Sanil15 commented on a change in pull request #1227: SAMZA-2404: [SEP-22] Container Placement Handler for dispatching container placement messages between metastore and JobCoordinator URL: https://github.com/apache/samza/pull/1227#discussion_r366495690
########## File path: samza-core/src/main/java/org/apache/samza/clustermanager/container/placement/ContainerPlacementMessageObjectMapper.java ########## @@ -0,0 +1,119 @@ +/* + * 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.samza.clustermanager.container.placement; + +import java.io.IOException; +import java.time.Duration; +import java.util.HashMap; +import java.util.Map; +import java.util.UUID; +import org.apache.samza.container.placement.ContainerPlacementMessage; +import org.apache.samza.container.placement.ContainerPlacementRequestMessage; +import org.apache.samza.container.placement.ContainerPlacementResponseMessage; +import org.codehaus.jackson.JsonGenerator; +import org.codehaus.jackson.JsonNode; +import org.codehaus.jackson.JsonParser; +import org.codehaus.jackson.ObjectCodec; +import org.codehaus.jackson.Version; +import org.codehaus.jackson.map.DeserializationContext; +import org.codehaus.jackson.map.JsonDeserializer; +import org.codehaus.jackson.map.JsonSerializer; +import org.codehaus.jackson.map.ObjectMapper; +import org.codehaus.jackson.map.SerializerProvider; +import org.codehaus.jackson.map.jsontype.NamedType; +import org.codehaus.jackson.map.module.SimpleModule; + +/** + * Object mapper for serializing and deserializing Container placement messages + */ +public class ContainerPlacementMessageObjectMapper { + + private ContainerPlacementMessageObjectMapper() { + } + + static ObjectMapper getObjectMapper() { + ObjectMapper objectMapper = new ObjectMapper(); + SimpleModule module = new SimpleModule("ContainerPlacementModule", new Version(1, 0, 0, "")); + module.addSerializer(ContainerPlacementMessage.class, + new ContainerPlacementMessageObjectMapper.ContainerPlacementMessageSerializer()); + module.addDeserializer(ContainerPlacementMessage.class, + new ContainerPlacementMessageObjectMapper.ContainerPlacementMessageDeserializer()); + objectMapper.registerModule(module); + objectMapper.registerSubtypes(new NamedType(ContainerPlacementResponseMessage.class)); + objectMapper.registerSubtypes(new NamedType(ContainerPlacementRequestMessage.class)); + return objectMapper; + } + + static class ContainerPlacementMessageSerializer extends JsonSerializer<ContainerPlacementMessage> { + @Override + public void serialize(ContainerPlacementMessage value, JsonGenerator jsonGenerator, SerializerProvider provider) + throws IOException { + Map<String, Object> containerPlacementMessageMap = new HashMap<String, Object>(); + if (value instanceof ContainerPlacementRequestMessage) { + containerPlacementMessageMap.put("subType", ContainerPlacementRequestMessage.class.getSimpleName()); + } else if (value instanceof ContainerPlacementResponseMessage) { + containerPlacementMessageMap.put("subType", ContainerPlacementResponseMessage.class.getSimpleName()); + containerPlacementMessageMap.put("responseMessage", + ((ContainerPlacementResponseMessage) value).getResponseMessage()); + } Review comment: Nice question, a couple of things to note: 1. ContainerPlacementMessageSerializer can only be used for serializing a ContainerPlacementMessage which has two subtypes only, so I don't think a type check is required here since it's implicit 2. However, if a user writes a JSON payload with a different type using a custom serializer under the same namespace in meta store ContainerPlacementMessageDeserialzer will read that message as null which is handled everywhere as Optional in ContainerPlacementUtil 3. Now if the user writes a corrupted message to Metastore with null fields for required fields, then deserializer is gonna throw an exception ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
