aliehsaeedii commented on code in PR #21345: URL: https://github.com/apache/kafka/pull/21345#discussion_r2768862037
########## streams/src/main/java/org/apache/kafka/streams/state/HeadersBytesStore.java: ########## @@ -0,0 +1,68 @@ +/* + * 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.streams.state; + +import org.apache.kafka.common.utils.ByteUtils; + +import java.io.ByteArrayOutputStream; +import java.io.DataOutputStream; +import java.io.IOException; +import java.nio.ByteBuffer; + +/** + * Marker interface to indicate that a bytes store understands the value-with-headers format + * and can convert legacy "plain value" entries to the new format. + * <p> + * Per the KIP, the value format is: [header_length(varint)][headers_bytes][payload_bytes] + * where payload_bytes is the existing serialized value (e.g., [timestamp(8)][value] for timestamped stores). + */ +public interface HeadersBytesStore { + + /** + * Converts a legacy value (without headers) to the header-embedded format. + * <p> + * For timestamped stores, the legacy format is: [timestamp(8)][value] + * The new format is: [header_length(2)][headers][timestamp(8)][value] + * <p> + * This method adds empty headers to the existing value format. + * + * @param key the key bytes (may be used for context-dependent conversion; typically unused) + * @param value the legacy value bytes (for timestamped stores: [timestamp(8)][value]) + * @return the value in header-embedded format with empty headers + */ + static byte[] convertToHeaderFormat(final byte[] key, final byte[] value) { + if (value == null) { + return null; + } + + try (ByteArrayOutputStream baos = new ByteArrayOutputStream(); + DataOutputStream out = new DataOutputStream(baos)) { + + // Empty headers serialize to an empty byte array (per HeadersSerializer.serialize()) + final byte[] emptyHeadersBytes = new byte[0]; + + // Write format: [headers_size(varint)][headers_bytes][payload] + ByteUtils.writeVarint(emptyHeadersBytes.length, out); // headers_size = 0 Review Comment: Sorry the PR is dirty. It was developed in multiple phases with the focus of just an end-end test -- 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]
