satishd commented on a change in pull request #10271: URL: https://github.com/apache/kafka/pull/10271#discussion_r620531430
########## File path: raft/src/main/java/org/apache/kafka/raft/metadata/AbstractMetadataRecordSerde.java ########## @@ -0,0 +1,82 @@ +/* + * 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.kafka.raft.metadata; + +import org.apache.kafka.common.errors.SerializationException; +import org.apache.kafka.common.metadata.MetadataRecordType; +import org.apache.kafka.common.protocol.ApiMessage; +import org.apache.kafka.common.protocol.ObjectSerializationCache; +import org.apache.kafka.common.protocol.Readable; +import org.apache.kafka.common.protocol.Writable; +import org.apache.kafka.common.utils.ByteUtils; +import org.apache.kafka.metadata.ApiMessageAndVersion; +import org.apache.kafka.raft.RecordSerde; + +/** + * This is an implementation of {@code RecordSerde} with {@code ApiMessageAndVersion} but implementors need to implement + * {@link #apiMessageFor(short)} to return a {@code ApiMessage} instance for the given {@code apiKey}. + * + * This can be used as the underlying serialization mechanism for any metadata kind of log storage. + */ +public abstract class AbstractMetadataRecordSerde implements RecordSerde<ApiMessageAndVersion> { + private static final short DEFAULT_FRAME_VERSION = 0; + private static final int DEFAULT_FRAME_VERSION_SIZE = ByteUtils.sizeOfUnsignedVarint(DEFAULT_FRAME_VERSION); + + @Override + public int recordSize(ApiMessageAndVersion data, + ObjectSerializationCache serializationCache) { + int size = DEFAULT_FRAME_VERSION_SIZE; + size += ByteUtils.sizeOfUnsignedVarint(data.message().apiKey()); + size += ByteUtils.sizeOfUnsignedVarint(data.version()); + size += data.message().size(serializationCache, data.version()); + return size; + } + + @Override + public void write(ApiMessageAndVersion data, + ObjectSerializationCache serializationCache, + Writable out) { + out.writeUnsignedVarint(DEFAULT_FRAME_VERSION); + out.writeUnsignedVarint(data.message().apiKey()); + out.writeUnsignedVarint(data.version()); + data.message().write(out, serializationCache, data.version()); + } + + @Override + public ApiMessageAndVersion read(Readable input, + int size) { + short frameVersion = (short) input.readUnsignedVarint(); + if (frameVersion != DEFAULT_FRAME_VERSION) { + throw new SerializationException("Could not deserialize metadata record due to unknown frame version " + + frameVersion + "(only frame version " + DEFAULT_FRAME_VERSION + " is supported)"); + } + + short apiKey = (short) input.readUnsignedVarint(); + short version = (short) input.readUnsignedVarint(); + ApiMessage record = apiMessageFor(apiKey); + record.read(input, version); + return new ApiMessageAndVersion(record, version); + } + + /** + * Return {@code ApiMessage} instance for the given {@code apiKey}. This is used while deserializing the bytes + * payload into the respective {@code ApiMessage} in {@link #read(Readable, int)} method. + * + * @param apiKey apiKey for which a {@code ApiMessage} to be created. + */ + public abstract ApiMessage apiMessageFor(short apiKey); Review comment: I guess it very unlikely to have such a use case in the future. If we encounter such a use case in the future, we can have a workaround to define a message in another topic and create a converter for one message definition to the other. -- 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: us...@infra.apache.org
