (int i = 0; i < fields.size(); i++) {
+ final Schema.Field field = fields.get(i);
+ final GenericRecord record = (GenericRecord)
recordObj;
--- End diff --
Move cast out of the loop
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