wgtmac commented on code in PR #242: URL: https://github.com/apache/iceberg-cpp/pull/242#discussion_r2383731425
########## 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 { + +namespace { + +constexpr std::array<uint8_t, 256> BuildHexTable() { + std::array<uint8_t, 256> buf{}; + for (int32_t i = 0; i < 256; i++) { + if (i >= '0' && i <= '9') { + buf[i] = static_cast<uint8_t>(i - '0'); + } else if (i >= 'a' && i <= 'f') { + buf[i] = static_cast<uint8_t>(i - 'a' + 10); + } else if (i >= 'A' && i <= 'F') { + buf[i] = static_cast<uint8_t>(i - 'A' + 10); + } else { + buf[i] = 0xFF; + } + } + return buf; +} + +constexpr std::array<uint8_t, 256> BuildShl4Table() { + std::array<uint8_t, 256> buf{}; + for (int32_t i = 0; i < 256; i++) { + buf[i] = static_cast<uint8_t>(i << 4); + } + return buf; +} + +constexpr auto kHexTable = BuildHexTable(); +constexpr auto kShl4Table = BuildShl4Table(); + +// Parse a UUID string without dashes, e.g. "67e5504410b1426f9247bb680e5fe0c8" +inline Result<Uuid> ParseSimple(std::string_view s) { + ICEBERG_DCHECK(s.size() == 32, "s must be 32 characters long"); + + std::array<uint8_t, 16> uuid{}; + for (size_t i = 0; i < 16; i++) { + uint8_t h1 = kHexTable[static_cast<uint8_t>(s[i * 2])]; + uint8_t h2 = kHexTable[static_cast<uint8_t>(s[i * 2 + 1])]; + + if ((h1 | h2) == 0xFF) { + return InvalidArgument("Invalid UUID string: {}", s); + } + + uuid[i] = static_cast<uint8_t>(kShl4Table[h1] | h2); + } + return Uuid(std::move(uuid)); +} + +// Parse a UUID string with dashes, e.g. "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" +inline Result<Uuid> ParseHyphenated(std::string_view s) { + ICEBERG_DCHECK(s.size() == 36, "s must be 36 characters long"); + + // Check that dashes are in the right places + if (!(s[8] == '-' && s[13] == '-' && s[18] == '-' && s[23] == '-')) { + return InvalidArgument("Invalid UUID string: {}", s); + } + + constexpr std::array<size_t, 8> positions = {0, 4, 9, 14, 19, 24, 28, 32}; + std::array<uint8_t, 16> uuid{}; + + for (size_t j = 0; j < 8; j++) { + size_t i = positions[j]; + uint8_t h1 = kHexTable[static_cast<uint8_t>(s[i])]; + uint8_t h2 = kHexTable[static_cast<uint8_t>(s[i + 1])]; + uint8_t h3 = kHexTable[static_cast<uint8_t>(s[i + 2])]; + uint8_t h4 = kHexTable[static_cast<uint8_t>(s[i + 3])]; + + if ((h1 | h2 | h3 | h4) == 0xFF) { + return InvalidArgument("Invalid UUID string: {}", s); + } + + uuid[j * 2] = static_cast<uint8_t>(kShl4Table[h1] | h2); + uuid[j * 2 + 1] = static_cast<uint8_t>(kShl4Table[h3] | h4); + } + + return Uuid(std::move(uuid)); +} + +} // namespace + +Uuid::Uuid(std::array<uint8_t, kLength> 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)); +} + +Result<Uuid> Uuid::FromString(std::string_view str) { + if (str.size() == 32) { + return ParseSimple(str); + } else if (str.size() == 36) { + return ParseHyphenated(str); + } else { + return InvalidArgument("Invalid UUID string: {}", str); + } +} + +Result<Uuid> Uuid::FromBytes(std::span<const uint8_t> bytes) { + if (bytes.size() != kLength) [[unlikely]] { + return InvalidArgument("UUID byte array must be exactly {} bytes, was {}", kLength, + bytes.size()); + } + std::array<uint8_t, kLength> data; + std::memcpy(data.data(), bytes.data(), kLength); + return Uuid(std::move(data)); +} + +uint8_t Uuid::operator[](size_t index) const { + ICEBERG_CHECK(index < kLength, "UUID index out of range: {}", index); + return data_[index]; +} + +std::array<uint8_t, Uuid::kLength> Uuid::ToBigEndianBytes() const { return data_; } Review Comment: Sounds good! -- This is an automated message from the Apache Git Service. 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