It's an emoji version of spdlog! Plus some new levels of logging.
WHO WANTS A LOG LIKE:
[info] This is an info
BUT NOT:
[💬] This is an info
?
TRACE 🐾
DEBUG 🔧
INFO 📢
TIMING ⏰
FUNNY 🤣
WARN 🤔 *
JOKER 🤡
GHOST 👻
SUCCESS 🎉
ERROR 🚨
FINISH ✅
CRITICAL ❌
OFF O (yes, this is not an emoji since it's never used by users)
* I tried to use ⚠️. Since it is 21th Century now, The last one is totally unacceptable.
Use it just like spdlog, and you have more choices:
some_logger->trace("This is Trace");
some_logger->debug("This is Debug");
some_logger->info("This is Info");
some_logger->timing("This is Timing");
some_logger->funny("This is Funny");
some_logger->warn("This is Warn");
some_logger->joker("This is Joker");
some_logger->ghost("This is Ghost");
some_logger->success("This is Success");
some_logger->error("This is Error");
some_logger->finish("This is Finish");
some_logger->critical("This is Critical");
Here are what you got:
[2024-10-15 18:24:57.617] [some_logger_name] [🐾] This is Trace
[2024-10-15 18:24:57.617] [some_logger_name] [🔧] This is Debug
[2024-10-15 18:24:57.617] [some_logger_name] [💬] This is Info
[2024-10-15 18:24:57.617] [some_logger_name] [⏰] This is Timing
[2024-10-15 18:24:57.617] [some_logger_name] [🤣] This is Funny
[2024-10-15 18:24:57.617] [some_logger_name] [🤔] This is Warn
[2024-10-15 18:24:57.617] [some_logger_name] [🤡] This is Joker
[2024-10-15 18:24:57.617] [some_logger_name] [👻] This is Ghost
[2024-10-15 18:24:57.617] [some_logger_name] [🎉] This is Success
[2024-10-15 18:24:57.617] [some_logger_name] [🚨] This is Error
[2024-10-15 18:24:57.617] [some_logger_name] [✅] This is Finish
[2024-10-15 18:24:57.617] [some_logger_name] [❌] This is Critical
Tips: If you are using logging format that truncates the log_level_name, be careful, since emojis don't have a uniform string length and your truncation could result in weird output.
Thanks to spdlog for its clean and tidy design and implementation, making this change very easy.
Following is the README of spdlog:
Very fast, header-only/compiled, C++ logging library. 
Copy the include folder to your build tree and use a C++11 compiler.
$ git clone https://github.com/gabime/spdlog.git
$ cd spdlog && mkdir build && cd build
$ cmake .. && make -jsee example CMakeLists.txt on how to use.
- Linux, FreeBSD, OpenBSD, Solaris, AIX
- Windows (msvc 2013+, cygwin)
- macOS (clang 3.5+)
- Android
- Debian:
sudo apt install libspdlog-dev - Homebrew:
brew install spdlog - MacPorts:
sudo port install spdlog - FreeBSD:
pkg install spdlog - Fedora:
dnf install spdlog - Gentoo:
emerge dev-libs/spdlog - Arch Linux:
pacman -S spdlog - openSUSE:
sudo zypper in spdlog-devel - vcpkg:
vcpkg install spdlog - conan:
conan install --requires=spdlog/[*] - conda:
conda install -c conda-forge spdlog - build2:
depends: spdlog ^1.8.2
- Very fast (see benchmarks below).
- Headers only or compiled
- Feature-rich formatting, using the excellent fmt library.
- Asynchronous mode (optional)
- Custom formatting.
- Multi/Single threaded loggers.
- Various log targets:
- Rotating log files.
- Daily log files.
- Console logging (colors supported).
- syslog.
- Windows event log.
- Windows debugger (
OutputDebugString(..)). - Log to Qt widgets (example).
- Easily extendable with custom log targets.
- Log filtering - log levels can be modified at runtime as well as compile time.
- Support for loading log levels from argv or environment var.
- Backtrace support - store debug messages in a ring buffer and display them later on demand.
#include "spdlog/spdlog.h"
int main()
{
spdlog::info("Welcome to spdlog!");
spdlog::error("Some error message with arg: {}", 1);
spdlog::warn("Easy padding in numbers like {:08d}", 12);
spdlog::critical("Support for int: {0:d}; hex: {0:x}; oct: {0:o}; bin: {0:b}", 42);
spdlog::info("Support for floats {:03.2f}", 1.23456);
spdlog::info("Positional args are {1} {0}..", "too", "supported");
spdlog::info("{:<30}", "left aligned");
spdlog::set_level(spdlog::level::debug); // Set global log level to debug
spdlog::debug("This message should be displayed..");
// change log pattern
spdlog::set_pattern("[%H:%M:%S %z] [%n] [%^---%L---%$] [thread %t] %v");
// Compile time log levels
// Note that this does not change the current log level, it will only
// remove (depending on SPDLOG_ACTIVE_LEVEL) the call on the release code.
SPDLOG_TRACE("Some trace message with param {}", 42);
SPDLOG_DEBUG("Some debug message");
}
#include "spdlog/spdlog.h"
#include "spdlog/sinks/stdout_color_sinks.h"
void stdout_example()
{
// create a color multi-threaded logger
auto console = spdlog::stdout_color_mt("console");
auto err_logger = spdlog::stderr_color_mt("stderr");
spdlog::get("console")->info("loggers can be retrieved from a global registry using the spdlog::get(logger_name)");
}#include "spdlog/sinks/basic_file_sink.h"
void basic_logfile_example()
{
try
{
auto logger = spdlog::basic_logger_mt("basic_logger", "logs/basic-log.txt");
}
catch (const spdlog::spdlog_ex &ex)
{
std::cout << "Log init failed: " << ex.what() << std::endl;
}
}#include "spdlog/sinks/rotating_file_sink.h"
void rotating_example()
{
// Create a file rotating logger with 5 MB size max and 3 rotated files
auto max_size = 1048576 * 5;
auto max_files = 3;
auto logger = spdlog::rotating_logger_mt("some_logger_name", "logs/rotating.txt", max_size, max_files);
}#include "spdlog/sinks/daily_file_sink.h"
void daily_example()
{
// Create a daily logger - a new file is created every day at 2:30 am
auto logger = spdlog::daily_logger_mt("daily_logger", "logs/daily.txt", 2, 30);
}
// Debug messages can be stored in a ring buffer instead of being logged immediately.
// This is useful to display debug logs only when needed (e.g. when an error happens).
// When needed, call dump_backtrace() to dump them to your log.
spdlog::enable_backtrace(32); // Store the latest 32 messages in a buffer.
// or my_logger->enable_backtrace(32)..
for(int i = 0; i < 100; i++)
{
spdlog::debug("Backtrace message {}", i); // not logged yet..
}
// e.g. if some error happened:
spdlog::dump_backtrace(); // log them now! show the last 32 messages
// or my_logger->dump_backtrace(32)..// periodically flush all *registered* loggers every 3 seconds:
// warning: only use if all your loggers are thread-safe ("_mt" loggers)
spdlog::flush_every(std::chrono::seconds(3));
// Stopwatch support for spdlog
#include "spdlog/stopwatch.h"
void stopwatch_example()
{
spdlog::stopwatch sw;
spdlog::debug("Elapsed {}", sw);
spdlog::debug("Elapsed {:.3}", sw);
}
// many types of std::container<char> types can be used.
// ranges are supported too.
// format flags:
// {:X} - print in uppercase.
// {:s} - don't separate each byte with space.
// {:p} - don't print the position on each line start.
// {:n} - don't split the output into lines.
// {:a} - show ASCII if :n is not set.
#include "spdlog/fmt/bin_to_hex.h"
void binary_example()
{
auto console = spdlog::get("console");
std::array<char, 80> buf;
console->info("Binary example: {}", spdlog::to_hex(buf));
console->info("Another binary example:{:n}", spdlog::to_hex(std::begin(buf), std::begin(buf) + 10));
// more examples:
// logger->info("uppercase: {:X}", spdlog::to_hex(buf));
// logger->info("uppercase, no delimiters: {:Xs}", spdlog::to_hex(buf));
// logger->info("uppercase, no delimiters, no position info: {:Xsp}", spdlog::to_hex(buf));
}
// create a logger with 2 targets, with different log levels and formats.
// The console will show only warnings or errors, while the file will log all.
void multi_sink_example()
{
auto console_sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt>();
console_sink->set_level(spdlog::level::warn);
console_sink->set_pattern("[multi_sink_example] [%^%l%$] %v");
auto file_sink = std::make_shared<spdlog::sinks::basic_file_sink_mt>("logs/multisink.txt", true);
file_sink->set_level(spdlog::level::trace);
spdlog::logger logger("multi_sink", {console_sink, file_sink});
logger.set_level(spdlog::level::debug);
logger.warn("this should appear in both console and file");
logger.info("this message should not appear in the console, only in the file");
}// create a logger with a lambda function callback, the callback will be called
// each time something is logged to the logger
void callback_example()
{
auto callback_sink = std::make_shared<spdlog::sinks::callback_sink_mt>([](const spdlog::details::log_msg &msg) {
// for example you can be notified by sending an email to yourself
});
callback_sink->set_level(spdlog::level::err);
auto console_sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt>();
spdlog::logger logger("custom_callback_logger", {console_sink, callback_sink});
logger.info("some info log");
logger.error("critical issue"); // will notify you
}#include "spdlog/async.h"
#include "spdlog/sinks/basic_file_sink.h"
void async_example()
{
// default thread pool settings can be modified *before* creating the async logger:
// spdlog::init_thread_pool(8192, 1); // queue with 8k items and 1 backing thread.
auto async_file = spdlog::basic_logger_mt<spdlog::async_factory>("async_file_logger", "logs/async_log.txt");
// alternatively:
// auto async_file = spdlog::create_async<spdlog::sinks::basic_file_sink_mt>("async_file_logger", "logs/async_log.txt");
}
#include "spdlog/async.h"
#include "spdlog/sinks/stdout_color_sinks.h"
#include "spdlog/sinks/rotating_file_sink.h"
void multi_sink_example2()
{
spdlog::init_thread_pool(8192, 1);
auto stdout_sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt >();
auto rotating_sink = std::make_shared<spdlog::sinks::rotating_file_sink_mt>("mylog.txt", 1024*1024*10, 3);
std::vector<spdlog::sink_ptr> sinks {stdout_sink, rotating_sink};
auto logger = std::make_shared<spdlog::async_logger>("loggername", sinks.begin(), sinks.end(), spdlog::thread_pool(), spdlog::async_overflow_policy::block);
spdlog::register_logger(logger);
}template<>
struct fmt::formatter<my_type> : fmt::formatter<std::string>
{
auto format(my_type my, format_context &ctx) const -> decltype(ctx.out())
{
return format_to(ctx.out(), "[my_type i={}]", my.i);
}
};
void user_defined_example()
{
spdlog::info("user defined type: {}", my_type(14));
}
// Log patterns can contain custom flags.
// the following example will add new flag '%*' - which will be bound to a <my_formatter_flag> instance.
#include "spdlog/pattern_formatter.h"
class my_formatter_flag : public spdlog::custom_flag_formatter
{
public:
void format(const spdlog::details::log_msg &, const std::tm &, spdlog::memory_buf_t &dest) override
{
std::string some_txt = "custom-flag";
dest.append(some_txt.data(), some_txt.data() + some_txt.size());
}
std::unique_ptr<custom_flag_formatter> clone() const override
{
return spdlog::details::make_unique<my_formatter_flag>();
}
};
void custom_flags_example()
{
auto formatter = std::make_unique<spdlog::pattern_formatter>();
formatter->add_flag<my_formatter_flag>('*').set_pattern("[%n] [%*] [%^%l%$] %v");
spdlog::set_formatter(std::move(formatter));
}
void err_handler_example()
{
// can be set globally or per logger(logger->set_error_handler(..))
spdlog::set_error_handler([](const std::string &msg) { spdlog::get("console")->error("*** LOGGER ERROR ***: {}", msg); });
spdlog::get("console")->info("some invalid message to trigger an error {}{}{}{}", 3);
}
#include "spdlog/sinks/syslog_sink.h"
void syslog_example()
{
std::string ident = "spdlog-example";
auto syslog_logger = spdlog::syslog_logger_mt("syslog", ident, LOG_PID);
syslog_logger->warn("This is warning that will end up in syslog.");
}#include "spdlog/sinks/android_sink.h"
void android_example()
{
std::string tag = "spdlog-android";
auto android_logger = spdlog::android_logger_mt("android", tag);
android_logger->critical("Use \"adb shell logcat\" to view this message.");
}#include "spdlog/cfg/env.h"
int main (int argc, char *argv[])
{
spdlog::cfg::load_env_levels();
// or from the command line:
// ./example SPDLOG_LEVEL=info,mylogger=trace
// #include "spdlog/cfg/argv.h" // for loading levels from argv
// spdlog::cfg::load_argv_levels(argc, argv);
}So then you can:
$ export SPDLOG_LEVEL=info,mylogger=trace
$ ./example// You can get callbacks from spdlog before/after a log file has been opened or closed.
// This is useful for cleanup procedures or for adding something to the start/end of the log file.
void file_events_example()
{
// pass the spdlog::file_event_handlers to file sinks for open/close log file notifications
spdlog::file_event_handlers handlers;
handlers.before_open = [](spdlog::filename_t filename) { spdlog::info("Before opening {}", filename); };
handlers.after_open = [](spdlog::filename_t filename, std::FILE *fstream) { fputs("After opening\n", fstream); };
handlers.before_close = [](spdlog::filename_t filename, std::FILE *fstream) { fputs("Before closing\n", fstream); };
handlers.after_close = [](spdlog::filename_t filename) { spdlog::info("After closing {}", filename); };
auto my_logger = spdlog::basic_logger_st("some_logger", "logs/events-sample.txt", true, handlers);
}void replace_default_logger_example()
{
auto new_logger = spdlog::basic_logger_mt("new_default_logger", "logs/new-default-log.txt", true);
spdlog::set_default_logger(new_logger);
spdlog::info("new logger log message");
}#include "spdlog/spdlog.h"
#include "spdlog/sinks/qt_sinks.h"
MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent)
{
setMinimumSize(640, 480);
auto log_widget = new QTextEdit(this);
setCentralWidget(log_widget);
int max_lines = 500; // keep the text widget to max 500 lines. remove old lines if needed.
auto logger = spdlog::qt_color_logger_mt("qt_logger", log_widget, max_lines);
logger->info("Some info message");
}// Mapped Diagnostic Context (MDC) is a map that stores key-value pairs (string values) in thread local storage.
// Each thread maintains its own MDC, which loggers use to append diagnostic information to log outputs.
// Note: it is not supported in asynchronous mode due to its reliance on thread-local storage.
#include "spdlog/mdc.h"
void mdc_example()
{
spdlog::mdc::put("key1", "value1");
spdlog::mdc::put("key2", "value2");
// if not using the default format, use the %& formatter to print mdc data
// spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [%&] %v");
}Below are some benchmarks done in Ubuntu 64 bit, Intel i7-4770 CPU @ 3.40GHz
[info] **************************************************************
[info] Single thread, 1,000,000 iterations
[info] **************************************************************
[info] basic_st Elapsed: 0.17 secs 5,777,626/sec
[info] rotating_st Elapsed: 0.18 secs 5,475,894/sec
[info] daily_st Elapsed: 0.20 secs 5,062,659/sec
[info] empty_logger Elapsed: 0.07 secs 14,127,300/sec
[info] **************************************************************
[info] C-string (400 bytes). Single thread, 1,000,000 iterations
[info] **************************************************************
[info] basic_st Elapsed: 0.41 secs 2,412,483/sec
[info] rotating_st Elapsed: 0.72 secs 1,389,196/sec
[info] daily_st Elapsed: 0.42 secs 2,393,298/sec
[info] null_st Elapsed: 0.04 secs 27,446,957/sec
[info] **************************************************************
[info] 10 threads, competing over the same logger object, 1,000,000 iterations
[info] **************************************************************
[info] basic_mt Elapsed: 0.60 secs 1,659,613/sec
[info] rotating_mt Elapsed: 0.62 secs 1,612,493/sec
[info] daily_mt Elapsed: 0.61 secs 1,638,305/sec
[info] null_mt Elapsed: 0.16 secs 6,272,758/sec
[info] -------------------------------------------------
[info] Messages : 1,000,000
[info] Threads : 10
[info] Queue : 8,192 slots
[info] Queue memory : 8,192 x 272 = 2,176 KB
[info] -------------------------------------------------
[info]
[info] *********************************
[info] Queue Overflow Policy: block
[info] *********************************
[info] Elapsed: 1.70784 secs 585,535/sec
[info] Elapsed: 1.69805 secs 588,910/sec
[info] Elapsed: 1.7026 secs 587,337/sec
[info]
[info] *********************************
[info] Queue Overflow Policy: overrun
[info] *********************************
[info] Elapsed: 0.372816 secs 2,682,285/sec
[info] Elapsed: 0.379758 secs 2,633,255/sec
[info] Elapsed: 0.373532 secs 2,677,147/sec
Documentation can be found in the wiki pages.
Thanks to JetBrains for donating product licenses to help develop spdlog 