/* Copyright 2016 The TensorFlow Authors. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
==============================================================================*/

#include "tensorflow/core/platform/profile_utils/cpu_utils.h"

#include <limits>
#include <mutex>

#include "tensorflow/core/platform/logging.h"
#include "tensorflow/core/platform/profile_utils/android_armv7a_cpu_utils_helper.h"

namespace tensorflow {
namespace profile_utils {

/* static */ constexpr int64 CpuUtils::INVALID_FREQUENCY;

static ICpuUtilsHelper* cpu_utils_helper_instance_ = nullptr;

/* static */ int64 CpuUtils::GetCycleCounterFrequency() {
  static const int64 cpu_frequency = GetCycleCounterFrequencyImpl();
  return cpu_frequency;
}

/* static */ double CpuUtils::GetMicroSecPerClock() {
  static const double micro_sec_per_clock =
      (1000.0 * 1000.0) / static_cast<double>(GetCycleCounterFrequency());
  return micro_sec_per_clock;
}

/* static */ void CpuUtils::ResetClockCycle() {
  GetCpuUtilsHelperSingletonInstance().ResetClockCycle();
}

/* static */ void CpuUtils::EnableClockCycleProfiling(const bool enable) {
  GetCpuUtilsHelperSingletonInstance().EnableClockCycleProfiling(enable);
}

/* static */ std::chrono::duration<double> CpuUtils::ConvertClockCycleToTime(
    const int64 clock_cycle) {
  return std::chrono::duration<double>(static_cast<double>(clock_cycle) /
                                       GetCycleCounterFrequency());
}

/* static */ int64 CpuUtils::GetCycleCounterFrequencyImpl() {
// TODO(satok): do not switch by macro here
#if defined(__ANDROID__)
  return GetCpuUtilsHelperSingletonInstance().CalculateCpuFrequency();
#elif defined(__linux__)
  double bogomips;
  FILE* fp = popen("grep '^bogomips' /proc/cpuinfo | head -1", "r");
  if (fp == nullptr) {
    return INVALID_FREQUENCY;
  }
  const int retval_of_bogomips = fscanf(fp, "bogomips : %lf", &bogomips);
  if (retval_of_bogomips <= 0) {
    return INVALID_FREQUENCY;
  }
  pclose(fp);
  const double freq_ghz = bogomips / 1000.0 / 2.0;
  if (retval_of_bogomips != 1 || freq_ghz < 0.01) {
    LOG(WARNING) << "Failed to get CPU frequency: " << freq_ghz << " Hz";
    return INVALID_FREQUENCY;
  }
  return static_cast<int64>(freq_ghz * 1000.0 * 1000.0 * 1000.0);
#elif defined(__APPLE__)
  int64 freq_hz;
  FILE* fp =
      popen("sysctl hw | grep hw.cpufrequency_max: | cut -d' ' -f 2", "r");
  if (fp == nullptr) {
    return INVALID_FREQUENCY;
  }
  if (fscanf(fp, "%lld", &freq_hz) != 1) {
    return INVALID_FREQUENCY;
  }
  pclose(fp);
  if (freq_hz < 1e6) {
    LOG(WARNING) << "Failed to get CPU frequency: " << freq_hz << " Hz";
    return INVALID_FREQUENCY;
  }
  return freq_hz;
#else
  // TODO(satok): Support other OS if needed
  // Return INVALID_FREQUENCY on unsupported OS
  return INVALID_FREQUENCY;
#endif
}

/* static */ ICpuUtilsHelper& CpuUtils::GetCpuUtilsHelperSingletonInstance() {
  static std::once_flag flag;
  std::call_once(flag, []() {
    if (cpu_utils_helper_instance_ != nullptr) {
      LOG(FATAL) << "cpu_utils_helper_instance_ is already instantiated.";
    }
#if defined(__ANDROID__) && (__ANDROID_API__ >= 21) && \
    (defined(__ARM_ARCH_7A__) || defined(__aarch64__))
    cpu_utils_helper_instance_ = new AndroidArmV7ACpuUtilsHelper();
#else
      cpu_utils_helper_instance_ = new DefaultCpuUtilsHelper();
#endif
  });
  return *cpu_utils_helper_instance_;
}

}  // namespace profile_utils
}  // namespace tensorflow
