spdlog

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

Install

Just copy the headers:

• Copy the source folder 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 below).
• Headers only, just copy and use.
• Feature rich call style using the excellent fmt library.
• Optional printf syntax support.
• 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.

Benchmarks

Below are some benchmarks 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 async logger	spdlog async mode
1	1.850s	0.216s
10	0.943s	0.173s
100	0.959s	0.202s

Usage Example

#define SPDLOG_TRACE_ON
#define SPDLOG_DEBUG_ON
// include only what you used from the below 
#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 pages.