zhjwpku commented on code in PR #242: URL: https://github.com/apache/iceberg-cpp/pull/242#discussion_r2379479665
########## src/iceberg/util/uuid.h: ########## @@ -0,0 +1,81 @@ +/* + * 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 + +#include <array> +#include <cstdint> +#include <span> +#include <string_view> + +#include "iceberg/iceberg_export.h" +#include "iceberg/result.h" + +/// \file iceberg/util/uuid.h +/// \brief UUID (Universally Unique Identifier) representation. + +namespace iceberg { + +class ICEBERG_EXPORT Uuid { + public: + Uuid() = delete; + constexpr static size_t kUuidSize = 16; + + explicit Uuid(std::array<uint8_t, kUuidSize> data); + + /// \brief Generate a random UUID (version 4). + static Uuid GenerateV4(); + + /// \brief Generate UUID version 7 per RFC 9562, with the current timestamp. + static Uuid GenerateV7(); + + /// \brief Generate UUID version 7 per RFC 9562, with the given timestamp. + /// + /// UUID version 7 consists of a Unix timestamp in milliseconds (48 bits) and + /// 74 random bits, excluding the required version and variant bits. + /// + /// \param unix_ts_ms number of milliseconds since start of the UNIX epoch + /// + /// \note unix_ts_ms cannot be negative per RFC. + static Uuid GenerateV7(uint64_t unix_ts_ms); + + /// \brief Create a UUID from a string in standard format. + static Result<Uuid> FromString(std::string_view str); + + /// \brief Create a UUID from a 16-byte array. + static Result<Uuid> FromBytes(std::span<const uint8_t> bytes); + + /// \brief Get the raw bytes of the UUID. + std::span<const uint8_t> bytes() const { return data_; } + + /// \brief Access individual bytes of the UUID. + uint8_t operator[](size_t index) const; + + /// \brief Convert the UUID to a string in standard format. + std::string ToString() const; + + friend bool operator==(const Uuid& lhs, const Uuid& rhs) { Review Comment: I can't think of a scenario where we'd need to compare two UUIDs right now. We can add that functionality later if needed, along with better documentation. ########## src/iceberg/util/uuid.cc: ########## @@ -0,0 +1,221 @@ +/* + * 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. + */ + +#include "iceberg/util/uuid.h" + +#include <chrono> +#include <cstdint> +#include <cstring> +#include <random> +#include <string> + +#include "iceberg/exception.h" +#include "iceberg/result.h" +#include "iceberg/util/int128.h" +#include "iceberg/util/macros.h" + +namespace iceberg { + +Uuid::Uuid(std::array<uint8_t, kUuidSize> data) : data_(std::move(data)) {} + +Uuid Uuid::GenerateV4() { + static std::random_device rd; + static std::mt19937 gen(rd()); + static std::uniform_int_distribution<uint64_t> distrib( + std::numeric_limits<uint64_t>::min(), std::numeric_limits<uint64_t>::max()); + std::array<uint8_t, 16> uuid; + + // Generate two random 64-bit integers + uint64_t high_bits = distrib(gen); + uint64_t low_bits = distrib(gen); + + // Combine them into a uint128_t + uint128_t random_128_bit_number = (static_cast<uint128_t>(high_bits) << 64) | low_bits; + + // Copy the bytes into the uuid array + std::memcpy(uuid.data(), &random_128_bit_number, 16); + + // Set magic numbers for a "version 4" (pseudorandom) UUID and variant, + // see https://datatracker.ietf.org/doc/html/rfc9562#name-uuid-version-4 + uuid[6] = (uuid[6] & 0x0F) | 0x40; + // Set variant field, top two bits are 1, 0 + uuid[8] = (uuid[8] & 0x3F) | 0x80; + + return Uuid(std::move(uuid)); +} + +Uuid Uuid::GenerateV7() { + // Get the current time in milliseconds since the Unix epoch + auto now = std::chrono::system_clock::now(); + auto duration_since_epoch = now.time_since_epoch(); + auto unix_ts_ms = + std::chrono::duration_cast<std::chrono::milliseconds>(duration_since_epoch).count(); + + return GenerateV7(static_cast<uint64_t>(unix_ts_ms)); +} + +Uuid Uuid::GenerateV7(uint64_t unix_ts_ms) { + std::array<uint8_t, 16> uuid = {}; + + // Set the timestamp (in milliseconds since Unix epoch) + uuid[0] = (unix_ts_ms >> 40) & 0xFF; + uuid[1] = (unix_ts_ms >> 32) & 0xFF; + uuid[2] = (unix_ts_ms >> 24) & 0xFF; + uuid[3] = (unix_ts_ms >> 16) & 0xFF; + uuid[4] = (unix_ts_ms >> 8) & 0xFF; + uuid[5] = unix_ts_ms & 0xFF; + + // Generate random bytes for the remaining fields + static std::random_device rd; + static std::mt19937 gen(rd()); + static std::uniform_int_distribution<uint16_t> distrib( + std::numeric_limits<uint16_t>::min(), std::numeric_limits<uint16_t>::max()); + + // Note: uint8_t is invalid for uniform_int_distribution on Windows + for (size_t i = 6; i < 16; i += 2) { + auto rand = static_cast<uint16_t>(distrib(gen)); + uuid[i] = (rand >> 8) & 0xFF; + uuid[i + 1] = rand & 0xFF; + } + + // Set magic numbers for a "version 7" (pseudorandom) UUID and variant, + // see https://www.rfc-editor.org/rfc/rfc9562#name-version-field + uuid[6] = (uuid[6] & 0x0F) | 0x70; + // set variant field, top two bits are 1, 0 + uuid[8] = (uuid[8] & 0x3F) | 0x80; + + return Uuid(std::move(uuid)); +} + +namespace { Review Comment: moved, thanks. -- This is an automated message from the Apache Git Service. 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