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.

While this lib is optimized to be fast with SIMD operations, it is possible to run it on any architecture with portable implementations of SIMD instructions like simd-everywhere

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