Levin

A very light-weight thread-safe extensible logging framework for C++.

This framework makes data-races in log-outputs a thing of the past.

Framework

Levin is a very small library consisting of only two public header files:

• Log.h: This header defines the logging-methods, include it in any source-file you want to log something in

• Logger.h: This header contains the Logger-classes. You only need to include this file if you want to customize the logging output (style, destination, ...)

To support multi-threaded applications, any thread writing logs has its own instance of an output-stream where it assembles the logging output in.

With the call of the endl function, the message is written to the output in a thread-safe fashion.

Usage

Currently, Levin's severity levels (log functions) are based on the standard RFC5424, that define the follow severity levels.

Value	Severity	Description
0	Emergency	System is unusable
1	Alert	Action must be taken immediately
2	Critical	Critical conditions
3	Error	Error conditions
4	Warning	Warning conditions
5	Notice	Normal but significant conditions
6	Informational	Informational messages
7	Debug	Debug-level messages

//Top of the file:
#include <Levin/Levin.hpp>

using namespace Levin;

//Where you want to log:
Log::Debug("This is a debug message");
Log::Informational("This is purely informational");
Log::Warning("Supports full C++ stream syntax, hence we can log {} as well as {}", 12, 42.42);
Log::Error("Something bad happened here!");
Log::Critical("Something really catastrophic happened! Do somthing, NOW!!");
Log::Emergency("Imminent failure, the system will shut down");
Log::Alert("This is a {} message", "alert");

It is important to note that Levin uses Flossy to format the strings, resulting in a formatting of strings inspired in Python 3.

Log::Information("The first value passed is {}, and the second is {}!", 42, "foo");

For see the Format Specification Language consult the documentation of Flossy

Configuration

Levin can optionally be configured in several ways:

Resetting logger to the nullptr disables logging for the remainder of the program's life. This also shuts down the logging-thread, so no CPU time is wasted. By default, the LOGGER is set to ConsoleLogger (see section Extensions).

Extensions

In the current version, Levin comes with three built-in Loggers:

• ConsoleLogger: writes every log to std::cout and std::cerr, where any log with the levels Emergency, Alert, Critical and Error are written to std::cerr and any other log goes to std::cout.
  This Logger is enabled by default.

• FileLogger: Logs the output to a file, specified by a file-name given as constructor-argument.

• ColoredLogger: Writes any log to std::cout but uses console colors to highlight more critical messages.

To write your own Logger, simply follow this easy steps:

1. Write a Logger-class publicly extending Logger (in the header-file Logger.h) and overwrite at least message.
2. Use the function Log::SetNewLogger from the static class Log to set the logger to an instance of your custom class.
3. Done!

How to Compile

git clone --depth=1 https://github.com/Andres6936/Levin.git
cd Levin && mkdir Build
cd Build && cmake ..
make 

How to use the library as a downloadable dependency

To use this library, you need the script written by TheLartians, named CPM.cmake (acronym for CMake Package Manager). Add it to your project, for example, under the CMakeModules and then in your CMakeFiles.txt write the following:

• The directory CMakeModules is used to store CMake Scripts, in case you use another directory for these purposes it will be necessary that references properly CPM.cmake to be able to download the dependency.

Include(CMakeModules/CPM.cmake)

CPMAddPackage(
  NAME Levin
  VERSION 2020.1228
  GITHUB_REPOSITORY Andres6936/Levin
)
 
TARGET_LINK_LIBRARIES(<TARGET> PRIVATE Levin::Framework)

Please, in the VERSION option you should preferably specify the latest version available consult here