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# 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 source [folder](https://github.com/gabime/spdlog/tree/master/include/spdlog) to your build tree and use a C++11 compiler
## Platforms
* Linux (gcc 4.8.1+, clang 3.5+)
* Windows (visual studio 2013+, cygwin/mingw with g++ 4.9.1+)
* Mac OSX (clang 3.5+)
##Features
* Very fast - performance is the primary goal (see [benchmarks](#benchmarks) below).
* Headers only.
* No dependencies - just copy and use.
* Feature rich [call style](#usage-example) using the excellent [fmt](https://github.com/fmtlib/fmt) library.
* 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.
* Multi/Single threaded loggers.
* Various log targets:
* Rotating log files.
* Daily log files.
* Console logging (colors supported).
* Linux syslog.
* 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++
#include <iostream>
#include "spdlog/spdlog.h"
int main(int, char* [])
{
namespace spd = spdlog;
try
{
// console logger (multithreaded and with color)
auto console = spd::stdout_logger_mt("console", true);
console->info("Welcome to spdlog!") ;
console->info("An info message example {}..", 1);
//Formatting examples
console->info("Easy padding in numbers like {:08d}", 12);
console->info("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");
console->info("{:>30}", "right aligned");
console->info("{:^30}", "centered");
//
// 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("Now it should..");
//
// Create a basic multithreaded file logger (or "basic_logger_st" for single threaded logger)
//
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);
//
// 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");
spd::get("console")->info("loggers can be retrieved from a global registry using the spdlog::get(logger_name) function");
//
// Compile time debug or trace macros.
// Enabled #ifdef SPDLOG_DEBUG_ON or #ifdef 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..
//
size_t q_size = 8192; //queue size must be power of 2
spdlog::set_async_mode(q_size);
auto async_file= spd::daily_logger_st("async_file_logger", "logs/async_log.txt");
async_file->info("This is async log..Should be very fast!");
//
// syslog example. linux only..
//
#ifdef __linux__
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. This is Linux only!");
#endif
}
catch (const spd::spdlog_ex& ex)
{
std::cout << "Log failed: " << ex.what() << std::endl;
}
}
```
## Documentation
Documentation can be found in the [wiki](https://github.com/gabime/spdlog/wiki/1.-QuickStart) pages.
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