# spdlog
Very fast, header-only/compiled, C++ logging library. [](https://travis-ci.org/gabime/spdlog) [](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, v1.4.0)
```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`
## 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 or other 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 {}", {});
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!
spdlog::flush_every(std::chrono::seconds(3));
```
---
#### Log binary data in hex
```c++
// many types of std::container<char> 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<char, 80> 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<spdlog::sinks::stdout_color_sink_mt>();
console_sink->set_level(spdlog::level::warn);
console_sink->set_pattern("[multi_sink_example] [%^%l%$] %v");
auto file_sink = std::make_shared<spdlog::sinks::basic_file_sink_mt>("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<spdlog::async_factory>("async_file_logger", "logs/async_log.txt");
// alternatively:
// auto async_file = spdlog::create_async<spdlog::sinks::basic_file_sink_mt>("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<spdlog::sinks::stdout_color_sink_mt >();
auto rotating_sink = std::make_shared<spdlog::sinks::rotating_file_sink_mt>("mylog.txt", 1024*1024*10, 3);
std::vector<spdlog::sink_ptr> sinks {stdout_sink, rotating_sink};
auto logger = std::make_shared<spdlog::async_logger>("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<typename OStream>
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 sharing same logger, 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] Total iters : 3
[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.