Backend.h

#pragma once

#include "quill/backend/BackendManager.h"
#include "quill/backend/BackendOptions.h"
#include "quill/backend/SignalHandler.h"
#include "quill/core/Attributes.h"
#include "quill/core/QuillError.h"

#include <atomic>
#include <csignal>
#include <cstdint>
#include <cstdlib>
#include <mutex>

QUILL_BEGIN_NAMESPACE

constexpr uint32_t VersionMajor{11};
constexpr uint32_t VersionMinor{1};
constexpr uint32_t VersionPatch{0};
constexpr uint32_t Version{VersionMajor * 10000 + VersionMinor * 100 + VersionPatch};

class Backend
{
public:
  QUILL_ATTRIBUTE_COLD static void start(BackendOptions const& options = BackendOptions{})
  {
    std::call_once(detail::BackendManager::instance().get_start_once_flag(),
                   [options]()
                   {
                     // Ensure SignalHandlerContext singleton is constructed before atexit
                     // registration so it is alive when the atexit handler runs during shutdown.
                     (void)detail::SignalHandlerContext::instance();

                     // Run the backend worker thread, we wait here until the thread enters the main loop
                     detail::BackendManager::instance().start_backend_thread(options);

                     // Set up an exit handler to call stop when the main application exits.
                     // always call stop on destruction to log everything. std::atexit seems to be
                     // working better with dll on windows compared to using ~LogManagerSingleton().
                     if (!detail::BackendManager::instance().is_atexit_registered())
                     {
                       detail::BackendManager::instance().set_atexit_registered();
                       std::atexit([]() { Backend::stop(); });
                     }
                   });
  }
  
  template <typename TFrontendOptions>
  QUILL_ATTRIBUTE_COLD static void start(BackendOptions const& backend_options,
                                         SignalHandlerOptions const& signal_handler_options)
  {
    std::call_once(detail::BackendManager::instance().get_start_once_flag(),
                   [backend_options, signal_handler_options]()
                   {
#if defined(_WIN32)
                     detail::init_exception_handler<TFrontendOptions>();
#else
        // We do not want signal handler to run in the backend worker thread
        // Block signals in the main thread so when we spawn the backend worker thread it inherits
        // the master
        sigset_t set, oldset;
        sigfillset(&set);
        sigprocmask(SIG_SETMASK, &set, &oldset);
        detail::init_signal_handler<TFrontendOptions>(signal_handler_options.catchable_signals);
#endif

                     // Run the backend worker thread, we wait here until the thread enters the main loop
                     detail::BackendManager::instance().start_backend_thread(backend_options);

                     detail::SignalHandlerContext::instance().logger_name = signal_handler_options.logger_name;

                     detail::SignalHandlerContext::instance().excluded_logger_substrings =
                       signal_handler_options.excluded_logger_substrings;

                     detail::SignalHandlerContext::instance().signal_handler_timeout_seconds.store(
                       signal_handler_options.timeout_seconds);

                     // We need to update the signal handler with some backend thread details
                     detail::SignalHandlerContext::instance().backend_thread_id.store(
                       detail::BackendManager::instance().get_backend_thread_id());

#if defined(_WIN32)
      // nothing to do
#else
                     // Unblock signals in the main thread so subsequent threads do not inherit the blocked mask
                     sigprocmask(SIG_SETMASK, &oldset, nullptr);
#endif

                     // Set up an exit handler to call stop when the main application exits.
                     // always call stop on destruction to log everything. std::atexit seems to be
                     // working better with dll on windows compared to using ~LogManagerSingleton().
                     if (!detail::BackendManager::instance().is_atexit_registered())
                     {
                       detail::BackendManager::instance().set_atexit_registered();
                       std::atexit([]() { Backend::stop(); });
                     }
                   });
  }

  QUILL_ATTRIBUTE_COLD static void stop()
  {
    detail::SignalHandlerContext::instance().backend_thread_id.store(0);
    detail::BackendManager::instance().stop_backend_thread();
    detail::deinit_signal_handler();
  }

  static void notify() noexcept { detail::BackendManager::instance().notify_backend_thread(); }

  QUILL_NODISCARD static bool is_running() noexcept
  {
    return detail::BackendManager::instance().is_backend_thread_running();
  }

  QUILL_NODISCARD static uint32_t get_thread_id() noexcept
  {
    return detail::BackendManager::instance().get_backend_thread_id();
  }

  QUILL_NODISCARD static uint64_t convert_rdtsc_to_epoch_time(uint64_t rdtsc_value) noexcept
  {
    return detail::BackendManager::instance().convert_rdtsc_to_epoch_time(rdtsc_value);
  }

  QUILL_ATTRIBUTE_COLD static ManualBackendWorker* acquire_manual_backend_worker()
  {
    ManualBackendWorker* manual_backend_worker{nullptr};

    std::call_once(
      detail::BackendManager::instance().get_start_once_flag(), [&manual_backend_worker]() mutable
      { manual_backend_worker = detail::BackendManager::instance().get_manual_backend_worker(); });

    if (!manual_backend_worker)
    {
      QUILL_THROW(
        QuillError{"acquire_manual_backend_worker() can only be called once per process. "
                   "Additionally, it should not be "
                   "called when start() has already been invoked"});
    }

    return manual_backend_worker;
  }
};

QUILL_END_NAMESPACE