grpc/test/cpp/qps/usage_timer.cc

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#include "test/cpp/qps/usage_timer.h"

#include <fstream>
#include <string>
#include <sstream>

#include <grpc/support/time.h>
#include <sys/resource.h>
#include <sys/time.h>
UsageTimer::UsageTimer() : start_(Sample()) {}

double UsageTimer::Now() {
  auto ts = gpr_now(GPR_CLOCK_REALTIME);
  return ts.tv_sec + 1e-9 * ts.tv_nsec;
}

static double time_double(struct timeval* tv) {
  return tv->tv_sec + 1e-6 * tv->tv_usec;
}

static void get_cpu_usage(unsigned long long* total_cpu_time,
                         unsigned long long* idle_cpu_time) {
   std::ifstream proc_stat("/proc/stat");
   proc_stat.ignore(5);
   std::string cpu_time_str;
   std::string first_line;
   std::getline(proc_stat, first_line);
   std::stringstream first_line_s(first_line);
   for(int i = 0; i < 10; ++i) {
     std::getline(first_line_s, cpu_time_str, ' ');
     *total_cpu_time += std::stoi(cpu_time_str);
     if (i == 3) {
       *idle_cpu_time = std::stoi(cpu_time_str);
     }
   }
}

UsageTimer::Result UsageTimer::Sample() {
  struct rusage usage;
  struct timeval tv;
  gettimeofday(&tv, NULL);
  getrusage(RUSAGE_SELF, &usage);

  Result r;
  r.wall = time_double(&tv);
  r.user = time_double(&usage.ru_utime);
  r.system = time_double(&usage.ru_stime);
  r.total_cpu_time = 0;
  r.idle_cpu_time = 0;
  get_cpu_usage(&r.total_cpu_time, &r.idle_cpu_time);
  return r;
}

UsageTimer::Result UsageTimer::Mark() const {
  Result s = Sample();
  Result r;
  r.wall = s.wall - start_.wall;
  r.user = s.user - start_.user;
  r.system = s.system - start_.system;
  r.total_cpu_time = s.total_cpu_time - start_.total_cpu_time;
  r.idle_cpu_time = s.idle_cpu_time - start_.idle_cpu_time;

  return r;
}