Skip to content

Spdlog

Super fast C++ logging library.

Example

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

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

        //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 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);
        for(int i = 0; i < 10; ++i)
              file_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 ***");
        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");

        //
        // 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 = 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;
    }
}


// Example of user defined class with operator<<
class some_class {};
std::ostream& operator<<(std::ostream& os, const some_class& c) { return os << "some_class"; }

void custom_class_example()
{
    some_class c;
    spdlog::get("console")->info("custom class with operator<<: {}..", c);
    spdlog::get("console")->info() << "custom class with operator<<: " << c << "..";
}

Pattern flags

Pattern flags are in the form of %[flag] and resembles strftime function. Anything that is not pattern flag will be logged as is..

flag

meaning

example

%v

The actual text to log

"some user text"

%t

Thread id

"1232"

%n

Logger's name

"some logger name"

%l

The log level of the message

"debug", "info", etc

%L

Short log level of the message

"D", "I", etc

%a

Abbreviated weekday name

"Thu"

%A

Full weekday name

"Thursday"

%b

Abbreviated month name

"Aug"

%B

Full month name

"August"

%c

Date and time representation

"Thu Aug 23 15:35:46 2014"

%C

Year in 2 digits

"14"

%Y

Year in 4 digits

"2014"

%D or %x

Short MM/DD/YY date

"08/23/14"

%m

Month 1-12

"11"

%d

Day of month 1-31

"29"

%H

Hours in 24 format 0-23

"23"

%I

Hours in 12 format 1-12

"11"

%M

Minutes 0-59

"59"

%S

Seconds 0-59

"58"

%e

Millisecond part of the current second 0-999

"678"

%f

Microsecond part of the current second 0-999999

"056789"

%F

Nanosecond part of the current second 0-999999999

"256789123"

%p

AM/PM

"AM"

%r

12 hour clock

"02:55:02 pm"

%R

24-hour HH:MM time, equivalent to %H:%M

"23:55"

%T or %X

ISO 8601 time format (HH:MM:SS), equivalent to %H:%M:%S

"23:55:59"

%z

ISO 8601 offset from UTC in timezone ([+/-]HH:MM)

"+02:00"

%%

The % sign

"%"

%+

spdlog's default format

"[2014-31-10 23:46:59.678] [info] [mylogger] Some message"

Local Download

spdlog master 04b0634
Spdlog-04b0634.tar.gz

Favorite site