C++ Cross-Platform High-Resolution Timer

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I'm looking to implement a simple timer mechanism in C++. The code should work in Windows and Linux. The resolution should be as precise as possible (at least millisecond accuracy). This will be used to simply track the passage of time, not to implement any kind of event-driven design. What is the best tool to accomplish this?

14 Answers

I found this which looks promising, and is extremely straightforward, not sure if there are any drawbacks:

https://gist.github.com/ForeverZer0/0a4f80fc02b96e19380ebb7a3debbee5

/* ----------------------------------------------------------------------- */
/*
Easy embeddable cross-platform high resolution timer function. For each 
platform we select the high resolution timer. You can call the 'ns()' 
function in your file after embedding this. 
*/
#include <stdint.h>
#if defined(__linux)
#  define HAVE_POSIX_TIMER
#  include <time.h>
#  ifdef CLOCK_MONOTONIC
#     define CLOCKID CLOCK_MONOTONIC
#  else
#     define CLOCKID CLOCK_REALTIME
#  endif
#elif defined(__APPLE__)
#  define HAVE_MACH_TIMER
#  include <mach/mach_time.h>
#elif defined(_WIN32)
#  define WIN32_LEAN_AND_MEAN
#  include <windows.h>
#endif
static uint64_t ns() {
static uint64_t is_init = 0;
#if defined(__APPLE__)
    static mach_timebase_info_data_t info;
    if (0 == is_init) {
        mach_timebase_info(&info);
        is_init = 1;
    }
    uint64_t now;
    now = mach_absolute_time();
    now *= info.numer;
    now /= info.denom;
    return now;
#elif defined(__linux)
    static struct timespec linux_rate;
    if (0 == is_init) {
        clock_getres(CLOCKID, &linux_rate);
        is_init = 1;
    }
    uint64_t now;
    struct timespec spec;
    clock_gettime(CLOCKID, &spec);
    now = spec.tv_sec * 1.0e9 + spec.tv_nsec;
    return now;
#elif defined(_WIN32)
    static LARGE_INTEGER win_frequency;
    if (0 == is_init) {
        QueryPerformanceFrequency(&win_frequency);
        is_init = 1;
    }
    LARGE_INTEGER now;
    QueryPerformanceCounter(&now);
    return (uint64_t) ((1e9 * now.QuadPart)  / win_frequency.QuadPart);
#endif
}
/* ----------------------------------------------------------------------- */-------------------------------- */
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