extended_logger.hpp

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// SPDX-FileCopyrightText: 2026 Jarosław Pelczar <jarek@jpelczar.com>
//
// SPDX-License-Identifier: BSD-2-Clause
 
#pragma once
 
#include "extended_msg.hpp"
#include "extended_sink.hpp"
#include "logger.hpp"
 
namespace microfmt::log {
 
using log_meta_callback = log_meta (*)(void *user, const log_msg &msg) noexcept;
 
class RELOCO_POINTER meta_decorator {
public:
  void set_callback(log_meta_callback cb, void *user = nullptr) noexcept {
    cb_ = cb;
    user_ = user;
  }
 
  [[nodiscard]] extended_log_msg operator()(const log_msg &msg) const noexcept {
    return extended_log_msg(msg, cb_ != nullptr ? cb_(user_, msg) : log_meta{});
  }
 
  // Caller-built extended records already carry their metadata.
  [[nodiscard]] const extended_log_msg &operator()(const extended_log_msg &msg) const noexcept { return msg; }
 
private:
  log_meta_callback cb_{nullptr};
  void *user_{nullptr};
};
 
template <std::size_t MaxSinks = 4, std::size_t MsgBufferCapacity = 256, typename Mutex = detail::null_mutex>
class extended_logger : public basic_logger<MaxSinks, MsgBufferCapacity, Mutex, extended_log_sink, meta_decorator> {
  using base = basic_logger<MaxSinks, MsgBufferCapacity, Mutex, extended_log_sink, meta_decorator>;
 
public:
  using base::base;
  using base::log;
 
  // low-level formatting: raw character pointers and integer width conversions bounded by the buffer sizes checked
  // here.
  RELOCO_BEGIN_UNSAFE_CODE
  void set_meta_callback(log_meta_callback cb, void *user = nullptr) noexcept {
    this->decorator().set_callback(cb, user);
  }
  RELOCO_END_UNSAFE_CODE
 
  void log(const extended_log_msg &msg) const noexcept {
    if (this->should_log(msg.lvl)) {
      this->dispatch(msg);
    }
  }
};
 
} // namespace microfmt::log