Very fast, header only, C++ logging library. 
- Copy the source folder to your build tree and use a C++11 compiler.
- 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:
pacman -S spdlog-git - vcpkg:
vcpkg install spdlog
- Linux, FreeBSD, Solaris
- Windows (vc 2013+, cygwin/mingw)
- Mac OSX (clang 3.5+)
- Android
- Very fast - performance is the primary goal (see benchmarks below).
- Headers only, just copy and use.
- Feature rich call style using the excellent fmt library.
- Extremely fast asynchronous mode (optional) - using lockfree queues and other tricks to reach millions of calls/sec.
- Custom formatting.
- Conditional Logging
- 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.
Below are some benchmarks comparing popular log libraries under Ubuntu 64 bit, Intel i7-4770 CPU @ 3.40GHz
Time needed to log 1,000,000 lines in synchronous mode (in seconds, the best of 3 runs):
| threads | boost log 1.54 | glog | easylogging | spdlog |
|---|---|---|---|---|
| 1 | 4.169s | 1.066s | 0.975s | 0.302s |
| 10 | 6.180s | 3.032s | 2.857s | 0.968s |
| 100 | 5.981s | 1.139s | 4.512s | 0.497s |
Time needed to log 1,000,000 lines in asynchronous mode, i.e. the time it takes to put them in the async queue (in seconds, the best of 3 runs):
| threads | g2log async logger | spdlog async mode |
|---|---|---|
| 1 | 1.850s | 0.216s |
| 10 | 0.943s | 0.173s |
| 100 | 0.959s | 0.202s |
#include "spdlog/spdlog.h"
#include <iostream>
#include <memory>
void async_example();
void syslog_example();
void user_defined_example();
void err_handler_example();
namespace spd = spdlog;
int main(int, char*[])
{
try
{
// Console logger with color
auto console = spd::stdout_color_mt("console");
console->info("Welcome to spdlog!");
console->error("Some error message with arg{}..", 1);
// Conditional logging example
auto i = 2;
console->warn_if(i != 0, "an important message");
// Formatting examples
console->warn("Easy padding in numbers like {:08d}", 12);
console->critical("Support for int: {0:d}; hex: {0:x}; oct: {0:o}; bin: {0:b}", 42);
console->info("Support for floats {:03.2f}", 1.23456);
console->info("Positional args are {1} {0}..", "too", "supported");
console->info("{:<30}", "left aligned");
spd::get("console")->info("loggers can be retrieved from a global registry using the spdlog::get(logger_name) function");
// Create basic file logger (not rotated)
auto my_logger = spd::basic_logger_mt("basic_logger", "logs/basic.txt");
my_logger->info("Some log message");
// Create a file rotating logger with 5mb size max and 3 rotated files
auto rotating_logger = spd::rotating_logger_mt("some_logger_name", "logs/mylogfile", 1048576 * 5, 3);
for (int i = 0; i < 10; ++i)
rotating_logger->info("{} * {} equals {:>10}", i, i, i*i);
// Create a daily logger - a new file is created every day on 2:30am
auto daily_logger = spd::daily_logger_mt("daily_logger", "logs/daily", 2, 30);
// trigger flush if the log severity is error or higher
daily_logger->flush_on(spd::level::err);
daily_logger->info(123.44);
// Customize msg format for all messages
spd::set_pattern("*** [%H:%M:%S %z] [thread %t] %v ***");
rotating_logger->info("This is another message with custom format");
// Runtime log levels
spd::set_level(spd::level::info); //Set global log level to info
console->debug("This message shold not be displayed!");
console->set_level(spd::level::debug); // Set specific logger's log level
console->debug("This message shold be displayed..");
// Compile time log levels
// define SPDLOG_DEBUG_ON or SPDLOG_TRACE_ON
SPDLOG_TRACE(console, "Enabled only #ifdef SPDLOG_TRACE_ON..{} ,{}", 1, 3.23);
SPDLOG_DEBUG(console, "Enabled only #ifdef SPDLOG_DEBUG_ON.. {} ,{}", 1, 3.23);
// Asynchronous logging is very fast..
// Just call spdlog::set_async_mode(q_size) and all created loggers from now on will be asynchronous..
async_example();
// syslog example. linux/osx only
syslog_example();
// android example. compile with NDK
android_example();
// Log user-defined types example
user_defined_example();
// Change default log error handler
err_handler_example();
// Apply a function on all registered loggers
spd::apply_all([&](std::shared_ptr<spd::logger> l)
{
l->info("End of example.");
});
// Release and close all loggers
spd::drop_all();
}
// Exceptions will only be thrown upon failed logger or sink construction (not during logging)
catch (const spd::spdlog_ex& ex)
{
std::cout << "Log init failed: " << ex.what() << std::endl;
return 1;
}
}
void async_example()
{
size_t q_size = 4096; //queue size must be power of 2
spd::set_async_mode(q_size);
auto async_file = spd::daily_logger_st("async_file_logger", "logs/async_log.txt");
for (int i = 0; i < 100; ++i)
async_file->info("Async message #{}", i);
}
//syslog example
void syslog_example()
{
#ifdef SPDLOG_ENABLE_SYSLOG
std::string ident = "spdlog-example";
auto syslog_logger = spd::syslog_logger("syslog", ident, LOG_PID);
syslog_logger->warn("This is warning that will end up in syslog..");
#endif
}
// user defined types logging by implementing operator<<
struct my_type
{
int i;
template<typename OStream>
friend OStream& operator<<(OStream& os, const my_type &c)
{
return os << "[my_type i="<<c.i << "]";
}
};
#include <spdlog/fmt/ostr.h> // must be included
void user_defined_example()
{
spd::get("console")->info("user defined type: {}", my_type { 14 });
}
//
//custom error handler
//
void err_handler_example()
{
spd::set_error_handler([](const std::string& msg) {
std::cerr << "my err handler: " << msg << std::endl;
});
// (or logger->set_error_handler(..) to set for specific logger)
}
Documentation can be found in the wiki pages.