Exemple #1
0
  private Token receive0() {
    Node s = new Node(null, false); // the node to append

    retry:
    for (; ; ) { // restart on append race
      Object item = tryMatch(null, null, false);
      if (item != NO_MATCH) {
        s.item = item;
        return new Token(s, null);
      }

      Node pred = tryAppend(s, false);
      if (pred == null) continue retry; // lost race vs opposite mode

      if (sendClosed) {
        s.item = CHANNEL_CLOSED;
        unsplice(pred, s);
        setReceiveClosed();
        return new Token(s, null);
      }

      requestUnpark(s, Strand.currentStrand());
      return new Token(s, pred);
    }
  }
Exemple #2
0
 private static ActorRef getCurrentActor() {
   ActorRef actorRef = LocalActor.self();
   if (actorRef == null) {
     // create a "dummy actor" on the current strand
     Actor actor =
         new Actor(Strand.currentStrand(), null, new MailboxConfig(5, OverflowPolicy.THROW)) {
           @Override
           protected Object doRun() throws InterruptedException, SuspendExecution {
             throw new AssertionError();
           }
         };
     actorRef = new TempActor(actor);
   }
   return actorRef;
 }
Exemple #3
0
  /**
   * Spins/yields/blocks until node s is matched or caller gives up.
   *
   * @param s the waiting node
   * @param pred the predecessor of s, or s itself if it has no predecessor, or null if unknown (the
   *     null case does not occur in any current calls but may in possible future extensions)
   * @param e the comparison value for checking match
   * @param timed if true, wait only until timeout elapses
   * @param nanos timeout in nanosecs, used only if timed is true
   * @return matched item, or e if unmatched on interrupt or timeout
   */
  private Message awaitMatch(Node s, Node pred, Message e, boolean timed, long nanos)
      throws SuspendExecution {
    long lastTime = timed ? System.nanoTime() : 0L;
    Strand w = Strand.currentStrand();
    int spins =
        (w.isFiber()
            ? 0
            : -1); // no spins in fiber; otherwise, initialized after first item and cancel checks
    ThreadLocalRandom randomYields = null; // bound if needed

    if (spins == 0) requestUnpark(s, w);

    for (; ; ) {
      Object item = s.item;

      if (item == CHANNEL_CLOSED) setReceiveClosed();

      if (item != e) { // matched
        // assert item != s;
        s.forgetContents(); // avoid garbage
        return this.<Message>cast(item);
      }
      if ((w.isInterrupted() || (timed && nanos <= 0)) && s.casItem(e, s)) { // cancel
        unsplice(pred, s);
        return e;
      }

      if (spins < 0) { // establish spins at/near front
        if ((spins = spinsFor(pred, s.isData)) > 0) randomYields = ThreadLocalRandom.current();
      } else if (spins > 0) { // spin
        --spins;
        if (randomYields.nextInt(CHAINED_SPINS) == 0) Strand.yield(); // occasionally yield
      } else if (s.waiter == null) {
        requestUnpark(s, w); // request unpark then recheck
      } else if (timed) {
        long now = System.nanoTime();
        if ((nanos -= now - lastTime) > 0) Strand.parkNanos(this, nanos);
        lastTime = now;
      } else {
        Strand.park(this);
      }
    }
  }