hourly_file_sink.h

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// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)
 
#pragma once
 
#include <spdlog/common.h>
#include <spdlog/details/file_helper.h>
#include <spdlog/details/null_mutex.h>
#include <spdlog/fmt/fmt.h>
#include <spdlog/sinks/base_sink.h>
#include <spdlog/details/os.h>
#include <spdlog/details/circular_q.h>
#include <spdlog/details/synchronous_factory.h>
 
#include <chrono>
#include <cstdio>
#include <ctime>
#include <mutex>
#include <string>
 
namespace spdlog
{
    namespace sinks
    {
 
        /*
         * Generator of Hourly log file names in format basename.YYYY-MM-DD-HH.ext
         */
        struct hourly_filename_calculator
        {
            // Create filename for the form basename.YYYY-MM-DD-H
            static filename_t calc_filename(const filename_t& filename, const tm& now_tm)
            {
                filename_t basename, ext;
                std::tie(basename, ext) = details::file_helper::split_by_extension(filename);
                return fmt_lib::format(SPDLOG_FILENAME_T("{}_{:04d}-{:02d}-{:02d}_{:02d}{}"), basename, now_tm.tm_year + 1900, now_tm.tm_mon + 1,
                                       now_tm.tm_mday, now_tm.tm_hour, ext);
            }
        };
 
        /*
         * Rotating file sink based on time.
         * If truncate != false , the created file will be truncated.
         * If max_files > 0, retain only the last max_files and delete previous.
         */
        template <typename Mutex, typename FileNameCalc = hourly_filename_calculator>
        class hourly_file_sink final : public base_sink<Mutex>
        {
        public:
            // create hourly file sink which rotates on given time
            hourly_file_sink(
                filename_t base_filename, bool truncate = false, uint16_t max_files = 0, const file_event_handlers& event_handlers = {})
                : base_filename_(std::move(base_filename)), file_helper_{event_handlers}, truncate_(truncate), max_files_(max_files), filenames_q_()
            {
                auto now      = log_clock::now();
                auto filename = FileNameCalc::calc_filename(base_filename_, now_tm(now));
                file_helper_.open(filename, truncate_);
                remove_init_file_ = file_helper_.size() == 0;
                rotation_tp_      = next_rotation_tp_();
 
                if (max_files_ > 0)
                {
                    init_filenames_q_();
                }
            }
 
            filename_t filename()
            {
                std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
                return file_helper_.filename();
            }
 
        protected:
            void sink_it_(const details::log_msg& msg) override
            {
                auto time          = msg.time;
                bool should_rotate = time >= rotation_tp_;
                if (should_rotate)
                {
                    if (remove_init_file_)
                    {
                        file_helper_.close();
                        details::os::remove(file_helper_.filename());
                    }
                    auto filename = FileNameCalc::calc_filename(base_filename_, now_tm(time));
                    file_helper_.open(filename, truncate_);
                    rotation_tp_ = next_rotation_tp_();
                }
                remove_init_file_ = false;
                memory_buf_t formatted;
                base_sink<Mutex>::formatter_->format(msg, formatted);
                file_helper_.write(formatted);
 
                // Do the cleaning only at the end because it might throw on failure.
                if (should_rotate && max_files_ > 0)
                {
                    delete_old_();
                }
            }
 
            void flush_() override
            {
                file_helper_.flush();
            }
 
        private:
            void init_filenames_q_()
            {
                using details::os::path_exists;
 
                filenames_q_ = details::circular_q<filename_t>(static_cast<size_t>(max_files_));
                std::vector<filename_t> filenames;
                auto                    now = log_clock::now();
                while (filenames.size() < max_files_)
                {
                    auto filename = FileNameCalc::calc_filename(base_filename_, now_tm(now));
                    if (!path_exists(filename))
                    {
                        break;
                    }
                    filenames.emplace_back(filename);
                    now -= std::chrono::hours(1);
                }
                for (auto iter = filenames.rbegin(); iter != filenames.rend(); ++iter)
                {
                    filenames_q_.push_back(std::move(*iter));
                }
            }
 
            tm now_tm(log_clock::time_point tp)
            {
                time_t tnow = log_clock::to_time_t(tp);
                return spdlog::details::os::localtime(tnow);
            }
 
            log_clock::time_point next_rotation_tp_()
            {
                auto now           = log_clock::now();
                tm   date          = now_tm(now);
                date.tm_min        = 0;
                date.tm_sec        = 0;
                auto rotation_time = log_clock::from_time_t(std::mktime(&date));
                if (rotation_time > now)
                {
                    return rotation_time;
                }
                return {rotation_time + std::chrono::hours(1)};
            }
 
            // Delete the file N rotations ago.
            // Throw spdlog_ex on failure to delete the old file.
            void delete_old_()
            {
                using details::os::filename_to_str;
                using details::os::remove_if_exists;
 
                filename_t current_file = file_helper_.filename();
                if (filenames_q_.full())
                {
                    auto old_filename = std::move(filenames_q_.front());
                    filenames_q_.pop_front();
                    bool ok = remove_if_exists(old_filename) == 0;
                    if (!ok)
                    {
                        filenames_q_.push_back(std::move(current_file));
                        SPDLOG_THROW(spdlog_ex("Failed removing hourly file " + filename_to_str(old_filename), errno));
                    }
                }
                filenames_q_.push_back(std::move(current_file));
            }
 
            filename_t                      base_filename_;
            log_clock::time_point           rotation_tp_;
            details::file_helper            file_helper_;
            bool                            truncate_;
            uint16_t                        max_files_;
            details::circular_q<filename_t> filenames_q_;
            bool                            remove_init_file_;
        };
 
        using hourly_file_sink_mt = hourly_file_sink<std::mutex>;
        using hourly_file_sink_st = hourly_file_sink<details::null_mutex>;
 
    } // namespace sinks
 
    //
    // factory functions
    //
    template <typename Factory = spdlog::synchronous_factory>
    inline std::shared_ptr<logger> hourly_logger_mt(const std::string& logger_name, const filename_t& filename, bool truncate = false, uint16_t max_files = 0, const file_event_handlers& event_handlers = {})
    {
        return Factory::template create<sinks::hourly_file_sink_mt>(logger_name, filename, truncate, max_files, event_handlers);
    }
 
    template <typename Factory = spdlog::synchronous_factory>
    inline std::shared_ptr<logger> hourly_logger_st(const std::string& logger_name, const filename_t& filename, bool truncate = false, uint16_t max_files = 0, const file_event_handlers& event_handlers = {})
    {
        return Factory::template create<sinks::hourly_file_sink_st>(logger_name, filename, truncate, max_files, event_handlers);
    }
} // namespace spdlog