Compare boost directory_iterator and QDirIterator

gistfile1.txt

#include <QDirIterator>
#include <chrono>
#include <experimental/filesystem>
#include <boost/filesystem.hpp>
#include <iostream>
#include <functional>

#define TEST_PATH "/home/master/test"

unsigned long long get_time_for_qiter() {
    using namespace std::chrono;
    QDirIterator qiter(TEST_PATH);
    int num_files = 0;
    auto start_time = high_resolution_clock::now();
    while (qiter.hasNext()) {
        num_files++;
        qiter.next();
    }
    return (high_resolution_clock::now() - start_time).count();
}

unsigned long long get_time_for_ts() {
    using namespace std::chrono;
    using namespace std::experimental;
    int num_files = 0;
    auto start_time = high_resolution_clock::now();
    for (auto &_: filesystem::directory_iterator(TEST_PATH)) {
        num_files++;
    }
    return (high_resolution_clock::now() - start_time).count();
}

unsigned long long get_time_for_boost() {
    using namespace std::chrono;
    using namespace boost;
    int num_files = 0;
    auto start_time = high_resolution_clock::now();
    for (auto &_: filesystem::directory_iterator(TEST_PATH)) {
        num_files++;
    }
    return (high_resolution_clock::now() - start_time).count();
}


unsigned long long loop_test(std::function<double()> func) {
    unsigned long long time_sum = 0;
    for (int i=0; i < 10; ++i)
        time_sum += func();
    return time_sum;
}


int main(int argc, char *argv[])
{
    std::cout << "QDirIterator: " << loop_test(get_time_for_qiter) << " sesonds" << std::endl;
    std::cout << "boost directory_iterator: " << loop_test(get_time_for_boost) << " sesonds" << std::endl;
    std::cout << "c++17 directory_iterator: " << loop_test(get_time_for_ts) << " sesonds" << std::endl;
}

the test dir contains 1M files generated using the following script:

#!/usr/bin/env python

if __name__ == "__main__":
        for i in range(1000000):
                with open('%s.tmp' % hash(str(i)), 'w'):
                        continue