/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
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 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */

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

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

#include <grpc/support/log.h>
#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) {
#ifdef __linux__
  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::stol(cpu_time_str);
    if (i == 3) {
      *idle_cpu_time = std::stol(cpu_time_str);
    }
  }
#else
  gpr_log(GPR_INFO, "get_cpu_usage(): Non-linux platform is not supported.");
#endif
}

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;
}