diff --git a/src/details/file_helper.cpp b/src/details/file_helper.cpp
new file mode 100644
index 00000000..51bc46bd
--- /dev/null
+++ b/src/details/file_helper.cpp
@@ -0,0 +1,179 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+
+#include <spdlog/details/file_helper.h>
+
+#include <spdlog/details/os.h>
+#include <spdlog/common.h>
+
+#include <cerrno>
+#include <chrono>
+#include <cstdio>
+#include <string>
+#include <thread>
+#include <tuple>
+
+namespace spdlog {
+namespace details {
+
+ file_helper::file_helper(const file_event_handlers &event_handlers)
+    : event_handlers_(event_handlers)
+{}
+
+ file_helper::~file_helper()
+{
+    close();
+}
+
+ void file_helper::open(const filename_t &fname, bool truncate)
+{
+    close();
+    filename_ = fname;
+
+    auto *mode = SPDLOG_FILENAME_T("ab");
+    auto *trunc_mode = SPDLOG_FILENAME_T("wb");
+
+    if (event_handlers_.before_open)
+    {
+        event_handlers_.before_open(filename_);
+    }
+    for (int tries = 0; tries < open_tries_; ++tries)
+    {
+        // create containing folder if not exists already.
+        os::create_dir(os::dir_name(fname));
+        if (truncate)
+        {
+            // Truncate by opening-and-closing a tmp file in "wb" mode, always
+            // opening the actual log-we-write-to in "ab" mode, since that
+            // interacts more politely with eternal processes that might
+            // rotate/truncate the file underneath us.
+            std::FILE *tmp;
+            if (os::fopen_s(&tmp, fname, trunc_mode))
+            {
+                continue;
+            }
+            std::fclose(tmp);
+        }
+        if (!os::fopen_s(&fd_, fname, mode))
+        {
+            if (event_handlers_.after_open)
+            {
+                event_handlers_.after_open(filename_, fd_);
+            }
+            return;
+        }
+
+        details::os::sleep_for_millis(open_interval_);
+    }
+
+    throw_spdlog_ex("Failed opening file " + os::filename_to_str(filename_) + " for writing", errno);
+}
+
+ void file_helper::reopen(bool truncate)
+{
+    if (filename_.empty())
+    {
+        throw_spdlog_ex("Failed re opening file - was not opened before");
+    }
+    this->open(filename_, truncate);
+}
+
+ void file_helper::flush()
+{
+    if (std::fflush(fd_) != 0)
+    {
+        throw_spdlog_ex("Failed flush to file " + os::filename_to_str(filename_), errno);
+    }
+}
+
+ void file_helper::sync()
+{
+    if (!os::fsync(fd_))
+    {
+        throw_spdlog_ex("Failed to fsync file " + os::filename_to_str(filename_), errno);
+    }
+}
+
+ void file_helper::close()
+{
+    if (fd_ != nullptr)
+    {
+        if (event_handlers_.before_close)
+        {
+            event_handlers_.before_close(filename_, fd_);
+        }
+
+        std::fclose(fd_);
+        fd_ = nullptr;
+
+        if (event_handlers_.after_close)
+        {
+            event_handlers_.after_close(filename_);
+        }
+    }
+}
+
+ void file_helper::write(const memory_buf_t &buf)
+{
+    size_t msg_size = buf.size();
+    auto data = buf.data();
+    if (std::fwrite(data, 1, msg_size, fd_) != msg_size)
+    {
+        throw_spdlog_ex("Failed writing to file " + os::filename_to_str(filename_), errno);
+    }
+}
+
+ size_t file_helper::size() const
+{
+    if (fd_ == nullptr)
+    {
+        throw_spdlog_ex("Cannot use size() on closed file " + os::filename_to_str(filename_));
+    }
+    return os::filesize(fd_);
+}
+
+ const filename_t &file_helper::filename() const
+{
+    return filename_;
+}
+
+//
+// return file path and its extension:
+//
+// "mylog.txt" => ("mylog", ".txt")
+// "mylog" => ("mylog", "")
+// "mylog." => ("mylog.", "")
+// "/dir1/dir2/mylog.txt" => ("/dir1/dir2/mylog", ".txt")
+//
+// the starting dot in filenames is ignored (hidden files):
+//
+// ".mylog" => (".mylog". "")
+// "my_folder/.mylog" => ("my_folder/.mylog", "")
+// "my_folder/.mylog.txt" => ("my_folder/.mylog", ".txt")
+ std::tuple<filename_t, filename_t> file_helper::split_by_extension(const filename_t &fname)
+{
+    auto ext_index = fname.rfind('.');
+
+    // no valid extension found - return whole path and empty string as
+    // extension
+    if (ext_index == filename_t::npos || ext_index == 0 || ext_index == fname.size() - 1)
+    {
+        return std::make_tuple(fname, filename_t());
+    }
+
+    // treat cases like "/etc/rc.d/somelogfile or "/abc/.hiddenfile"
+    auto folder_index = fname.find_last_of(details::os::folder_seps_filename);
+    if (folder_index != filename_t::npos && folder_index >= ext_index - 1)
+    {
+        return std::make_tuple(fname, filename_t());
+    }
+
+    // finally - return a valid base and extension tuple
+    return std::make_tuple(fname.substr(0, ext_index), fname.substr(ext_index));
+}
+
+} // namespace details
+} // namespace spdlog
diff --git a/src/details/log_msg.cpp b/src/details/log_msg.cpp
new file mode 100644
index 00000000..738c6324
--- /dev/null
+++ b/src/details/log_msg.cpp
@@ -0,0 +1,35 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+#    include <spdlog/details/log_msg.h>
+
+#include <spdlog/details/os.h>
+
+namespace spdlog {
+namespace details {
+
+ log_msg::log_msg(spdlog::log_clock::time_point log_time, spdlog::source_loc loc, string_view_t a_logger_name,
+    spdlog::level lvl, spdlog::string_view_t msg)
+    : logger_name(a_logger_name)
+    , log_level(lvl)
+    , time(log_time)
+#ifndef SPDLOG_NO_THREAD_ID
+    , thread_id(os::thread_id())
+#endif
+    , source(loc)
+    , payload(msg)
+{}
+
+ log_msg::log_msg(
+    spdlog::source_loc loc, string_view_t a_logger_name, spdlog::level lvl, spdlog::string_view_t msg)
+    : log_msg(os::now(), loc, a_logger_name, lvl, msg)
+{}
+
+ log_msg::log_msg(string_view_t a_logger_name, spdlog::level lvl, spdlog::string_view_t msg)
+    : log_msg(os::now(), source_loc{}, a_logger_name, lvl, msg)
+{}
+
+} // namespace details
+} // namespace spdlog
diff --git a/src/details/log_msg_buffer.cpp b/src/details/log_msg_buffer.cpp
new file mode 100644
index 00000000..a8b5b8ca
--- /dev/null
+++ b/src/details/log_msg_buffer.cpp
@@ -0,0 +1,58 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+#    include <spdlog/details/log_msg_buffer.h>
+
+namespace spdlog {
+namespace details {
+
+ log_msg_buffer::log_msg_buffer(const log_msg &orig_msg)
+    : log_msg{orig_msg}
+{
+    buffer.append(logger_name.begin(), logger_name.end());
+    buffer.append(payload.begin(), payload.end());
+    update_string_views();
+}
+
+ log_msg_buffer::log_msg_buffer(const log_msg_buffer &other)
+    : log_msg{other}
+{
+    buffer.append(logger_name.begin(), logger_name.end());
+    buffer.append(payload.begin(), payload.end());
+    update_string_views();
+}
+
+ log_msg_buffer::log_msg_buffer(log_msg_buffer &&other) noexcept
+    : log_msg{other}
+    , buffer{std::move(other.buffer)}
+{
+    update_string_views();
+}
+
+ log_msg_buffer &log_msg_buffer::operator=(const log_msg_buffer &other)
+{
+    log_msg::operator=(other);
+    buffer.clear();
+    buffer.append(other.buffer.data(), other.buffer.data() + other.buffer.size());
+    update_string_views();
+    return *this;
+}
+
+ log_msg_buffer &log_msg_buffer::operator=(log_msg_buffer &&other) noexcept
+{
+    log_msg::operator=(other);
+    buffer = std::move(other.buffer);
+    update_string_views();
+    return *this;
+}
+
+ void log_msg_buffer::update_string_views()
+{
+    logger_name = string_view_t{buffer.data(), logger_name.size()};
+    payload = string_view_t{buffer.data() + logger_name.size(), payload.size()};
+}
+
+} // namespace details
+} // namespace spdlog
diff --git a/src/details/os.cpp b/src/details/os.cpp
new file mode 100644
index 00000000..e991f9cf
--- /dev/null
+++ b/src/details/os.cpp
@@ -0,0 +1,630 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+#    include <spdlog/details/os.h>
+
+#include <spdlog/common.h>
+
+#include <algorithm>
+#include <chrono>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <ctime>
+#include <string>
+#include <thread>
+#include <array>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#ifdef _WIN32
+
+#    include <io.h>      // for _get_osfhandle, _isatty, _fileno
+#    include <process.h> // for _get_pid
+#    include <spdlog/details/windows_include.h>
+#    include <fileapi.h> // for FlushFileBuffers
+
+#    ifdef __MINGW32__
+#        include <share.h>
+#    endif
+
+#    if defined(SPDLOG_WCHAR_FILENAMES)
+#        include <limits>
+#        include <cassert>
+#    endif
+
+#    include <direct.h> // for _mkdir/_wmkdir
+
+#else // unix
+
+#    include <fcntl.h>
+#    include <unistd.h>
+
+#    ifdef __linux__
+#        include <sys/syscall.h> //Use gettid() syscall under linux to get thread id
+
+#    elif defined(_AIX)
+#        include <pthread.h> // for pthread_getthrds_np
+
+#    elif defined(__DragonFly__) || defined(__FreeBSD__)
+#        include <pthread_np.h> // for pthread_getthreadid_np
+
+#    elif defined(__NetBSD__)
+#        include <lwp.h> // for _lwp_self
+
+#    elif defined(__sun)
+#        include <thread.h> // for thr_self
+#    endif
+
+#endif // unix
+
+#if defined __APPLE__
+#    include <AvailabilityMacros.h>
+#endif
+
+#ifndef __has_feature          // Clang - feature checking macros.
+#    define __has_feature(x) 0 // Compatibility with non-clang compilers.
+#endif
+
+namespace spdlog {
+namespace details {
+namespace os {
+
+ spdlog::log_clock::time_point now() noexcept
+{
+
+#if defined __linux__ && defined SPDLOG_CLOCK_COARSE
+    timespec ts;
+    ::clock_gettime(CLOCK_REALTIME_COARSE, &ts);
+    return std::chrono::time_point<log_clock, typename log_clock::duration>(
+        std::chrono::duration_cast<typename log_clock::duration>(std::chrono::seconds(ts.tv_sec) + std::chrono::nanoseconds(ts.tv_nsec)));
+
+#else
+    return log_clock::now();
+#endif
+}
+ std::tm localtime(const std::time_t &time_tt) noexcept
+{
+
+#ifdef _WIN32
+    std::tm tm;
+    ::localtime_s(&tm, &time_tt);
+#else
+    std::tm tm;
+    ::localtime_r(&time_tt, &tm);
+#endif
+    return tm;
+}
+
+ std::tm localtime() noexcept
+{
+    std::time_t now_t = ::time(nullptr);
+    return localtime(now_t);
+}
+
+ std::tm gmtime(const std::time_t &time_tt) noexcept
+{
+
+#ifdef _WIN32
+    std::tm tm;
+    ::gmtime_s(&tm, &time_tt);
+#else
+    std::tm tm;
+    ::gmtime_r(&time_tt, &tm);
+#endif
+    return tm;
+}
+
+ std::tm gmtime() noexcept
+{
+    std::time_t now_t = ::time(nullptr);
+    return gmtime(now_t);
+}
+
+// fopen_s on non windows for writing
+ bool fopen_s(FILE **fp, const filename_t &filename, const filename_t &mode)
+{
+#ifdef _WIN32
+#    ifdef SPDLOG_WCHAR_FILENAMES
+    *fp = ::_wfsopen((filename.c_str()), mode.c_str(), _SH_DENYNO);
+#    else
+    *fp = ::_fsopen((filename.c_str()), mode.c_str(), _SH_DENYNO);
+#    endif
+#    if defined(SPDLOG_PREVENT_CHILD_FD)
+    if (*fp != nullptr)
+    {
+        auto file_handle = reinterpret_cast<HANDLE>(_get_osfhandle(::_fileno(*fp)));
+        if (!::SetHandleInformation(file_handle, HANDLE_FLAG_INHERIT, 0))
+        {
+            ::fclose(*fp);
+            *fp = nullptr;
+        }
+    }
+#    endif
+#else // unix
+#    if defined(SPDLOG_PREVENT_CHILD_FD)
+    const int mode_flag = mode == SPDLOG_FILENAME_T("ab") ? O_APPEND : O_TRUNC;
+    const int fd = ::open((filename.c_str()), O_CREAT | O_WRONLY | O_CLOEXEC | mode_flag, mode_t(0644));
+    if (fd == -1)
+    {
+        return true;
+    }
+    *fp = ::fdopen(fd, mode.c_str());
+    if (*fp == nullptr)
+    {
+        ::close(fd);
+    }
+#    else
+    *fp = ::fopen((filename.c_str()), mode.c_str());
+#    endif
+#endif
+
+    return *fp == nullptr;
+}
+
+ int remove(const filename_t &filename) noexcept
+{
+#if defined(_WIN32) && defined(SPDLOG_WCHAR_FILENAMES)
+    return ::_wremove(filename.c_str());
+#else
+    return std::remove(filename.c_str());
+#endif
+}
+
+ int remove_if_exists(const filename_t &filename) noexcept
+{
+    return path_exists(filename) ? remove(filename) : 0;
+}
+
+ int rename(const filename_t &filename1, const filename_t &filename2) noexcept
+{
+#if defined(_WIN32) && defined(SPDLOG_WCHAR_FILENAMES)
+    return ::_wrename(filename1.c_str(), filename2.c_str());
+#else
+    return std::rename(filename1.c_str(), filename2.c_str());
+#endif
+}
+
+// Return true if path exists (file or directory)
+ bool path_exists(const filename_t &filename) noexcept
+{
+#ifdef _WIN32
+#    ifdef SPDLOG_WCHAR_FILENAMES
+    auto attribs = ::GetFileAttributesW(filename.c_str());
+#    else
+    auto attribs = ::GetFileAttributesA(filename.c_str());
+#    endif
+    return attribs != INVALID_FILE_ATTRIBUTES;
+#else // common linux/unix all have the stat system call
+    struct stat buffer;
+    return (::stat(filename.c_str(), &buffer) == 0);
+#endif
+}
+
+#ifdef _MSC_VER
+// avoid warning about unreachable statement at the end of filesize()
+#    pragma warning(push)
+#    pragma warning(disable : 4702)
+#endif
+
+// Return file size according to open FILE* object
+ size_t filesize(FILE *f)
+{
+    if (f == nullptr)
+    {
+        throw_spdlog_ex("Failed getting file size. fd is null");
+    }
+#if defined(_WIN32) && !defined(__CYGWIN__)
+    int fd = ::_fileno(f);
+#    if defined(_WIN64) // 64 bits
+    __int64 ret = ::_filelengthi64(fd);
+    if (ret >= 0)
+    {
+        return static_cast<size_t>(ret);
+    }
+
+#    else // windows 32 bits
+    long ret = ::_filelength(fd);
+    if (ret >= 0)
+    {
+        return static_cast<size_t>(ret);
+    }
+#    endif
+
+#else // unix
+// OpenBSD and AIX doesn't compile with :: before the fileno(..)
+#    if defined(__OpenBSD__) || defined(_AIX)
+    int fd = fileno(f);
+#    else
+    int fd = ::fileno(f);
+#    endif
+// 64 bits(but not in osx, linux/musl or cygwin, where fstat64 is deprecated)
+#    if ((defined(__linux__) && defined(__GLIBC__)) || defined(__sun) || defined(_AIX)) && (defined(__LP64__) || defined(_LP64))
+    struct stat64 st;
+    if (::fstat64(fd, &st) == 0)
+    {
+        return static_cast<size_t>(st.st_size);
+    }
+#    else // other unix or linux 32 bits or cygwin
+    struct stat st;
+    if (::fstat(fd, &st) == 0)
+    {
+        return static_cast<size_t>(st.st_size);
+    }
+#    endif
+#endif
+    throw_spdlog_ex("Failed getting file size from fd", errno);
+    return 0; // will not be reached.
+}
+
+#ifdef _MSC_VER
+#    pragma warning(pop)
+#endif
+
+// Return utc offset in minutes or throw spdlog_ex on failure
+ int utc_minutes_offset(const std::tm &tm)
+{
+
+#ifdef _WIN32
+#    if _WIN32_WINNT < _WIN32_WINNT_WS08
+    TIME_ZONE_INFORMATION tzinfo;
+    auto rv = ::GetTimeZoneInformation(&tzinfo);
+#    else
+    DYNAMIC_TIME_ZONE_INFORMATION tzinfo;
+    auto rv = ::GetDynamicTimeZoneInformation(&tzinfo);
+#    endif
+    if (rv == TIME_ZONE_ID_INVALID)
+        throw_spdlog_ex("Failed getting timezone info. ", errno);
+
+    int offset = -tzinfo.Bias;
+    if (tm.tm_isdst)
+    {
+        offset -= tzinfo.DaylightBias;
+    }
+    else
+    {
+        offset -= tzinfo.StandardBias;
+    }
+    return offset;
+#else
+
+#    if defined(sun) || defined(__sun) || defined(_AIX) || (defined(__NEWLIB__) && !defined(__TM_GMTOFF)) ||                               \
+        (!defined(_BSD_SOURCE) && !defined(_GNU_SOURCE))
+    // 'tm_gmtoff' field is BSD extension and it's missing on SunOS/Solaris
+    struct helper
+    {
+        static long int calculate_gmt_offset(const std::tm &localtm = details::os::localtime(), const std::tm &gmtm = details::os::gmtime())
+        {
+            int local_year = localtm.tm_year + (1900 - 1);
+            int gmt_year = gmtm.tm_year + (1900 - 1);
+
+            long int days = (
+                // difference in day of year
+                localtm.tm_yday -
+                gmtm.tm_yday
+
+                // + intervening leap days
+                + ((local_year >> 2) - (gmt_year >> 2)) - (local_year / 100 - gmt_year / 100) +
+                ((local_year / 100 >> 2) - (gmt_year / 100 >> 2))
+
+                // + difference in years * 365 */
+                + static_cast<long int>(local_year - gmt_year) * 365);
+
+            long int hours = (24 * days) + (localtm.tm_hour - gmtm.tm_hour);
+            long int mins = (60 * hours) + (localtm.tm_min - gmtm.tm_min);
+            long int secs = (60 * mins) + (localtm.tm_sec - gmtm.tm_sec);
+
+            return secs;
+        }
+    };
+
+    auto offset_seconds = helper::calculate_gmt_offset(tm);
+#    else
+    auto offset_seconds = tm.tm_gmtoff;
+#    endif
+
+    return static_cast<int>(offset_seconds / 60);
+#endif
+}
+
+// Return current thread id as size_t
+// It exists because the std::this_thread::get_id() is much slower(especially
+// under VS 2013)
+ size_t _thread_id() noexcept
+{
+#ifdef _WIN32
+    return static_cast<size_t>(::GetCurrentThreadId());
+#elif defined(__linux__)
+#    if defined(__ANDROID__) && defined(__ANDROID_API__) && (__ANDROID_API__ < 21)
+#        define SYS_gettid __NR_gettid
+#    endif
+    return static_cast<size_t>(::syscall(SYS_gettid));
+#elif defined(_AIX)
+    struct __pthrdsinfo buf;
+    int reg_size = 0;
+    pthread_t pt = pthread_self();
+    int retval = pthread_getthrds_np(&pt, PTHRDSINFO_QUERY_TID, &buf, sizeof(buf), NULL, &reg_size);
+    int tid = (!retval) ? buf.__pi_tid : 0;
+    return static_cast<size_t>(tid);
+#elif defined(__DragonFly__) || defined(__FreeBSD__)
+    return static_cast<size_t>(::pthread_getthreadid_np());
+#elif defined(__NetBSD__)
+    return static_cast<size_t>(::_lwp_self());
+#elif defined(__OpenBSD__)
+    return static_cast<size_t>(::getthrid());
+#elif defined(__sun)
+    return static_cast<size_t>(::thr_self());
+#elif __APPLE__
+    uint64_t tid;
+    // There is no pthread_threadid_np prior to 10.6, and it is not supported on any PPC,
+    // including 10.6.8 Rosetta. __POWERPC__ is Apple-specific define encompassing ppc and ppc64.
+#    if (MAC_OS_X_VERSION_MAX_ALLOWED < 1060) || defined(__POWERPC__)
+    tid = pthread_mach_thread_np(pthread_self());
+#    elif MAC_OS_X_VERSION_MIN_REQUIRED < 1060
+    if (&pthread_threadid_np)
+    {
+        pthread_threadid_np(nullptr, &tid);
+    }
+    else
+    {
+        tid = pthread_mach_thread_np(pthread_self());
+    }
+#    else
+    pthread_threadid_np(nullptr, &tid);
+#    endif
+    return static_cast<size_t>(tid);
+#else // Default to standard C++11 (other Unix)
+    return static_cast<size_t>(std::hash<std::thread::id>()(std::this_thread::get_id()));
+#endif
+}
+
+// Return current thread id as size_t (from thread local storage)
+ size_t thread_id() noexcept
+{
+    // cache thread id in tls
+    static thread_local const size_t tid = _thread_id();
+    return tid;
+}
+
+// This is avoid msvc issue in sleep_for that happens if the clock changes.
+// See https://github.com/gabime/spdlog/issues/609
+ void sleep_for_millis(unsigned int milliseconds) noexcept
+{
+#if defined(_WIN32)
+    ::Sleep(milliseconds);
+#else
+    std::this_thread::sleep_for(std::chrono::milliseconds(milliseconds));
+#endif
+}
+
+// wchar support for windows file names (SPDLOG_WCHAR_FILENAMES must be defined)
+#if defined(_WIN32) && defined(SPDLOG_WCHAR_FILENAMES)
+ std::string filename_to_str(const filename_t &filename)
+{
+    memory_buf_t buf;
+    wstr_to_utf8buf(filename, buf);
+    return SPDLOG_BUF_TO_STRING(buf);
+}
+#else
+ std::string filename_to_str(const filename_t &filename)
+{
+    return filename;
+}
+#endif
+
+ int pid() noexcept
+{
+
+#ifdef _WIN32
+    return static_cast<int>(::GetCurrentProcessId());
+#else
+    return static_cast<int>(::getpid());
+#endif
+}
+
+// Determine if the terminal supports colors
+// Based on: https://github.com/agauniyal/rang/
+ bool is_color_terminal() noexcept
+{
+#ifdef _WIN32
+    return true;
+#else
+
+    static const bool result = []() {
+        const char *env_colorterm_p = std::getenv("COLORTERM");
+        if (env_colorterm_p != nullptr)
+        {
+            return true;
+        }
+
+        static constexpr std::array<const char *, 16> terms = {{"ansi", "color", "console", "cygwin", "gnome", "konsole", "kterm", "linux",
+            "msys", "putty", "rxvt", "screen", "vt100", "xterm", "alacritty", "vt102"}};
+
+        const char *env_term_p = std::getenv("TERM");
+        if (env_term_p == nullptr)
+        {
+            return false;
+        }
+
+        return std::any_of(terms.begin(), terms.end(), [&](const char *term) { return std::strstr(env_term_p, term) != nullptr; });
+    }();
+
+    return result;
+#endif
+}
+
+// Determine if the terminal attached
+// Source: https://github.com/agauniyal/rang/
+ bool in_terminal(FILE *file) noexcept
+{
+
+#ifdef _WIN32
+    return ::_isatty(_fileno(file)) != 0;
+#else
+    return ::isatty(fileno(file)) != 0;
+#endif
+}
+
+#if defined(SPDLOG_WCHAR_FILENAMES) && defined(_WIN32)
+ void wstr_to_utf8buf(wstring_view_t wstr, memory_buf_t &target)
+{
+    if (wstr.size() > static_cast<size_t>((std::numeric_limits<int>::max)()) / 2 - 1)
+    {
+        throw_spdlog_ex("UTF-16 string is too big to be converted to UTF-8");
+    }
+
+    int wstr_size = static_cast<int>(wstr.size());
+    if (wstr_size == 0)
+    {
+        target.resize(0);
+        return;
+    }
+
+    int result_size = static_cast<int>(target.capacity());
+    if ((wstr_size + 1) * 2 > result_size)
+    {
+        result_size = ::WideCharToMultiByte(CP_UTF8, 0, wstr.data(), wstr_size, NULL, 0, NULL, NULL);
+    }
+
+    if (result_size > 0)
+    {
+        target.resize(result_size);
+        result_size = ::WideCharToMultiByte(CP_UTF8, 0, wstr.data(), wstr_size, target.data(), result_size, NULL, NULL);
+
+        if (result_size > 0)
+        {
+            target.resize(result_size);
+            return;
+        }
+    }
+
+    throw_spdlog_ex(fmt_lib::format("WideCharToMultiByte failed. Last error: {}", ::GetLastError()));
+}
+
+ void utf8_to_wstrbuf(string_view_t str, wmemory_buf_t &target)
+{
+    if (str.size() > static_cast<size_t>((std::numeric_limits<int>::max)()) - 1)
+    {
+        throw_spdlog_ex("UTF-8 string is too big to be converted to UTF-16");
+    }
+
+    int str_size = static_cast<int>(str.size());
+    if (str_size == 0)
+    {
+        target.resize(0);
+        return;
+    }
+
+    // find the size to allocate for the result buffer
+    int result_size = ::MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, str.data(), str_size, NULL, 0);
+
+    if (result_size > 0)
+    {
+        target.resize(result_size);
+        result_size = ::MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, str.data(), str_size, target.data(), result_size);
+        if (result_size > 0)
+        {
+            assert(result_size == target.size());
+            return;
+        }
+    }
+
+    throw_spdlog_ex(fmt_lib::format("MultiByteToWideChar failed. Last error: {}", ::GetLastError()));
+}
+#endif // defined(SPDLOG_WCHAR_FILENAMES) && defined(_WIN32)
+
+// return true on success
+static  bool mkdir_(const filename_t &path)
+{
+#ifdef _WIN32
+#    ifdef SPDLOG_WCHAR_FILENAMES
+    return ::_wmkdir(path.c_str()) == 0;
+#    else
+    return ::_mkdir(path.c_str()) == 0;
+#    endif
+#else
+    return ::mkdir(path.c_str(), mode_t(0755)) == 0;
+#endif
+}
+
+// create the given directory - and all directories leading to it
+// return true on success or if the directory already exists
+ bool create_dir(const filename_t &path)
+{
+    if (path_exists(path))
+    {
+        return true;
+    }
+
+    if (path.empty())
+    {
+        return false;
+    }
+
+    size_t search_offset = 0;
+    do
+    {
+        auto token_pos = path.find_first_of(folder_seps_filename, search_offset);
+        // treat the entire path as a folder if no folder separator not found
+        if (token_pos == filename_t::npos)
+        {
+            token_pos = path.size();
+        }
+
+        auto subdir = path.substr(0, token_pos);
+
+        if (!subdir.empty() && !path_exists(subdir) && !mkdir_(subdir))
+        {
+            return false; // return error if failed creating dir
+        }
+        search_offset = token_pos + 1;
+    } while (search_offset < path.size());
+
+    return true;
+}
+
+// Return directory name from given path or empty string
+// "abc/file" => "abc"
+// "abc/" => "abc"
+// "abc" => ""
+// "abc///" => "abc//"
+ filename_t dir_name(const filename_t &path)
+{
+    auto pos = path.find_last_of(folder_seps_filename);
+    return pos != filename_t::npos ? path.substr(0, pos) : filename_t{};
+}
+
+std::string  getenv(const char *field)
+{
+
+#if defined(_MSC_VER)
+#    if defined(__cplusplus_winrt)
+    return std::string{}; // not supported under uwp
+#    else
+    size_t len = 0;
+    char buf[128];
+    bool ok = ::getenv_s(&len, buf, sizeof(buf), field) == 0;
+    return ok ? buf : std::string{};
+#    endif
+#else // revert to getenv
+    char *buf = ::getenv(field);
+    return buf ? buf : std::string{};
+#endif
+}
+
+// Do fsync by FILE handlerpointer
+// Return true on success
+ bool fsync(FILE *fp)
+{
+#ifdef _WIN32
+    return FlushFileBuffers(reinterpret_cast<HANDLE>(_get_osfhandle(_fileno(fp)))) != 0;
+#else
+    return ::fsync(fileno(fp)) == 0;
+#endif
+}
+
+} // namespace os
+} // namespace details
+} // namespace spdlog
diff --git a/src/details/periodic_worker.cpp b/src/details/periodic_worker.cpp
new file mode 100644
index 00000000..82098c70
--- /dev/null
+++ b/src/details/periodic_worker.cpp
@@ -0,0 +1,26 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+#    include <spdlog/details/periodic_worker.h>
+
+namespace spdlog {
+namespace details {
+
+// stop the worker thread and join it
+ periodic_worker::~periodic_worker()
+{
+    if (worker_thread_.joinable())
+    {
+        {
+            std::lock_guard<std::mutex> lock(mutex_);
+            active_ = false;
+        }
+        cv_.notify_one();
+        worker_thread_.join();
+    }
+}
+
+} // namespace details
+} // namespace spdlog
diff --git a/src/details/registry.cpp b/src/details/registry.cpp
new file mode 100644
index 00000000..babc31d7
--- /dev/null
+++ b/src/details/registry.cpp
@@ -0,0 +1,287 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+#    include <spdlog/details/registry.h>
+
+#include <spdlog/common.h>
+#include <spdlog/details/periodic_worker.h>
+#include <spdlog/logger.h>
+#include <spdlog/pattern_formatter.h>
+
+#ifndef SPDLOG_DISABLE_DEFAULT_LOGGER
+// support for the default stdout color logger
+#    ifdef _WIN32
+#        include <spdlog/sinks/wincolor_sink.h>
+#    else
+#        include <spdlog/sinks/ansicolor_sink.h>
+#    endif
+#endif // SPDLOG_DISABLE_DEFAULT_LOGGER
+
+#include <chrono>
+#include <functional>
+#include <memory>
+#include <string>
+#include <unordered_map>
+
+namespace spdlog {
+namespace details {
+
+ registry::registry()
+    : formatter_(new pattern_formatter())
+{
+
+#ifndef SPDLOG_DISABLE_DEFAULT_LOGGER
+    // create default logger (ansicolor_stdout_sink_mt or wincolor_stdout_sink_mt in windows).
+#    ifdef _WIN32
+    auto color_sink = std::make_shared<sinks::wincolor_stdout_sink_mt>();
+#    else
+    auto color_sink = std::make_shared<sinks::ansicolor_stdout_sink_mt>();
+#    endif
+
+    const char *default_logger_name = "";
+    default_logger_ = std::make_shared<spdlog::logger>(default_logger_name, std::move(color_sink));
+    loggers_[default_logger_name] = default_logger_;
+
+#endif // SPDLOG_DISABLE_DEFAULT_LOGGER
+}
+
+ registry::~registry() = default;
+
+ void registry::register_logger(std::shared_ptr<logger> new_logger)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    register_logger_(std::move(new_logger));
+}
+
+ void registry::initialize_logger(std::shared_ptr<logger> new_logger)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    new_logger->set_formatter(formatter_->clone());
+
+    if (err_handler_)
+    {
+        new_logger->set_error_handler(err_handler_);
+    }
+
+    // set new level according to previously configured level or default level
+    auto it = log_levels_.find(new_logger->name());
+    auto new_level = it != log_levels_.end() ? it->second : global_log_level_;
+    new_logger->set_level(new_level);
+
+    new_logger->flush_on(flush_level_);
+
+    if (automatic_registration_)
+    {
+        register_logger_(std::move(new_logger));
+    }
+}
+
+ std::shared_ptr<logger> registry::get(const std::string &logger_name)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    auto found = loggers_.find(logger_name);
+    return found == loggers_.end() ? nullptr : found->second;
+}
+
+ std::shared_ptr<logger> registry::default_logger()
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    return default_logger_;
+}
+
+// Return raw ptr to the default logger.
+// To be used directly by the spdlog default api (e.g. spdlog::info)
+// This make the default API faster, but cannot be used concurrently with set_default_logger().
+// e.g do not call set_default_logger() from one thread while calling spdlog::info() from another.
+ logger *registry::get_default_raw()
+{
+    return default_logger_.get();
+}
+
+// set default logger.
+// default logger is stored in default_logger_ (for faster retrieval) and in the loggers_ map.
+ void registry::set_default_logger(std::shared_ptr<logger> new_default_logger)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    // remove previous default logger from the map
+    if (default_logger_ != nullptr)
+    {
+        loggers_.erase(default_logger_->name());
+    }
+    if (new_default_logger != nullptr)
+    {
+        loggers_[new_default_logger->name()] = new_default_logger;
+    }
+    default_logger_ = std::move(new_default_logger);
+}
+
+ void registry::set_tp(std::shared_ptr<thread_pool> tp)
+{
+    std::lock_guard<std::recursive_mutex> lock(tp_mutex_);
+    tp_ = std::move(tp);
+}
+
+ std::shared_ptr<thread_pool> registry::get_tp()
+{
+    std::lock_guard<std::recursive_mutex> lock(tp_mutex_);
+    return tp_;
+}
+
+// Set global formatter. Each sink in each logger will get a clone of this object
+ void registry::set_formatter(std::unique_ptr<formatter> formatter)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    formatter_ = std::move(formatter);
+    for (auto &l : loggers_)
+    {
+        l.second->set_formatter(formatter_->clone());
+    }
+}
+
+ void registry::set_level(level level)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    for (auto &l : loggers_)
+    {
+        l.second->set_level(level);
+    }
+    global_log_level_ = level;
+}
+
+ void registry::flush_on(level level)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    for (auto &l : loggers_)
+    {
+        l.second->flush_on(level);
+    }
+    flush_level_ = level;
+}
+
+ void registry::set_error_handler(err_handler handler)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    for (auto &l : loggers_)
+    {
+        l.second->set_error_handler(handler);
+    }
+    err_handler_ = std::move(handler);
+}
+
+ void registry::apply_all(const std::function<void(const std::shared_ptr<logger>)> &fun)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    for (auto &l : loggers_)
+    {
+        fun(l.second);
+    }
+}
+
+ void registry::flush_all()
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    for (auto &l : loggers_)
+    {
+        l.second->flush();
+    }
+}
+
+ void registry::drop(const std::string &logger_name)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    auto is_default_logger = default_logger_ && default_logger_->name() == logger_name;
+    loggers_.erase(logger_name);
+    if (is_default_logger)
+    {
+        default_logger_.reset();
+    }
+}
+
+ void registry::drop_all()
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    loggers_.clear();
+    default_logger_.reset();
+}
+
+// clean all resources and threads started by the registry
+ void registry::shutdown()
+{
+    {
+        std::lock_guard<std::mutex> lock(flusher_mutex_);
+        periodic_flusher_.reset();
+    }
+
+    drop_all();
+
+    {
+        std::lock_guard<std::recursive_mutex> lock(tp_mutex_);
+        tp_.reset();
+    }
+}
+
+ std::recursive_mutex &registry::tp_mutex()
+{
+    return tp_mutex_;
+}
+
+ void registry::set_automatic_registration(bool automatic_registration)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    automatic_registration_ = automatic_registration;
+}
+
+ void registry::set_levels(log_levels levels, level *global_level)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    log_levels_ = std::move(levels);
+    auto global_level_requested = global_level != nullptr;
+    global_log_level_ = global_level_requested ? *global_level : global_log_level_;
+
+    for (auto &logger : loggers_)
+    {
+        auto logger_entry = log_levels_.find(logger.first);
+        if (logger_entry != log_levels_.end())
+        {
+            logger.second->set_level(logger_entry->second);
+        }
+        else if (global_level_requested)
+        {
+            logger.second->set_level(*global_level);
+        }
+    }
+}
+
+ registry &registry::instance()
+{
+    static registry s_instance;
+    return s_instance;
+}
+
+ void registry::apply_logger_env_levels(std::shared_ptr<logger> new_logger)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    auto it = log_levels_.find(new_logger->name());
+    auto new_level = it != log_levels_.end() ? it->second : global_log_level_;
+    new_logger->set_level(new_level);
+}
+
+ void registry::throw_if_exists_(const std::string &logger_name)
+{
+    if (loggers_.find(logger_name) != loggers_.end())
+    {
+        throw_spdlog_ex("logger with name '" + logger_name + "' already exists");
+    }
+}
+
+ void registry::register_logger_(std::shared_ptr<logger> new_logger)
+{
+    auto logger_name = new_logger->name();
+    throw_if_exists_(logger_name);
+    loggers_[logger_name] = std::move(new_logger);
+}
+
+} // namespace details
+} // namespace spdlog
diff --git a/src/details/thread_pool.cpp b/src/details/thread_pool.cpp
new file mode 100644
index 00000000..ac335a72
--- /dev/null
+++ b/src/details/thread_pool.cpp
@@ -0,0 +1,150 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+#include <spdlog/details/thread_pool.h>
+
+#include <spdlog/common.h>
+#include <cassert>
+
+namespace spdlog {
+namespace details {
+
+ thread_pool::thread_pool(
+    size_t q_max_items, size_t threads_n, std::function<void()> on_thread_start, std::function<void()> on_thread_stop)
+    : q_(q_max_items)
+{
+    if (threads_n == 0 || threads_n > 1000)
+    {
+        throw_spdlog_ex("spdlog::thread_pool(): invalid threads_n param (valid "
+                        "range is 1-1000)");
+    }
+    for (size_t i = 0; i < threads_n; i++)
+    {
+        threads_.emplace_back([this, on_thread_start, on_thread_stop] {
+            on_thread_start();
+            this->thread_pool::worker_loop_();
+            on_thread_stop();
+        });
+    }
+}
+
+ thread_pool::thread_pool(size_t q_max_items, size_t threads_n, std::function<void()> on_thread_start)
+    : thread_pool(q_max_items, threads_n, on_thread_start, [] {})
+{}
+
+ thread_pool::thread_pool(size_t q_max_items, size_t threads_n)
+    : thread_pool(
+          q_max_items, threads_n, [] {}, [] {})
+{}
+
+// message all threads to terminate gracefully join them
+ thread_pool::~thread_pool()
+{
+    SPDLOG_TRY
+    {
+        for (size_t i = 0; i < threads_.size(); i++)
+        {
+            post_async_msg_(async_msg(async_msg_type::terminate), async_overflow_policy::block);
+        }
+
+        for (auto &t : threads_)
+        {
+            t.join();
+        }
+    }
+    SPDLOG_CATCH_STD
+}
+
+void  thread_pool::post_log(async_logger_ptr &&worker_ptr, const details::log_msg &msg, async_overflow_policy overflow_policy)
+{
+    async_msg async_m(std::move(worker_ptr), async_msg_type::log, msg);
+    post_async_msg_(std::move(async_m), overflow_policy);
+}
+
+void  thread_pool::post_flush(async_logger_ptr &&worker_ptr, async_overflow_policy overflow_policy)
+{
+    post_async_msg_(async_msg(std::move(worker_ptr), async_msg_type::flush), overflow_policy);
+}
+
+size_t  thread_pool::overrun_counter()
+{
+    return q_.overrun_counter();
+}
+
+void  thread_pool::reset_overrun_counter()
+{
+    q_.reset_overrun_counter();
+}
+
+size_t  thread_pool::discard_counter()
+{
+    return q_.discard_counter();
+}
+
+void  thread_pool::reset_discard_counter()
+{
+    q_.reset_discard_counter();
+}
+
+size_t  thread_pool::queue_size()
+{
+    return q_.size();
+}
+
+void  thread_pool::post_async_msg_(async_msg &&new_msg, async_overflow_policy overflow_policy)
+{
+    if (overflow_policy == async_overflow_policy::block)
+    {
+        q_.enqueue(std::move(new_msg));
+    }
+    else if (overflow_policy == async_overflow_policy::overrun_oldest)
+    {
+        q_.enqueue_nowait(std::move(new_msg));
+    }
+    else
+    {
+        assert(overflow_policy == async_overflow_policy::discard_new);
+        q_.enqueue_if_have_room(std::move(new_msg));
+    }
+}
+
+void  thread_pool::worker_loop_()
+{
+    while (process_next_msg_()) {}
+}
+
+// process next message in the queue
+// return true if this thread should still be active (while no terminate msg
+// was received)
+bool  thread_pool::process_next_msg_()
+{
+    async_msg incoming_async_msg;
+    q_.dequeue(incoming_async_msg);
+
+    switch (incoming_async_msg.msg_type)
+    {
+    case async_msg_type::log: {
+        incoming_async_msg.worker_ptr->backend_sink_it_(incoming_async_msg);
+        return true;
+    }
+    case async_msg_type::flush: {
+        incoming_async_msg.worker_ptr->backend_flush_();
+        return true;
+    }
+
+    case async_msg_type::terminate: {
+        return false;
+    }
+
+    default: {
+        assert(false);
+    }
+    }
+
+    return true;
+}
+
+} // namespace details
+} // namespace spdlog