timer.h

 
// clang-format off
//
// Boost Software License - Version 1.0 - August 17th, 2003
// 
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
// clang-format on
 
#ifndef INCG_529e391f2915453388028b848b3dcbd6
#define INCG_529e391f2915453388028b848b3dcbd6
 
#include <spdlog/logger.h>
 
#include <chrono>
#include <cstdint>
#include <memory>
#include <string>
#include <variant>
 
#include "lf_assert.h"
 
namespace lf::base {

class Timer {
 public:
  struct cpu_times {
    std::chrono::nanoseconds wall;
    std::chrono::nanoseconds user;
    std::chrono::nanoseconds system;
  };

  explicit Timer(bool start = true) noexcept : times_() {
    if (start) {
      Start();
    } else {
      times_ =
          cpu_times{std::chrono::nanoseconds(0), std::chrono::nanoseconds(0),
                    std::chrono::nanoseconds(0)};
      is_stopped_ = true;
    }
  }

  [[nodiscard]] bool IsStopped() const noexcept { return is_stopped_; }

  [[nodiscard]] cpu_times Elapsed() const noexcept;

  [[nodiscard]] std::string Format(
      std::string_view format = kDefaultFormat) const;

  void Start() noexcept;

  void Stop() noexcept;

  void Resume() noexcept;

  inline static std::string kDefaultFormat =
      "{w:.6}s wall, {u:.6}s user + {s:.6}s system = {t:.6}s CPU ({p:.3}%)";
 
 private:
  cpu_times times_;
  bool is_stopped_;
};

class AutoTimer {
 public:
  explicit AutoTimer(std::string format = Timer::kDefaultFormat);

  explicit AutoTimer(std::ostream& stream,
                     std::string format = Timer::kDefaultFormat);

  explicit AutoTimer(
      std::shared_ptr<spdlog::logger> logger,
      spdlog::level::level_enum level = spdlog::level::level_enum::info,
      std::string format = Timer::kDefaultFormat);
 
  AutoTimer(const AutoTimer&) = default;
  AutoTimer(AutoTimer&&) = default;
  AutoTimer& operator=(const AutoTimer&) = default;
  AutoTimer& operator=(AutoTimer&&) = default;

  ~AutoTimer();

  [[nodiscard]] std::ostream& ostream() const;

  [[nodiscard]] const std::shared_ptr<spdlog::logger>& logger() const;

  [[nodiscard]] const std::string& FormatString() const;

  void Report();

  [[nodiscard]] Timer::cpu_times Elapsed() const noexcept;

  [[nodiscard]] std::string Format(
      std::string_view format = Timer::kDefaultFormat) const;
 
 private:
  Timer timer_;
  std::string format_;
 
  // ostream is stored as pointer so assignment operator works.
  std::variant<std::ostream*, std::pair<std::shared_ptr<spdlog::logger>,
                                        spdlog::level::level_enum>>
      output_;
};
 
}  // namespace lf::base
 
#endif  // INCG_529e391f2915453388028b848b3dcbd6