Crudely Measure Execution Time of PRNGs in <random>

time_random_generators.cpp

#include <iostream>
#include <random>
#include <chrono>
#include <array>
#include <functional>
#include <algorithm>

struct scoped_timer
{
    scoped_timer(std::string name)
        : start(std::chrono::high_resolution_clock::now()), test_name(name) {}
    ~scoped_timer()
    {
        auto end = std::chrono::high_resolution_clock::now();
        auto duration = std::chrono::duration_cast<std::chrono::duration<double, std::milli>>(end - start);

        std::cout << test_name << ": " << duration.count()  << "ms\n";
    }

    std::chrono::high_resolution_clock::time_point start;
    std::string test_name;
};

const int iterations = 1'000'000;

void test_mt19937()
{
    std::array<int, iterations> arr;
    std::default_random_engine re;
    std::mt19937 g(re());
    std::uniform_int_distribution<> d;

    std::generate(arr.begin(), arr.end(), std::bind(d, g));
}

void test_mt19937_64()
{
    std::array<int, iterations> arr;
    std::default_random_engine re;
    std::mt19937_64 g(re());
    std::uniform_int_distribution<> d;

    std::generate(arr.begin(), arr.end(), std::bind(d, g));
}

void test_ranlux24()
{
    std::array<int, iterations> arr;
    std::default_random_engine re;
    std::ranlux24 g(re());
    std::uniform_int_distribution<> d;

    std::generate(arr.begin(), arr.end(), std::bind(d, g));
}

void test_ranlux48()
{
    std::array<int, iterations> arr;
    std::default_random_engine re;
    std::ranlux48 g(re());
    std::uniform_int_distribution<> d;

    std::generate(arr.begin(), arr.end(), std::bind(d, g));
}

void test_minstd_rand()
{
    std::array<int, iterations> arr;
    std::default_random_engine re;
    std::minstd_rand g(re());
    std::uniform_int_distribution<> d;

    std::generate(arr.begin(), arr.end(), std::bind(d, g));
}

void test_minstd_rand0()
{
    std::array<int, iterations> arr;
    std::default_random_engine re;
    std::minstd_rand0 g(re());
    std::uniform_int_distribution<> d;

    std::generate(arr.begin(), arr.end(), std::bind(d, g));
}

void test_knuth_b()
{
    std::array<int, iterations> arr;
    std::default_random_engine re;
    std::knuth_b g(re());
    std::uniform_int_distribution<> d;

    std::generate(arr.begin(), arr.end(), std::bind(d, g));
}

int main()
{
    {
        scoped_timer timer("std::mt19937");
        test_mt19937();
    }
    {
        scoped_timer timer("std::mt19937_64");
        test_mt19937_64();
    }
    {
        scoped_timer timer("std::ranlux24");
        test_ranlux24();
    }
    {
        scoped_timer timer("std::ranlux48");
        test_ranlux48();
    }
    {
        scoped_timer timer("std::minstd_rand");
        test_minstd_rand();
    }
    {
        scoped_timer timer("std::knuth_b");
        test_knuth_b();
    }
}
/*
Output:
    std::mt19937: 31.5352ms
    std::mt19937_64: 22.8085ms
    std::ranlux24: 216.86ms
    std::ranlux48: 332.197ms
    std::minstd_rand: 49.1883ms
    std::knuth_b: 57.1808ms
*/