[GitHub] [incubator-hudi] afilipchik commented on a change in pull request #1562: [HUDI-837]: implemented custom deserializer for AvroKafkaSource

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afilipchik commented on a change in pull request #1562:
URL: https://github.com/apache/incubator-hudi/pull/1562#discussion_r419843893



##########
File path: hudi-utilities/src/main/java/org/apache/hudi/utilities/sources/serde/HoodieAvroKafkaDeserializer.java
##########
@@ -0,0 +1,78 @@
+/*
+ * 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.hudi.utilities.sources.serde;
+
+import org.apache.hudi.common.config.TypedProperties;
+import org.apache.hudi.utilities.UtilHelpers;
+import org.apache.hudi.utilities.schema.SchemaProvider;
+
+import io.confluent.kafka.serializers.AbstractKafkaAvroDeserializer;
+import io.confluent.kafka.serializers.KafkaAvroDeserializerConfig;
+import kafka.serializer.Decoder;
+import kafka.utils.VerifiableProperties;
+import org.apache.avro.Schema;
+import org.apache.kafka.common.errors.SerializationException;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Properties;
+
+/**
+ * This is a custom implementation of kafka.serializer.Decoder<T> which aims at deserializing all the incoming messages
+ * with same schema (which is latest).
+ */
+public class HoodieAvroKafkaDeserializer extends AbstractKafkaAvroDeserializer implements Decoder<Object> {

Review comment:
       probably should be called Confluent... as it assumes that schema registry is from confluent.

##########
File path: hudi-utilities/src/main/java/org/apache/hudi/utilities/sources/serde/HoodieAvroKafkaDeserializer.java
##########
@@ -0,0 +1,78 @@
+/*
+ * 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.hudi.utilities.sources.serde;
+
+import org.apache.hudi.common.config.TypedProperties;
+import org.apache.hudi.utilities.UtilHelpers;
+import org.apache.hudi.utilities.schema.SchemaProvider;
+
+import io.confluent.kafka.serializers.AbstractKafkaAvroDeserializer;
+import io.confluent.kafka.serializers.KafkaAvroDeserializerConfig;
+import kafka.serializer.Decoder;
+import kafka.utils.VerifiableProperties;
+import org.apache.avro.Schema;
+import org.apache.kafka.common.errors.SerializationException;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Properties;
+
+/**
+ * This is a custom implementation of kafka.serializer.Decoder<T> which aims at deserializing all the incoming messages
+ * with same schema (which is latest).
+ */
+public class HoodieAvroKafkaDeserializer extends AbstractKafkaAvroDeserializer implements Decoder<Object> {
+
+  private final Schema sourceSchema;
+  private static final String SCHEMA_PROVIDER_CLASS_PROP = "hoodie.deltastreamer.schemaprovider.class";
+
+  public HoodieAvroKafkaDeserializer(VerifiableProperties properties) {
+    this.configure(new KafkaAvroDeserializerConfig(properties.props()));
+    TypedProperties typedProperties = new TypedProperties();
+    copyProperties(typedProperties, properties.props());
+    try {
+      SchemaProvider schemaProvider = UtilHelpers.createSchemaProvider(

Review comment:
       Oh, right. We actually have internal implementation which is very similar to this one, except reader schema thing.

##########
File path: hudi-utilities/src/main/java/org/apache/hudi/utilities/sources/serde/HoodieAvroKafkaDeserializer.java
##########
@@ -0,0 +1,78 @@
+/*
+ * 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.hudi.utilities.sources.serde;
+
+import org.apache.hudi.common.config.TypedProperties;
+import org.apache.hudi.utilities.UtilHelpers;
+import org.apache.hudi.utilities.schema.SchemaProvider;
+
+import io.confluent.kafka.serializers.AbstractKafkaAvroDeserializer;
+import io.confluent.kafka.serializers.KafkaAvroDeserializerConfig;
+import kafka.serializer.Decoder;
+import kafka.utils.VerifiableProperties;
+import org.apache.avro.Schema;
+import org.apache.kafka.common.errors.SerializationException;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Properties;
+
+/**
+ * This is a custom implementation of kafka.serializer.Decoder<T> which aims at deserializing all the incoming messages
+ * with same schema (which is latest).
+ */
+public class HoodieAvroKafkaDeserializer extends AbstractKafkaAvroDeserializer implements Decoder<Object> {
+
+  private final Schema sourceSchema;
+  private static final String SCHEMA_PROVIDER_CLASS_PROP = "hoodie.deltastreamer.schemaprovider.class";
+
+  public HoodieAvroKafkaDeserializer(VerifiableProperties properties) {
+    this.configure(new KafkaAvroDeserializerConfig(properties.props()));
+    TypedProperties typedProperties = new TypedProperties();
+    copyProperties(typedProperties, properties.props());
+    try {
+      SchemaProvider schemaProvider = UtilHelpers.createSchemaProvider(
+          typedProperties.getString(SCHEMA_PROVIDER_CLASS_PROP), typedProperties);
+      sourceSchema = Objects.requireNonNull(schemaProvider).getSourceSchema();
+    } catch (IOException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  @Override
+  public Object fromBytes(byte[] bytes) {
+    return deserialize(bytes);
+  }
+
+  @Override
+  protected Object deserialize(boolean includeSchemaAndVersion, String topic, Boolean isKey, byte[] payload, Schema readerSchema) throws SerializationException {
+    if (readerSchema != null) {
+      return super.deserialize(includeSchemaAndVersion, topic, isKey, payload, readerSchema);
+    }

Review comment:
       What does this check do? Should we always use sourceSchema over reader schema if it is not null as if I specified source schema I expect it to be used? 
   
   What situation will have reader schema specified and preferred?

##########
File path: hudi-utilities/src/main/java/org/apache/hudi/utilities/sources/AvroKafkaSource.java
##########
@@ -45,11 +46,14 @@
 
   private final KafkaOffsetGen offsetGen;
 
+  private final String useCustomDeserializerProp = "hoodie.deltastreamer.kafka.custom.avro.deserializer";
+
   public AvroKafkaSource(TypedProperties props, JavaSparkContext sparkContext, SparkSession sparkSession,
       SchemaProvider schemaProvider) {
     super(props, sparkContext, sparkSession, schemaProvider);
+    boolean useCustomDeserializer = props.getBoolean(useCustomDeserializerProp, false);
     props.put("key.deserializer", StringDeserializer.class);
-    props.put("value.deserializer", KafkaAvroDeserializer.class);
+    props.put("value.deserializer", useCustomDeserializer ? HoodieAvroKafkaDeserializer.class : KafkaAvroDeserializer.class);

Review comment:
       is it fair to assume confluent is default for avro?




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