# spdlog
Very fast, header only, C++ logging library. [](https://travis-ci.org/gabime/spdlog) [](https://ci.appveyor.com/project/gabime/spdlog)
## Install
#### Just copy the headers:
* Copy the source [folder](https://github.com/gabime/spdlog/tree/master/include/spdlog) 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, Solaris
* Windows (vc 2013+, cygwin)
* Mac OSX (clang 3.5+)
* Android
## Features
* Very fast - performance is the primary goal (see [benchmarks](#benchmarks) below).
* Headers only, just copy and use.
* Feature rich [call style](#usage-example) using the excellent [fmt](https://github.com/fmtlib/fmt) library.
* Optional printf syntax support.
* Extremely fast asynchronous mode (optional) - using lockfree queues and other tricks to reach millions of calls/sec.
* [Custom](https://github.com/gabime/spdlog/wiki/3.-Custom-formatting) 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](include/spdlog/sinks/sink.h) interface).
* Severity based filtering - threshold levels can be modified in runtime as well as in compile time.
## Benchmarks
Below are some [benchmarks](bench) comparing popular log libraries under Ubuntu 64 bit, Intel i7-4770 CPU @ 3.40GHz
#### Synchronous mode
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|
#### Asynchronous mode
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 <sup>async logger</sup> |spdlog <sup>async mode</sup>|
|:-------|:-----:|-------------------------:|
|1| 1.850s |0.216s |
|10| 0.943s |0.173s|
|100| 0.959s |0.202s|
## Usage Example
```c++
#define SPDLOG_TRACE_ON
#define SPDLOG_DEBUG_ON
// include only features that you use
#include "spdlog/sinks/daily_file_sink.h"
#include "spdlog/sinks/rotating_file_sink.h"
#include "spdlog/sinks/simple_file_sink.h"
#include "spdlog/sinks/stdout_color_sinks.h"
#include <iostream>
#include <memory>
void async_example();
void user_defined_example();
void err_handler_example();
namespace spd = spdlog;
int main(int, char *[])
{
try
{
auto console = spdlog::stdout_color_st("console");
console->info("Welcome to spdlog!");
console->info("Welcome to spdlog!");
console->error("Some error message with arg: {}", 1);
err_handler_example();
// 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-log.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/rotating.txt", 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.txt", 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");
console->info("This an info message with custom format");
console->error("This an error message with custom format");
// Change format back to to default
spd::set_pattern("%+");
// Runtime log levels
spd::set_level(spd::level::info); // Set global log level to info
console->debug("This message should not be displayed!");
console->set_level(spd::level::debug); // Set specific logger's log level
console->debug("This message should 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();
// 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<spdlog::logger> l) { l->info("End of example."); });
// Release and close all loggers
spdlog::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;
}
}
// must be included to use async logger
#include "spdlog/async.h"
void async_example()
{
auto async_file = spd::basic_logger_mt<spdlog::create_async>("async_file_logger", "logs/async_log.txt");
for (int i = 0; i < 100; ++i)
{
async_file->info("Async message #{}", i);
}
// you can also modify thread pool settings *before* creating the logger:
// spdlog::init_thread_pool(32768, 4); // queue with 32k of pre allocated items and 4 backing threads.
// if not called a defaults are: preallocated 8192 queue items and 1 worker thread.
}
// syslog example (linux/osx/freebsd)
#ifndef _WIN32
#include "spdlog/sinks/syslog_sink.h"
void syslog_example()
{
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
// Android example
#if defined(__ANDROID__)
#incude "spdlog/sinks/android_sink.h"
void android_example()
{
std::string tag = "spdlog-android";
auto android_logger = spd::android_logger("android", tag);
android_logger->critical("Use \"adb shell logcat\" to view this message.");
}
#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()
{
// can be set globaly or per logger(logger->set_error_handler(..))
spdlog::set_error_handler([](const std::string &msg) { spd::get("console")->error("*******my err handler: {}", msg); });
spd::get("console")->info("some invalid message to trigger an error {}{}{}{}", 3);
// spd::get("console")->info("some invalid message to trigger an error {}{}{}{}", 3);
}
```
## Documentation
Documentation can be found in the [wiki](https://github.com/gabime/spdlog/wiki/1.-QuickStart) pages.