text: // Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
  // Distributed under the MIT License (http://opensource.org/licenses/MIT)
  
  #pragma once
  
  #include <spdlog/details/log_msg_buffer.h>
  #include <spdlog/details/circular_q.h>
  
  #include <atomic>
  #include <mutex>
  #include <functional>
  
  // Store log messages in circular buffer.
  // Useful for storing debug data in case of error/warning happens.
  
  namespace spdlog {
  namespace details {
  class SPDLOG_API backtracer
  {
      mutable std::mutex mutex_;
      std::atomic<bool> enabled_{false};
      circular_q<log_msg_buffer> messages_;
  
  public:
      backtracer() = default;
      backtracer(const backtracer &other);
  
      backtracer(backtracer &&other) SPDLOG_NOEXCEPT;
      backtracer &operator=(backtracer other);
  
      void enable(size_t size);
      void disable();
      bool enabled() const;
      void push_back(const log_msg &msg);
  
      // pop all items in the q and apply the given fun on each of them.
      void foreach_pop(std::function<void(const details::log_msg &)> fun);
  };
  
  } // namespace details
  } // namespace spdlog
  
  #ifdef SPDLOG_HEADER_ONLY
  #include "backtracer-inl.h"
  #endif