spdlog/README.md
2014-12-21 01:30:39 +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 - just copy and use.
* Cross platform - Linux / Windows on 32/64 bits.
* **new!** Feature rich [call style](#usage-example) using the excellent [cppformat](http://cppformat.github.io/) library.
* ostream call style is supported too.
* 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 popular log libraries under Ubuntu 64 bit, Intel i7-4770 CPU @ 3.40GHz
#### Synchronous mode
Time needed to log 1,000,000 lines under synchronous mode (in seconds, the best of 3 runs):
|threads|boost log|glog |easylogging |spdlog|
|-------|:-------:|:-----:|----------:|------:|
|1| 4.169s |1.066s |0.975s |0.302s|
|10| 16.029 |3.032s |2.857s |0.968s|
|100| 15.008 |1.139s |4.512s |0.497s|
#### Asynchronous mode
Time needed to log 1,000,000 lines under asynchronous mode, i.e. the time it takes to put them in the async queue (in seconds, the best of 3 runs):
|threads|g2log |spdlog<sup>async mode</sup>|
|:-------|:-----:|-------------------------:|
|1| 1.850s |0.216s |
|10| 0.943s |0.173s|
|100| 0.959s |0.202s|
## Usage Example
```c++
#include <iostream>
#include "spdlog/spdlog.h"
int main(int, char* [])
{
namespace spd = spdlog;
try
{
// 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");
//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);
file_logger->set_level(spd::level::info);
for(int i = 0; i < 10; ++i)
file_logger->info("{} * {} equals {:>10}", i, i, i*i);
//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");
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
//
#ifdef __linux__
std::string ident = "my_app";
auto syslog_logger = spd::syslog_logger("syslog", ident, LOG_PID | LOG_PERROR);
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;
}
}
```