# spdlog Very fast, header-only/compiled, C++ logging library. [![Build Status](https://travis-ci.org/gabime/spdlog.svg?branch=master)](https://travis-ci.org/gabime/spdlog)  [![Build status](https://ci.appveyor.com/api/projects/status/d2jnxclg20vd0o50?svg=true)](https://ci.appveyor.com/project/gabime/spdlog) ## Install #### Header only version Copy the source [folder](https://github.com/gabime/spdlog/tree/v1.x/include/spdlog) to your build tree and use a C++11 compiler. #### Static lib version (recommended - much faster compile times) ```console $ git clone https://github.com/gabime/spdlog.git $ cd spdlog && mkdir build && cd build $ cmake .. && make -j ``` see example [CMakeLists.txt](https://github.com/gabime/spdlog/blob/v1.x/example/CMakeLists.txt) on how to use. ## Platforms * Linux, FreeBSD, OpenBSD, Solaris, AIX * Windows (msvc 2013+, cygwin) * macOS (clang 3.5+) * Android ## Package managers: * 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` * conan: `spdlog/[>=1.4.1]@bincrafters/stable` ## Features * Very fast (see [benchmarks](#benchmarks) below). * Headers only, just copy and use. Or use as a compiled library. * Feature rich formatting, using the excellent [fmt](https://github.com/fmtlib/fmt) library. * **New!** [Backtrace](#backtrace-support) support - store debug messages in a ring buffer and display later on demand. * Fast asynchronous mode (optional) * [Custom](https://github.com/gabime/spdlog/wiki/3.-Custom-formatting) formatting. * 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](include/spdlog/sinks/sink.h) interface). * Severity based filtering - threshold levels can be modified in runtime as well as in compile time. ## Usage samples #### Basic usage ```c++ #include "spdlog/spdlog.h" #include "spdlog/sinks/basic_file_sink.h" int main() { spdlog::info("Welcome to spdlog!"); spdlog::error("Some error message with arg: {}", 1); spdlog::warn("Easy padding in numbers like {:08d}", 12); spdlog::critical("Support for int: {0:d}; hex: {0:x}; oct: {0:o}; bin: {0:b}", 42); spdlog::info("Support for floats {:03.2f}", 1.23456); spdlog::info("Positional args are {1} {0}..", "too", "supported"); spdlog::info("{:<30}", "left aligned"); spdlog::set_level(spdlog::level::debug); // Set global log level to debug spdlog::debug("This message should be displayed.."); // change log pattern spdlog::set_pattern("[%H:%M:%S %z] [%n] [%^---%L---%$] [thread %t] %v"); // Compile time log levels // define SPDLOG_ACTIVE_LEVEL to desired level SPDLOG_TRACE("Some trace message with param {}", 42); SPDLOG_DEBUG("Some debug message"); // Set the default logger to file logger auto file_logger = spdlog::basic_logger_mt("basic_logger", "logs/basic.txt"); spdlog::set_default_logger(file_logger); } ``` #### create stdout/stderr logger object ```c++ #include "spdlog/spdlog.h" #include "spdlog/sinks/stdout_color_sinks.h" void stdout_example() { // create color multi threaded logger auto console = spdlog::stdout_color_mt("console"); auto err_logger = spdlog::stderr_color_mt("stderr"); spdlog::get("console")->info("loggers can be retrieved from a global registry using the spdlog::get(logger_name)"); } ``` --- #### Basic file logger ```c++ #include "spdlog/sinks/basic_file_sink.h" void basic_logfile_example() { try { auto my_logger = spdlog::basic_logger_mt("basic_logger", "logs/basic-log.txt"); } catch (const spdlog::spdlog_ex &ex) { std::cout << "Log init failed: " << ex.what() << std::endl; } } ``` --- #### Rotating files ```c++ #include "spdlog/sinks/rotating_file_sink.h" void rotating_example() { // Create a file rotating logger with 5mb size max and 3 rotated files auto rotating_logger = spdlog::rotating_logger_mt("some_logger_name", "logs/rotating.txt", 1048576 * 5, 3); } ``` --- #### Daily files ```c++ #include "spdlog/sinks/daily_file_sink.h" void daily_example() { // Create a daily logger - a new file is created every day on 2:30am auto daily_logger = spdlog::daily_logger_mt("daily_logger", "logs/daily.txt", 2, 30); } ``` --- #### Backtrace support ```c++ // Loggers can store in a ring buffer all messages (including debug/trace) and display later on demand. // When needed, call dump_backtrace() to see them spdlog::enable_backtrace(32); // create ring buffer with capacity of 32 messages // or my_logger->enable_backtrace(32).. for(int i = 0; i < 100; i++) { spdlog::debug("Backtrace message {}", i); // not logged yet.. } // e.g. if some error happened: spdlog::dump_backtrace(); // log them now! show the last 32 messages // or my_logger->dump_backtrace(32).. ``` --- #### Periodic flush ```c++ // periodically flush all *registered* loggers every 3 seconds: // warning: only use if all your loggers are thread safe ("_mt" loggers) spdlog::flush_every(std::chrono::seconds(3)); ``` --- #### Log binary data in hex ```c++ // many types of std::container types can be used. // ranges are supported too. // format flags: // {:X} - print in uppercase. // {:s} - don't separate each byte with space. // {:p} - don't print the position on each line start. // {:n} - don't split the output to lines. #include "spdlog/fmt/bin_to_hex.h" void binary_example() { auto console = spdlog::get("console"); std::array buf; console->info("Binary example: {}", spdlog::to_hex(buf)); console->info("Another binary example:{:n}", spdlog::to_hex(std::begin(buf), std::begin(buf) + 10)); // more examples: // logger->info("uppercase: {:X}", spdlog::to_hex(buf)); // logger->info("uppercase, no delimiters: {:Xs}", spdlog::to_hex(buf)); // logger->info("uppercase, no delimiters, no position info: {:Xsp}", spdlog::to_hex(buf)); } ``` --- #### Logger with multi sinks - each with different format and log level ```c++ // create logger with 2 targets with different log levels and formats. // the console will show only warnings or errors, while the file will log all. void multi_sink_example() { auto console_sink = std::make_shared(); console_sink->set_level(spdlog::level::warn); console_sink->set_pattern("[multi_sink_example] [%^%l%$] %v"); auto file_sink = std::make_shared("logs/multisink.txt", true); file_sink->set_level(spdlog::level::trace); spdlog::logger logger("multi_sink", {console_sink, file_sink}); logger.set_level(spdlog::level::debug); logger.warn("this should appear in both console and file"); logger.info("this message should not appear in the console, only in the file"); } ``` --- #### Asynchronous logging ```c++ #include "spdlog/async.h" #include "spdlog/sinks/basic_file_sink.h" void async_example() { // default thread pool settings can be modified *before* creating the async logger: // spdlog::init_thread_pool(8192, 1); // queue with 8k items and 1 backing thread. auto async_file = spdlog::basic_logger_mt("async_file_logger", "logs/async_log.txt"); // alternatively: // auto async_file = spdlog::create_async("async_file_logger", "logs/async_log.txt"); } ``` --- #### Asynchronous logger with multi sinks ```c++ #include "spdlog/sinks/stdout_color_sinks.h" #include "spdlog/sinks/rotating_file_sink.h" void multi_sink_example2() { spdlog::init_thread_pool(8192, 1); auto stdout_sink = std::make_shared(); auto rotating_sink = std::make_shared("mylog.txt", 1024*1024*10, 3); std::vector sinks {stdout_sink, rotating_sink}; auto logger = std::make_shared("loggername", sinks.begin(), sinks.end(), spdlog::thread_pool(), spdlog::async_overflow_policy::block); spdlog::register_logger(logger); } ``` --- #### User defined types ```c++ // user defined types logging by implementing operator<< #include "spdlog/fmt/ostr.h" // must be included struct my_type { int i; template friend OStream &operator<<(OStream &os, const my_type &c) { return os << "[my_type i=" << c.i << "]"; } }; void user_defined_example() { spdlog::get("console")->info("user defined type: {}", my_type{14}); } ``` --- #### Custom error handler ```c++ void err_handler_example() { // can be set globally or per logger(logger->set_error_handler(..)) spdlog::set_error_handler([](const std::string &msg) { spdlog::get("console")->error("*** LOGGER ERROR ***: {}", msg); }); spdlog::get("console")->info("some invalid message to trigger an error {}{}{}{}", 3); } ``` --- #### syslog ```c++ #include "spdlog/sinks/syslog_sink.h" void syslog_example() { std::string ident = "spdlog-example"; auto syslog_logger = spdlog::syslog_logger_mt("syslog", ident, LOG_PID); syslog_logger->warn("This is warning that will end up in syslog."); } ``` --- #### Android example ```c++ #include "spdlog/sinks/android_sink.h" void android_example() { std::string tag = "spdlog-android"; auto android_logger = spdlog::android_logger_mt("android", tag); android_logger->critical("Use \"adb shell logcat\" to view this message."); } ``` ## Benchmarks Below are some [benchmarks](https://github.com/gabime/spdlog/blob/v1.x/bench/bench.cpp) done in Ubuntu 64 bit, Intel i7-4770 CPU @ 3.40GHz #### Synchronous mode ``` [info] ************************************************************** [info] Single thread, 1,000,000 iterations [info] ************************************************************** [info] basic_st Elapsed: 0.17 secs 5,777,626/sec [info] rotating_st Elapsed: 0.18 secs 5,475,894/sec [info] daily_st Elapsed: 0.20 secs 5,062,659/sec [info] empty_logger Elapsed: 0.07 secs 14,127,300/sec [info] ************************************************************** [info] C-string (400 bytes). Single thread, 1,000,000 iterations [info] ************************************************************** [info] basic_st Elapsed: 0.41 secs 2,412,483/sec [info] rotating_st Elapsed: 0.72 secs 1,389,196/sec [info] daily_st Elapsed: 0.42 secs 2,393,298/sec [info] null_st Elapsed: 0.04 secs 27,446,957/sec [info] ************************************************************** [info] 10 threads, competing over the same logger object, 1,000,000 iterations [info] ************************************************************** [info] basic_mt Elapsed: 0.60 secs 1,659,613/sec [info] rotating_mt Elapsed: 0.62 secs 1,612,493/sec [info] daily_mt Elapsed: 0.61 secs 1,638,305/sec [info] null_mt Elapsed: 0.16 secs 6,272,758/sec ``` #### ASynchronous mode ``` [info] ------------------------------------------------- [info] Messages : 1,000,000 [info] Threads : 10 [info] Queue : 8,192 slots [info] Queue memory : 8,192 x 272 = 2,176 KB [info] ------------------------------------------------- [info] [info] ********************************* [info] Queue Overflow Policy: block [info] ********************************* [info] Elapsed: 1.70784 secs 585,535/sec [info] Elapsed: 1.69805 secs 588,910/sec [info] Elapsed: 1.7026 secs 587,337/sec [info] [info] ********************************* [info] Queue Overflow Policy: overrun [info] ********************************* [info] Elapsed: 0.372816 secs 2,682,285/sec [info] Elapsed: 0.379758 secs 2,633,255/sec [info] Elapsed: 0.373532 secs 2,677,147/sec ``` ## Documentation Documentation can be found in the [wiki](https://github.com/gabime/spdlog/wiki/1.-QuickStart) pages.