CppLog

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

CppLog 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.

To support parallel logging into different outputs, the per-thread Logger-instance can be set at any point without affecting any other thread.

Usage

//Top of the file:
#include "log.h"

//...

//Where you want to log:
log::debug() << "This is a debug message" << log::endl;
log::info() << "This is purely informational" << log::endl;
log::warn() << "Supports full C++ stream syntax, hence we can log " << 12 << " as well as " << 42.42 << log::endl;
log::error() << "Something bad happened here!" << log::endl;
log::severe() << "Something really catastrophic happened! Do somthing, NOW!!" << log::endl;

Configuration

CppLog can optionally be configured in several ways:

• The macro CPPLOG_NAMESPACE determines the namespace, the logging framework is accessible in (defaults to "log"). CPPLOG_NAMESPACE can be chosen freely, as long as it remains a valid C++11 namespace name.
• Setting the global variable DEFAULT_LOGGER in the framework's namespace (by default log::DEFAULT_LOGGER) determines the logger to be used. Resetting DEFAULT_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 DEFAULT_LOGGER is set to ConsoleLogger (see section Extensions).
• The function setThreadLogger can be used to set a custom logger for the current thread to allow for logging parallel executions to different outputs.

Extensions

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

• ConsoleLogger: writes every log to std::cout and std::cerr, where any log with the levels ERROR and SEVERE 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 logMessage.
2. Use the global variable DEFAULT_LOGGER to set the logger to an instance of your custom class
3. Done!