LoggableException.scala

/**
 * Base trait for all classes that wants to be able use the logging infrastructure.
 * 
 * @author <a href="http://jonasboner.com">Jonas Bon&#233;r</a>
 */
trait Logging {
  @transient var log = Logger.get(this.getClass.getName)
}

/**
 * LoggableException is a subclass of Exception and can be used as the base exception
 * for application specific exceptions.
 * <p/>
 * It keeps track of the exception is logged or not and also stores the unique id,
 * so that it can be carried all along to the client tier and displayed to the end user.
 * The end user can call up the customer support using this number.
 * 
 * @author <a href="http://jonasboner.com">Jonas Bon&#233;r</a>
 */
class LoggableException(message: String) extends RuntimeException(message) with Logging {
  private val uniqueId = getExceptionID
  private var originalException: Option[Exception] = None
  private var isLogged = false

  def this(baseException: Exception) = {
    this("")
    originalException = Some(baseException)
  }

  def logException = synchronized {
    if (!isLogged) {
      log.error("Logged Exception [%s] %s", uniqueId, getStackTraceAsString)
      isLogged = true
    }
 }

  def getExceptionID: String = {
    val hostname = try {
      InetAddress.getLocalHost.getHostName
    } catch {
      case e: UnknownHostException =>
        log.error("Could not get hostname to generate loggable exception")
        "N/A"
    }
    hostname + "_" + System.currentTimeMillis
  }

  def getStackTraceAsString: String = {
    val sw = new StringWriter
    val pw = new PrintWriter(sw)
    originalException match {
      case Some(e) => e.printStackTrace(pw)
      case None =>    printStackTrace(pw)
    }
    sw.toString
  }
}