waiting_utils.hpp

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#ifndef BOOST_FAIRNESS_WAITING_UTILS_HPP
#define BOOST_FAIRNESS_WAITING_UTILS_HPP
#include <chrono>
 
#define NOW std::chrono::high_resolution_clock::now()
 
namespace utils::waiting{
    enum class WaitingLevel { Milli, Micro, Nano };
 
    /*
    std::this_thread::sleep_for is too imprecise, and also I could make a bunch of variables during busy waiting to simulate heated cpu caches.
    */
 
    template <WaitingLevel level>
    void busy_wait(uint32_t utime) {
        int i = 0;
        auto begin = NOW;
        if constexpr (level == WaitingLevel::Milli)
            for(;std::chrono::duration_cast<std::chrono::milliseconds>(NOW - begin).count() < utime;){
                benchmark::DoNotOptimize(i += 1);
            }
        if constexpr (level == WaitingLevel::Micro)
            for(;std::chrono::duration_cast<std::chrono::microseconds>(NOW - begin).count() < utime;){
                benchmark::DoNotOptimize(i += 1);
            }
        if constexpr (level == WaitingLevel::Nano)
            for(;std::chrono::duration_cast<std::chrono::nanoseconds>(NOW - begin).count() < utime;){
                benchmark::DoNotOptimize(i += 1);
            }
    }
    void busy_wait(uint32_t utime) {…}
 
    void busy_wait_50milli_benchmark(benchmark::State& state) {
        for (auto _ : state){
            busy_wait<WaitingLevel::Milli>(50);
        }
    }
    void busy_wait_50milli_benchmark(benchmark::State& state) {…}
 
    void busy_wait_50micro_benchmark(benchmark::State& state) {
        for (auto _ : state){
            busy_wait<WaitingLevel::Micro>(50);
        }
    }
    void busy_wait_50micro_benchmark(benchmark::State& state) {…}
 
    void busy_wait_50nano_benchmark(benchmark::State& state) {
        for (auto _ : state){
            busy_wait<WaitingLevel::Nano>(50);
        }
    }
    void busy_wait_50nano_benchmark(benchmark::State& state) {…}
 
}
namespace utils::waiting {…}
 
#undef NOW
#endif // BOOST_FAIRNESS_WAITING_UTILS_HPP