rotating_file_sink-inl.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
 
#ifndef SPDLOG_HEADER_ONLY
#include <spdlog/sinks/rotating_file_sink.h>
#endif
 
#include <spdlog/common.h>
 
#include <spdlog/details/file_helper.h>
#include <spdlog/details/null_mutex.h>
#include <spdlog/fmt/fmt.h>
 
#include <cerrno>
#include <chrono>
#include <ctime>
#include <mutex>
#include <string>
#include <tuple>
 
namespace spdlog
{
    namespace sinks
    {
 
        template <typename Mutex>
        SPDLOG_INLINE rotating_file_sink<Mutex>::rotating_file_sink(
            filename_t base_filename, std::size_t max_size, std::size_t max_files, bool rotate_on_open, const file_event_handlers& event_handlers)
            : base_filename_(std::move(base_filename)), max_size_(max_size), max_files_(max_files), file_helper_{event_handlers}
        {
            if (max_size == 0)
            {
                throw_spdlog_ex("rotating sink constructor: max_size arg cannot be zero");
            }
 
            if (max_files > 200000)
            {
                throw_spdlog_ex("rotating sink constructor: max_files arg cannot exceed 200000");
            }
            file_helper_.open(calc_filename(base_filename_, 0));
            current_size_ = file_helper_.size(); // expensive. called only once
            if (rotate_on_open && current_size_ > 0)
            {
                rotate_();
                current_size_ = 0;
            }
        }
 
        // calc filename according to index and file extension if exists.
        // e.g. calc_filename("logs/mylog.txt, 3) => "logs/mylog.3.txt".
        template <typename Mutex>
        SPDLOG_INLINE filename_t rotating_file_sink<Mutex>::calc_filename(const filename_t& filename, std::size_t index)
        {
            if (index == 0u)
            {
                return filename;
            }
 
            filename_t basename, ext;
            std::tie(basename, ext) = details::file_helper::split_by_extension(filename);
            return fmt_lib::format(SPDLOG_FILENAME_T("{}.{}{}"), basename, index, ext);
        }
 
        template <typename Mutex>
        SPDLOG_INLINE filename_t rotating_file_sink<Mutex>::filename()
        {
            std::lock_guard<Mutex> lock(base_sink<Mutex>::mutex_);
            return file_helper_.filename();
        }
 
        template <typename Mutex>
        SPDLOG_INLINE void rotating_file_sink<Mutex>::sink_it_(const details::log_msg& msg)
        {
            memory_buf_t formatted;
            base_sink<Mutex>::formatter_->format(msg, formatted);
            auto new_size = current_size_ + formatted.size();
 
            // rotate if the new estimated file size exceeds max size.
            // rotate only if the real size > 0 to better deal with full disk (see issue #2261).
            // we only check the real size when new_size > max_size_ because it is relatively expensive.
            if (new_size > max_size_)
            {
                file_helper_.flush();
                if (file_helper_.size() > 0)
                {
                    rotate_();
                    new_size = formatted.size();
                }
            }
            file_helper_.write(formatted);
            current_size_ = new_size;
        }
 
        template <typename Mutex>
        SPDLOG_INLINE void rotating_file_sink<Mutex>::flush_()
        {
            file_helper_.flush();
        }
 
        // Rotate files:
        // log.txt -> log.1.txt
        // log.1.txt -> log.2.txt
        // log.2.txt -> log.3.txt
        // log.3.txt -> delete
        template <typename Mutex>
        SPDLOG_INLINE void rotating_file_sink<Mutex>::rotate_()
        {
            using details::os::filename_to_str;
            using details::os::path_exists;
 
            file_helper_.close();
            for (auto i = max_files_; i > 0; --i)
            {
                filename_t src = calc_filename(base_filename_, i - 1);
                if (!path_exists(src))
                {
                    continue;
                }
                filename_t target = calc_filename(base_filename_, i);
 
                if (!rename_file_(src, target))
                {
                    // if failed try again after a small delay.
                    // this is a workaround to a windows issue, where very high rotation
                    // rates can cause the rename to fail with permission denied (because of antivirus?).
                    details::os::sleep_for_millis(100);
                    if (!rename_file_(src, target))
                    {
                        file_helper_.reopen(true); // truncate the log file anyway to prevent it to grow beyond its limit!
                        current_size_ = 0;
                        throw_spdlog_ex("rotating_file_sink: failed renaming " + filename_to_str(src) + " to " + filename_to_str(target), errno);
                    }
                }
            }
            file_helper_.reopen(true);
        }
 
        // delete the target if exists, and rename the src file  to target
        // return true on success, false otherwise.
        template <typename Mutex>
        SPDLOG_INLINE bool rotating_file_sink<Mutex>::rename_file_(const filename_t& src_filename, const filename_t& target_filename)
        {
            // try to delete the target file in case it already exists.
            (void)details::os::remove(target_filename);
            return details::os::rename(src_filename, target_filename) == 0;
        }
 
    } // namespace sinks
} // namespace spdlog