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 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 interface).
• Optional async logging .
• Log levels.

Benchmarks

Here are some benchmarks comparing spdlog vs other libs on Ubuntu 64 bits, Intel i7-4770 CPU @ 3.40GHz.

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

#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;
}