spdlog/include/spdlog/logger.h

// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)

#pragma once

// Thread safe logger (except for set_error_handler())
// Has name, log level, vector of std::shared sink pointers and formatter
// Upon each log write the logger:
// 1. Checks if its log level is enough to log the message and if yes:
// 2. Call the underlying sinks to do the job.
// 3. Each sink use its own private copy of a formatter to format the message
// and send to its destination.
//
// The use of private formatter per sink provides the opportunity to cache some
// formatted data, and support for different format per sink.

#include <cassert>
#include <vector>

#include "common.h"
#include "details/log_msg.h"
#include "sinks/sink.h"

#ifndef SPDLOG_NO_EXCEPTIONS
    #define SPDLOG_LOGGER_CATCH(location)                                                         \
        catch (const std::exception &ex) {                                                        \
            if (!location.empty()) {                                                              \
                err_handler_(                                                                     \
                    fmt_lib::format("{} [{}({})]", ex.what(), location.filename, location.line)); \
            } else {                                                                              \
                err_handler_(ex.what());                                                          \
            }                                                                                     \
        }                                                                                         \
        catch (...) {                                                                             \
            err_handler_("Rethrowing unknown exception in logger");                               \
            throw;                                                                                \
        }
#else
    #define SPDLOG_LOGGER_CATCH(location)
#endif

namespace spdlog {

class SPDLOG_API logger {
public:
    // Empty logger
    explicit logger(std::string name)
        : name_(std::move(name)) {}

    // Logger with range on sinks
    template <typename It>
    logger(std::string name, It begin, It end)
        : name_(std::move(name)),
          sinks_(begin, end) {}

    // Logger with single sink
    logger(std::string name, sink_ptr single_sink)
        : logger(std::move(name), {std::move(single_sink)}) {}

    // Logger with sinks init list
    logger(std::string name, sinks_init_list sinks)
        : logger(std::move(name), sinks.begin(), sinks.end()) {}

    logger(const logger &other) noexcept;
    logger(logger &&other) noexcept;

    virtual ~logger() = default;

    // log functions
    template <typename... Args>
    void log(source_loc loc, level lvl, format_string_t<Args...> fmt, Args &&...args) {
        if (should_log(lvl)) {
            log_with_format_(loc, lvl, details::to_string_view(fmt), std::forward<Args>(args)...);
        }
    }

    template <typename... Args>
    void log(level lvl, format_string_t<Args...> fmt, Args &&...args) {
        if (should_log(lvl)) {
            log_with_format_(source_loc{}, lvl, details::to_string_view(fmt),
                             std::forward<Args>(args)...);
        }
    }

    template <typename S, typename = is_convertible_to_sv<S>, typename... Args>
    void log(source_loc loc, level lvl, S fmt, Args &&...args) {
        if (should_log(lvl)) {
            log_with_format_(loc, lvl, fmt, std::forward<Args>(args)...);
        }
    }

    // log with no format string, just string message
    void log(source_loc loc, level lvl, string_view_t msg) {
        if (should_log(lvl)) {
            sink_it_(details::log_msg(loc, name_, lvl, msg));
        }
    }

    void log(level lvl, string_view_t msg) {
        if (should_log(lvl)) {
            sink_it_(details::log_msg(source_loc{}, name_, lvl, msg));
        }
    }

    // support for custom time
    void log(log_clock::time_point log_time, source_loc loc, level lvl, string_view_t msg) {
        if (should_log(lvl)) {
            sink_it_(details::log_msg(log_time, loc, name_, lvl, msg));
        }
    }

#ifdef SPDLOG_SOURCE_LOCATION  // off by default. define SPDLOG_SOURCE_LOCATION before including
                               // spdlog to enable.
    template <typename... Args>
    void trace(loc_with_fmt fmt, Args &&...args) {
        log(fmt.loc, level::trace, fmt.fmt_string, std::forward<Args>(args)...);
    }

    template <typename... Args>
    void debug(loc_with_fmt fmt, Args &&...args) {
        log(fmt.loc, level::debug, fmt.fmt_string, std::forward<Args>(args)...);
    }

    template <typename... Args>
    void info(loc_with_fmt fmt, Args &&...args) {
        log(fmt.loc, level::info, fmt.fmt_string, std::forward<Args>(args)...);
    }

    template <typename... Args>
    void warn(loc_with_fmt fmt, Args &&...args) {
        log(fmt.loc, level::warn, fmt.fmt_string, std::forward<Args>(args)...);
    }

    template <typename... Args>
    void error(loc_with_fmt fmt, Args &&...args) {
        log(fmt.loc, level::err, fmt.fmt_string, std::forward<Args>(args)...);
    }

    template <typename... Args>
    void critical(loc_with_fmt fmt, Args &&...args) {
        log(fmt.loc, level::critical, fmt.fmt_string, std::forward<Args>(args)...);
    }

    // log functions with no format string, just string

    void trace(string_view_t msg, source_loc loc = source_loc::current()) {
        log(loc, level::trace, msg);
    }

    void debug(string_view_t msg, source_loc loc = source_loc::current()) {
        log(loc, level::debug, msg);
    }

    void info(string_view_t msg, source_loc loc = source_loc::current()) {
        log(loc, level::info, msg);
    }

    void warn(string_view_t msg, source_loc loc = source_loc::current()) {
        log(loc, level::warn, msg);
    }

    void error(string_view_t msg, source_loc loc = source_loc::current()) {
        log(loc, level::err, msg);
    }

    void critical(string_view_t msg, source_loc loc = source_loc::current()) {
        log(loc, level::critical, msg);
    }
#else   // without source location
    template <typename... Args>
    void trace(format_string_t<Args...> fmt, Args &&...args) {
        log(level::trace, fmt, std::forward<Args>(args)...);
    }

    template <typename... Args>
    void debug(format_string_t<Args...> fmt, Args &&...args) {
        log(level::debug, fmt, std::forward<Args>(args)...);
    }

    template <typename... Args>
    void info(format_string_t<Args...> fmt, Args &&...args) {
        log(level::info, fmt, std::forward<Args>(args)...);
    }

    template <typename... Args>
    void warn(format_string_t<Args...> fmt, Args &&...args) {
        log(level::warn, fmt, std::forward<Args>(args)...);
    }

    template <typename... Args>
    void error(format_string_t<Args...> fmt, Args &&...args) {
        log(level::err, fmt, std::forward<Args>(args)...);
    }

    template <typename... Args>
    void critical(format_string_t<Args...> fmt, Args &&...args) {
        log(level::critical, fmt, std::forward<Args>(args)...);
    }

    // log functions with no format string, just string
    void trace(string_view_t msg) { log(level::trace, msg); }
    void debug(string_view_t msg) { log(level::debug, msg); }
    void info(string_view_t msg) { log(level::info, msg); }
    void warn(string_view_t msg) { log(level::warn, msg); }
    void error(string_view_t msg) { log(level::err, msg); }
    void critical(string_view_t msg) { log(level::critical, msg); }
#endif  // SPDLOG_SOURCE_LOCATION

    // return true if logging is enabled for the given level.
    [[nodiscard]] bool should_log(level msg_level) const {
        return msg_level >= level_.load(std::memory_order_relaxed);
    }

    // set the level of logging
    void set_level(level level);

    // return the active log level
    [[nodiscard]] level log_level() const;

    // return the name of the logger
    [[nodiscard]] const std::string &name() const;

    // set formatting for the sinks in this logger.
    // each sink will get a separate instance of the formatter object.
    void set_formatter(std::unique_ptr<formatter> f);

    // set formatting for the sinks in this logger.
    // equivalent to
    //     set_formatter(make_unique<pattern_formatter>(pattern, time_type))
    // Note: each sink will get a new instance of a formatter object, replacing the old one.
    void set_pattern(std::string pattern, pattern_time_type time_type = pattern_time_type::local);

    // flush functions
    void flush();
    void flush_on(level level);
    [[nodiscard]] level flush_level() const;

    // sinks
    [[nodiscard]] const std::vector<sink_ptr> &sinks() const;
    [[nodiscard]] std::vector<sink_ptr> &sinks();

    // error handler
    void set_error_handler(err_handler);

    // create new logger with same sinks and configuration.
    virtual std::shared_ptr<logger> clone(std::string logger_name);

protected:
    std::string name_;
    std::vector<sink_ptr> sinks_;
    spdlog::atomic_level_t level_{level::info};
    spdlog::atomic_level_t flush_level_{level::off};
    err_handler custom_err_handler_{nullptr};

    // common implementation for after templated public api has been resolved to format string and
    // args
    template <typename... Args>
    void log_with_format_(source_loc loc, level lvl, string_view_t fmt, Args &&...args) {
        assert(should_log(lvl));
        SPDLOG_TRY {
#ifdef SPDLOG_USE_STD_FORMAT
            auto formatted = std::vformat(fmt, std::make_format_args(args...));
            sink_it_(details::log_msg(loc, name_, lvl, formatted));
#else  // use {fmt} lib
            memory_buf_t buf;
            fmt::vformat_to(std::back_inserter(buf), fmt, fmt::make_format_args(args...));
            sink_it_(details::log_msg(loc, name_, lvl, string_view_t(buf.data(), buf.size())));
#endif
        }
        SPDLOG_LOGGER_CATCH(loc)
    }

    // log the given message (if the given log level is high enough)
    virtual void sink_it_(const details::log_msg &msg) {
        assert(should_log(msg.log_level));
        for (auto &sink : sinks_) {
            if (sink->should_log(msg.log_level)) {
                SPDLOG_TRY { sink->log(msg); }
                SPDLOG_LOGGER_CATCH(msg.source)
            }
        }

        if (should_flush_(msg)) {
            flush_();
        }
    }
    virtual void flush_();
    bool should_flush_(const details::log_msg &msg);

    // handle errors during logging.
    // default handler prints the error to stderr at max rate of 1 message/sec.
    void err_handler_(const std::string &msg);
};

}  // namespace spdlog