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

rev 50107 : [mq]: pp2_work

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, 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

@@ -64,10 +64,11 @@
             ReferenceQueue<?> queue = r.queue;
             if ((queue == NULL) || (queue == ENQUEUED)) {
                 return false;
             }
             assert queue == this;
+            // Self-loop end, so if a FinalReference it remains inactive.
             r.next = (head == null) ? r : head;
             head = r;
             queueLength++;
             // Update r.queue *after* adding to list, to avoid race
             // with concurrent enqueued checks and fast-path poll().

@@ -88,11 +89,14 @@
             // Update r.queue *before* removing from list, to avoid
             // race with concurrent enqueued checks and fast-path
             // poll().  Volatiles ensure ordering.
             @SuppressWarnings("unchecked")
             Reference<? extends T> rn = r.next;
+            // Handle self-looped next as end of list designator.
             head = (rn == r) ? null : rn;
+            // Self-loop next rather than setting to null, so if a
+            // FinalReference it remains inactive.
             r.next = r;
             queueLength--;
             if (r instanceof FinalReference) {
                 VM.addFinalRefCount(-1);
             }