Simple trick for getting a logger

6

Another trick I used. Not sure if it’s faster or not. I didn’t store logger instance anywhere, in my benchmarks logback is very fast so it doesn’t make sense to store it IMO.

private fun getFunctionLogger(anchorFunction: () -> String): Logger {
  fun getLoggerName(): String {
    val anchorClassName = anchorFunction.javaClass.name
    // anchorClassName: my.pckg.FileKt$func$1, we should return my.pckg.FileKt.func
    val lastDollarIndex = anchorClassName.lastIndexOf('$')
    if (lastDollarIndex == -1 ) return anchorClassName
    val prevLastDollarIndex = anchorClassName.lastIndexOf('$', startIndex = lastDollarIndex - 1)
    if (prevLastDollarIndex == -1) return anchorClassName
    return anchorClassName.substring(0, prevLastDollarIndex) + '.' +
        anchorClassName.substring(prevLastDollarIndex + 1, lastDollarIndex)
  }
  return LoggerFactory.getLogger(getLoggerName())
}

fun logTrace(message: () -> String) {
  val logger = getFunctionLogger(message)
  if (logger.isTraceEnabled) logger.trace(message())
}

Basically when you’re using logTrace, you passing lambda which is instance of anonymous Java class and its name could be used to create logger name.