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root/jsr166/jsr166/src/main/java/util/concurrent/LinkedTransferQueue.java
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Comparing jsr166/src/main/java/util/concurrent/LinkedTransferQueue.java (file contents):
Revision 1.143 by jsr166, Sun Jan 15 00:00:14 2017 UTC vs.
Revision 1.144 by jsr166, Sun Jan 15 01:16:22 2017 UTC

# Line 568 | Line 568 | public class LinkedTransferQueue<E> exte
568      }
569  
570      /**
571 <     * Collapse dead (matched) nodes between pred and q.
571 >     * Collapses dead (matched) nodes between pred and q.
572       * @param pred the last known live node, or null if none
573       * @param c the first dead node
574       * @param p the last dead node
# Line 590 | Line 590 | public class LinkedTransferQueue<E> exte
590              ? pred : p;
591      }
592  
593 +    /**
594 +     * Collapses dead (matched) nodes between h and p.
595 +     * h was once head, and all nodes between h and p are dead.
596 +     */
597 +    private void skipDeadNodesNearHead(Node h, Node p) {
598 +        // assert h != p;
599 +        // assert p.isMatched();
600 +        // find live or trailing node, starting at p
601 +        for (Node q; (q = p.next) != null; ) {
602 +            if (!q.isMatched()) {
603 +                p = q;
604 +                break;
605 +            }
606 +            if (p == (p = q))
607 +                return;
608 +        }
609 +        if (h == HEAD.getAcquire(this) && casHead(h, p))
610 +            h.selfLink();
611 +    }
612 +
613      /* Possible values for "how" argument in xfer method. */
614  
615      private static final int NOW   = 0; // for untimed poll, tryTransfer
# Line 622 | Line 642 | public class LinkedTransferQueue<E> exte
642                          break;
643                      if (p.tryMatch(item, e)) {
644                          // collapse at least 2
645 <                        if (h != p) tryCollapseHead: {
626 <                            // find live or trailing node
627 <                            for (Node q; (q = p.next) != null; ) {
628 <                                if (!q.isMatched()) {
629 <                                    p = q;
630 <                                    break;
631 <                                }
632 <                                if (p == (p = q))
633 <                                    break tryCollapseHead;
634 <                            }
635 <                            if (h == head && casHead(h, p))
636 <                                h.selfLink();
637 <                        }
645 >                        if (h != p) skipDeadNodesNearHead(h, p);
646                          @SuppressWarnings("unchecked") E itemE = (E) item;
647                          return itemE;
648                      }
# Line 668 | Line 676 | public class LinkedTransferQueue<E> exte
676      private Node tryAppend(Node s, boolean haveData) {
677          // assert head != null;
678          // assert tail != null;
679 +        // assert s.isData == haveData;
680          for (Node t = tail, p = t;;) {        // move p to last node and append
681              Node n, u;                        // temps for reads of next & tail
682              if (p == null)

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