src/share/classes/java/lang/ref/ReferenceQueue.java

*** 1,7 ****
  /*
!  * Copyright (c) 1997, 2005, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
--- 1,7 ----
  /*
!  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
*** 38,66 ****
      /**
       * Constructs a new reference-object queue.
       */
      public ReferenceQueue() { }
  
!     private static class Null extends ReferenceQueue {
!         boolean enqueue(Reference r) {
              return false;
          }
      }
  
!     static ReferenceQueue NULL = new Null();
!     static ReferenceQueue ENQUEUED = new Null();
  
      static private class Lock { };
      private Lock lock = new Lock();
      private volatile Reference<? extends T> head = null;
      private long queueLength = 0;
  
      boolean enqueue(Reference<? extends T> r) { /* Called only by Reference class */
          synchronized (lock) {
              // Check that since getting the lock this reference hasn't already been
              // enqueued (and even then removed)
!             ReferenceQueue queue = r.queue;
              if ((queue == NULL) || (queue == ENQUEUED)) {
                  return false;
              }
              assert queue == this;
              r.queue = ENQUEUED;
--- 38,66 ----
      /**
       * Constructs a new reference-object queue.
       */
      public ReferenceQueue() { }
  
!     private static class Null<S> extends ReferenceQueue<S> {
!         boolean enqueue(Reference<? extends S> r) {
              return false;
          }
      }
  
!     static ReferenceQueue<Object> NULL = new Null<>();
!     static ReferenceQueue<Object> ENQUEUED = new Null<>();
  
      static private class Lock { };
      private Lock lock = new Lock();
      private volatile Reference<? extends T> head = null;
      private long queueLength = 0;
  
      boolean enqueue(Reference<? extends T> r) { /* Called only by Reference class */
          synchronized (lock) {
              // Check that since getting the lock this reference hasn't already been
              // enqueued (and even then removed)
!             ReferenceQueue<?> queue = r.queue;
              if ((queue == NULL) || (queue == ENQUEUED)) {
                  return false;
              }
              assert queue == this;
              r.queue = ENQUEUED;
*** 73,86 ****
              lock.notifyAll();
              return true;
          }
      }
  
      private Reference<? extends T> reallyPoll() {       /* Must hold lock */
          Reference<? extends T> r = head;
          if (r != null) {
!             head = (r.next == r) ? null : r.next;
              r.queue = NULL;
              r.next = r;
              queueLength--;
              if (r instanceof FinalReference) {
                  sun.misc.VM.addFinalRefCount(-1);
--- 73,89 ----
              lock.notifyAll();
              return true;
          }
      }
  
+     @SuppressWarnings("unchecked")
      private Reference<? extends T> reallyPoll() {       /* Must hold lock */
          Reference<? extends T> r = head;
          if (r != null) {
!             head = (r.next == r) ?
!                 null :
!                 r.next; // Unchecked due to the next field having a raw type in Reference
              r.queue = NULL;
              r.next = r;
              queueLength--;
              if (r instanceof FinalReference) {
                  sun.misc.VM.addFinalRefCount(-1);