diff --git a/docs/index.md b/docs/index.md index 8b1378917..3cd4a76ed 100644 --- a/docs/index.md +++ b/docs/index.md @@ -1 +1,463 @@ +# spdlog + + +[![ci](https://github.com/gabime/spdlog/actions/workflows/linux.yml/badge.svg)](https://github.com/gabime/spdlog/actions/workflows/linux.yml)  +[![ci](https://github.com/gabime/spdlog/actions/workflows/windows.yml/badge.svg)](https://github.com/gabime/spdlog/actions/workflows/windows.yml)  +[![ci](https://github.com/gabime/spdlog/actions/workflows/macos.yml/badge.svg)](https://github.com/gabime/spdlog/actions/workflows/macos.yml)  +[![Release](https://img.shields.io/github/release/gabime/spdlog.svg)](https://github.com/gabime/spdlog/releases/latest) + +Fast C++ logging library + +## Install +```console +$ git clone https://github.com/gabime/spdlog.git +$ cd spdlog && mkdir build && cd build +$ cmake .. && cmake --build . +``` + +see example [CMakeLists.txt](https://github.com/gabime/spdlog/blob/v2.x/example/CMakeLists.txt) on how to use. + +## Platforms +* Linux, FreeBSD, OpenBSD, Solaris, AIX +* Windows (msvc, cygwin) +* macOS +* Android + +## Package managers: +* Debian: `sudo apt install libspdlog-dev` +* Homebrew: `brew install spdlog` +* MacPorts: `sudo port install spdlog` +* FreeBSD: `pkg install spdlog` +* Fedora: `dnf install spdlog` +* Gentoo: `emerge dev-libs/spdlog` +* Arch Linux: `pacman -S spdlog` +* openSUSE: `sudo zypper in spdlog-devel` +* vcpkg: `vcpkg install spdlog` +* conan: `conan install --requires=spdlog/[*]` +* conda: `conda install -c conda-forge spdlog` +* build2: ```depends: spdlog ^1.8.2``` + + +## Features +* Very fast (see [benchmarks](#benchmarks) below). +* Headers only or compiled +* Feature-rich formatting, using the excellent [fmt](https://github.com/fmtlib/fmt) library. +* 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 event log. + * Windows debugger (```OutputDebugString(..)```). + * Log to Qt widgets ([example](#log-to-qt-with-nice-colors)). + * Easily [extendable](https://github.com/gabime/spdlog/wiki/4.-Sinks#implementing-your-own-sink) with custom log targets. +* Log filtering - log levels can be modified at runtime as well as compile time. +* Support for loading log levels from argv or environment var. + +## Usage samples + +#### Basic usage +```c++ +#include "spdlog/spdlog.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"); +} + +``` +--- +#### Create stdout/stderr logger object +```c++ +#include "spdlog/spdlog.h" +#include "spdlog/sinks/stdout_color_sinks.h" +void stdout_example() +{ + // create a 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 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 5 MB size max and 3 rotated files + auto max_size = 1048576 * 5; + auto max_files = 3; + auto logger = spdlog::rotating_logger_mt("some_logger_name", "logs/rotating.txt", max_size, max_files); +} +``` + +--- +#### Daily files +```c++ + +#include "spdlog/sinks/daily_file_sink.h" +void daily_example() +{ + // Create a daily logger - a new file is created every day at 2:30 am + auto logger = spdlog::daily_logger_mt("daily_logger", "logs/daily.txt", 2, 30); +} + +``` + + +--- +#### 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)); + +``` + +--- +#### Stopwatch +```c++ +// Stopwatch support for spdlog +#include "spdlog/stopwatch.h" +void stopwatch_example() +{ + spdlog::stopwatch sw; + spdlog::debug("Elapsed {}", sw); + spdlog::debug("Elapsed {:.3}", sw); +} + +``` + +--- +#### 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 into lines. +// {:a} - show ASCII if :n is not set. + +#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 a different format and log level +```c++ + +// create a 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"); +} +``` + +--- +#### User-defined callbacks about log events +```c++ + +// create a logger with a lambda function callback, the callback will be called +// each time something is logged to the logger +void callback_example() +{ + auto callback_sink = std::make_shared([](const spdlog::details::log_msg &msg) { + // for example you can be notified by sending an email to yourself + }); + callback_sink->set_level(spdlog::level::err); + + auto console_sink = std::make_shared(); + spdlog::logger logger("custom_callback_logger", {console_sink, callback_sink}); + + logger.info("some info log"); + logger.error("critical issue"); // will notify you +} +``` + +--- +#### Asynchronous logging +```c++ +#include "spdlog/async.h" +#include "spdlog/sinks/basic_file_sink.h" +void async_example() +{ + // TODO +} + +``` + +--- +#### User-defined types +```c++ +template<> +struct fmt::formatter : fmt::formatter +{ + auto format(my_type my, format_context &ctx) const -> decltype(ctx.out()) + { + return format_to(ctx.out(), "[my_type i={}]", my.i); + } +}; + +void user_defined_example() +{ + spdlog::info("user defined type: {}", my_type(14)); +} + +``` + +--- +#### User-defined flags in the log pattern +```c++ +// Log patterns can contain custom flags. +// the following example will add new flag '%*' - which will be bound to a instance. +#include "spdlog/pattern_formatter.h" +class my_formatter_flag : public spdlog::custom_flag_formatter +{ +public: + void format(const spdlog::details::log_msg &, const std::tm &, spdlog::memory_buf_t &dest) override + { + std::string some_txt = "custom-flag"; + dest.append(some_txt.data(), some_txt.data() + some_txt.size()); + } + + std::unique_ptr clone() const override + { + return std::make_unique(); + } +}; + +void custom_flags_example() +{ + auto formatter = std::make_unique(); + formatter->add_flag('*').set_pattern("[%n] [%*] [%^%l%$] %v"); + spdlog::set_formatter(std::move(formatter)); +} + +``` + +--- +#### Custom error handler +```c++ +void err_handler_example() +{ + // can be set globally or per logger(logger->set_error_handler(..)) + spdlog::set_error_handler([](const std::string &msg) { spdlog::get("console")->error("*** LOGGER ERROR ***: {}", msg); }); + spdlog::get("console")->info("some invalid message to trigger an error {}{}{}{}", 3); +} + +``` + +--- +#### syslog +```c++ +#include "spdlog/sinks/syslog_sink.h" +void syslog_example() +{ + std::string ident = "spdlog-example"; + auto syslog_logger = spdlog::syslog_logger_mt("syslog", ident, LOG_PID); + syslog_logger->warn("This is warning that will end up in syslog."); +} +``` +--- +#### Android example +```c++ +#include "spdlog/sinks/android_sink.h" +void android_example() +{ + std::string tag = "spdlog-android"; + auto android_logger = spdlog::android_logger_mt("android", tag); + android_logger->critical("Use \"adb shell logcat\" to view this message."); +} +``` + +--- +#### Load log levels from the env variable or argv + +```c++ +#include "spdlog/cfg/env.h" +int main (int argc, char *argv[]) +{ + spdlog::cfg::load_env_levels(); + // or from the command line: + // ./example SPDLOG_LEVEL=info,mylogger=trace + // #include "spdlog/cfg/argv.h" // for loading levels from argv + // spdlog::cfg::load_argv_levels(argc, argv); +} +``` +So then you can: + +```console +$ export SPDLOG_LEVEL=info,mylogger=trace +$ ./example +``` + + +--- +#### Log file open/close event handlers +```c++ +// You can get callbacks from spdlog before/after a log file has been opened or closed. +// This is useful for cleanup procedures or for adding something to the start/end of the log file. +void file_events_example() +{ + // pass the spdlog::file_event_handlers to file sinks for open/close log file notifications + spdlog::file_event_handlers handlers; + handlers.before_open = [](spdlog::filename_t filename) { spdlog::info("Before opening {}", filename); }; + handlers.after_open = [](spdlog::filename_t filename, std::FILE *fstream) { fputs("After opening\n", fstream); }; + handlers.before_close = [](spdlog::filename_t filename, std::FILE *fstream) { fputs("Before closing\n", fstream); }; + handlers.after_close = [](spdlog::filename_t filename) { spdlog::info("After closing {}", filename); }; + auto my_logger = spdlog::basic_logger_st("some_logger", "logs/events-sample.txt", true, handlers); +} +``` + +--- +#### Replace the Default Logger +```c++ +void replace_global_logger_example() +{ + auto new_logger = spdlog::basic_logger_mt("new_global_logger", "logs/new-default-log.txt", true); + spdlog::set_global_logger(new_logger); + spdlog::info("new logger log message"); +} +``` + +--- +#### Log to Qt with nice colors +```c++ +#include "spdlog/spdlog.h" +#include "spdlog/sinks/qt_sinks.h" +MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) +{ + setMinimumSize(640, 480); + auto log_widget = new QTextEdit(this); + setCentralWidget(log_widget); + int max_lines = 500; // keep the text widget to max 500 lines. remove old lines if needed. + auto logger = spdlog::qt_color_logger_mt("qt_logger", log_widget, max_lines); + logger->info("Some info message"); +} +``` + +--- +## Benchmarks + +Below are some [benchmarks](https://github.com/gabime/spdlog/blob/v2.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. + +--- + +Thanks to [JetBrains](https://www.jetbrains.com/?from=spdlog) for donating product licenses to help develop **spdlog**