satishd commented on a change in pull request #10271: URL: https://github.com/apache/kafka/pull/10271#discussion_r645659750
########## File path: raft/src/main/java/org/apache/kafka/raft/metadata/AbstractApiMessageSerde.java ########## @@ -0,0 +1,93 @@ +/* + * 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.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 {@link 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 records defined with {@link ApiMessage}s. + * <p></p> + * Serialization format for the given {@code ApiMessageAndVersion} is below: + * <p></p> + * <pre> + * [data_frame_version header message] + * header => [api_key version] + * + * data_frame_version : This is the header version, current value is 0. Header includes both api_key and version. + * api_key : apiKey of {@code ApiMessageAndVersion} object. + * version : version of {@code ApiMessageAndVersion} object. + * message : serialized message of {@code ApiMessageAndVersion} object. + * </pre> + */ +public abstract class AbstractApiMessageSerde 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: @dengziming Below are the two implementations of `AbstractApiMessageSerde` and they do not share same records types. - [BytesApiMessageSerde](https://github.com/apache/kafka/blob/trunk/server-common/src/main/java/org/apache/kafka/server/common/serialization/BytesApiMessageSerde.java#L41rl) ```BytesApiMessageSerde.this.apiMessageFor(apiKey);``` - [MetadataRecordSerde](https://github.com/apache/kafka/blob/trunk/metadata/src/main/java/org/apache/kafka/metadata/MetadataRecordSerde.java#L27) ```MetadataRecordType.fromId(apiKey).newMetadataRecord();``` -- This is an automated message from the Apache Git Service. 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