Overview

MentaLog is a straightforward logging library that stays out of the way and gets the job done with the beauty of simplicity. It is also very fast and produces ZERO garbage.

In a nutshell, it offers:

• Flexible and easy way to log: a single method, varargs, placeholders and more
• The logs are enumerations, so you can pass them around and access them easily in a non-intrusive way
• Superb performance with latencies around 300 nanoseconds @ 2.53Ghz (more info)
• It allocates ZERO memory and creates no garbage when logging to a file, so no overhead with object instantiation and GC! (more info)
• Encoders for the objects you want to log, so you don't create any garbage with calls to toString() (more info)
• Support for Interceptors, so you can intercept the ByteBuffer containing the log message and do whatever you want, such as send to a syslog or implement your own log server (more info)
• It supports colors when logging to the console (more info)
• Programmatic DSL configuration: no xml or annotations (more info)
• Conventions and defaults for everything: don't configure anything if you don't want to, just use it and it will work
• Synchronized and non-synchronized options
• Print class names and line numbers with your logs for debugging (more info)
• Supports filtering the log messages by package and class name so you can filter out noise when debugging (more info)

Quick Start

package org.mentalog;

import static org.mentalog.Log.*; // to use MentaLog that's all you have to do!

public class QuickStart {
	
	public static void main(String[] args) {

		// by default, logs go to the console
		Warn.log("This is a log message!", "user=", "foo", "age=", 21);
		
		// System.out output:
		// 21:11:17.263-WARN This is a log message! user=foo age=21
		
		// or you can use placeholders:
		Warn.log("This is a log message! user={} age={}", "foo", 21);
		
		// System.out output:
		// 21:11:18.263-WARN This is a log message! user=foo age=21
		
		// if you want to color you logs by level, you can:
		Log.setColors(true);
		
		Fatal.log("This is a log message! user={} age={}", "foo", 21);
		
		// System.out output in RED:
		// 21:11:17.263-FATAL This is a log message! user=foo age=21
		
		// logging to a file: (files cannot support colors so the colors flag above will be ignored)
		Log.setFile(true);
		
		// a file Warn.log in the current directory will be created (or opened in append mode):
		Warn.log("Hello there!", "msg=", "hi");
		
		// contents written to file:
		// LOG OPENED - 19/09/2011 21:15:42.627
		// 21:15:42.630 Hello there! msg=hi
		
		// if you want to change the directory where the file will be created:
		Log.setDir("/var/log/myLogs");
		
		// you can also roll the file whenever you want...
		Warn.roll();
		
		// setting the log level
		Log.setLevel(Debug); // the levels are Debug, Info, Warn, Error, Alert and Fatal
		
		// or if you want to just enable or disable a single level
		Error.enable(true); // no matter what the level is, it will be logged
		Error.enable(false); // not matter what the level is, it will NOT be logged 
		Error.enable(null); // go by the current log level
		
		// creating your own log files
		Logger audit = Log.createLogger("/var/log/myLogs" /* log dir */, "audit" /* filename */, false /* isSynchronized */, true /* asynchronous */);
		
		audit.log("This is a log message!", "user=", "foo", "age=", 21);
		
		// prints to the file /var/log/myLogs/audit.log:
		// 21:11:17.263 This is a log message! user=foo age=21
		
		// you can also roll and close your audit log whenever you want:
		audit.roll();
		audit.close();
	}
}