tproll

Lightweight logging backend for SLF4J

Simple logging backend, designed to have minimal overhead and easy setup, while being flexible when you need it.

Install

This is a SLF4J backend, so make sure you have SLF4J API. Then, get it from jitpack:

For convenience:

jitpack at https://jitpack.io
org.slf4j:slf4j-api:1.7.36
com.github.Darkyenus:tproll:1.5.2

Use

If you have tproll and SLF4J API on classpath, you can start using SLF4J logging as usual. By default, the backend is logging to the stdout/err only, and from info level up. All configuration is done through code. No XML, no json, no new languages to learn. To change log level, call com.darkyen.tproll.TPLogger.DEBUG() and other static functions.

What happens, when I log something? The message goes through SLF4J API to the TPLogger class, which performs early log level check and then performs parameter substitution. Result goes to the LogFunction (set globally, for all loggers, through TPLogger.setLogFunction(func)).

LogFunction is an interface, which handles what should happen with the message next. By default, it is printed out to stdout/err (through LogFunction.SIMPLE_LOG_FUNCTION). This logger is generally enough early in development and it is still useful later.

Next logical step is logging to a file. For this, use FileLogFunction, which logs to a file (or multiple files, one file for each restart, this can be configured). Convenience constructor is provided, which could be enough for most applications (new FileLogFunction(new File("<log directory>"))). If you need something more advanced/specific, you can create your own ILogFileHandler or just LogFileCreationStrategy for the default LogFileHandler. This may look like a lot of classes, but don't worry, most are short and don't do many things, they are split for customizability.

What if I want to log to a file AND to stdout/err at the same time? Just use LogFunctionMultiplexer with the desired logging functions passed as constructor parameters. This class can also route various log messages to different LogFunctions using Markers. See the JavaDoc!

tproll uses/doesn't use colors, how do I tell it to turn them on/off? Color is used only when outputting to the stdout/err, so don't worry about it polluting log files. Color support detection is somewhat naive, so it may not correctly detect the desired value. To override it, set either Java property tproll.color ($ java -Dtproll.color=true -jar ...) or environment variable TPROLL_COLOR to true to enable color, or false to disable.

What is the supported Java version? The code is compiled with language level of Java 8, but the usage of Java 8 APIs is kept to a minimum and build so that code fails gracefully when running without them, for example on Android or on a different API-restricted platform. One exception is that java.time APIs are required. On Android, use helper library or whatever is the suggested workaround nowadays.

Example

TL;DR, what do I need to copy/paste to leverage this framework?

import org.slf4j.LoggerFactory;
import org.slf4j.Logger;

private static final Logger LOG = LoggerFactory.getLogger(Main.class);

public static void main(String[] args) throws Exception {
    TPLogger.setLogFunction(
            new LogFunctionMultiplexer(
                    SimpleLogFunction.CONSOLE_LOG_FUNCTION, // Log to console...
                    new FileLogFunction(new File("test logs")) // and to a file in "test logs" directory
            ));

    LOG.warn("tproll {} !", (System.currentTimeMillis() & 1) == 0 ? "is great" : "rules");

    //Add this line to log unhandled exceptions in your threads
    TPLogger.attachUnhandledExceptionLogger();
}