UUID has been updated to use a better hash and no unnecessary allocations (Big thanks to mosra!)

This commit is contained in:
2026-01-31 13:45:15 +02:00
parent ff062567d8
commit edb0055224
2 changed files with 17 additions and 54 deletions

View File

@@ -6,18 +6,18 @@
* v. 2.0. If a copy of the MPL was not distributed with this file, You can
* obtain one at http://mozilla.org/MPL/2.0/.
*/
#ifndef GUARD_TOURMALINE_TYPES_H
#define GUARD_TOURMALINE_TYPES_H
#include "TourmalineExternal/random/xoshiro.h"
#include <cstdint>
#include <functional>
#include <memory>
#include <string>
namespace Tourmaline::Type {
class UUID {
public:
constexpr static uint8_t BitLength = 128;
constexpr static uint8_t QWORDLength = BitLength / 64;
constexpr static uint8_t ByteLength = BitLength / 8;
[[nodiscard]]
std::string asString() const;
bool operator==(const UUID &rhs) const;
@@ -25,14 +25,8 @@ public:
UUID(uint64_t firstHalf, uint64_t secondHalf);
UUID(const std::string &uuid);
UUID(const UUID &uuid);
UUID(UUID &&uuid) noexcept;
UUID &operator=(const UUID &uuid);
UUID &operator=(UUID &&uuid);
~UUID() = default;
private:
std::unique_ptr<uint64_t[]> data = std::make_unique<uint64_t[]>(QWORDLength);
uint64_t firstHalf = 0, secondHalf = 0;
friend struct std::hash<Tourmaline::Type::UUID>;
};
} // namespace Tourmaline::Type
@@ -40,10 +34,9 @@ private:
namespace std {
template <> struct hash<Tourmaline::Type::UUID> {
size_t operator()(const Tourmaline::Type::UUID &uuid) const noexcept {
const auto data = uuid.data.get();
size_t h1 = std::hash<uint64_t>{}(data[0]),
h2 = std::hash<uint64_t>{}(data[1]);
return h1 ^ (h2 << 1);
uint64_t hash = Xoshiro::splitmix64(uuid.firstHalf);
hash += uuid.secondHalf;
return Xoshiro::splitmix64(hash);
}
};

View File

@@ -13,57 +13,27 @@
#include <cstdint>
#include <cstring>
#include <format>
#include <memory>
#include <string>
using namespace Tourmaline::Type;
std::string UUID::asString() const {
return std::format("{:016X}{:016X}", data[0], data[1]);
return std::format("{:016X}{:016X}", firstHalf, secondHalf);
}
bool UUID::operator==(const UUID &rhs) const {
// Since size may be increased
for (uint8_t index = 0; index < QWORDLength; index++) {
if (this->data[index] != rhs.data[index]) {
return false;
}
}
return true;
return firstHalf == rhs.firstHalf && secondHalf == rhs.secondHalf;
}
UUID::UUID(const UUID &uuid) {
std::memcpy(data.get(), uuid.data.get(), UUID::ByteLength);
}
UUID &UUID::operator=(const UUID &uuid) {
if (this != &uuid) [[likely]] {
std::memcpy(data.get(), uuid.data.get(), UUID::ByteLength);
}
return *this;
}
UUID &UUID::operator=(UUID &&uuid) {
if (this != &uuid) [[likely]] {
data.swap(uuid.data);
}
return *this;
}
UUID::UUID(UUID &&uuid) noexcept { data.swap(uuid.data); }
UUID::UUID(uint64_t firstHalf, uint64_t secondHalf) {
data[0] = firstHalf;
data[1] = secondHalf;
}
UUID::UUID(uint64_t firstHalf, uint64_t secondHalf)
: firstHalf(firstHalf), secondHalf(secondHalf) {}
UUID::UUID(const std::string &uuid) {
// We are assuming that it is a valid UUID, if not then somewhere else this
// UUID should cause an error
auto start = uuid.c_str(), half = start + ByteLength,
tail = half + ByteLength; // Each UUID element is 16 characters padded
auto start = uuid.c_str(), half = start + 16,
tail = half + 16; // Each UUID element is 16 characters padded
std::from_chars(start, half, data[0], 16);
std::from_chars(half, tail, data[1], 16);
std::from_chars(start, half, firstHalf, 16);
std::from_chars(half, tail, secondHalf, 16);
}