C++时间处理2-获取系统开机到现在的运行时间

// for Unix-like system
#include <sys/time.h>

uint64_t clocktime_us()
{
    struct timespec ts;
    clock_gettime(CLOCK_MONOTONIC, &ts);
    return (uint64_t)ts.tv_sec * 1000000ULL + ts.tv_nsec / kThousand;
}

#include <cstdint>

/**
 * @brief Time unit enum.
 *
 */
enum class timeunit
{
    /** second */
    s,
    /** millisecond */
    ms,
    /** microsecond */
    us,
};

/**
 * @brief Get current clock time for monotone increment time.
 *
 * @param unit time unit
 * @return uint64_t clock time
 */
uint64_t clocktime(timeunit unit);

#include "timeutil.h"
#include <chrono>

uint64_t clocktime(timeunit unit)
{
    // for C++11 and later
    auto run_time = std::chrono::steady_clock::now();
    auto run_time_duration = std::chrono::duration_cast<std::chrono::microseconds>(run_time.time_since_epoch()).count();
    auto us = static_cast<uint64_t>(run_time_duration);

    uint64_t t = 0;
    switch (unit)
    {
    case timeunit::s:
        t = us2s(us);
        break;
    case timeunit::ms:
        t = us2ms(us);
        break;
    case timeunit::us:
        t = us;
        break;
    default:
        break;
    }
    return t;
}

#include "timeutil.h"
#include "common.hpp"

void TestClocktime()
{
    PrintSubTitle("TestClocktime");

    auto s = cutl::clocktime(cutl::timeunit::s);
    auto ms = cutl::clocktime(cutl::timeunit::ms);
    auto us = cutl::clocktime(cutl::timeunit::us);
    std::cout << "duration time from system start( s): " << s << std::endl;
    std::cout << "duration time from system start(ms): " << ms << std::endl;
    std::cout << "duration time from system start(us): " << us << std::endl;
}