text: // Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
  // Distributed under the MIT License (http://opensource.org/licenses/MIT)
  
  #pragma once
  
  // Fast asynchronous logger.
  // Uses pre allocated queue.
  // Creates a single back thread to pop messages from the queue and log them.
  //
  // Upon each log write the logger:
  //    1. Checks if its log level is enough to log the message
  //    2. Push a new copy of the message to a queue (or block the caller until
  //    space is available in the queue)
  // Upon destruction, logs all remaining messages in the queue before
  // destructing..
  
  #include "spdlog/logger.h"
  
  namespace spdlog {
  
  // Async overflow policy - block by default.
  enum class async_overflow_policy
  {
      block,         // Block until message can be enqueued
      overrun_oldest // Discard oldest message in the queue if full when trying to
                     // add new item.
  };
  
  namespace details {
  class thread_pool;
  }
  
  class async_logger final : public std::enable_shared_from_this<async_logger>, public logger
  {
      friend class details::thread_pool;
  
  public:
      template<typename It>
      async_logger(eastl::string logger_name, It begin, It end, std::weak_ptr<details::thread_pool> tp,
          async_overflow_policy overflow_policy = async_overflow_policy::block)
          : logger(std::move(logger_name), begin, end)
          , thread_pool_(std::move(tp))
          , overflow_policy_(overflow_policy)
      {}
  
      async_logger(eastl::string logger_name, sinks_init_list sinks_list, std::weak_ptr<details::thread_pool> tp,
          async_overflow_policy overflow_policy = async_overflow_policy::block);
  
      async_logger(eastl::string logger_name, sink_ptr single_sink, std::weak_ptr<details::thread_pool> tp,
          async_overflow_policy overflow_policy = async_overflow_policy::block);
  
      std::shared_ptr<logger> clone(eastl::string new_name) override;
  
  protected:
      void sink_it_(const details::log_msg &msg) override;
      void flush_() override;
      void backend_sink_it_(const details::log_msg &incoming_log_msg);
      void backend_flush_();
  
  private:
      std::weak_ptr<details::thread_pool> thread_pool_;
      async_overflow_policy overflow_policy_;
  };
  } // namespace spdlog
  
  #ifdef SPDLOG_HEADER_ONLY
  #include "async_logger-inl.h"
  #endif
  