zero-log is a logging framework for Scala, which is designed to take advantage of Scala feature to let logging faster and simpler.

Why use zero-log instead of log4j, logback, etc...

• Zero cost if the log is disabled by compile-time configuration.
• Zero XML or Propertis files you need to write.
• 10+ times faster for string formatting than any other Java logging libraries (log4j, logback, ...).
• Support @scala.annotation.elidable.

For more comparation, see log4j VS zero-log.

Performance

zero-log is extremely fast.

Thanks to Scala's @elidable, when using compile-time configuration, the cost for disabled logs can be exactly zero.

zero-log's string formatting can be 10+ times faster than any other Java logging libraries. See Fastring for more information.

Usage

You only need call ZeroLoggerFactory.newLogger(this) to get the logger, and call logger.info() to log. No more configuation for simple use.

package com.yourDomain.yourProject
object Sample {
  implicit val (logger, formatter, appender) = ZeroLoggerFactory.newLogger(this)

  def main(args: Array[String]) {
    logger.info("Logging in a Singleton.")
    logger.fine("Hello,")
    logger.warning("World!")
    logger.finest(fast"Faster string formatting: args.length is ${args.length}")
    new Sample
  }
}

class Sample {
  import Sample._

  logger.info("Logging in a class instance.")
  logger.finer("Hello,")
  logger.severe("World!", new Exception("With some Exception"))
}

Note: By default, only logging level info, warning and severe are enabled, and the other levels are disabled.

Configure logging level, formatting, or target

Unlike log4j, logback, java.util.logging, the zero-log does not load any XML or Properties file as configuration. Instead, zero-log use ZeroLoggerFactory to configure logging level, logging formatting, or logging target. If you need custom configuration, just put your own ZeroLoggerFactory on scalac's source path.

For example, you may create a file at src/main/scala/zero-log.config.scala to change logging level for com.yourDomain.yourProject.Sample:

import com.dongxiguo.zeroLog.Filter
import com.dongxiguo.zeroLog.formatters.SimpleFormatter
import com.dongxiguo.zeroLog.appenders.ConsoleAppender

// Set global default logging level to Warning, and send logs to ConsoleAppender
object ZeroLoggerFactory {
  final def newLogger(singleton: Singleton) =
    (Filter.Warning, SimpleFormatter, ConsoleAppender)
}

package com.yourDomain.yourProject {
  object ZeroLoggerFactory {
    // Set package com.yourDomain.yourProject's default logging level to Info
    final def newLogger(singleton: Singleton) =
      (Filter.Info, SimpleFormatter, ConsoleAppender)

    // Set Sample's logging level to Finest
    final def newLogger(singleton: Sample.type) =
      (Filter.Finest, SimpleFormatter, ConsoleAppender)
  }
}

Look at logger's initializing code in Sample.scala:

  implicit val (logger, formatter, appender) = ZeroLoggerFactory.newLogger(this)

When Sample.scala is compiled with zero-log.config.scala, ZeroLoggerFactory.newLogger will be resolved as com.yourDomain.yourProject.ZeroLoggerFactory.newLogger. So logger and formatter will be the result of newLogger you defined at zero-log.config.scala, which are Filter.Finest , SimpleFormatter, and ConsoleAppender for Sample.

Run-time configuration

When you create a library, you may want the user of your library to be able to change logging settings without change your library's source code.

Don't worry. zero-log can resolve ZeroLoggerFactory by reflection. Just call ZeroLoggerFactory.newLogger without com.yourDomain.yourProject.ZeroLoggerFactory in source path, and ship your library without com.yourDomain.yourProject.ZeroLoggerFactory in your release. Your users can define their own com.yourDomain.yourProject.ZeroLoggerFactory or com.yourDomain.ZeroLoggerFactory, which are resoved by zero-log at run-time.

Downloads

Binary release and scaladocs can be found on Maven central repository. You may download these files directly, or add dependency to zero-log in your building management tool's configuration:

Sbt

If you use sbt 0.12.x or 0.13.x, add following configuration to your build.sbt:

libraryDependencies += "com.dongxiguo" %% "zero-log" % "0.3.6"

Maven

Or add following configuration if you use maven:

<properties>
	<scala.version>2.11.0</scala.version>
</properties>
<dependency>
	<groupId>com.dongxiguo</groupId>
	<artifactId>zero-log_2.10</artifactId>
	<version>0.3.6</version>
	<scope>compile</scope>
</dependency>