emkornfield commented on code in PR #603: URL: https://github.com/apache/iceberg-cpp/pull/603#discussion_r2993034830
########## src/iceberg/puffin/puffin_format.h: ########## @@ -0,0 +1,89 @@ +/* + * 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. + */ + +#pragma once + +/// \file iceberg/puffin/puffin_format.h +/// Puffin file format constants and utilities. + +#include <array> +#include <cstdint> +#include <span> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/puffin/file_metadata.h" +#include "iceberg/result.h" + +namespace iceberg::puffin { + +/// \brief Puffin file format constants. +struct ICEBERG_EXPORT PuffinFormat { + /// Magic bytes: "PFA1" (Puffin Fratercula arctica, version 1) + static constexpr std::array<uint8_t, 4> kMagic = {0x50, 0x46, 0x41, 0x31}; + + static constexpr int32_t kMagicLength = 4; + static constexpr int32_t kFooterStartMagicOffset = 0; + static constexpr int32_t kFooterStartMagicLength = kMagicLength; + static constexpr int32_t kFooterStructPayloadSizeOffset = 0; + static constexpr int32_t kFooterStructFlagsOffset = kFooterStructPayloadSizeOffset + 4; + static constexpr int32_t kFooterStructFlagsLength = 4; + static constexpr int32_t kFooterStructMagicOffset = + kFooterStructFlagsOffset + kFooterStructFlagsLength; + + /// Total length of the footer struct: payload_size(4) + flags(4) + magic(4) + static constexpr int32_t kFooterStructLength = kFooterStructMagicOffset + kMagicLength; + + /// Default compression codec for footer payload. + static constexpr PuffinCompressionCodec kFooterCompressionCodec = + PuffinCompressionCodec::kLz4; Review Comment: I think this is actually a real compatibility concern where java puffin readers would likely break if a compressed footer was ever properly written. Java has never implemented lz4 compression: https://github.com/apache/iceberg/blob/8a51a685894eace51474f512b46a187566f27202/core/src/main/java/org/apache/iceberg/puffin/PuffinFormat.java#L112 which IIUC means anything written with a compressed footer would not be readable from Java. If you agree with this assessment it might be misreading the code but might be worth a discussion on the mailing list. -- 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]
