elog

A C++11 logging framework with high emphasys on performance.

Please note this is a template library (released under LGPLv3) hence the main itself is simply a test to show the performance/usage; the current version compiles on Linux, still it should be easy to adapt to Windows or other architectures.

Also note this is now pretty much work in progress!

Building

Simply invoke make (make release for optimized build) and the main should compile.

How do I include in my project(s)?

Feel free to copy the file elog.h, elog.cpp and include it wherever needed; see license.

How do I use it in my code?

After including the header and cpp, one can use respective macros as defined in main.cpp. As example:

ELOG_INIT("test.log");
...
...
ELOG_INFO("some ", "log ", "here ", 123, '\t', -12.45);
...
...
ELOG_SET_LEVEL(elog::level_fatal|elog::level_error); // only log errors and fatal events
ELOG_DEBUG("xyz"); // will be skipped at runtime
ELOG_ERROR("This is an error!"); // will be printed
...
...
ELOG_SET_LEVEL(elog::level_all); // print everything again - default
...
...
ELOG_CLEANUP();

A more comprehensive way of using it would be (in main):

int main(int argc, char *argv[]) {
	try {
		ELOG_INIT("mylogfile.log");
		...
		...
		...
		...
		ELOG_INFO("Some ", "info ", "here! ", 4.5, -123);
		...
		...
		ELOG_DEBUG("Some ", "debug");
		...
		...
		ELOG_CLEANUP();
	} catch(const elog::exception& e) {
		std::cerr << "elog exception: " << e.what() << std::endl;
		return -1;
	} catch(const std::exception& e) {
		ELOG_ERROR("Exception: ", e.what());
		ELOG_CLEANUP();
		return -2;
	} catch(...) {
		ELOG_ERROR("Unknownw exception");
		ELOG_CLEANUP();
		return -3;
	}
}

F.A.Q.s

Is this code working only for a specific platform?

I have developed primarily on Linux (Ubuntu 16.04.3) altough I have used std interfaces as much as I can - this code should be used as it is on Windows/MacOS/... .

I've has a look at the macros and would like to invoke the elog API directly. What do the paramters for elog::logger::init achieve really?

Following a quick summary:

fname will specify the base filename of the log
s_ordering will have the separated writing logger I/O thread ordering the log events - adds a tiny bit more of CPU but makes the log stricly sequential
e_sz specifies how many entries are pre-allocated in the logging table - this is a control parameter that you can tune depending on how many threads and how frequently those are writing into the log
roll_log_sz specified how many bytes we can write into the logfile before it gets rolled (i.e. renamed to log name.0, then log name.1 and so on ...)

Can you describe a bit the inner guts of this logging framework?

to come

License

This software is licensed under the LGPLv3, so you can include the header in your source code and just say thanks - no need to release your sources (unless you modify the template that is).

Other licensing

I'm also open to potentially let people use this under another license, better suited to commercial firms; please contact me in case you may be interested - altough at this early stage I don't see why you would be...

Acknowledgements & thanks

Would like to thank very much Carl Cook for his inspirational speeches 2016 C++ and CppCon 2017 - he also has a Github account (I swear I was inspired by talks, no copy of his variadicLogging or FastLogger).

Emanem/elog