benchmarks | ||
tests | ||
vendor/google | ||
.gitignore | ||
.gitmodules | ||
CMakeLists.txt | ||
endianness.h | ||
example.cpp | ||
LICENSE | ||
README.md | ||
uuid_v4.h |
uuid_v4
This is a fast C++ header-only library to generate, serialize, print and parse UUIDs version 4 variant 1 as specified in RFC-4122. It heavily relies on SIMD operations (instruction sets SSE4.1/AVX/AVX2), c++11 PRNG library and some c++17 features.
This library generates UUIDs with pseudo-random numbers, seeded by true (hardware) random. It is not a cryptographically secure way of generating UUIDs.
Update Notes
The namespace changed from UUID
to UUIDv4
to avoid a conflict with a windows.h dependency.
Usage
Include "uuid_v4.h"
and "endianness.h"
.
To start generating UUIDs you need to create an object UUIDv4::UUIDGenerator<random_generator>
where random_generator is a c++11 Random number engine (see random).
It is highly recommended to use the default engine std::mt19937_64
as it has a SIMD implementation (at least in libstdc++) and provides better randomness.
#include "uuid_v4"
UUIDv4::UUIDGenerator<std::mt19937_64> uuidGenerator;
UUIDv4::UUID uuid = uuidGenerator.getUUID();
Serializing an UUID to a byte string (16 bytes)
std::string bytes = uuid.bytes();
or
std::string bytes1;
uuid.bytes(bytes1);
or
char bytes2[16];
uuid.bytes(bytes2);
Pretty-printing an UUID (36 bytes)
std::string s = uuid.str();
or
std::string s1;
uuid.str(s1);
or
char s2[36];
uuid.bytes(s2);
Loading an UUID from a byte string (16 bytes)
UUIDv4::UUID uuid(bytes);
Parsing an UUID from a pretty string (36 bytes)
UUIDv4::UUID uuid = UUIDv4::UUID::fromStrFactory(string);
or
UUIDv4::UUID uuid;
uuid.fromStr(string);
Comparing UUIDs
UUIDv4::UUIDGenerator<std::mt19937_64> uuidGenerator;
UUIDv4::UUID uuid1 = uuidGenerator.getUUID();
UUIDv4::UUID uuid2 = uuidGenerator.getUUID();
if (uuid1 == uuid2) {
std::cout << "1 in 10^36 chances of this printing" << std::endl
}
stream operations
std::cout << uuid << std::endl;
std::cin >> uuid;
Benchmarks
Comparing generation time
- Basic approach generating directly a string basic
- libuuid libuuid uses /dev/urandom (cryptographically secure)
- Boost UUID boost uses /dev/urandom (cryptographically secure)
- Boost UUID with mt19937_64
- UUID_v4 (this project)
Benchmark | Time | CPU | Iterations |
---|---|---|---|
Basic | 16098 ns | 16021 ns | 42807 |
Libuuid | 298655 ns | 293749 ns | 2405 |
BoostUUID | 48476 ns | 48357 ns | 14689 |
BoostUUIDmt19937 | 2673 ns | 2665 ns | 262395 |
UUID_v4 | 1117 ns | 1114 ns | 618670 |
Timings of UUIDs operations, there is a scale factor on x100. i.e UUIDGeneration takes 11.34ns to build one uuid.
Benchmark | Time | CPU | Iterations |
---|---|---|---|
UUIDGeneration | 1134 ns | 1117 ns | 618589 |
UUIDSerializeAlloc | 3197 ns | 3182 ns | 214742 |
UUIDSerializeByRef | 211 ns | 211 ns | 3312380 |
UUIDSerializeCharArray | 64 ns | 64 ns | 10747617 |
UUIDPretty | 3424 ns | 3415 ns | 206672 |
UUIDPrettyByRef | 211 ns | 209 ns | 3319069 |
UUIDPrettyCharArray | 88 ns | 88 ns | 7916795 |
UUIDLoad | 64 ns | 63 ns | 10837304 |
UUIDParse | 320 ns | 316 ns | 2206306 |
UUIDParseInPlace | 317 ns | 313 ns | 2222561 |
UUIDEqual | 50 ns | 49 ns | 12978765 |
UUIDCompare | 65 ns | 65 ns | 10672186 |
Building
This project uses CMake to build tests and benchmarks. If you do not have googletest and googlebenchmark installed globally
git clone --recurse-submodules https://github.com/crashoz/uuid_v4.git
otherwise
git clone https://github.com/crashoz/uuid_v4.git
Then build
mkdir build
cd build
cmake -Dtest=ON -Dbenchmark=ON ..
make
./tests/uuid_v4_test
./benchmarks/uuid_v4_benchmark