@inline private[this] def cas()

in util-core/src/main/scala/com/twitter/util/Promise.scala [503:542]

• 27 lines of code
• 12 McCabe index (conditional complexity)

  @inline private[this] def cas(oldState: Any, newState: Any): Boolean =
    unsafe.compareAndSwapObject(this, stateOff, oldState, newState)

  /**
   * (Re)sets the interrupt handler. There is only
   * one active interrupt handler.
   *
   * @param f the new interrupt handler
   */
  final def setInterruptHandler(f: PartialFunction[Throwable, Unit]): Unit =
    setInterruptHandler0(f, WaitQueue.empty)

  @tailrec
  private final def setInterruptHandler0(
    f: PartialFunction[Throwable, Unit],
    wq: WaitQueue[A]
  ): Unit =
    state match {
      case s: Transforming[A] =>
        if (!cas(s, new Interruptible(WaitQueue.merge(wq, s.waitq), f, Local.save())))
          setInterruptHandler0(f, wq)

      case waitq: WaitQueue[A] =>
        if (!cas(waitq, new Interruptible(WaitQueue.merge(wq, waitq), f, Local.save())))
          setInterruptHandler0(f, wq)

      case t: Try[A] /* Done */ => wq.runInScheduler(t)

      case s: Interruptible[A] =>
        if (!cas(s, new Interruptible(WaitQueue.merge(wq, s.waitq), f, Local.save())))
          setInterruptHandler0(f, wq)

      case p: Promise[A] /* Linked */ => p.setInterruptHandler0(f, wq)

      case s: Interrupted[A] =>
        if ((wq ne WaitQueue.Empty) &&
          !cas(s, new Interrupted(WaitQueue.merge(wq, s.waitq), s.signal)))
          setInterruptHandler0(f, wq)
        else f.applyOrElse(s.signal, Promise.AlwaysUnit)
    }