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 - just copy and use.
• Cross platform - Linux / Windows on 32/64 bits.
• new! Feature rich call style using the excellent cppformat library.
• ostream call style is supported too.
• Extremely fast asynchronous mode (optional) - use of lockfree queues and other tricks to reach millions of calls per second from multiple threads.
• 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).
• Severity based filtering - threshold levels can be modified in runtime.

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 under synchronous mode (in seconds, the best of 3 runs):

threads	boost log	glog	easylogging	spdlog
1	4.169s	1.066s	0.975s	0.302s
10	16.029	3.032s	2.857s	0.968s
100	15.008	1.139s	4.512s	0.497s

Asynchronous mode

Time needed to log 1,000,000 lines under asynchronous mode, i.e. the time it takes to put them in the async queue (in seconds, the best of 3 runs):

threads	g2log	spdlogasync mode
1	1.850s	0.216s
10	0.943s	0.173s
100	0.959s	0.202s

Usage Example

#include <iostream>
#include "spdlog/spdlog.h"

int main(int, char* [])
{
    namespace spd = spdlog;
    try
    {
        // Set log level to all loggers to debug and above
        spd::set_level(spd::level::debug);

        //Create console, multithreaded logger
        auto console = spd::stdout_logger_mt("console");
        console->info("Welcome to spdlog!") ;
        console->info("An info message example {}..", 1);
        console->info() << "Streams are supported too  " << 1;

        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");
       
        // Create a file rotating logger with 5mb size max and 3 rotated files
        auto file_logger = spd::rotating_logger_mt("file_logger", "logs/mylogfile", 1048576 * 5, 3);
        file_logger->set_level(spd::level::info);
        for(int i = 0; i < 10; ++i)
		      file_logger->info("{} * {} equals {:>10}", i, i, i*i);

        // Customize msg format for all messages
        spd::set_pattern("*** [%H:%M:%S %z] [thread %t] %v ***");
        file_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");

        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 = 1048576; //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;
    }
}