在C ++的主要逻辑中接收实际/用户/系统时间

Question

在C ++中是否存在等效的UNIX时间，它可以在main中提供实际，用户和系统执行时间？或者是否有非平凡的方法来使用chrono等来实现相同的功能？

无法找到record all three timestamps的计时用法，但only the real time based on timeclock link。

旨在远离重定向操作符和可执行文件，并尝试在主要内部嵌入时间逻辑。 time a.out 2> log.txt

Answer 1

解决使用sys/times.h和clock_t。

对于这两种方法，使用times.h记录系统时间sys，并且clock_t的REALTIME对于user记录更准确。

#include <iostream>
#include <sys/times.h>

std::string parse_tim(intmax_t milliseconds) {
  std::string parsed;

  intmax_t s = milliseconds / 1000;
  intmax_t m = s / 60;
  intmax_t h = m / 60;
  intmax_t d = h / 24;

  if(d > 0)
    parsed = parsed + std::to_string(d) + "d";
  if(! parsed.empty() || h > 0)
    parsed = parsed + std::to_string(h%24) + "h";
  if(! parsed.empty() || m > 0)
    parsed = parsed + std::to_string(m%60) + "m";

  parsed = parsed + std::to_string(s%60) + ".";
  parsed = parsed + std::to_string(milliseconds%1000) + "s";

  return parsed;
}

int main(int argc, char** argv) {

  static struct tms st_cpu, en_cpu;
  struct timespec ts1, tw1, ts2, tw2;

  static clock_t st_time = times(&st_cpu);
  clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts1);
  clock_gettime(CLOCK_REALTIME, &tw1);


  // Perform operations
  // Perform operation
  // Perform actions


  static clock_t en_time = times(&en_cpu);
  clock_gettime(CLOCK_REALTIME, &tw2);
  clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts2);

  auto real_clock = (intmax_t)(en_time - st_time) * 10;
  auto user_clock = (intmax_t)(en_cpu.tms_utime - st_cpu.tms_utime) * 10;
  auto sys_clock = (intmax_t)(en_cpu.tms_stime - st_cpu.tms_stime) * 10;
  std::cerr << "time.h\treal\t" << parse_tim(real_clock) << "\t"
            << "user\t" << parse_tim(user_clock) << "\t"
            << "sys\t" << parse_tim(sys_clock) << std::endl;

  auto real_dur = intmax_t(1000.0*tw2.tv_sec + 1e-6*tw2.tv_nsec - (1000.0*tw1.tv_sec + 1e-6*tw1.tv_nsec));
  auto user_dur = intmax_t(1000.0*ts2.tv_sec + 1e-6*ts2.tv_nsec - (1000.0*ts1.tv_sec + 1e-6*ts1.tv_nsec));
  auto sys_dur = intmax_t(en_cpu.tms_stime - st_cpu.tms_stime) * 10;
  std::cerr << "clock_t\treal\t" << parse_tim(real_dur) << "\t"
            << "user\t" << parse_tim(user_dur) << "\t"
            << "sys\t" << parse_tim(sys_dur) << std::endl;

  return 0;
}

time ./a.out

time.h    real  4m2.460s    user    5m57.140s   sys 21.830s
clock_t   real  4m2.457s    user    6m18.976s   sys 21.830s

real    4m2.498s
user    6m22.816s
sys     0m26.865s