spdlog/README.md
2014-12-07 09:41:21 +02:00

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# 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](#benchmarks) below).
* Headers only.
* No dependencies.
* Cross platform - Linux / Windows on 32/64 bits.
* **new!** Feature rich cppfromat [call style](http://cppformat.readthedocs.org/en/stable/syntax.html) using the excellent [cppformat](http://cppformat.github.io/) library.
* Example: ```logger.info("Hello {} {:08x}!!", "world", 42);```
* ostream call style: ```logger.info() << "Hello << "logger";```
* **new!** Extremely fast asynchronous mode (optional) - use of lockfree queues and other tricks to reach millions of calls per second from multiple threads.
* [Custom](https://github.com/gabime/spdlog/wiki/Custom-formatting) 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](include/spdlog/sinks/sink.h) interface).
* Severity based filtering - threshold levels can be modified in runtime.
## Benchmarks
Below are some [benchmarks](bench) comparing the time needed to log 1,000,000 lines to file under Ubuntu 64 bit, Intel i7-4770 CPU @ 3.40GHz (the best of 3 runs for each logger):
|threads|boost log|glog|g2log <sup>async mode</sup>|spdlog|spdlog <sup>async mode</sup>|
|-------|:-------:|:-----:|------:|------:|------:|
|1|4.779s|1.109s|3.155s|0.319s|0.212s
|10|15.151ss|3.546s|3.500s|0.641s|0.199s|
## Usage Example
```c++
#include <iostream>
#include "spdlog/spdlog.h"
int main(int, char* [])
{
namespace spd = spdlog;
try
{
std::string filename = "logs/spdlog_example";
// 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");
//See cppformat syntax documation here:
//http://cppformat.readthedocs.org/en/stable/syntax.html
//Create a file rotating logger with 5mb size max and 3 rotated files
auto file_logger = spd::rotating_logger_mt("file_logger", filename, 1024 * 1024 * 5, 3);
for(int i = 0; i < 10; ++i)
file_logger->info("{} * {} equals {:>10}", i, i, i*i);
//Customize msg format
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(file_logger, "This is a trace message (only #ifdef _DEBUG)", 123);
//
// Asynchronous logging is easy..
// Just call spdlog::set_async_mode(max_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
//
#ifdef __linux__
auto syslog_logger = spd::syslog_logger("syslog");
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;
}
}
```