private def registerInterruptHook()

in kernel/src/main/scala/org/apache/toree/boot/layer/HookInitialization.scala [68:121]
35 lines of code
5 McCabe index (conditional complexity)

  private def registerInterruptHook(config: Config, interpreter: Interpreter): Unit = {
    val self = this

    import sun.misc.{Signal, SignalHandler}

    // TODO: Signals are not a good way to handle this since JVM only has the
    // proprietary sun API that is not necessarily available on all platforms
    Signal.handle(new Signal("INT"), new SignalHandler() {
      private val MaxSignalTime: Long = 3000 // 3 seconds
      var lastSignalReceived: Long    = 0

      def handle(sig: Signal) = {
        val currentTime = System.currentTimeMillis()
        if (currentTime - lastSignalReceived > MaxSignalTime) {
          logger.info("Resetting code execution!")
          interpreter.interrupt()

          // TODO: Cancel group representing current code execution
          //sparkContext.cancelJobGroup()

          logger.info("Enter Ctrl-C twice to shutdown!")
          lastSignalReceived = currentTime
        } else {
          logger.info("Shutting down kernel")
          self.shutdown()
        }
      }
    })
    // Define handler for alternate signal that will be fired in cases where
    // the caller is in a background process in order to interrupt
    // cell operations - since SIGINT doesn't propagate in those cases.
    // Like INT above except we don't need to deal with shutdown in
    // repeated situations.
    val altSigintOption = "alternate_sigint"
    if (config.hasPath(altSigintOption)) {
      val altSigint = config.getString(altSigintOption)

      try {
        Signal.handle(new Signal(altSigint), new SignalHandler() {

            def handle(sig: Signal) = {
              logger.info("Resetting code execution due to interrupt!")
              interpreter.interrupt()

              // TODO: Cancel group representing current code execution
              //sparkContext.cancelJobGroup()
            }
        })
      } catch {
        case e:Exception => logger.warn("Error occurred establishing alternate signal handler " +
          "(--alternate-sigint = " + altSigint + ").  Error: " + e.getMessage )
      }
    }
  }