szetszwo commented on code in PR #4693: URL: https://github.com/apache/ozone/pull/4693#discussion_r1193214415
########## hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/utils/db/Proto3Codec.java: ########## @@ -0,0 +1,106 @@ +/* + * 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.hadoop.hdds.utils.db; + +import org.apache.ratis.thirdparty.com.google.protobuf.CodedOutputStream; +import org.apache.ratis.thirdparty.com.google.protobuf.InvalidProtocolBufferException; +import org.apache.ratis.thirdparty.com.google.protobuf.MessageLite; +import org.apache.ratis.thirdparty.com.google.protobuf.Parser; + +import javax.annotation.Nonnull; +import java.io.IOException; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ConcurrentMap; +import java.util.function.IntFunction; + +/** + * Codecs to serialize/deserialize Protobuf v3 messages. + */ +public final class Proto3Codec<M extends MessageLite> + implements Codec<M> { + private static final ConcurrentMap<Class<? extends MessageLite>, + Codec<? extends MessageLite>> CODECS + = new ConcurrentHashMap<>(); + + /** + * @return the {@link Codec} for the given class. + */ + public static <T extends MessageLite> Codec<T> get(Class<T> clazz) { + final Codec<?> codec = CODECS.computeIfAbsent(clazz, Proto3Codec::new); + return (Codec<T>) codec; + } Review Comment: The map is to enforce singleton. We may consider `Proto3Codec::new` expensive since it uses reflection to create an object. Suppose we return a new object as below ```java public static <T extends MessageLite> Codec<T> getNew(Class<T> clazz) { return new Proto3Codec(clazz); } ``` Then, it can possibly be misused as ```java getNew().toCodecBuffer(message, allocator); ``` i.e. it creates a new codec for each serialization. -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
