spdlog

Very fast, header only, C++ logging library.   

Install

#### Just copy the headers:

* Copy the source folder to your build tree and use a C++11 compiler.

#### Or use your favorite package manager:

* Ubuntu: apt-get install libspdlog-dev
* Homebrew: brew install spdlog
* FreeBSD: cd /usr/ports/devel/spdlog/ && make install clean
* Fedora: yum install spdlog
* Gentoo: emerge dev-libs/spdlog
* Arch Linux: yaourt -S spdlog-git
* vcpkg: vcpkg install spdlog

Platforms

* Linux, FreeBSD, OpenBSD, Solaris, AIX
* Windows (msvc 2013+, cygwin)
* macOS (clang 3.5+)
* Android

Features

* Very fast (see benchmarks below).
* Headers only, just copy and use.
* Feature rich formatting, using the excellent fmt library.
* Fast asynchronous mode (optional)
* Custom formatting.
* Multi/Single threaded loggers.
* Various log targets:
* Rotating log files.
* Daily log files.
* Console logging (colors supported).
* syslog.
* Windows debugger (``OutputDebugString(..)`)
* Easily extendable with custom log targets (just implement a single function in the sink interface).
* Severity based filtering - threshold levels can be modified in runtime as well as in compile time.
* Binary data logging.

Benchmarks

Below are some benchmarks done in Ubuntu 64 bit, Intel i7-4770 CPU @ 3.40GHz

#### Synchronous mode
`
*
Single thread, 1,000,000 iterations
*
basic_st... Elapsed: 0.181652 5,505,042/sec
rotating_st... Elapsed: 0.181781 5,501,117/sec
daily_st... Elapsed: 0.187595 5,330,630/sec
null_st... Elapsed: 0.0504704 19,813,602/sec
*
10 threads sharing same logger, 1,000,000 iterations
*
basic_mt... Elapsed: 0.616035 1,623,284/sec
rotating_mt... Elapsed: 0.620344 1,612,008/sec
daily_mt... Elapsed: 0.648353 1,542,369/sec
null_mt... Elapsed: 0.151972 6,580,166/sec
`
#### Asynchronous mode
`
*
10 threads sharing same logger, 1,000,000 iterations
*
async... Elapsed: 0.350066 2,856,606/sec
async... Elapsed: 0.314865 3,175,960/sec
async... Elapsed: 0.349851 2,858,358/sec
`

Usage samples

#### Basic usage
`c++
#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
// define SPDLOG_ACTIVE_LEVEL to desired level
SPDLOG_TRACE("Some trace message with param {}", {});
SPDLOG_DEBUG("Some debug message");

// Set the default logger to file logger
auto file_logger = spdlog::basic_logger_mt("basic_logger", "logs/basic.txt");
spdlog::set_default_logger(file_logger);
}
`
#### create stdout/stderr logger object
`c++
#include "spdlog/spdlog.h"
#include "spdlog/sinks/stdout_color_sinks.h"
void stdout_example()
{
// create 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)");
}
`
---
#### Basic file logger
`c++
#include "spdlog/sinks/basic_file_sink.h"
void basic_logfile_example()
{
try
{
auto my_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;
}
}
`
---
#### Rotating files
`c++
#include "spdlog/sinks/rotating_file_sink.h"
void rotating_example()
{
// Create a file rotating logger with 5mb size max and 3 rotated files
auto rotating_logger = spdlog::rotating_logger_mt("some_logger_name", "logs/rotating.txt", 1048576 * 5, 3);
}
`

---
#### Daily files
`c++

#include "spdlog/sinks/daily_file_sink.h"
void daily_example()
{
// Create a daily logger - a new file is created every day on 2:30am
auto daily_logger = spdlog::daily_logger_mt("daily_logger", "logs/daily.txt", 2, 30);
}

`

---
#### Cloning loggers
`c++
// clone a logger and give it new name.
// Useful for creating subsystem loggers from some "root" logger
void clone_example()
{
auto network_logger = spdlog::get("root")->clone("network");
network_logger->info("Logging network stuff..");
}
`

---
#### Periodic flush
`c++
// periodically flush all registered loggers every 3 seconds:
// warning: only use if all your loggers are thread safe!
spdlog::flush_every(std::chrono::seconds(3));

`

---
#### Binary logging
`c++
// log binary data as hex.
// many types of std::container 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 to lines.

#include "spdlog/fmt/bin_to_hex.h"

void binary_example()
{
auto console = spdlog::get("console");
std::array 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));
}

`

---
#### Logger with multi sinks - each with different format and log level
`c++

// create 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();
console_sink->set_level(spdlog::level::warn);
console_sink->set_pattern("[multi_sink_example] [%^%l%$] %v");

auto file_sink = std::make_shared("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");
}
`

---
#### Asynchronous logging
`c++
#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("async_file_logger", "logs/async_log.txt");
// alternatively:
// auto async_file = spdlog::create_async("async_file_logger", "logs/async_log.txt");
}

`

---
#### Asynchronous logger with multi sinks
`c++
#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();
auto rotating_sink = std::make_shared("mylog.txt", 1024102410, 3);
std::vector sinks {stdout_sink, rotating_sink};
auto logger = std::make_shared("loggername", sinks.begin(), sinks.end(), spdlog::thread_pool(), spdlog::async_overflow_policy::block);
spdlog::register_logger(logger);
}
`

---
#### User defined types
`c++
// user defined types logging by implementing operator<<
#include "spdlog/fmt/ostr.h" // must be included
struct my_type
{
int i;
template
friend OStream &operator<<(OStream &os, const my_type &c)
{
return os << "[my_type i=" << c.i << "]";
}
};

void user_defined_example()
{
spdlog::get("console")->info("user defined type: {}", my_type{14});
}

`
---
#### Custom error handler
`c++
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);
}

`
---
#### syslog
`c++
#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.");
}
`
---
#### Android example
`c++
#include "spdlog/sinks/android_sink.h"
void android_example()
{
std::string tag = "spdlog-android";
auto android_logger = spdlog::android_logger("android", tag);
android_logger->critical("Use \"adb shell logcat\" to view this message.");
}
``

Documentation

Documentation can be found in the wiki pages.