spdlog/README.md

# spdlog

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


## Install
Just copy the files to your build tree and use a C++11 compiler


## Tested on:
* gcc 4.8.1 and above
* clang 3.5
* visual studio 2013
* mingw with g++ 4.9.x

##Features
* Very fast - performance is the primary goal (see becnhmarks below).
* Headers only.
* No dependencies.
* Cross platform - Linux / Windows on 32/64 bits.
* Variadic-template/stream call styles: ```logger.info("variadic", x, y) << "or stream" << x << y;```
* [Custom](https://github.com/gabime/spdlog/wiki/Custom-formatting) formatting.
* Multi/Single threaded loggers.
* Various log targets:
    * Rotating log files.
    * Daily log files.
    * Console logging.
    * Linux syslog.
    * Easily extendable with custom log targets  (just implement a single function in the [sink](include/spdlog/sinks/sink.h) interface).
* Optional async logging .
* Log levels.




## Benchmarks

Here are some [benchmarks](bench) comparing spdlog vs other libs <sup>(Ubuntu 64, Intel i7-4770 CPU @ 3.40GHz)</sup>.

The bench writes 1,000,000 log lines to a rotating log file (using shared synchronous logger object):

#### Single thread bench
|library|log lines|threads|elapsed|
|-------|:-------:|:-----:|------:|
|*boost log v1.56*|1,000,000|1|**4.207s**|
|*glog v0.3.3*|1,000,000|1|**1.077s**|
|*spdlog*|1,000,000|1|**0.975s**|



#### 10 threads bench
|library|log lines|threads|elapsed|
|-------|:-------:|:-----:|------:|
|*boost log v1.56*|1,000,000|10|**6.592s**|
|*glog v0.3.3*|1,000,000|10|**1.678s**|
|*spdlog*|1,000,000|10|**0.961s**|




## Usage Example
```c++
#include <iostream>
#include "spdlog/spdlog.h"

int main(int, char* [])
{
    namespace spd = spdlog;

    try
    {
        std::string filename = "spdlog_example";
        auto console = spd::stdout_logger_mt("console");
        console->info("Welcome to spdlog!") ;
        console->info() << "Creating file " << filename << "..";

        auto file_logger = spd::rotating_logger_mt("file_logger", filename, 1024 * 1024 * 5, 3);
        file_logger->info("Log file message number", 1);

        for (int i = 0; i < 100; ++i)
        {
            auto square = i*i;
            file_logger->info() << i << '*' << i << '=' << square << " (" << "0x" << std::hex << square << ")";
        }

        // Change log level to all loggers to warning and above
        spd::set_level(spd::level::WARN);
        console->info("This should not be displayed");
        console->warn("This should!");
        spd::set_level(spd::level::INFO);

        // Change format pattern to all loggers
        spd::set_pattern(" **** %Y-%m-%d %H:%M:%S.%e %l **** %v");
        spd::get("console")->info("This is another message with different format");
    }
    catch (const spd::spdlog_ex& ex)
    {
        std::cout << "Log failed: " << ex.what() << std::endl;
    }
    return 0;
}
```