changeset 1471:eb27b5587e18

Merge
author sherman
date Wed, 29 Jul 2009 11:19:14 -0700
parents eb5173d782ca 49573ab3096a
children 61d174a58edf
files test/java/util/concurrent/ConcurrentLinkedQueue/ConcurrentQueueLoops.java test/java/util/concurrent/ConcurrentLinkedQueue/LoopHelpers.java
diffstat 32 files changed, 2247 insertions(+), 908 deletions(-) [+]
line wrap: on
line diff
--- a/make/common/shared/Defs-control.gmk	Fri Jul 24 11:22:29 2009 -0700
+++ b/make/common/shared/Defs-control.gmk	Wed Jul 29 11:19:14 2009 -0700
@@ -92,9 +92,9 @@
 dummy := $(shell $(MKDIR) -p $(TEMP_DIR))
 
 # The language version we want for this jdk build
-SOURCE_LANGUAGE_VERSION=5
+SOURCE_LANGUAGE_VERSION=7
 # The class version we want for this jdk build
-TARGET_CLASS_VERSION=5
+TARGET_CLASS_VERSION=7
 
 # The MESSAGE, WARNING and ERROR files are used to store sanity check and 
 # source check messages, warnings and errors. 
--- a/make/common/shared/Defs-java.gmk	Fri Jul 24 11:22:29 2009 -0700
+++ b/make/common/shared/Defs-java.gmk	Wed Jul 29 11:19:14 2009 -0700
@@ -122,13 +122,13 @@
   JAVACFLAGS  += -Werror
 endif
 
-# Add the source level (currently all source is 1.5, should this be 1.6?)
-SOURCE_LANGUAGE_VERSION = 5
+# Add the source level
+SOURCE_LANGUAGE_VERSION = 7
 LANGUAGE_VERSION = -source $(SOURCE_LANGUAGE_VERSION)
 JAVACFLAGS  += $(LANGUAGE_VERSION)
 
-# Add the class version we want (currently this is 5, should it be 6 or even 7?)
-TARGET_CLASS_VERSION = 5
+# Add the class version we want
+TARGET_CLASS_VERSION = 7
 CLASS_VERSION = -target $(TARGET_CLASS_VERSION)
 JAVACFLAGS  += $(CLASS_VERSION)
 JAVACFLAGS  += -encoding ascii
--- a/make/java/dyn/Makefile	Fri Jul 24 11:22:29 2009 -0700
+++ b/make/java/dyn/Makefile	Wed Jul 29 11:19:14 2009 -0700
@@ -33,8 +33,8 @@
 
 # The sources built here use new language syntax to generate
 # method handle calls.  Let's be sure we are using that format.
-#LANGUAGE_VERSION = -source 7
-#CLASS_VERSION = -target 7
+LANGUAGE_VERSION = -source 7
+CLASS_VERSION = -target 7
 
 # Actually, it will be less disruptive to compile with the same
 # -target option as the rest of the system, and just turn on
--- a/src/share/classes/com/sun/jndi/ldap/Filter.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/src/share/classes/com/sun/jndi/ldap/Filter.java	Wed Jul 29 11:19:14 2009 -0700
@@ -93,9 +93,7 @@
 
         int filtOffset[] = new int[1];
 
-        for (filtOffset[0] = filterStart;
-             filtOffset[0] < filterEnd;
-             filtOffset[0]++) {
+        for (filtOffset[0] = filterStart; filtOffset[0] < filterEnd;) {
             switch (filter[filtOffset[0]]) {
             case '(':
                 filtOffset[0]++;
@@ -104,18 +102,21 @@
                 case '&':
                     encodeComplexFilter(ber, filter,
                         LDAP_FILTER_AND, filtOffset, filterEnd);
+                    // filtOffset[0] has pointed to char after right paren
                     parens--;
                     break;
 
                 case '|':
                     encodeComplexFilter(ber, filter,
                         LDAP_FILTER_OR, filtOffset, filterEnd);
+                    // filtOffset[0] has pointed to char after right paren
                     parens--;
                     break;
 
                 case '!':
                     encodeComplexFilter(ber, filter,
                         LDAP_FILTER_NOT, filtOffset, filterEnd);
+                    // filtOffset[0] has pointed to char after right paren
                     parens--;
                     break;
 
@@ -143,8 +144,8 @@
 
                     encodeSimpleFilter(ber, filter, filtOffset[0], nextOffset);
 
-                    // points to right parens; for loop will increment beyond parens
-                    filtOffset[0] = nextOffset;
+                    // points to the char after right paren.
+                    filtOffset[0] = nextOffset + 1;
 
                     parens--;
                     break;
@@ -170,9 +171,14 @@
                 filtOffset[0] = filterEnd; // force break from outer
                 break;
             }
+
+            if (parens < 0) {
+                throw new InvalidSearchFilterException(
+                                                "Unbalanced parenthesis");
+            }
         }
 
-        if (parens > 0) {
+        if (parens != 0) {
             throw new InvalidSearchFilterException("Unbalanced parenthesis");
         }
 
--- a/src/share/classes/java/lang/Character.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/src/share/classes/java/lang/Character.java	Wed Jul 29 11:19:14 2009 -0700
@@ -2784,8 +2784,13 @@
      * @since  1.5
      */
     public static int toCodePoint(char high, char low) {
-        return ((high - MIN_HIGH_SURROGATE) << 10)
-            + (low - MIN_LOW_SURROGATE) + MIN_SUPPLEMENTARY_CODE_POINT;
+        // Optimized form of:
+        // return ((high - MIN_HIGH_SURROGATE) << 10)
+        //         + (low - MIN_LOW_SURROGATE)
+        //         + MIN_SUPPLEMENTARY_CODE_POINT;
+        return ((high << 10) + low) + (MIN_SUPPLEMENTARY_CODE_POINT
+                                       - (MIN_HIGH_SURROGATE << 10)
+                                       - MIN_LOW_SURROGATE);
     }
 
     /**
@@ -3071,9 +3076,10 @@
     }
 
     static void toSurrogates(int codePoint, char[] dst, int index) {
-        int offset = codePoint - MIN_SUPPLEMENTARY_CODE_POINT;
-        dst[index+1] = (char)((offset & 0x3ff) + MIN_LOW_SURROGATE);
-        dst[index] = (char)((offset >>> 10) + MIN_HIGH_SURROGATE);
+        // We write elements "backwards" to guarantee all-or-nothing
+        dst[index+1] = (char)((codePoint & 0x3ff) + MIN_LOW_SURROGATE);
+        dst[index] = (char)((codePoint >>> 10)
+            + (MIN_HIGH_SURROGATE - (MIN_SUPPLEMENTARY_CODE_POINT >>> 10)));
     }
 
     /**
--- a/src/share/classes/java/util/concurrent/ConcurrentLinkedQueue.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/src/share/classes/java/util/concurrent/ConcurrentLinkedQueue.java	Wed Jul 29 11:19:14 2009 -0700
@@ -34,9 +34,13 @@
  */
 
 package java.util.concurrent;
-import java.util.*;
-import java.util.concurrent.atomic.*;
 
+import java.util.AbstractQueue;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+import java.util.Queue;
 
 /**
  * An unbounded thread-safe {@linkplain Queue queue} based on linked nodes.
@@ -47,9 +51,9 @@
  * queue the shortest time. New elements
  * are inserted at the tail of the queue, and the queue retrieval
  * operations obtain elements at the head of the queue.
- * A <tt>ConcurrentLinkedQueue</tt> is an appropriate choice when
+ * A {@code ConcurrentLinkedQueue} is an appropriate choice when
  * many threads will share access to a common collection.
- * This queue does not permit <tt>null</tt> elements.
+ * This queue does not permit {@code null} elements.
  *
  * <p>This implementation employs an efficient &quot;wait-free&quot;
  * algorithm based on one described in <a
@@ -57,7 +61,7 @@
  * Fast, and Practical Non-Blocking and Blocking Concurrent Queue
  * Algorithms</a> by Maged M. Michael and Michael L. Scott.
  *
- * <p>Beware that, unlike in most collections, the <tt>size</tt> method
+ * <p>Beware that, unlike in most collections, the {@code size} method
  * is <em>NOT</em> a constant-time operation. Because of the
  * asynchronous nature of these queues, determining the current number
  * of elements requires a traversal of the elements.
@@ -87,51 +91,102 @@
     private static final long serialVersionUID = 196745693267521676L;
 
     /*
-     * This is a straight adaptation of Michael & Scott algorithm.
-     * For explanation, read the paper.  The only (minor) algorithmic
-     * difference is that this version supports lazy deletion of
-     * internal nodes (method remove(Object)) -- remove CAS'es item
-     * fields to null. The normal queue operations unlink but then
-     * pass over nodes with null item fields. Similarly, iteration
-     * methods ignore those with nulls.
+     * This is a modification of the Michael & Scott algorithm,
+     * adapted for a garbage-collected environment, with support for
+     * interior node deletion (to support remove(Object)).  For
+     * explanation, read the paper.
      *
-     * Also note that like most non-blocking algorithms in this
-     * package, this implementation relies on the fact that in garbage
+     * Note that like most non-blocking algorithms in this package,
+     * this implementation relies on the fact that in garbage
      * collected systems, there is no possibility of ABA problems due
      * to recycled nodes, so there is no need to use "counted
      * pointers" or related techniques seen in versions used in
      * non-GC'ed settings.
+     *
+     * The fundamental invariants are:
+     * - There is exactly one (last) Node with a null next reference,
+     *   which is CASed when enqueueing.  This last Node can be
+     *   reached in O(1) time from tail, but tail is merely an
+     *   optimization - it can always be reached in O(N) time from
+     *   head as well.
+     * - The elements contained in the queue are the non-null items in
+     *   Nodes that are reachable from head.  CASing the item
+     *   reference of a Node to null atomically removes it from the
+     *   queue.  Reachability of all elements from head must remain
+     *   true even in the case of concurrent modifications that cause
+     *   head to advance.  A dequeued Node may remain in use
+     *   indefinitely due to creation of an Iterator or simply a
+     *   poll() that has lost its time slice.
+     *
+     * The above might appear to imply that all Nodes are GC-reachable
+     * from a predecessor dequeued Node.  That would cause two problems:
+     * - allow a rogue Iterator to cause unbounded memory retention
+     * - cause cross-generational linking of old Nodes to new Nodes if
+     *   a Node was tenured while live, which generational GCs have a
+     *   hard time dealing with, causing repeated major collections.
+     * However, only non-deleted Nodes need to be reachable from
+     * dequeued Nodes, and reachability does not necessarily have to
+     * be of the kind understood by the GC.  We use the trick of
+     * linking a Node that has just been dequeued to itself.  Such a
+     * self-link implicitly means to advance to head.
+     *
+     * Both head and tail are permitted to lag.  In fact, failing to
+     * update them every time one could is a significant optimization
+     * (fewer CASes). This is controlled by local "hops" variables
+     * that only trigger helping-CASes after experiencing multiple
+     * lags.
+     *
+     * Since head and tail are updated concurrently and independently,
+     * it is possible for tail to lag behind head (why not)?
+     *
+     * CASing a Node's item reference to null atomically removes the
+     * element from the queue.  Iterators skip over Nodes with null
+     * items.  Prior implementations of this class had a race between
+     * poll() and remove(Object) where the same element would appear
+     * to be successfully removed by two concurrent operations.  The
+     * method remove(Object) also lazily unlinks deleted Nodes, but
+     * this is merely an optimization.
+     *
+     * When constructing a Node (before enqueuing it) we avoid paying
+     * for a volatile write to item by using lazySet instead of a
+     * normal write.  This allows the cost of enqueue to be
+     * "one-and-a-half" CASes.
+     *
+     * Both head and tail may or may not point to a Node with a
+     * non-null item.  If the queue is empty, all items must of course
+     * be null.  Upon creation, both head and tail refer to a dummy
+     * Node with null item.  Both head and tail are only updated using
+     * CAS, so they never regress, although again this is merely an
+     * optimization.
      */
 
     private static class Node<E> {
         private volatile E item;
         private volatile Node<E> next;
 
-        private static final
-            AtomicReferenceFieldUpdater<Node, Node>
-            nextUpdater =
-            AtomicReferenceFieldUpdater.newUpdater
-            (Node.class, Node.class, "next");
-        private static final
-            AtomicReferenceFieldUpdater<Node, Object>
-            itemUpdater =
-            AtomicReferenceFieldUpdater.newUpdater
-            (Node.class, Object.class, "item");
-
-        Node(E x) { item = x; }
-
-        Node(E x, Node<E> n) { item = x; next = n; }
+        Node(E item) {
+            // Piggyback on imminent casNext()
+            lazySetItem(item);
+        }
 
         E getItem() {
             return item;
         }
 
         boolean casItem(E cmp, E val) {
-            return itemUpdater.compareAndSet(this, cmp, val);
+            return UNSAFE.compareAndSwapObject(this, itemOffset, cmp, val);
         }
 
         void setItem(E val) {
-            itemUpdater.set(this, val);
+            item = val;
+        }
+
+        void lazySetItem(E val) {
+            UNSAFE.putOrderedObject(this, itemOffset, val);
+        }
+
+        void lazySetNext(Node<E> val) {
+            UNSAFE.putOrderedObject(this, nextOffset, val);
         }
 
         Node<E> getNext() {
@@ -139,52 +194,55 @@
         }
 
         boolean casNext(Node<E> cmp, Node<E> val) {
-            return nextUpdater.compareAndSet(this, cmp, val);
+            return UNSAFE.compareAndSwapObject(this, nextOffset, cmp, val);
         }
 
-        void setNext(Node<E> val) {
-            nextUpdater.set(this, val);
-        }
+        // Unsafe mechanics
 
+        private static final sun.misc.Unsafe UNSAFE =
+            sun.misc.Unsafe.getUnsafe();
+        private static final long nextOffset =
+            objectFieldOffset(UNSAFE, "next", Node.class);
+        private static final long itemOffset =
+            objectFieldOffset(UNSAFE, "item", Node.class);
     }
 
-    private static final
-        AtomicReferenceFieldUpdater<ConcurrentLinkedQueue, Node>
-        tailUpdater =
-        AtomicReferenceFieldUpdater.newUpdater
-        (ConcurrentLinkedQueue.class, Node.class, "tail");
-    private static final
-        AtomicReferenceFieldUpdater<ConcurrentLinkedQueue, Node>
-        headUpdater =
-        AtomicReferenceFieldUpdater.newUpdater
-        (ConcurrentLinkedQueue.class,  Node.class, "head");
-
-    private boolean casTail(Node<E> cmp, Node<E> val) {
-        return tailUpdater.compareAndSet(this, cmp, val);
-    }
-
-    private boolean casHead(Node<E> cmp, Node<E> val) {
-        return headUpdater.compareAndSet(this, cmp, val);
-    }
-
+    /**
+     * A node from which the first live (non-deleted) node (if any)
+     * can be reached in O(1) time.
+     * Invariants:
+     * - all live nodes are reachable from head via succ()
+     * - head != null
+     * - (tmp = head).next != tmp || tmp != head
+     * Non-invariants:
+     * - head.item may or may not be null.
+     * - it is permitted for tail to lag behind head, that is, for tail
+     *   to not be reachable from head!
+     */
+    private transient volatile Node<E> head = new Node<E>(null);
 
     /**
-     * Pointer to header node, initialized to a dummy node.  The first
-     * actual node is at head.getNext().
+     * A node from which the last node on list (that is, the unique
+     * node with node.next == null) can be reached in O(1) time.
+     * Invariants:
+     * - the last node is always reachable from tail via succ()
+     * - tail != null
+     * Non-invariants:
+     * - tail.item may or may not be null.
+     * - it is permitted for tail to lag behind head, that is, for tail
+     *   to not be reachable from head!
+     * - tail.next may or may not be self-pointing to tail.
      */
-    private transient volatile Node<E> head = new Node<E>(null, null);
-
-    /** Pointer to last node on list **/
     private transient volatile Node<E> tail = head;
 
 
     /**
-     * Creates a <tt>ConcurrentLinkedQueue</tt> that is initially empty.
+     * Creates a {@code ConcurrentLinkedQueue} that is initially empty.
      */
     public ConcurrentLinkedQueue() {}
 
     /**
-     * Creates a <tt>ConcurrentLinkedQueue</tt>
+     * Creates a {@code ConcurrentLinkedQueue}
      * initially containing the elements of the given collection,
      * added in traversal order of the collection's iterator.
      * @param c the collection of elements to initially contain
@@ -201,7 +259,7 @@
     /**
      * Inserts the specified element at the tail of this queue.
      *
-     * @return <tt>true</tt> (as specified by {@link Collection#add})
+     * @return {@code true} (as specified by {@link Collection#add})
      * @throws NullPointerException if the specified element is null
      */
     public boolean add(E e) {
@@ -209,107 +267,135 @@
     }
 
     /**
+     * We don't bother to update head or tail pointers if fewer than
+     * HOPS links from "true" location.  We assume that volatile
+     * writes are significantly more expensive than volatile reads.
+     */
+    private static final int HOPS = 1;
+
+    /**
+     * Try to CAS head to p. If successful, repoint old head to itself
+     * as sentinel for succ(), below.
+     */
+    final void updateHead(Node<E> h, Node<E> p) {
+        if (h != p && casHead(h, p))
+            h.lazySetNext(h);
+    }
+
+    /**
+     * Returns the successor of p, or the head node if p.next has been
+     * linked to self, which will only be true if traversing with a
+     * stale pointer that is now off the list.
+     */
+    final Node<E> succ(Node<E> p) {
+        Node<E> next = p.getNext();
+        return (p == next) ? head : next;
+    }
+
+    /**
      * Inserts the specified element at the tail of this queue.
      *
-     * @return <tt>true</tt> (as specified by {@link Queue#offer})
+     * @return {@code true} (as specified by {@link Queue#offer})
      * @throws NullPointerException if the specified element is null
      */
     public boolean offer(E e) {
         if (e == null) throw new NullPointerException();
-        Node<E> n = new Node<E>(e, null);
+        Node<E> n = new Node<E>(e);
+        retry:
         for (;;) {
             Node<E> t = tail;
-            Node<E> s = t.getNext();
-            if (t == tail) {
-                if (s == null) {
-                    if (t.casNext(s, n)) {
-                        casTail(t, n);
-                        return true;
-                    }
+            Node<E> p = t;
+            for (int hops = 0; ; hops++) {
+                Node<E> next = succ(p);
+                if (next != null) {
+                    if (hops > HOPS && t != tail)
+                        continue retry;
+                    p = next;
+                } else if (p.casNext(null, n)) {
+                    if (hops >= HOPS)
+                        casTail(t, n);  // Failure is OK.
+                    return true;
                 } else {
-                    casTail(t, s);
+                    p = succ(p);
                 }
             }
         }
     }
 
     public E poll() {
-        for (;;) {
-            Node<E> h = head;
-            Node<E> t = tail;
-            Node<E> first = h.getNext();
-            if (h == head) {
-                if (h == t) {
-                    if (first == null)
-                        return null;
-                    else
-                        casTail(t, first);
-                } else if (casHead(h, first)) {
-                    E item = first.getItem();
-                    if (item != null) {
-                        first.setItem(null);
-                        return item;
-                    }
-                    // else skip over deleted item, continue loop,
+        Node<E> h = head;
+        Node<E> p = h;
+        for (int hops = 0; ; hops++) {
+            E item = p.getItem();
+
+            if (item != null && p.casItem(item, null)) {
+                if (hops >= HOPS) {
+                    Node<E> q = p.getNext();
+                    updateHead(h, (q != null) ? q : p);
                 }
+                return item;
             }
+            Node<E> next = succ(p);
+            if (next == null) {
+                updateHead(h, p);
+                break;
+            }
+            p = next;
         }
+        return null;
     }
 
-    public E peek() { // same as poll except don't remove item
+    public E peek() {
+        Node<E> h = head;
+        Node<E> p = h;
+        E item;
         for (;;) {
-            Node<E> h = head;
-            Node<E> t = tail;
-            Node<E> first = h.getNext();
-            if (h == head) {
-                if (h == t) {
-                    if (first == null)
-                        return null;
-                    else
-                        casTail(t, first);
-                } else {
-                    E item = first.getItem();
-                    if (item != null)
-                        return item;
-                    else // remove deleted node and continue
-                        casHead(h, first);
-                }
+            item = p.getItem();
+            if (item != null)
+                break;
+            Node<E> next = succ(p);
+            if (next == null) {
+                break;
             }
+            p = next;
         }
+        updateHead(h, p);
+        return item;
     }
 
     /**
-     * Returns the first actual (non-header) node on list.  This is yet
-     * another variant of poll/peek; here returning out the first
-     * node, not element (so we cannot collapse with peek() without
-     * introducing race.)
+     * Returns the first live (non-deleted) node on list, or null if none.
+     * This is yet another variant of poll/peek; here returning the
+     * first node, not element.  We could make peek() a wrapper around
+     * first(), but that would cost an extra volatile read of item,
+     * and the need to add a retry loop to deal with the possibility
+     * of losing a race to a concurrent poll().
      */
     Node<E> first() {
+        Node<E> h = head;
+        Node<E> p = h;
+        Node<E> result;
         for (;;) {
-            Node<E> h = head;
-            Node<E> t = tail;
-            Node<E> first = h.getNext();
-            if (h == head) {
-                if (h == t) {
-                    if (first == null)
-                        return null;
-                    else
-                        casTail(t, first);
-                } else {
-                    if (first.getItem() != null)
-                        return first;
-                    else // remove deleted node and continue
-                        casHead(h, first);
-                }
+            E item = p.getItem();
+            if (item != null) {
+                result = p;
+                break;
             }
+            Node<E> next = succ(p);
+            if (next == null) {
+                result = null;
+                break;
+            }
+            p = next;
         }
+        updateHead(h, p);
+        return result;
     }
 
-
     /**
-     * Returns <tt>true</tt> if this queue contains no elements.
+     * Returns {@code true} if this queue contains no elements.
      *
-     * @return <tt>true</tt> if this queue contains no elements
+     * @return {@code true} if this queue contains no elements
      */
     public boolean isEmpty() {
         return first() == null;
@@ -317,8 +403,8 @@
 
     /**
      * Returns the number of elements in this queue.  If this queue
-     * contains more than <tt>Integer.MAX_VALUE</tt> elements, returns
-     * <tt>Integer.MAX_VALUE</tt>.
+     * contains more than {@code Integer.MAX_VALUE} elements, returns
+     * {@code Integer.MAX_VALUE}.
      *
      * <p>Beware that, unlike in most collections, this method is
      * <em>NOT</em> a constant-time operation. Because of the
@@ -329,7 +415,7 @@
      */
     public int size() {
         int count = 0;
-        for (Node<E> p = first(); p != null; p = p.getNext()) {
+        for (Node<E> p = first(); p != null; p = succ(p)) {
             if (p.getItem() != null) {
                 // Collections.size() spec says to max out
                 if (++count == Integer.MAX_VALUE)
@@ -340,16 +426,16 @@
     }
 
     /**
-     * Returns <tt>true</tt> if this queue contains the specified element.
-     * More formally, returns <tt>true</tt> if and only if this queue contains
-     * at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
+     * Returns {@code true} if this queue contains the specified element.
+     * More formally, returns {@code true} if and only if this queue contains
+     * at least one element {@code e} such that {@code o.equals(e)}.
      *
      * @param o object to be checked for containment in this queue
-     * @return <tt>true</tt> if this queue contains the specified element
+     * @return {@code true} if this queue contains the specified element
      */
     public boolean contains(Object o) {
         if (o == null) return false;
-        for (Node<E> p = first(); p != null; p = p.getNext()) {
+        for (Node<E> p = first(); p != null; p = succ(p)) {
             E item = p.getItem();
             if (item != null &&
                 o.equals(item))
@@ -360,23 +446,29 @@
 
     /**
      * Removes a single instance of the specified element from this queue,
-     * if it is present.  More formally, removes an element <tt>e</tt> such
-     * that <tt>o.equals(e)</tt>, if this queue contains one or more such
+     * if it is present.  More formally, removes an element {@code e} such
+     * that {@code o.equals(e)}, if this queue contains one or more such
      * elements.
-     * Returns <tt>true</tt> if this queue contained the specified element
+     * Returns {@code true} if this queue contained the specified element
      * (or equivalently, if this queue changed as a result of the call).
      *
      * @param o element to be removed from this queue, if present
-     * @return <tt>true</tt> if this queue changed as a result of the call
+     * @return {@code true} if this queue changed as a result of the call
      */
     public boolean remove(Object o) {
         if (o == null) return false;
-        for (Node<E> p = first(); p != null; p = p.getNext()) {
+        Node<E> pred = null;
+        for (Node<E> p = first(); p != null; p = succ(p)) {
             E item = p.getItem();
             if (item != null &&
                 o.equals(item) &&
-                p.casItem(item, null))
+                p.casItem(item, null)) {
+                Node<E> next = succ(p);
+                if (pred != null && next != null)
+                    pred.casNext(p, next);
                 return true;
+            }
+            pred = p;
         }
         return false;
     }
@@ -397,7 +489,7 @@
     public Object[] toArray() {
         // Use ArrayList to deal with resizing.
         ArrayList<E> al = new ArrayList<E>();
-        for (Node<E> p = first(); p != null; p = p.getNext()) {
+        for (Node<E> p = first(); p != null; p = succ(p)) {
             E item = p.getItem();
             if (item != null)
                 al.add(item);
@@ -415,22 +507,22 @@
      * <p>If this queue fits in the specified array with room to spare
      * (i.e., the array has more elements than this queue), the element in
      * the array immediately following the end of the queue is set to
-     * <tt>null</tt>.
+     * {@code null}.
      *
      * <p>Like the {@link #toArray()} method, this method acts as bridge between
      * array-based and collection-based APIs.  Further, this method allows
      * precise control over the runtime type of the output array, and may,
      * under certain circumstances, be used to save allocation costs.
      *
-     * <p>Suppose <tt>x</tt> is a queue known to contain only strings.
+     * <p>Suppose {@code x} is a queue known to contain only strings.
      * The following code can be used to dump the queue into a newly
-     * allocated array of <tt>String</tt>:
+     * allocated array of {@code String}:
      *
      * <pre>
      *     String[] y = x.toArray(new String[0]);</pre>
      *
-     * Note that <tt>toArray(new Object[0])</tt> is identical in function to
-     * <tt>toArray()</tt>.
+     * Note that {@code toArray(new Object[0])} is identical in function to
+     * {@code toArray()}.
      *
      * @param a the array into which the elements of the queue are to
      *          be stored, if it is big enough; otherwise, a new array of the
@@ -441,11 +533,12 @@
      *         this queue
      * @throws NullPointerException if the specified array is null
      */
+    @SuppressWarnings("unchecked")
     public <T> T[] toArray(T[] a) {
         // try to use sent-in array
         int k = 0;
         Node<E> p;
-        for (p = first(); p != null && k < a.length; p = p.getNext()) {
+        for (p = first(); p != null && k < a.length; p = succ(p)) {
             E item = p.getItem();
             if (item != null)
                 a[k++] = (T)item;
@@ -458,7 +551,7 @@
 
         // If won't fit, use ArrayList version
         ArrayList<E> al = new ArrayList<E>();
-        for (Node<E> q = first(); q != null; q = q.getNext()) {
+        for (Node<E> q = first(); q != null; q = succ(q)) {
             E item = q.getItem();
             if (item != null)
                 al.add(item);
@@ -511,7 +604,15 @@
             lastRet = nextNode;
             E x = nextItem;
 
-            Node<E> p = (nextNode == null)? first() : nextNode.getNext();
+            Node<E> pred, p;
+            if (nextNode == null) {
+                p = first();
+                pred = null;
+            } else {
+                pred = nextNode;
+                p = succ(nextNode);
+            }
+
             for (;;) {
                 if (p == null) {
                     nextNode = null;
@@ -523,8 +624,13 @@
                     nextNode = p;
                     nextItem = item;
                     return x;
-                } else // skip over nulls
-                    p = p.getNext();
+                } else {
+                    // skip over nulls
+                    Node<E> next = succ(p);
+                    if (pred != null && next != null)
+                        pred.casNext(p, next);
+                    p = next;
+                }
             }
         }
 
@@ -549,7 +655,7 @@
     /**
      * Save the state to a stream (that is, serialize it).
      *
-     * @serialData All of the elements (each an <tt>E</tt>) in
+     * @serialData All of the elements (each an {@code E}) in
      * the proper order, followed by a null
      * @param s the stream
      */
@@ -560,7 +666,7 @@
         s.defaultWriteObject();
 
         // Write out all elements in the proper order.
-        for (Node<E> p = first(); p != null; p = p.getNext()) {
+        for (Node<E> p = first(); p != null; p = succ(p)) {
             Object item = p.getItem();
             if (item != null)
                 s.writeObject(item);
@@ -579,10 +685,11 @@
         throws java.io.IOException, ClassNotFoundException {
         // Read in capacity, and any hidden stuff
         s.defaultReadObject();
-        head = new Node<E>(null, null);
+        head = new Node<E>(null);
         tail = head;
         // Read in all elements and place in queue
         for (;;) {
+            @SuppressWarnings("unchecked")
             E item = (E)s.readObject();
             if (item == null)
                 break;
@@ -591,4 +698,35 @@
         }
     }
 
+    // Unsafe mechanics
+
+    private static final sun.misc.Unsafe UNSAFE = sun.misc.Unsafe.getUnsafe();
+    private static final long headOffset =
+        objectFieldOffset(UNSAFE, "head", ConcurrentLinkedQueue.class);
+    private static final long tailOffset =
+        objectFieldOffset(UNSAFE, "tail", ConcurrentLinkedQueue.class);
+
+    private boolean casTail(Node<E> cmp, Node<E> val) {
+        return UNSAFE.compareAndSwapObject(this, tailOffset, cmp, val);
+    }
+
+    private boolean casHead(Node<E> cmp, Node<E> val) {
+        return UNSAFE.compareAndSwapObject(this, headOffset, cmp, val);
+    }
+
+    private void lazySetHead(Node<E> val) {
+        UNSAFE.putOrderedObject(this, headOffset, val);
+    }
+
+    static long objectFieldOffset(sun.misc.Unsafe UNSAFE,
+                                  String field, Class<?> klazz) {
+        try {
+            return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
+        } catch (NoSuchFieldException e) {
+            // Convert Exception to corresponding Error
+            NoSuchFieldError error = new NoSuchFieldError(field);
+            error.initCause(e);
+            throw error;
+        }
+    }
 }
--- a/src/share/classes/java/util/concurrent/LinkedBlockingDeque.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/src/share/classes/java/util/concurrent/LinkedBlockingDeque.java	Wed Jul 29 11:19:14 2009 -0700
@@ -34,8 +34,13 @@
  */
 
 package java.util.concurrent;
-import java.util.*;
-import java.util.concurrent.locks.*;
+
+import java.util.AbstractQueue;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.ReentrantLock;
 
 /**
  * An optionally-bounded {@linkplain BlockingDeque blocking deque} based on
@@ -73,6 +78,20 @@
     /*
      * Implemented as a simple doubly-linked list protected by a
      * single lock and using conditions to manage blocking.
+     *
+     * To implement weakly consistent iterators, it appears we need to
+     * keep all Nodes GC-reachable from a predecessor dequeued Node.
+     * That would cause two problems:
+     * - allow a rogue Iterator to cause unbounded memory retention
+     * - cause cross-generational linking of old Nodes to new Nodes if
+     *   a Node was tenured while live, which generational GCs have a
+     *   hard time dealing with, causing repeated major collections.
+     * However, only non-deleted Nodes need to be reachable from
+     * dequeued Nodes, and reachability does not necessarily have to
+     * be of the kind understood by the GC.  We use the trick of
+     * linking a Node that has just been dequeued to itself.  Such a
+     * self-link implicitly means to jump to "first" (for next links)
+     * or "last" (for prev links).
      */
 
     /*
@@ -86,9 +105,27 @@
 
     /** Doubly-linked list node class */
     static final class Node<E> {
+        /**
+         * The item, or null if this node has been removed.
+         */
         E item;
+
+        /**
+         * One of:
+         * - the real predecessor Node
+         * - this Node, meaning the predecessor is tail
+         * - null, meaning there is no predecessor
+         */
         Node<E> prev;
+
+        /**
+         * One of:
+         * - the real successor Node
+         * - this Node, meaning the successor is head
+         * - null, meaning there is no successor
+         */
         Node<E> next;
+
         Node(E x, Node<E> p, Node<E> n) {
             item = x;
             prev = p;
@@ -96,23 +133,37 @@
         }
     }
 
-    /** Pointer to first node */
-    private transient Node<E> first;
-    /** Pointer to last node */
-    private transient Node<E> last;
+    /**
+     * Pointer to first node.
+     * Invariant: (first == null && last == null) ||
+     *            (first.prev == null && first.item != null)
+     */
+    transient Node<E> first;
+
+    /**
+     * Pointer to last node.
+     * Invariant: (first == null && last == null) ||
+     *            (last.next == null && last.item != null)
+     */
+    transient Node<E> last;
+
     /** Number of items in the deque */
     private transient int count;
+
     /** Maximum number of items in the deque */
     private final int capacity;
+
     /** Main lock guarding all access */
-    private final ReentrantLock lock = new ReentrantLock();
+    final ReentrantLock lock = new ReentrantLock();
+
     /** Condition for waiting takes */
     private final Condition notEmpty = lock.newCondition();
+
     /** Condition for waiting puts */
     private final Condition notFull = lock.newCondition();
 
     /**
-     * Creates a <tt>LinkedBlockingDeque</tt> with a capacity of
+     * Creates a {@code LinkedBlockingDeque} with a capacity of
      * {@link Integer#MAX_VALUE}.
      */
     public LinkedBlockingDeque() {
@@ -120,10 +171,10 @@
     }
 
     /**
-     * Creates a <tt>LinkedBlockingDeque</tt> with the given (fixed) capacity.
+     * Creates a {@code LinkedBlockingDeque} with the given (fixed) capacity.
      *
      * @param capacity the capacity of this deque
-     * @throws IllegalArgumentException if <tt>capacity</tt> is less than 1
+     * @throws IllegalArgumentException if {@code capacity} is less than 1
      */
     public LinkedBlockingDeque(int capacity) {
         if (capacity <= 0) throw new IllegalArgumentException();
@@ -131,7 +182,7 @@
     }
 
     /**
-     * Creates a <tt>LinkedBlockingDeque</tt> with a capacity of
+     * Creates a {@code LinkedBlockingDeque} with a capacity of
      * {@link Integer#MAX_VALUE}, initially containing the elements of
      * the given collection, added in traversal order of the
      * collection's iterator.
@@ -142,8 +193,18 @@
      */
     public LinkedBlockingDeque(Collection<? extends E> c) {
         this(Integer.MAX_VALUE);
-        for (E e : c)
-            add(e);
+        final ReentrantLock lock = this.lock;
+        lock.lock(); // Never contended, but necessary for visibility
+        try {
+            for (E e : c) {
+                if (e == null)
+                    throw new NullPointerException();
+                if (!linkLast(e))
+                    throw new IllegalStateException("Deque full");
+            }
+        } finally {
+            lock.unlock();
+        }
     }
 
 
@@ -153,9 +214,9 @@
      * Links e as first element, or returns false if full.
      */
     private boolean linkFirst(E e) {
+        // assert lock.isHeldByCurrentThread();
         if (count >= capacity)
             return false;
-        ++count;
         Node<E> f = first;
         Node<E> x = new Node<E>(e, null, f);
         first = x;
@@ -163,6 +224,7 @@
             last = x;
         else
             f.prev = x;
+        ++count;
         notEmpty.signal();
         return true;
     }
@@ -171,9 +233,9 @@
      * Links e as last element, or returns false if full.
      */
     private boolean linkLast(E e) {
+        // assert lock.isHeldByCurrentThread();
         if (count >= capacity)
             return false;
-        ++count;
         Node<E> l = last;
         Node<E> x = new Node<E>(e, l, null);
         last = x;
@@ -181,6 +243,7 @@
             first = x;
         else
             l.next = x;
+        ++count;
         notEmpty.signal();
         return true;
     }
@@ -189,10 +252,14 @@
      * Removes and returns first element, or null if empty.
      */
     private E unlinkFirst() {
+        // assert lock.isHeldByCurrentThread();
         Node<E> f = first;
         if (f == null)
             return null;
         Node<E> n = f.next;
+        E item = f.item;
+        f.item = null;
+        f.next = f; // help GC
         first = n;
         if (n == null)
             last = null;
@@ -200,17 +267,21 @@
             n.prev = null;
         --count;
         notFull.signal();
-        return f.item;
+        return item;
     }
 
     /**
      * Removes and returns last element, or null if empty.
      */
     private E unlinkLast() {
+        // assert lock.isHeldByCurrentThread();
         Node<E> l = last;
         if (l == null)
             return null;
         Node<E> p = l.prev;
+        E item = l.item;
+        l.item = null;
+        l.prev = l; // help GC
         last = p;
         if (p == null)
             first = null;
@@ -218,31 +289,29 @@
             p.next = null;
         --count;
         notFull.signal();
-        return l.item;
+        return item;
     }
 
     /**
-     * Unlink e
+     * Unlinks x.
      */
-    private void unlink(Node<E> x) {
+    void unlink(Node<E> x) {
+        // assert lock.isHeldByCurrentThread();
         Node<E> p = x.prev;
         Node<E> n = x.next;
         if (p == null) {
-            if (n == null)
-                first = last = null;
-            else {
-                n.prev = null;
-                first = n;
-            }
+            unlinkFirst();
         } else if (n == null) {
-            p.next = null;
-            last = p;
+            unlinkLast();
         } else {
             p.next = n;
             n.prev = p;
+            x.item = null;
+            // Don't mess with x's links.  They may still be in use by
+            // an iterator.
+            --count;
+            notFull.signal();
         }
-        --count;
-        notFull.signalAll();
     }
 
     // BlockingDeque methods
@@ -270,6 +339,7 @@
      */
     public boolean offerFirst(E e) {
         if (e == null) throw new NullPointerException();
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             return linkFirst(e);
@@ -283,6 +353,7 @@
      */
     public boolean offerLast(E e) {
         if (e == null) throw new NullPointerException();
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             return linkLast(e);
@@ -297,6 +368,7 @@
      */
     public void putFirst(E e) throws InterruptedException {
         if (e == null) throw new NullPointerException();
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             while (!linkFirst(e))
@@ -312,6 +384,7 @@
      */
     public void putLast(E e) throws InterruptedException {
         if (e == null) throw new NullPointerException();
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             while (!linkLast(e))
@@ -329,15 +402,15 @@
         throws InterruptedException {
         if (e == null) throw new NullPointerException();
         long nanos = unit.toNanos(timeout);
+        final ReentrantLock lock = this.lock;
         lock.lockInterruptibly();
         try {
-            for (;;) {
-                if (linkFirst(e))
-                    return true;
+            while (!linkFirst(e)) {
                 if (nanos <= 0)
                     return false;
                 nanos = notFull.awaitNanos(nanos);
             }
+            return true;
         } finally {
             lock.unlock();
         }
@@ -351,15 +424,15 @@
         throws InterruptedException {
         if (e == null) throw new NullPointerException();
         long nanos = unit.toNanos(timeout);
+        final ReentrantLock lock = this.lock;
         lock.lockInterruptibly();
         try {
-            for (;;) {
-                if (linkLast(e))
-                    return true;
+            while (!linkLast(e)) {
                 if (nanos <= 0)
                     return false;
                 nanos = notFull.awaitNanos(nanos);
             }
+            return true;
         } finally {
             lock.unlock();
         }
@@ -384,6 +457,7 @@
     }
 
     public E pollFirst() {
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             return unlinkFirst();
@@ -393,6 +467,7 @@
     }
 
     public E pollLast() {
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             return unlinkLast();
@@ -402,6 +477,7 @@
     }
 
     public E takeFirst() throws InterruptedException {
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             E x;
@@ -414,6 +490,7 @@
     }
 
     public E takeLast() throws InterruptedException {
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             E x;
@@ -428,16 +505,16 @@
     public E pollFirst(long timeout, TimeUnit unit)
         throws InterruptedException {
         long nanos = unit.toNanos(timeout);
+        final ReentrantLock lock = this.lock;
         lock.lockInterruptibly();
         try {
-            for (;;) {
-                E x = unlinkFirst();
-                if (x != null)
-                    return x;
+            E x;
+            while ( (x = unlinkFirst()) == null) {
                 if (nanos <= 0)
                     return null;
                 nanos = notEmpty.awaitNanos(nanos);
             }
+            return x;
         } finally {
             lock.unlock();
         }
@@ -446,16 +523,16 @@
     public E pollLast(long timeout, TimeUnit unit)
         throws InterruptedException {
         long nanos = unit.toNanos(timeout);
+        final ReentrantLock lock = this.lock;
         lock.lockInterruptibly();
         try {
-            for (;;) {
-                E x = unlinkLast();
-                if (x != null)
-                    return x;
+            E x;
+            while ( (x = unlinkLast()) == null) {
                 if (nanos <= 0)
                     return null;
                 nanos = notEmpty.awaitNanos(nanos);
             }
+            return x;
         } finally {
             lock.unlock();
         }
@@ -480,6 +557,7 @@
     }
 
     public E peekFirst() {
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             return (first == null) ? null : first.item;
@@ -489,6 +567,7 @@
     }
 
     public E peekLast() {
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             return (last == null) ? null : last.item;
@@ -499,6 +578,7 @@
 
     public boolean removeFirstOccurrence(Object o) {
         if (o == null) return false;
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             for (Node<E> p = first; p != null; p = p.next) {
@@ -515,6 +595,7 @@
 
     public boolean removeLastOccurrence(Object o) {
         if (o == null) return false;
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             for (Node<E> p = last; p != null; p = p.prev) {
@@ -619,14 +700,15 @@
      * Returns the number of additional elements that this deque can ideally
      * (in the absence of memory or resource constraints) accept without
      * blocking. This is always equal to the initial capacity of this deque
-     * less the current <tt>size</tt> of this deque.
+     * less the current {@code size} of this deque.
      *
      * <p>Note that you <em>cannot</em> always tell if an attempt to insert
-     * an element will succeed by inspecting <tt>remainingCapacity</tt>
+     * an element will succeed by inspecting {@code remainingCapacity}
      * because it may be the case that another thread is about to
      * insert or remove an element.
      */
     public int remainingCapacity() {
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             return capacity - count;
@@ -642,22 +724,7 @@
      * @throws IllegalArgumentException      {@inheritDoc}
      */
     public int drainTo(Collection<? super E> c) {
-        if (c == null)
-            throw new NullPointerException();
-        if (c == this)
-            throw new IllegalArgumentException();
-        lock.lock();
-        try {
-            for (Node<E> p = first; p != null; p = p.next)
-                c.add(p.item);
-            int n = count;
-            count = 0;
-            first = last = null;
-            notFull.signalAll();
-            return n;
-        } finally {
-            lock.unlock();
-        }
+        return drainTo(c, Integer.MAX_VALUE);
     }
 
     /**
@@ -671,19 +738,14 @@
             throw new NullPointerException();
         if (c == this)
             throw new IllegalArgumentException();
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
-            int n = 0;
-            while (n < maxElements && first != null) {
-                c.add(first.item);
-                first.prev = null;
-                first = first.next;
-                --count;
-                ++n;
+            int n = Math.min(maxElements, count);
+            for (int i = 0; i < n; i++) {
+                c.add(first.item);   // In this order, in case add() throws.
+                unlinkFirst();
             }
-            if (first == null)
-                last = null;
-            notFull.signalAll();
             return n;
         } finally {
             lock.unlock();
@@ -712,16 +774,16 @@
     /**
      * Removes the first occurrence of the specified element from this deque.
      * If the deque does not contain the element, it is unchanged.
-     * More formally, removes the first element <tt>e</tt> such that
-     * <tt>o.equals(e)</tt> (if such an element exists).
-     * Returns <tt>true</tt> if this deque contained the specified element
+     * More formally, removes the first element {@code e} such that
+     * {@code o.equals(e)} (if such an element exists).
+     * Returns {@code true} if this deque contained the specified element
      * (or equivalently, if this deque changed as a result of the call).
      *
      * <p>This method is equivalent to
      * {@link #removeFirstOccurrence(Object) removeFirstOccurrence}.
      *
      * @param o element to be removed from this deque, if present
-     * @return <tt>true</tt> if this deque changed as a result of the call
+     * @return {@code true} if this deque changed as a result of the call
      */
     public boolean remove(Object o) {
         return removeFirstOccurrence(o);
@@ -733,6 +795,7 @@
      * @return the number of elements in this deque
      */
     public int size() {
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             return count;
@@ -742,15 +805,16 @@
     }
 
     /**
-     * Returns <tt>true</tt> if this deque contains the specified element.
-     * More formally, returns <tt>true</tt> if and only if this deque contains
-     * at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>.
+     * Returns {@code true} if this deque contains the specified element.
+     * More formally, returns {@code true} if and only if this deque contains
+     * at least one element {@code e} such that {@code o.equals(e)}.
      *
      * @param o object to be checked for containment in this deque
-     * @return <tt>true</tt> if this deque contains the specified element
+     * @return {@code true} if this deque contains the specified element
      */
     public boolean contains(Object o) {
         if (o == null) return false;
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             for (Node<E> p = first; p != null; p = p.next)
@@ -762,24 +826,46 @@
         }
     }
 
-    /**
-     * Variant of removeFirstOccurrence needed by iterator.remove.
-     * Searches for the node, not its contents.
+    /*
+     * TODO: Add support for more efficient bulk operations.
+     *
+     * We don't want to acquire the lock for every iteration, but we
+     * also want other threads a chance to interact with the
+     * collection, especially when count is close to capacity.
      */
-    boolean removeNode(Node<E> e) {
-        lock.lock();
-        try {
-            for (Node<E> p = first; p != null; p = p.next) {
-                if (p == e) {
-                    unlink(p);
-                    return true;
-                }
-            }
-            return false;
-        } finally {
-            lock.unlock();
-        }
-    }
+
+//     /**
+//      * Adds all of the elements in the specified collection to this
+//      * queue.  Attempts to addAll of a queue to itself result in
+//      * {@code IllegalArgumentException}. Further, the behavior of
+//      * this operation is undefined if the specified collection is
+//      * modified while the operation is in progress.
+//      *
+//      * @param c collection containing elements to be added to this queue
+//      * @return {@code true} if this queue changed as a result of the call
+//      * @throws ClassCastException            {@inheritDoc}
+//      * @throws NullPointerException          {@inheritDoc}
+//      * @throws IllegalArgumentException      {@inheritDoc}
+//      * @throws IllegalStateException         {@inheritDoc}
+//      * @see #add(Object)
+//      */
+//     public boolean addAll(Collection<? extends E> c) {
+//         if (c == null)
+//             throw new NullPointerException();
+//         if (c == this)
+//             throw new IllegalArgumentException();
+//         final ReentrantLock lock = this.lock;
+//         lock.lock();
+//         try {
+//             boolean modified = false;
+//             for (E e : c)
+//                 if (linkLast(e))
+//                     modified = true;
+//             return modified;
+//         } finally {
+//             lock.unlock();
+//         }
+//     }
 
     /**
      * Returns an array containing all of the elements in this deque, in
@@ -794,7 +880,9 @@
      *
      * @return an array containing all of the elements in this deque
      */
+    @SuppressWarnings("unchecked")
     public Object[] toArray() {
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             Object[] a = new Object[count];
@@ -817,22 +905,22 @@
      * <p>If this deque fits in the specified array with room to spare
      * (i.e., the array has more elements than this deque), the element in
      * the array immediately following the end of the deque is set to
-     * <tt>null</tt>.
+     * {@code null}.
      *
      * <p>Like the {@link #toArray()} method, this method acts as bridge between
      * array-based and collection-based APIs.  Further, this method allows
      * precise control over the runtime type of the output array, and may,
      * under certain circumstances, be used to save allocation costs.
      *
-     * <p>Suppose <tt>x</tt> is a deque known to contain only strings.
+     * <p>Suppose {@code x} is a deque known to contain only strings.
      * The following code can be used to dump the deque into a newly
-     * allocated array of <tt>String</tt>:
+     * allocated array of {@code String}:
      *
      * <pre>
      *     String[] y = x.toArray(new String[0]);</pre>
      *
-     * Note that <tt>toArray(new Object[0])</tt> is identical in function to
-     * <tt>toArray()</tt>.
+     * Note that {@code toArray(new Object[0])} is identical in function to
+     * {@code toArray()}.
      *
      * @param a the array into which the elements of the deque are to
      *          be stored, if it is big enough; otherwise, a new array of the
@@ -843,14 +931,14 @@
      *         this deque
      * @throws NullPointerException if the specified array is null
      */
+    @SuppressWarnings("unchecked")
     public <T> T[] toArray(T[] a) {
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             if (a.length < count)
-                a = (T[])java.lang.reflect.Array.newInstance(
-                    a.getClass().getComponentType(),
-                    count
-                    );
+                a = (T[])java.lang.reflect.Array.newInstance
+                    (a.getClass().getComponentType(), count);
 
             int k = 0;
             for (Node<E> p = first; p != null; p = p.next)
@@ -864,6 +952,7 @@
     }
 
     public String toString() {
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             return super.toString();
@@ -877,8 +966,16 @@
      * The deque will be empty after this call returns.
      */
     public void clear() {
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
+            for (Node<E> f = first; f != null; ) {
+                f.item = null;
+                Node<E> n = f.next;
+                f.prev = null;
+                f.next = null;
+                f = n;
+            }
             first = last = null;
             count = 0;
             notFull.signalAll();
@@ -890,7 +987,7 @@
     /**
      * Returns an iterator over the elements in this deque in proper sequence.
      * The elements will be returned in order from first (head) to last (tail).
-     * The returned <tt>Iterator</tt> is a "weakly consistent" iterator that
+     * The returned {@code Iterator} is a "weakly consistent" iterator that
      * will never throw {@link ConcurrentModificationException},
      * and guarantees to traverse elements as they existed upon
      * construction of the iterator, and may (but is not guaranteed to)
@@ -906,7 +1003,7 @@
      * Returns an iterator over the elements in this deque in reverse
      * sequential order.  The elements will be returned in order from
      * last (tail) to first (head).
-     * The returned <tt>Iterator</tt> is a "weakly consistent" iterator that
+     * The returned {@code Iterator} is a "weakly consistent" iterator that
      * will never throw {@link ConcurrentModificationException},
      * and guarantees to traverse elements as they existed upon
      * construction of the iterator, and may (but is not guaranteed to)
@@ -921,7 +1018,7 @@
      */
     private abstract class AbstractItr implements Iterator<E> {
         /**
-         * The next node to return in next
+         * The next node to return in next()
          */
          Node<E> next;
 
@@ -939,15 +1036,44 @@
          */
         private Node<E> lastRet;
 
+        abstract Node<E> firstNode();
+        abstract Node<E> nextNode(Node<E> n);
+
         AbstractItr() {
-            advance(); // set to initial position
+            // set to initial position
+            final ReentrantLock lock = LinkedBlockingDeque.this.lock;
+            lock.lock();
+            try {
+                next = firstNode();
+                nextItem = (next == null) ? null : next.item;
+            } finally {
+                lock.unlock();
+            }
         }
 
         /**
-         * Advances next, or if not yet initialized, sets to first node.
-         * Implemented to move forward vs backward in the two subclasses.
+         * Advances next.
          */
-        abstract void advance();
+        void advance() {
+            final ReentrantLock lock = LinkedBlockingDeque.this.lock;
+            lock.lock();
+            try {
+                // assert next != null;
+                Node<E> s = nextNode(next);
+                if (s == next) {
+                    next = firstNode();
+                } else {
+                    // Skip over removed nodes.
+                    // May be necessary if multiple interior Nodes are removed.
+                    while (s != null && s.item == null)
+                        s = nextNode(s);
+                    next = s;
+                }
+                nextItem = (next == null) ? null : next.item;
+            } finally {
+                lock.unlock();
+            }
+        }
 
         public boolean hasNext() {
             return next != null;
@@ -967,52 +1093,39 @@
             if (n == null)
                 throw new IllegalStateException();
             lastRet = null;
-            // Note: removeNode rescans looking for this node to make
-            // sure it was not already removed. Otherwise, trying to
-            // re-remove could corrupt list.
-            removeNode(n);
-        }
-    }
-
-    /** Forward iterator */
-    private class Itr extends AbstractItr {
-        void advance() {
             final ReentrantLock lock = LinkedBlockingDeque.this.lock;
             lock.lock();
             try {
-                next = (next == null)? first : next.next;
-                nextItem = (next == null)? null : next.item;
+                if (n.item != null)
+                    unlink(n);
             } finally {
                 lock.unlock();
             }
         }
     }
 
-    /**
-     * Descending iterator for LinkedBlockingDeque
-     */
+    /** Forward iterator */
+    private class Itr extends AbstractItr {
+        Node<E> firstNode() { return first; }
+        Node<E> nextNode(Node<E> n) { return n.next; }
+    }
+
+    /** Descending iterator */
     private class DescendingItr extends AbstractItr {
-        void advance() {
-            final ReentrantLock lock = LinkedBlockingDeque.this.lock;
-            lock.lock();
-            try {
-                next = (next == null)? last : next.prev;
-                nextItem = (next == null)? null : next.item;
-            } finally {
-                lock.unlock();
-            }
-        }
+        Node<E> firstNode() { return last; }
+        Node<E> nextNode(Node<E> n) { return n.prev; }
     }
 
     /**
      * Save the state of this deque to a stream (that is, serialize it).
      *
      * @serialData The capacity (int), followed by elements (each an
-     * <tt>Object</tt>) in the proper order, followed by a null
+     * {@code Object}) in the proper order, followed by a null
      * @param s the stream
      */
     private void writeObject(java.io.ObjectOutputStream s)
         throws java.io.IOException {
+        final ReentrantLock lock = this.lock;
         lock.lock();
         try {
             // Write out capacity and any hidden stuff
@@ -1040,6 +1153,7 @@
         last = null;
         // Read in all elements and place in queue
         for (;;) {
+            @SuppressWarnings("unchecked")
             E item = (E)s.readObject();
             if (item == null)
                 break;
--- a/src/share/classes/java/util/concurrent/LinkedBlockingQueue.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/src/share/classes/java/util/concurrent/LinkedBlockingQueue.java	Wed Jul 29 11:19:14 2009 -0700
@@ -34,9 +34,14 @@
  */
 
 package java.util.concurrent;
-import java.util.concurrent.atomic.*;
-import java.util.concurrent.locks.*;
-import java.util.*;
+
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.AbstractQueue;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
 
 /**
  * An optionally-bounded {@linkplain BlockingQueue blocking queue} based on
@@ -86,15 +91,43 @@
      * items have been entered since the signal. And symmetrically for
      * takes signalling puts. Operations such as remove(Object) and
      * iterators acquire both locks.
+     *
+     * Visibility between writers and readers is provided as follows:
+     *
+     * Whenever an element is enqueued, the putLock is acquired and
+     * count updated.  A subsequent reader guarantees visibility to the
+     * enqueued Node by either acquiring the putLock (via fullyLock)
+     * or by acquiring the takeLock, and then reading n = count.get();
+     * this gives visibility to the first n items.
+     *
+     * To implement weakly consistent iterators, it appears we need to
+     * keep all Nodes GC-reachable from a predecessor dequeued Node.
+     * That would cause two problems:
+     * - allow a rogue Iterator to cause unbounded memory retention
+     * - cause cross-generational linking of old Nodes to new Nodes if
+     *   a Node was tenured while live, which generational GCs have a
+     *   hard time dealing with, causing repeated major collections.
+     * However, only non-deleted Nodes need to be reachable from
+     * dequeued Nodes, and reachability does not necessarily have to
+     * be of the kind understood by the GC.  We use the trick of
+     * linking a Node that has just been dequeued to itself.  Such a
+     * self-link implicitly means to advance to head.next.
      */
 
     /**
      * Linked list node class
      */
     static class Node<E> {
-        /** The item, volatile to ensure barrier separating write and read */
-        volatile E item;
+        E item;
+
+        /**
+         * One of:
+         * - the real successor Node
+         * - this Node, meaning the successor is head.next
+         * - null, meaning there is no successor (this is the last node)
+         */
         Node<E> next;
+
         Node(E x) { item = x; }
     }
 
@@ -104,10 +137,16 @@
     /** Current number of elements */
     private final AtomicInteger count = new AtomicInteger(0);
 
-    /** Head of linked list */
+    /**
+     * Head of linked list.
+     * Invariant: head.item == null
+     */
     private transient Node<E> head;
 
-    /** Tail of linked list */
+    /**
+     * Tail of linked list.
+     * Invariant: last.next == null
+     */
     private transient Node<E> last;
 
     /** Lock held by take, poll, etc */
@@ -151,18 +190,26 @@
 
     /**
      * Creates a node and links it at end of queue.
+     *
      * @param x the item
      */
-    private void insert(E x) {
+    private void enqueue(E x) {
+        // assert putLock.isHeldByCurrentThread();
+        // assert last.next == null;
         last = last.next = new Node<E>(x);
     }
 
     /**
-     * Removes a node from head of queue,
+     * Removes a node from head of queue.
+     *
      * @return the node
      */
-    private E extract() {
-        Node<E> first = head.next;
+    private E dequeue() {
+        // assert takeLock.isHeldByCurrentThread();
+        // assert head.item == null;
+        Node<E> h = head;
+        Node<E> first = h.next;
+        h.next = h; // help GC
         head = first;
         E x = first.item;
         first.item = null;
@@ -172,7 +219,7 @@
     /**
      * Lock to prevent both puts and takes.
      */
-    private void fullyLock() {
+    void fullyLock() {
         putLock.lock();
         takeLock.lock();
     }
@@ -180,14 +227,21 @@
     /**
      * Unlock to allow both puts and takes.
      */
-    private void fullyUnlock() {
+    void fullyUnlock() {
         takeLock.unlock();
         putLock.unlock();
     }
 
+//     /**
+//      * Tells whether both locks are held by current thread.
+//      */
+//     boolean isFullyLocked() {
+//         return (putLock.isHeldByCurrentThread() &&
+//                 takeLock.isHeldByCurrentThread());
+//     }
 
     /**
-     * Creates a <tt>LinkedBlockingQueue</tt> with a capacity of
+     * Creates a {@code LinkedBlockingQueue} with a capacity of
      * {@link Integer#MAX_VALUE}.
      */
     public LinkedBlockingQueue() {
@@ -195,10 +249,10 @@
     }
 
     /**
-     * Creates a <tt>LinkedBlockingQueue</tt> with the given (fixed) capacity.
+     * Creates a {@code LinkedBlockingQueue} with the given (fixed) capacity.
      *
      * @param capacity the capacity of this queue
-     * @throws IllegalArgumentException if <tt>capacity</tt> is not greater
+     * @throws IllegalArgumentException if {@code capacity} is not greater
      *         than zero
      */
     public LinkedBlockingQueue(int capacity) {
@@ -208,7 +262,7 @@
     }
 
     /**
-     * Creates a <tt>LinkedBlockingQueue</tt> with a capacity of
+     * Creates a {@code LinkedBlockingQueue} with a capacity of
      * {@link Integer#MAX_VALUE}, initially containing the elements of the
      * given collection,
      * added in traversal order of the collection's iterator.
@@ -219,8 +273,22 @@
      */
     public LinkedBlockingQueue(Collection<? extends E> c) {
         this(Integer.MAX_VALUE);
-        for (E e : c)
-            add(e);
+        final ReentrantLock putLock = this.putLock;
+        putLock.lock(); // Never contended, but necessary for visibility
+        try {
+            int n = 0;
+            for (E e : c) {
+                if (e == null)
+                    throw new NullPointerException();
+                if (n == capacity)
+                    throw new IllegalStateException("Queue full");
+                enqueue(e);
+                ++n;
+            }
+            count.set(n);
+        } finally {
+            putLock.unlock();
+        }
     }
 
 
@@ -241,10 +309,10 @@
      * Returns the number of additional elements that this queue can ideally
      * (in the absence of memory or resource constraints) accept without
      * blocking. This is always equal to the initial capacity of this queue
-     * less the current <tt>size</tt> of this queue.
+     * less the current {@code size} of this queue.
      *
      * <p>Note that you <em>cannot</em> always tell if an attempt to insert
-     * an element will succeed by inspecting <tt>remainingCapacity</tt>
+     * an element will succeed by inspecting {@code remainingCapacity}
      * because it may be the case that another thread is about to
      * insert or remove an element.
      */
@@ -261,8 +329,8 @@
      */
     public void put(E e) throws InterruptedException {
         if (e == null) throw new NullPointerException();
-        // Note: convention in all put/take/etc is to preset
-        // local var holding count  negative to indicate failure unless set.
+        // Note: convention in all put/take/etc is to preset local var
+        // holding count negative to indicate failure unless set.
         int c = -1;
         final ReentrantLock putLock = this.putLock;
         final AtomicInteger count = this.count;
@@ -273,18 +341,13 @@
              * not protected by lock. This works because count can
              * only decrease at this point (all other puts are shut
              * out by lock), and we (or some other waiting put) are
-             * signalled if it ever changes from
-             * capacity. Similarly for all other uses of count in
-             * other wait guards.
+             * signalled if it ever changes from capacity. Similarly
+             * for all other uses of count in other wait guards.
              */
-            try {
-                while (count.get() == capacity)
-                    notFull.await();
-            } catch (InterruptedException ie) {
-                notFull.signal(); // propagate to a non-interrupted thread
-                throw ie;
+            while (count.get() == capacity) {
+                notFull.await();
             }
-            insert(e);
+            enqueue(e);
             c = count.getAndIncrement();
             if (c + 1 < capacity)
                 notFull.signal();
@@ -299,7 +362,7 @@
      * Inserts the specified element at the tail of this queue, waiting if
      * necessary up to the specified wait time for space to become available.
      *
-     * @return <tt>true</tt> if successful, or <tt>false</tt> if
+     * @return {@code true} if successful, or {@code false} if
      *         the specified waiting time elapses before space is available.
      * @throws InterruptedException {@inheritDoc}
      * @throws NullPointerException {@inheritDoc}
@@ -314,23 +377,15 @@
         final AtomicInteger count = this.count;
         putLock.lockInterruptibly();
         try {
-            for (;;) {
-                if (count.get() < capacity) {
-                    insert(e);
-                    c = count.getAndIncrement();
-                    if (c + 1 < capacity)
-                        notFull.signal();
-                    break;
-                }
+            while (count.get() == capacity) {
                 if (nanos <= 0)
                     return false;
-                try {
-                    nanos = notFull.awaitNanos(nanos);
-                } catch (InterruptedException ie) {
-                    notFull.signal(); // propagate to a non-interrupted thread
-                    throw ie;
-                }
+                nanos = notFull.awaitNanos(nanos);
             }
+            enqueue(e);
+            c = count.getAndIncrement();
+            if (c + 1 < capacity)
+                notFull.signal();
         } finally {
             putLock.unlock();
         }
@@ -342,7 +397,7 @@
     /**
      * Inserts the specified element at the tail of this queue if it is
      * possible to do so immediately without exceeding the queue's capacity,
-     * returning <tt>true</tt> upon success and <tt>false</tt> if this queue
+     * returning {@code true} upon success and {@code false} if this queue
      * is full.
      * When using a capacity-restricted queue, this method is generally
      * preferable to method {@link BlockingQueue#add add}, which can fail to
@@ -360,7 +415,7 @@
         putLock.lock();
         try {
             if (count.get() < capacity) {
-                insert(e);
+                enqueue(e);
                 c = count.getAndIncrement();
                 if (c + 1 < capacity)
                     notFull.signal();
@@ -381,15 +436,10 @@
         final ReentrantLock takeLock = this.takeLock;
         takeLock.lockInterruptibly();
         try {
-            try {
-                while (count.get() == 0)
-                    notEmpty.await();
-            } catch (InterruptedException ie) {
-                notEmpty.signal(); // propagate to a non-interrupted thread
-                throw ie;
+            while (count.get() == 0) {
+                notEmpty.await();
             }
-
-            x = extract();
+            x = dequeue();
             c = count.getAndDecrement();
             if (c > 1)
                 notEmpty.signal();
@@ -409,23 +459,15 @@
         final ReentrantLock takeLock = this.takeLock;
         takeLock.lockInterruptibly();
         try {
-            for (;;) {
-                if (count.get() > 0) {
-                    x = extract();
-                    c = count.getAndDecrement();
-                    if (c > 1)
-                        notEmpty.signal();
-                    break;
-                }
+            while (count.get() == 0) {
                 if (nanos <= 0)
                     return null;
-                try {
-                    nanos = notEmpty.awaitNanos(nanos);
-                } catch (InterruptedException ie) {
-                    notEmpty.signal(); // propagate to a non-interrupted thread
-                    throw ie;
-                }
+                nanos = notEmpty.awaitNanos(nanos);
             }
+            x = dequeue();
+            c = count.getAndDecrement();
+            if (c > 1)
+                notEmpty.signal();
         } finally {
             takeLock.unlock();
         }
@@ -444,7 +486,7 @@
         takeLock.lock();
         try {
             if (count.get() > 0) {
-                x = extract();
+                x = dequeue();
                 c = count.getAndDecrement();
                 if (c > 1)
                     notEmpty.signal();
@@ -457,7 +499,6 @@
         return x;
     }
 
-
     public E peek() {
         if (count.get() == 0)
             return null;
@@ -475,43 +516,47 @@
     }
 
     /**
+     * Unlinks interior Node p with predecessor trail.
+     */
+    void unlink(Node<E> p, Node<E> trail) {
+        // assert isFullyLocked();
+        // p.next is not changed, to allow iterators that are
+        // traversing p to maintain their weak-consistency guarantee.
+        p.item = null;
+        trail.next = p.next;
+        if (last == p)
+            last = trail;
+        if (count.getAndDecrement() == capacity)
+            notFull.signal();
+    }
+
+    /**
      * Removes a single instance of the specified element from this queue,
-     * if it is present.  More formally, removes an element <tt>e</tt> such
-     * that <tt>o.equals(e)</tt>, if this queue contains one or more such
+     * if it is present.  More formally, removes an element {@code e} such
+     * that {@code o.equals(e)}, if this queue contains one or more such
      * elements.
-     * Returns <tt>true</tt> if this queue contained the specified element
+     * Returns {@code true} if this queue contained the specified element
      * (or equivalently, if this queue changed as a result of the call).
      *
      * @param o element to be removed from this queue, if present
-     * @return <tt>true</tt> if this queue changed as a result of the call
+     * @return {@code true} if this queue changed as a result of the call
      */
     public boolean remove(Object o) {
         if (o == null) return false;
-        boolean removed = false;
         fullyLock();
         try {
-            Node<E> trail = head;
-            Node<E> p = head.next;
-            while (p != null) {
+            for (Node<E> trail = head, p = trail.next;
+                 p != null;
+                 trail = p, p = p.next) {
                 if (o.equals(p.item)) {
-                    removed = true;
-                    break;
+                    unlink(p, trail);
+                    return true;
                 }
-                trail = p;
-                p = p.next;
             }
-            if (removed) {
-                p.item = null;
-                trail.next = p.next;
-                if (last == p)
-                    last = trail;
-                if (count.getAndDecrement() == capacity)
-                    notFull.signalAll();
-            }
+            return false;
         } finally {
             fullyUnlock();
         }
-        return removed;
     }
 
     /**
@@ -551,22 +596,22 @@
      * <p>If this queue fits in the specified array with room to spare
      * (i.e., the array has more elements than this queue), the element in
      * the array immediately following the end of the queue is set to
-     * <tt>null</tt>.
+     * {@code null}.
      *
      * <p>Like the {@link #toArray()} method, this method acts as bridge between
      * array-based and collection-based APIs.  Further, this method allows
      * precise control over the runtime type of the output array, and may,
      * under certain circumstances, be used to save allocation costs.
      *
-     * <p>Suppose <tt>x</tt> is a queue known to contain only strings.
+     * <p>Suppose {@code x} is a queue known to contain only strings.
      * The following code can be used to dump the queue into a newly
-     * allocated array of <tt>String</tt>:
+     * allocated array of {@code String}:
      *
      * <pre>
      *     String[] y = x.toArray(new String[0]);</pre>
      *
-     * Note that <tt>toArray(new Object[0])</tt> is identical in function to
-     * <tt>toArray()</tt>.
+     * Note that {@code toArray(new Object[0])} is identical in function to
+     * {@code toArray()}.
      *
      * @param a the array into which the elements of the queue are to
      *          be stored, if it is big enough; otherwise, a new array of the
@@ -577,6 +622,7 @@
      *         this queue
      * @throws NullPointerException if the specified array is null
      */
+    @SuppressWarnings("unchecked")
     public <T> T[] toArray(T[] a) {
         fullyLock();
         try {
@@ -586,7 +632,7 @@
                     (a.getClass().getComponentType(), size);
 
             int k = 0;
-            for (Node p = head.next; p != null; p = p.next)
+            for (Node<E> p = head.next; p != null; p = p.next)
                 a[k++] = (T)p.item;
             if (a.length > k)
                 a[k] = null;
@@ -612,11 +658,14 @@
     public void clear() {
         fullyLock();
         try {
-            head.next = null;
-            assert head.item == null;
-            last = head;
+            for (Node<E> p, h = head; (p = h.next) != null; h = p) {
+                h.next = h;
+                p.item = null;
+            }
+            head = last;
+            // assert head.item == null && head.next == null;
             if (count.getAndSet(0) == capacity)
-                notFull.signalAll();
+                notFull.signal();
         } finally {
             fullyUnlock();
         }
@@ -629,30 +678,7 @@
      * @throws IllegalArgumentException      {@inheritDoc}
      */
     public int drainTo(Collection<? super E> c) {
-        if (c == null)
-            throw new NullPointerException();
-        if (c == this)
-            throw new IllegalArgumentException();
-        Node<E> first;
-        fullyLock();
-        try {
-            first = head.next;
-            head.next = null;
-            assert head.item == null;
-            last = head;
-            if (count.getAndSet(0) == capacity)
-                notFull.signalAll();
-        } finally {
-            fullyUnlock();
-        }
-        // Transfer the elements outside of locks
-        int n = 0;
-        for (Node<E> p = first; p != null; p = p.next) {
-            c.add(p.item);
-            p.item = null;
-            ++n;
-        }
-        return n;
+        return drainTo(c, Integer.MAX_VALUE);
     }
 
     /**
@@ -666,33 +692,42 @@
             throw new NullPointerException();
         if (c == this)
             throw new IllegalArgumentException();
-        fullyLock();
+        boolean signalNotFull = false;
+        final ReentrantLock takeLock = this.takeLock;
+        takeLock.lock();
         try {
-            int n = 0;
-            Node<E> p = head.next;
-            while (p != null && n < maxElements) {
-                c.add(p.item);
-                p.item = null;
-                p = p.next;
-                ++n;
+            int n = Math.min(maxElements, count.get());
+            // count.get provides visibility to first n Nodes
+            Node<E> h = head;
+            int i = 0;
+            try {
+                while (i < n) {
+                    Node<E> p = h.next;
+                    c.add(p.item);
+                    p.item = null;
+                    h.next = h;
+                    h = p;
+                    ++i;
+                }
+                return n;
+            } finally {
+                // Restore invariants even if c.add() threw
+                if (i > 0) {
+                    // assert h.item == null;
+                    head = h;
+                    signalNotFull = (count.getAndAdd(-i) == capacity);
+                }
             }
-            if (n != 0) {
-                head.next = p;
-                assert head.item == null;
-                if (p == null)
-                    last = head;
-                if (count.getAndAdd(-n) == capacity)
-                    notFull.signalAll();
-            }
-            return n;
         } finally {
-            fullyUnlock();
+            takeLock.unlock();
+            if (signalNotFull)
+                signalNotFull();
         }
     }
 
     /**
      * Returns an iterator over the elements in this queue in proper sequence.
-     * The returned <tt>Iterator</tt> is a "weakly consistent" iterator that
+     * The returned {@code Iterator} is a "weakly consistent" iterator that
      * will never throw {@link ConcurrentModificationException},
      * and guarantees to traverse elements as they existed upon
      * construction of the iterator, and may (but is not guaranteed to)
@@ -706,7 +741,7 @@
 
     private class Itr implements Iterator<E> {
         /*
-         * Basic weak-consistent iterator.  At all times hold the next
+         * Basic weakly-consistent iterator.  At all times hold the next
          * item to hand out so that if hasNext() reports true, we will
          * still have it to return even if lost race with a take etc.
          */
@@ -715,17 +750,13 @@
         private E currentElement;
 
         Itr() {
-            final ReentrantLock putLock = LinkedBlockingQueue.this.putLock;
-            final ReentrantLock takeLock = LinkedBlockingQueue.this.takeLock;
-            putLock.lock();
-            takeLock.lock();
+            fullyLock();
             try {
                 current = head.next;
                 if (current != null)
                     currentElement = current.item;
             } finally {
-                takeLock.unlock();
-                putLock.unlock();
+                fullyUnlock();
             }
         }
 
@@ -733,54 +764,54 @@
             return current != null;
         }
 
+        /**
+         * Unlike other traversal methods, iterators need to handle:
+         * - dequeued nodes (p.next == p)
+         * - interior removed nodes (p.item == null)
+         */
+        private Node<E> nextNode(Node<E> p) {
+            Node<E> s = p.next;
+            if (p == s)
+                return head.next;
+            // Skip over removed nodes.
+            // May be necessary if multiple interior Nodes are removed.
+            while (s != null && s.item == null)
+                s = s.next;
+            return s;
+        }
+
         public E next() {
-            final ReentrantLock putLock = LinkedBlockingQueue.this.putLock;
-            final ReentrantLock takeLock = LinkedBlockingQueue.this.takeLock;
-            putLock.lock();
-            takeLock.lock();
+            fullyLock();
             try {
                 if (current == null)
                     throw new NoSuchElementException();
                 E x = currentElement;
                 lastRet = current;
-                current = current.next;
-                if (current != null)
-                    currentElement = current.item;
+                current = nextNode(current);
+                currentElement = (current == null) ? null : current.item;
                 return x;
             } finally {
-                takeLock.unlock();
-                putLock.unlock();
+                fullyUnlock();
             }
         }
 
         public void remove() {
             if (lastRet == null)
                 throw new IllegalStateException();
-            final ReentrantLock putLock = LinkedBlockingQueue.this.putLock;
-            final ReentrantLock takeLock = LinkedBlockingQueue.this.takeLock;
-            putLock.lock();
-            takeLock.lock();
+            fullyLock();
             try {
                 Node<E> node = lastRet;
                 lastRet = null;
-                Node<E> trail = head;
-                Node<E> p = head.next;
-                while (p != null && p != node) {
-                    trail = p;
-                    p = p.next;
-                }
-                if (p == node) {
-                    p.item = null;
-                    trail.next = p.next;
-                    if (last == p)
-                        last = trail;
-                    int c = count.getAndDecrement();
-                    if (c == capacity)
-                        notFull.signalAll();
+                for (Node<E> trail = head, p = trail.next;
+                     p != null;
+                     trail = p, p = p.next) {
+                    if (p == node) {
+                        unlink(p, trail);
+                        break;
+                    }
                 }
             } finally {
-                takeLock.unlock();
-                putLock.unlock();
+                fullyUnlock();
             }
         }
     }
@@ -789,7 +820,7 @@
      * Save the state to a stream (that is, serialize it).
      *
      * @serialData The capacity is emitted (int), followed by all of
-     * its elements (each an <tt>Object</tt>) in the proper order,
+     * its elements (each an {@code Object}) in the proper order,
      * followed by a null
      * @param s the stream
      */
@@ -815,6 +846,7 @@
     /**
      * Reconstitute this queue instance from a stream (that is,
      * deserialize it).
+     *
      * @param s the stream
      */
     private void readObject(java.io.ObjectInputStream s)
@@ -827,6 +859,7 @@
 
         // Read in all elements and place in queue
         for (;;) {
+            @SuppressWarnings("unchecked")
             E item = (E)s.readObject();
             if (item == null)
                 break;
--- a/src/share/classes/sun/nio/cs/Surrogate.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/src/share/classes/sun/nio/cs/Surrogate.java	Wed Jul 29 11:19:14 2009 -0700
@@ -30,7 +30,6 @@
 import java.nio.charset.MalformedInputException;
 import java.nio.charset.UnmappableCharacterException;
 
-
 /**
  * Utility class for dealing with surrogates.
  *
@@ -41,19 +40,15 @@
 
     private Surrogate() { }
 
-    // UTF-16 surrogate-character ranges
-    //
-    public static final char MIN_HIGH = '\uD800';
-    public static final char MAX_HIGH = '\uDBFF';
-    public static final char MIN_LOW  = '\uDC00';
-    public static final char MAX_LOW  = '\uDFFF';
-    public static final char MIN = MIN_HIGH;
-    public static final char MAX = MAX_LOW;
-
-    // Range of UCS-4 values that need surrogates in UTF-16
-    //
-    public static final int UCS4_MIN = 0x10000;
-    public static final int UCS4_MAX = (1 << 20) + UCS4_MIN - 1;
+    // TODO: Deprecate/remove the following redundant definitions
+    public static final char MIN_HIGH = Character.MIN_HIGH_SURROGATE;
+    public static final char MAX_HIGH = Character.MAX_HIGH_SURROGATE;
+    public static final char MIN_LOW  = Character.MIN_LOW_SURROGATE;
+    public static final char MAX_LOW  = Character.MAX_LOW_SURROGATE;
+    public static final char MIN      = Character.MIN_SURROGATE;
+    public static final char MAX      = Character.MAX_SURROGATE;
+    public static final int UCS4_MIN  = Character.MIN_SUPPLEMENTARY_CODE_POINT;
+    public static final int UCS4_MAX  = Character.MAX_CODE_POINT;
 
     /**
      * Tells whether or not the given UTF-16 value is a high surrogate.
@@ -77,35 +72,45 @@
     }
 
     /**
+     * Tells whether or not the given UCS-4 character is in the Basic
+     * Multilingual Plane, and can be represented using a single char.
+     */
+    public static boolean isBMP(int uc) {
+        return (int) (char) uc == uc;
+    }
+
+    /**
      * Tells whether or not the given UCS-4 character must be represented as a
      * surrogate pair in UTF-16.
      */
     public static boolean neededFor(int uc) {
-        return (uc >= UCS4_MIN) && (uc <= UCS4_MAX);
+        return Character.isSupplementaryCodePoint(uc);
     }
 
     /**
      * Returns the high UTF-16 surrogate for the given UCS-4 character.
      */
     public static char high(int uc) {
-        assert neededFor(uc);
-        return (char)(0xd800 | (((uc - UCS4_MIN) >> 10) & 0x3ff));
+        assert Character.isSupplementaryCodePoint(uc);
+        return (char)((uc >> 10)
+                      + (Character.MIN_HIGH_SURROGATE
+                         - (Character.MIN_SUPPLEMENTARY_CODE_POINT >> 10)));
     }
 
     /**
      * Returns the low UTF-16 surrogate for the given UCS-4 character.
      */
     public static char low(int uc) {
-        assert neededFor(uc);
-        return (char)(0xdc00 | ((uc - UCS4_MIN) & 0x3ff));
+        assert Character.isSupplementaryCodePoint(uc);
+        return (char)((uc & 0x3ff) + Character.MIN_LOW_SURROGATE);
     }
 
     /**
      * Converts the given surrogate pair into a 32-bit UCS-4 character.
      */
     public static int toUCS4(char c, char d) {
-        assert isHigh(c) && isLow(d);
-        return (((c & 0x3ff) << 10) | (d & 0x3ff)) + 0x10000;
+        assert Character.isHighSurrogate(c) && Character.isLowSurrogate(d);
+        return Character.toCodePoint(c, d);
     }
 
     /**
@@ -178,14 +183,14 @@
          *           object
          */
         public int parse(char c, CharBuffer in) {
-            if (Surrogate.isHigh(c)) {
+            if (Character.isHighSurrogate(c)) {
                 if (!in.hasRemaining()) {
                     error = CoderResult.UNDERFLOW;
                     return -1;
                 }
                 char d = in.get();
-                if (Surrogate.isLow(d)) {
-                    character = toUCS4(c, d);
+                if (Character.isLowSurrogate(d)) {
+                    character = Character.toCodePoint(c, d);
                     isPair = true;
                     error = null;
                     return character;
@@ -193,7 +198,7 @@
                 error = CoderResult.malformedForLength(1);
                 return -1;
             }
-            if (Surrogate.isLow(c)) {
+            if (Character.isLowSurrogate(c)) {
                 error = CoderResult.malformedForLength(1);
                 return -1;
             }
@@ -220,14 +225,14 @@
          */
         public int parse(char c, char[] ia, int ip, int il) {
             assert (ia[ip] == c);
-            if (Surrogate.isHigh(c)) {
+            if (Character.isHighSurrogate(c)) {
                 if (il - ip < 2) {
                     error = CoderResult.UNDERFLOW;
                     return -1;
                 }
                 char d = ia[ip + 1];
-                if (Surrogate.isLow(d)) {
-                    character = toUCS4(c, d);
+                if (Character.isLowSurrogate(d)) {
+                    character = Character.toCodePoint(c, d);
                     isPair = true;
                     error = null;
                     return character;
@@ -235,7 +240,7 @@
                 error = CoderResult.malformedForLength(1);
                 return -1;
             }
-            if (Surrogate.isLow(c)) {
+            if (Character.isLowSurrogate(c)) {
                 error = CoderResult.malformedForLength(1);
                 return -1;
             }
@@ -282,7 +287,7 @@
          *           error() will return a descriptive result object
          */
         public int generate(int uc, int len, CharBuffer dst) {
-            if (uc <= 0xffff) {
+            if (Surrogate.isBMP(uc)) {
                 if (Surrogate.is(uc)) {
                     error = CoderResult.malformedForLength(len);
                     return -1;
@@ -294,12 +299,7 @@
                 dst.put((char)uc);
                 error = null;
                 return 1;
-            }
-            if (uc < Surrogate.UCS4_MIN) {
-                error = CoderResult.malformedForLength(len);
-                return -1;
-            }
-            if (uc <= Surrogate.UCS4_MAX) {
+            } else if (Character.isSupplementaryCodePoint(uc)) {
                 if (dst.remaining() < 2) {
                     error = CoderResult.OVERFLOW;
                     return -1;
@@ -308,9 +308,10 @@
                 dst.put(Surrogate.low(uc));
                 error = null;
                 return 2;
+            } else {
+                error = CoderResult.unmappableForLength(len);
+                return -1;
             }
-            error = CoderResult.unmappableForLength(len);
-            return -1;
         }
 
         /**
@@ -330,7 +331,7 @@
          *           error() will return a descriptive result object
          */
         public int generate(int uc, int len, char[] da, int dp, int dl) {
-            if (uc <= 0xffff) {
+            if (Surrogate.isBMP(uc)) {
                 if (Surrogate.is(uc)) {
                     error = CoderResult.malformedForLength(len);
                     return -1;
@@ -342,12 +343,7 @@
                 da[dp] = (char)uc;
                 error = null;
                 return 1;
-            }
-            if (uc < Surrogate.UCS4_MIN) {
-                error = CoderResult.malformedForLength(len);
-                return -1;
-            }
-            if (uc <= Surrogate.UCS4_MAX) {
+            } else if (Character.isSupplementaryCodePoint(uc)) {
                 if (dl - dp < 2) {
                     error = CoderResult.OVERFLOW;
                     return -1;
@@ -356,11 +352,11 @@
                 da[dp + 1] = Surrogate.low(uc);
                 error = null;
                 return 2;
+            } else {
+                error = CoderResult.unmappableForLength(len);
+                return -1;
             }
-            error = CoderResult.unmappableForLength(len);
-            return -1;
         }
-
     }
 
 }
--- a/src/solaris/native/sun/nio/fs/UnixNativeDispatcher.c	Fri Jul 24 11:22:29 2009 -0700
+++ b/src/solaris/native/sun/nio/fs/UnixNativeDispatcher.c	Wed Jul 29 11:19:14 2009 -0700
@@ -85,19 +85,21 @@
 static jfieldID entry_dev;
 
 /**
- * System calls that may not be available at build time.
+ * System calls that may not be available at run time.
  */
 typedef int openat64_func(int, const char *, int, ...);
 typedef int fstatat64_func(int, const char *, struct stat64 *, int);
 typedef int unlinkat_func(int, const char*, int);
 typedef int renameat_func(int, const char*, int, const char*);
 typedef int futimesat_func(int, const char *, const struct timeval *);
+typedef DIR* fdopendir_func(int);
 
 static openat64_func* my_openat64_func = NULL;
 static fstatat64_func* my_fstatat64_func = NULL;
 static unlinkat_func* my_unlinkat_func = NULL;
 static renameat_func* my_renameat_func = NULL;
 static futimesat_func* my_futimesat_func = NULL;
+static fdopendir_func* my_fdopendir_func = NULL;
 
 /**
  * fstatat missing from glibc on Linux. Temporary workaround
@@ -183,7 +185,7 @@
     entry_options = (*env)->GetFieldID(env, clazz, "opts", "[B");
     entry_dev = (*env)->GetFieldID(env, clazz, "dev", "J");
 
-    /* system calls that might not be available at build time */
+    /* system calls that might not be available at run time */
 
 #if defined(__solaris__) && defined(_LP64)
     /* Solaris 64-bit does not have openat64/fstatat64 */
@@ -196,6 +198,7 @@
     my_unlinkat_func = (unlinkat_func*) dlsym(RTLD_DEFAULT, "unlinkat");
     my_renameat_func = (renameat_func*) dlsym(RTLD_DEFAULT, "renameat");
     my_futimesat_func = (futimesat_func*) dlsym(RTLD_DEFAULT, "futimesat");
+    my_fdopendir_func = (fdopendir_func*) dlsym(RTLD_DEFAULT, "fdopendir");
 
 #if defined(FSTATAT64_SYSCALL_AVAILABLE)
     /* fstatat64 missing from glibc */
@@ -205,7 +208,7 @@
 
     if (my_openat64_func != NULL &&  my_fstatat64_func != NULL &&
         my_unlinkat_func != NULL && my_renameat_func != NULL &&
-        my_futimesat_func != NULL)
+        my_futimesat_func != NULL && my_fdopendir_func != NULL)
     {
         flags |= sun_nio_fs_UnixNativeDispatcher_HAS_AT_SYSCALLS;
     }
@@ -565,8 +568,13 @@
 Java_sun_nio_fs_UnixNativeDispatcher_fdopendir(JNIEnv* env, jclass this, int dfd) {
     DIR* dir;
 
+    if (my_fdopendir_func == NULL) {
+        JNU_ThrowInternalError(env, "should not reach here");
+        return (jlong)-1;
+    }
+
     /* EINTR not listed as a possible error */
-    dir = fdopendir((int)dfd);
+    dir = (*my_fdopendir_func)((int)dfd);
     if (dir == NULL) {
         throwUnixException(env, errno);
     }
--- a/src/windows/classes/sun/nio/fs/WindowsPath.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/src/windows/classes/sun/nio/fs/WindowsPath.java	Wed Jul 29 11:19:14 2009 -0700
@@ -1177,14 +1177,20 @@
 
         /*
          * Windows treates symbolic links to directories differently than it
-         * does to other file types. For that reason we check if the exists and
-         * is a directory.
+         * does to other file types. For that reason we need to check if the
+         * target is a directory (or a directory junction).
          */
+        WindowsPath resolvedTarget;
+        if (target.type == WindowsPathType.RELATIVE) {
+            WindowsPath parent = getParent();
+            resolvedTarget = (parent == null) ? target : parent.resolve(target);
+        } else {
+            resolvedTarget = resolve(target);
+        }
         int flags = 0;
-        WindowsPath resolvedTarget =
-            WindowsPath.createFromNormalizedPath(getFileSystem(), resolve(target).path);
         try {
-            if (WindowsFileAttributes.get(resolvedTarget, true).isDirectory())
+            WindowsFileAttributes wattrs = WindowsFileAttributes.get(resolvedTarget, false);
+            if (wattrs.isDirectory() || wattrs.isDirectoryLink())
                 flags |= SYMBOLIC_LINK_FLAG_DIRECTORY;
         } catch (WindowsException x) {
             // unable to access target so assume target is not a directory
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/com/sun/jndi/ldap/BalancedParentheses.java	Wed Jul 29 11:19:14 2009 -0700
@@ -0,0 +1,259 @@
+/*
+ * Copyright 2009 Sun Microsystems, Inc.  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.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/**
+ * @test
+ * @bug 6449574
+ * @summary Invalid ldap filter is accepted and processed
+ */
+
+import java.io.*;
+import javax.naming.*;
+import javax.naming.directory.*;
+import java.util.Properties;
+import java.util.Hashtable;
+
+import java.net.Socket;
+import java.net.ServerSocket;
+
+public class BalancedParentheses {
+    // Should we run the client or server in a separate thread?
+    //
+    // Both sides can throw exceptions, but do you have a preference
+    // as to which side should be the main thread.
+    static boolean separateServerThread = true;
+
+    // use any free port by default
+    volatile int serverPort = 0;
+
+    // Is the server ready to serve?
+    volatile static boolean serverReady = false;
+
+    // Define the server side of the test.
+    //
+    // If the server prematurely exits, serverReady will be set to true
+    // to avoid infinite hangs.
+    void doServerSide() throws Exception {
+        ServerSocket serverSock = new ServerSocket(serverPort);
+
+        // signal client, it's ready to accecpt connection
+        serverPort = serverSock.getLocalPort();
+        serverReady = true;
+
+        // accept a connection
+        Socket socket = serverSock.accept();
+        System.out.println("Server: Connection accepted");
+
+        InputStream is = socket.getInputStream();
+        OutputStream os = socket.getOutputStream();
+
+        // read the bindRequest
+        while (is.read() != -1) {
+            // ignore
+            is.skip(is.available());
+            break;
+        }
+
+        byte[] bindResponse = {0x30, 0x0C, 0x02, 0x01, 0x01, 0x61, 0x07, 0x0A,
+                               0x01, 0x00, 0x04, 0x00, 0x04, 0x00};
+        // write bindResponse
+        os.write(bindResponse);
+        os.flush();
+
+        // ignore any more request.
+        while (is.read() != -1) {
+            // ignore
+            is.skip(is.available());
+        }
+
+        is.close();
+        os.close();
+        socket.close();
+        serverSock.close();
+    }
+
+    //  Define the client side of the test.
+    //
+    // If the server prematurely exits, serverReady will be set to true
+    // to avoid infinite hangs.
+    void doClientSide() throws Exception {
+        // Wait for server to get started.
+        while (!serverReady) {
+            Thread.sleep(50);
+        }
+
+        // set up the environment for creating the initial context
+        Hashtable<Object, Object> env = new Hashtable<Object, Object>();
+        env.put(Context.INITIAL_CONTEXT_FACTORY,
+                                "com.sun.jndi.ldap.LdapCtxFactory");
+        env.put(Context.PROVIDER_URL, "ldap://localhost:" + serverPort);
+        env.put("com.sun.jndi.ldap.read.timeout", "1000");
+
+        // env.put(Context.SECURITY_AUTHENTICATION, "simple");
+        // env.put(Context.SECURITY_PRINCIPAL,"cn=root");
+        // env.put(Context.SECURITY_CREDENTIALS,"root");
+
+        // create initial context
+        DirContext context = new InitialDirContext(env);
+
+        // searching
+        SearchControls scs = new SearchControls();
+        scs.setSearchScope(SearchControls.SUBTREE_SCOPE);
+
+        try {
+            NamingEnumeration answer = context.search(
+                                        "o=sun,c=us", "(&(cn=Bob)))", scs);
+        } catch (InvalidSearchFilterException isfe) {
+            // ignore, it is the expected filter exception.
+            System.out.println("Expected exception: " + isfe.getMessage());
+        } catch (NamingException ne) {
+            // maybe a read timeout exception, as the server does not response.
+            throw new Exception("Expect a InvalidSearchFilterException", ne);
+        }
+
+        try {
+            NamingEnumeration answer = context.search(
+                                        "o=sun,c=us", ")(&(cn=Bob)", scs);
+        } catch (InvalidSearchFilterException isfe) {
+            // ignore, it is the expected filter exception.
+            System.out.println("Expected exception: " + isfe.getMessage());
+        } catch (NamingException ne) {
+            // maybe a read timeout exception, as the server does not response.
+            throw new Exception("Expect a InvalidSearchFilterException", ne);
+        }
+
+        try {
+            NamingEnumeration answer = context.search(
+                                        "o=sun,c=us", "(&(cn=Bob))", scs);
+        } catch (InvalidSearchFilterException isfe) {
+            // ignore, it is the expected filter exception.
+            throw new Exception("Unexpected ISFE", isfe);
+        } catch (NamingException ne) {
+            // maybe a read timeout exception, as the server does not response.
+            System.out.println("Expected exception: " + ne.getMessage());
+        }
+
+        context.close();
+    }
+
+    /*
+     * ============================================================
+     * The remainder is just support stuff
+     */
+
+    // client and server thread
+    Thread clientThread = null;
+    Thread serverThread = null;
+
+    // client and server exceptions
+    volatile Exception serverException = null;
+    volatile Exception clientException = null;
+
+    void startServer(boolean newThread) throws Exception {
+        if (newThread) {
+            serverThread = new Thread() {
+                public void run() {
+                    try {
+                        doServerSide();
+                    } catch (Exception e) {
+                        /*
+                         * Our server thread just died.
+                         *
+                         * Release the client, if not active already...
+                         */
+                        System.err.println("Server died...");
+                        System.err.println(e);
+                        serverReady = true;
+                        serverException = e;
+                    }
+                }
+            };
+            serverThread.start();
+        } else {
+            doServerSide();
+        }
+    }
+
+    void startClient(boolean newThread) throws Exception {
+        if (newThread) {
+            clientThread = new Thread() {
+                public void run() {
+                    try {
+                        doClientSide();
+                    } catch (Exception e) {
+                        /*
+                         * Our client thread just died.
+                         */
+                        System.err.println("Client died...");
+                        clientException = e;
+                    }
+                }
+            };
+            clientThread.start();
+        } else {
+            doClientSide();
+        }
+    }
+
+    // Primary constructor, used to drive remainder of the test.
+    BalancedParentheses() throws Exception {
+        if (separateServerThread) {
+            startServer(true);
+            startClient(false);
+        } else {
+            startClient(true);
+            startServer(false);
+        }
+
+        /*
+         * Wait for other side to close down.
+         */
+        if (separateServerThread) {
+            serverThread.join();
+        } else {
+            clientThread.join();
+        }
+
+        /*
+         * When we get here, the test is pretty much over.
+         *
+         * If the main thread excepted, that propagates back
+         * immediately.  If the other thread threw an exception, we
+         * should report back.
+         */
+        if (serverException != null) {
+            System.out.print("Server Exception:");
+            throw serverException;
+        }
+        if (clientException != null) {
+            System.out.print("Client Exception:");
+            throw clientException;
+        }
+    }
+
+    public static void main(String[] args) throws Exception {
+        // start the test
+        new BalancedParentheses();
+    }
+
+}
--- a/test/java/nio/channels/AsynchronousChannelGroup/GroupOfOne.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/test/java/nio/channels/AsynchronousChannelGroup/GroupOfOne.java	Wed Jul 29 11:19:14 2009 -0700
@@ -44,9 +44,9 @@
         final AsynchronousServerSocketChannel listener =
             AsynchronousServerSocketChannel.open()
                 .bind(new InetSocketAddress(0));
-        listener.accept(null, new CompletionHandler<AsynchronousSocketChannel,Void>() {
+        listener.accept((Void)null, new CompletionHandler<AsynchronousSocketChannel,Void>() {
             public void completed(AsynchronousSocketChannel ch, Void att) {
-                listener.accept(null, this);
+                listener.accept((Void)null, this);
             }
             public void failed(Throwable exc, Void att) {
             }
@@ -81,13 +81,13 @@
         // 2. the close/shutdown completes
         final CountDownLatch latch = new CountDownLatch(2);
 
-        ch.connect(sa, null, new CompletionHandler<Void,Void>() {
+        ch.connect(sa, (Void)null, new CompletionHandler<Void,Void>() {
             public void completed(Void result, Void att)  {
                 System.out.println("Connected");
 
                 // initiate I/O operation that does not complete (successfully)
                 ByteBuffer buf = ByteBuffer.allocate(100);
-                ch.read(buf, null, new CompletionHandler<Integer,Void>() {
+                ch.read(buf, (Void)null, new CompletionHandler<Integer,Void>() {
                     public void completed(Integer bytesRead, Void att)  {
                         throw new RuntimeException();
                     }
--- a/test/java/nio/channels/AsynchronousChannelGroup/Identity.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/test/java/nio/channels/AsynchronousChannelGroup/Identity.java	Wed Jul 29 11:19:14 2009 -0700
@@ -78,15 +78,15 @@
         final AsynchronousServerSocketChannel listener =
             AsynchronousServerSocketChannel.open()
                 .bind(new InetSocketAddress(0));
-        listener.accept(null, new CompletionHandler<AsynchronousSocketChannel,Void>() {
+        listener.accept((Void)null, new CompletionHandler<AsynchronousSocketChannel,Void>() {
             public void completed(final AsynchronousSocketChannel ch, Void att) {
-                listener.accept(null, this);
+                listener.accept((Void)null, this);
 
                 final ByteBuffer buf = ByteBuffer.allocate(100);
-                ch.read(buf, null, new CompletionHandler<Integer,Void>() {
+                ch.read(buf, (Void)null, new CompletionHandler<Integer,Void>() {
                     public void completed(Integer bytesRead, Void att) {
                         buf.clear();
-                        ch.read(buf, null, this);
+                        ch.read(buf, (Void)null, this);
                     }
                     public void failed(Throwable exc, Void att) {
                     }
--- a/test/java/nio/channels/AsynchronousChannelGroup/Restart.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/test/java/nio/channels/AsynchronousChannelGroup/Restart.java	Wed Jul 29 11:19:14 2009 -0700
@@ -94,7 +94,7 @@
         for (int i=0; i<count; i++) {
             final CountDownLatch latch = new CountDownLatch(1);
 
-            listener.accept(null, new CompletionHandler<AsynchronousSocketChannel,Void>() {
+            listener.accept((Void)null, new CompletionHandler<AsynchronousSocketChannel,Void>() {
                 public void completed(AsynchronousSocketChannel ch, Void att) {
                     try {
                         ch.close();
--- a/test/java/nio/channels/AsynchronousChannelGroup/Unbounded.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/test/java/nio/channels/AsynchronousChannelGroup/Unbounded.java	Wed Jul 29 11:19:14 2009 -0700
@@ -45,10 +45,10 @@
         final AsynchronousServerSocketChannel listener =
             AsynchronousServerSocketChannel.open()
                 .bind(new InetSocketAddress(0));
-        listener.accept(null, new CompletionHandler<AsynchronousSocketChannel,Void>() {
+        listener.accept((Void)null, new CompletionHandler<AsynchronousSocketChannel,Void>() {
             public void completed(AsynchronousSocketChannel ch, Void att) {
                 queue.add(ch);
-                listener.accept(null, this);
+                listener.accept((Void)null, this);
             }
             public void failed(Throwable exc, Void att) {
             }
--- a/test/java/nio/channels/AsynchronousDatagramChannel/Basic.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/test/java/nio/channels/AsynchronousDatagramChannel/Basic.java	Wed Jul 29 11:19:14 2009 -0700
@@ -66,7 +66,7 @@
         // Test: datagram packet not received immediately
         dst.clear();
         final CountDownLatch latch = new CountDownLatch(1);
-        ch.receive(dst, null, new CompletionHandler<SocketAddress,Void>() {
+        ch.receive(dst, (Void)null, new CompletionHandler<SocketAddress,Void>() {
             public void completed(SocketAddress source, Void att) {
                 latch.countDown();
             }
@@ -82,7 +82,7 @@
         // Test: timeout
         dst.clear();
         final AtomicReference<Throwable> exception = new AtomicReference<Throwable>();
-        ch.receive(dst, 2, TimeUnit.SECONDS, null, new CompletionHandler<SocketAddress,Void>() {
+        ch.receive(dst, 2, TimeUnit.SECONDS, (Void)null, new CompletionHandler<SocketAddress,Void>() {
             public void completed(SocketAddress source, Void att) {
             }
             public void failed (Throwable exc, Void att) {
@@ -101,7 +101,7 @@
         // AsynchronousCloseException
         dst = ByteBuffer.allocateDirect(100);
         exception.set(null);
-        ch.receive(dst, null, new CompletionHandler<SocketAddress,Void>() {
+        ch.receive(dst, (Void)null, new CompletionHandler<SocketAddress,Void>() {
             public void completed(SocketAddress source, Void att) {
             }
             public void failed (Throwable exc, Void att) {
@@ -156,7 +156,7 @@
         // Test: datagram packet not received immediately
         dst.clear();
         final CountDownLatch l1 = new CountDownLatch(1);
-        ch.read(dst, null, new CompletionHandler<Integer,Void>() {
+        ch.read(dst, (Void)null, new CompletionHandler<Integer,Void>() {
             public void completed(Integer bytesRead, Void att) {
                 l1.countDown();
             }
@@ -172,7 +172,7 @@
         // Test: timeout
         dst.clear();
         final AtomicReference<Throwable> exception = new AtomicReference<Throwable>();
-        ch.read(dst, 2, TimeUnit.SECONDS, null, new CompletionHandler<Integer,Void>() {
+        ch.read(dst, 2, TimeUnit.SECONDS, (Void)null, new CompletionHandler<Integer,Void>() {
             public void completed(Integer bytesRead, Void att) {
             }
             public void failed (Throwable exc, Void att) {
@@ -191,7 +191,7 @@
         // AsynchronousCloseException
         dst.clear();
         exception.set(null);
-        ch.read(dst, null, new CompletionHandler<Integer,Void>() {
+        ch.read(dst, (Void)null, new CompletionHandler<Integer,Void>() {
             public void completed(Integer bytesRead, Void att) {
             }
             public void failed (Throwable exc, Void att) {
@@ -238,7 +238,7 @@
         // Test: send datagram packet to reader and check completion handler
         // is invoked
         final CountDownLatch l2 = new CountDownLatch(1);
-        ch.send(ByteBuffer.wrap(msg), sa, null, new CompletionHandler<Integer,Void>() {
+        ch.send(ByteBuffer.wrap(msg), sa, (Void)null, new CompletionHandler<Integer,Void>() {
             public void completed(Integer bytesSent, Void att) {
                 if (bytesSent != msg.length)
                     throw new RuntimeException("Unexpected number of bytes received");
@@ -261,7 +261,7 @@
         // Test: check that failed method is invoked
         ch.close();
         final CountDownLatch l3 = new CountDownLatch(1);
-        ch.send(ByteBuffer.wrap(msg), sa, null, new CompletionHandler<Integer,Void>() {
+        ch.send(ByteBuffer.wrap(msg), sa, (Void)null, new CompletionHandler<Integer,Void>() {
             public void completed(Integer bytesSent, Void att) {
                 throw new RuntimeException("completed method invoked");
             }
@@ -315,7 +315,7 @@
 
         // Test: write datagram and check completion handler is invoked
         final CountDownLatch l2 = new CountDownLatch(1);
-        ch.write(ByteBuffer.wrap(msg), null, new CompletionHandler<Integer,Void>() {
+        ch.write(ByteBuffer.wrap(msg), (Void)null, new CompletionHandler<Integer,Void>() {
             public void completed(Integer bytesSent, Void att) {
                 if (bytesSent != msg.length)
                     throw new RuntimeException("Unexpected number of bytes received");
@@ -372,7 +372,7 @@
             final CountDownLatch latch = new CountDownLatch(1);
             long timeout = (i == 0) ? 0L : 60L;
             Future<SocketAddress> remote = ch
-                .receive(ByteBuffer.allocate(100), timeout, TimeUnit.SECONDS, null,
+                .receive(ByteBuffer.allocate(100), timeout, TimeUnit.SECONDS, (Void)null,
                     new CompletionHandler<SocketAddress,Void>() {
                         public void completed(SocketAddress source, Void att) {
                         }
@@ -395,7 +395,7 @@
             final CountDownLatch latch = new CountDownLatch(1);
             long timeout = (i == 0) ? 0L : 60L;
             Future<Integer> result = ch
-                .read(ByteBuffer.allocate(100), timeout, TimeUnit.SECONDS, null,
+                .read(ByteBuffer.allocate(100), timeout, TimeUnit.SECONDS, (Void)null,
                     new CompletionHandler<Integer,Void>() {
                         public void completed(Integer bytesRead, Void att) {
                         }
--- a/test/java/nio/channels/AsynchronousFileChannel/Basic.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/test/java/nio/channels/AsynchronousFileChannel/Basic.java	Wed Jul 29 11:19:14 2009 -0700
@@ -190,7 +190,7 @@
             if (fl == null)
                 throw new RuntimeException("Unable to acquire lock");
             try {
-                ch.lock(null, new CompletionHandler<FileLock,Void> () {
+                ch.lock((Void)null, new CompletionHandler<FileLock,Void> () {
                     public void completed(FileLock result, Void att) {
                     }
                     public void failed(Throwable exc, Void att) {
@@ -217,7 +217,7 @@
         ByteBuffer buf = ByteBuffer.allocateDirect(100);
         final CountDownLatch latch = new CountDownLatch(1);
 
-        ch.read(buf, 0L, null, new CompletionHandler<Integer,Void>() {
+        ch.read(buf, 0L, (Void)null, new CompletionHandler<Integer,Void>() {
             public void completed(Integer result, Void att) {
                 try {
                     Thread.currentThread().interrupt();
@@ -311,7 +311,7 @@
                     final AtomicReference<Thread> invoker = new AtomicReference<Thread>();
                     final CountDownLatch latch = new CountDownLatch(1);
 
-                    ch.write(genBuffer(), 0L, null, new CompletionHandler<Integer,Void>() {
+                    ch.write(genBuffer(), 0L, (Void)null, new CompletionHandler<Integer,Void>() {
                         public void completed(Integer result, Void att) {
                             invoker.set(Thread.currentThread());
                             latch.countDown();
@@ -410,7 +410,7 @@
 
             // start write operation
             final CountDownLatch latch = new CountDownLatch(1);
-            Future<Integer> res = ch.write(genBuffer(), 0L, null,
+            Future<Integer> res = ch.write(genBuffer(), 0L, (Void)null,
                 new CompletionHandler<Integer,Void>() {
                     public void completed(Integer result, Void att) {
                     }
--- a/test/java/nio/channels/AsynchronousServerSocketChannel/Basic.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/test/java/nio/channels/AsynchronousServerSocketChannel/Basic.java	Wed Jul 29 11:19:14 2009 -0700
@@ -95,7 +95,7 @@
        final AtomicReference<Throwable> exception = new AtomicReference<Throwable>();
 
         // start accepting
-        listener.accept(null, new CompletionHandler<AsynchronousSocketChannel,Void>() {
+        listener.accept((Void)null, new CompletionHandler<AsynchronousSocketChannel,Void>() {
             public void completed(AsynchronousSocketChannel ch, Void att) {
                 try {
                     ch.close();
--- a/test/java/nio/channels/AsynchronousSocketChannel/Basic.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/test/java/nio/channels/AsynchronousSocketChannel/Basic.java	Wed Jul 29 11:19:14 2009 -0700
@@ -181,7 +181,7 @@
         }
         final AtomicReference<Throwable> connectException =
             new AtomicReference<Throwable>();
-        ch.connect(server.address(), null, new CompletionHandler<Void,Void>() {
+        ch.connect(server.address(), (Void)null, new CompletionHandler<Void,Void>() {
             public void completed(Void result, Void att) {
             }
             public void failed(Throwable exc, Void att) {
@@ -332,7 +332,7 @@
             // start read operation
             final CountDownLatch latch = new CountDownLatch(1);
             ByteBuffer buf = ByteBuffer.allocate(1);
-            Future<Integer> res = ch.read(buf, null,
+            Future<Integer> res = ch.read(buf, (Void)null,
                 new CompletionHandler<Integer,Void>() {
                     public void completed(Integer result, Void att) {
                     }
@@ -397,11 +397,11 @@
         // reads should complete immediately
         final ByteBuffer dst = ByteBuffer.allocateDirect(src.capacity() + 100);
         final CountDownLatch latch = new CountDownLatch(1);
-        ch.read(dst, null, new CompletionHandler<Integer,Void>() {
+        ch.read(dst, (Void)null, new CompletionHandler<Integer,Void>() {
             public void completed(Integer result, Void att) {
                 int n = result;
                 if (n > 0) {
-                    ch.read(dst, null, this);
+                    ch.read(dst, (Void)null, this);
                 } else {
                     latch.countDown();
                 }
@@ -450,10 +450,10 @@
         // read until the buffer is full
         final ByteBuffer dst = ByteBuffer.allocateDirect(src.capacity());
         final CountDownLatch latch = new CountDownLatch(1);
-        ch.read(dst, null, new CompletionHandler<Integer,Void>() {
+        ch.read(dst, (Void)null, new CompletionHandler<Integer,Void>() {
             public void completed(Integer result, Void att) {
                 if (dst.hasRemaining()) {
-                    ch.read(dst, null, this);
+                    ch.read(dst, (Void)null, this);
                 } else {
                     latch.countDown();
                 }
@@ -508,7 +508,7 @@
 
         // scattering read that completes ascynhronously
         final CountDownLatch latch = new CountDownLatch(1);
-        ch.read(dsts, 0, dsts.length, 0L, TimeUnit.SECONDS, null,
+        ch.read(dsts, 0, dsts.length, 0L, TimeUnit.SECONDS, (Void)null,
             new CompletionHandler<Long,Void>() {
                 public void completed(Long result, Void att) {
                     long n = result;
@@ -536,7 +536,7 @@
             dsts[i].rewind();
         }
         long n = ch
-            .read(dsts, 0, dsts.length, 0L, TimeUnit.SECONDS, null, null).get();
+            .read(dsts, 0, dsts.length, 0L, TimeUnit.SECONDS, (Void)null, null).get();
         if (n <= 0)
             throw new RuntimeException("No bytes read");
 
@@ -562,10 +562,10 @@
 
         // write all bytes and close connection when done
         final ByteBuffer src = genBuffer();
-        ch.write(src, null, new CompletionHandler<Integer,Void>() {
+        ch.write(src, (Void)null, new CompletionHandler<Integer,Void>() {
             public void completed(Integer result, Void att) {
                 if (src.hasRemaining()) {
-                    ch.write(src, null, this);
+                    ch.write(src, (Void)null, this);
                 } else {
                     try {
                         ch.close();
@@ -616,7 +616,7 @@
         // write buffers (should complete immediately)
         ByteBuffer[] srcs = genBuffers(1);
         long n = ch
-            .write(srcs, 0, srcs.length, 0L, TimeUnit.SECONDS, null, null).get();
+            .write(srcs, 0, srcs.length, 0L, TimeUnit.SECONDS, (Void)null, null).get();
         if (n <= 0)
             throw new RuntimeException("No bytes written");
 
@@ -629,7 +629,7 @@
         // write until socket buffer is full so as to create the conditions
         // for when a write does not complete immediately
         srcs = genBuffers(1);
-        ch.write(srcs, 0, srcs.length, 0L, TimeUnit.SECONDS, null,
+        ch.write(srcs, 0, srcs.length, 0L, TimeUnit.SECONDS, (Void)null,
             new CompletionHandler<Long,Void>() {
                 public void completed(Long result, Void att) {
                     long n = result;
@@ -639,7 +639,7 @@
                     if (continueWriting.get()) {
                         ByteBuffer[] srcs = genBuffers(8);
                         ch.write(srcs, 0, srcs.length, 0L, TimeUnit.SECONDS,
-                            null, this);
+                            (Void)null, this);
                     }
                 }
                 public void failed(Throwable exc, Void att) {
@@ -717,7 +717,7 @@
         // this read should timeout
         ByteBuffer dst = ByteBuffer.allocate(512);
         try {
-            ch.read(dst, 3, TimeUnit.SECONDS, null, null).get();
+            ch.read(dst, 3, TimeUnit.SECONDS, (Void)null, null).get();
             throw new RuntimeException("Read did not timeout");
         } catch (ExecutionException x) {
             if (!(x.getCause() instanceof InterruptedByTimeoutException))
--- a/test/java/nio/channels/AsynchronousSocketChannel/StressLoopback.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/test/java/nio/channels/AsynchronousSocketChannel/StressLoopback.java	Wed Jul 29 11:19:14 2009 -0700
@@ -99,7 +99,7 @@
         void start() {
             sentBuffer.position(0);
             sentBuffer.limit(sentBuffer.capacity());
-            channel.write(sentBuffer, null, new CompletionHandler<Integer,Void> () {
+            channel.write(sentBuffer, (Void)null, new CompletionHandler<Integer,Void> () {
                 public void completed(Integer nwrote, Void att) {
                     bytesSent += nwrote;
                     if (finished) {
@@ -107,7 +107,7 @@
                     } else {
                         sentBuffer.position(0);
                         sentBuffer.limit(sentBuffer.capacity());
-                        channel.write(sentBuffer, null, this);
+                        channel.write(sentBuffer, (Void)null, this);
                     }
                 }
                 public void failed(Throwable exc, Void att) {
@@ -142,14 +142,14 @@
         }
 
         void start() {
-            channel.read(readBuffer, null, new CompletionHandler<Integer,Void> () {
+            channel.read(readBuffer, (Void)null, new CompletionHandler<Integer,Void> () {
                 public void completed(Integer nread, Void att) {
                     if (nread < 0) {
                         closeUnchecked(channel);
                     } else {
                         bytesRead += nread;
                         readBuffer.clear();
-                        channel.read(readBuffer, null, this);
+                        channel.read(readBuffer, (Void)null, this);
                     }
                 }
                 public void failed(Throwable exc, Void att) {
--- a/test/java/nio/file/Path/Links.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/test/java/nio/file/Path/Links.java	Wed Jul 29 11:19:14 2009 -0700
@@ -22,7 +22,7 @@
  */
 
 /* @test
- * @bug 4313887 6838333
+ * @bug 4313887 6838333 6863864
  * @summary Unit test for java.nio.file.Path createSymbolicLink,
  *     readSymbolicLink, and createLink methods
  * @library ..
@@ -31,7 +31,6 @@
 import java.nio.file.*;
 import java.nio.file.attribute.*;
 import java.io.*;
-import java.util.*;
 
 public class Links {
 
@@ -47,7 +46,7 @@
      * Exercise createSymbolicLink and readLink methods
      */
     static void testSymLinks(Path dir) throws IOException {
-        Path link = dir.resolve("link");
+        final Path link = dir.resolve("link");
 
         // Check if sym links are supported
         try {
@@ -76,6 +75,63 @@
                 link.delete();
             }
         }
+
+        // Test links to directory
+        Path mydir = dir.resolve("mydir");
+        Path myfile = mydir.resolve("myfile");
+        try {
+            mydir.createDirectory();
+            myfile.createFile();
+
+            // link -> "mydir"
+            link.createSymbolicLink(mydir.getName());
+            assertTrue(link.readSymbolicLink().equals(mydir.getName()));
+
+            // Test access to directory via link
+            DirectoryStream<Path> stream = link.newDirectoryStream();
+            try {
+                boolean found = false;
+                for (Path entry: stream) {
+                    if (entry.getName().equals(myfile.getName())) {
+                        found = true;
+                        break;
+                    }
+                }
+                assertTrue(found);
+            } finally {
+                stream.close();
+            }
+
+            // Test link2 -> link -> mydir
+            final Path link2 = dir.resolve("link2");
+            Path target2 = link.getName();
+            link2.createSymbolicLink(target2);
+            try {
+                assertTrue(link2.readSymbolicLink().equals(target2));
+                link2.newDirectoryStream().close();
+            } finally {
+                link2.delete();
+            }
+
+            // Remove mydir and re-create link2 before re-creating mydir
+            // (This is a useful test on Windows to ensure that creating a
+            // sym link to a directory sym link creates the right type of link).
+            myfile.delete();
+            mydir.delete();
+            link2.createSymbolicLink(target2);
+            try {
+                assertTrue(link2.readSymbolicLink().equals(target2));
+                mydir.createDirectory();
+                link2.newDirectoryStream().close();
+            } finally {
+                link2.delete();
+            }
+
+        } finally {
+            myfile.deleteIfExists();
+            mydir.deleteIfExists();
+            link.deleteIfExists();
+        }
     }
 
     /**
--- a/test/java/util/Collection/MOAT.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/test/java/util/Collection/MOAT.java	Wed Jul 29 11:19:14 2009 -0700
@@ -426,6 +426,36 @@
         q.poll();
         equal(q.size(), 4);
         checkFunctionalInvariants(q);
+        if ((q instanceof LinkedBlockingQueue) ||
+            (q instanceof LinkedBlockingDeque) ||
+            (q instanceof ConcurrentLinkedQueue)) {
+            testQueueIteratorRemove(q);
+        }
+    }
+
+    private static void testQueueIteratorRemove(Queue<Integer> q) {
+        System.err.printf("testQueueIteratorRemove %s%n",
+                          q.getClass().getSimpleName());
+        q.clear();
+        for (int i = 0; i < 5; i++)
+            q.add(i);
+        Iterator<Integer> it = q.iterator();
+        check(it.hasNext());
+        for (int i = 3; i >= 0; i--)
+            q.remove(i);
+        equal(it.next(), 0);
+        equal(it.next(), 4);
+
+        q.clear();
+        for (int i = 0; i < 5; i++)
+            q.add(i);
+        it = q.iterator();
+        equal(it.next(), 0);
+        check(it.hasNext());
+        for (int i = 1; i < 4; i++)
+            q.remove(i);
+        equal(it.next(), 1);
+        equal(it.next(), 4);
     }
 
     private static void testList(final List<Integer> l) {
@@ -451,6 +481,11 @@
     }
 
     private static void testCollection(Collection<Integer> c) {
+        try { testCollection1(c); }
+        catch (Throwable t) { unexpected(t); }
+    }
+
+    private static void testCollection1(Collection<Integer> c) {
 
         System.out.println("\n==> " + c.getClass().getName());
 
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/java/util/concurrent/BlockingQueue/OfferDrainToLoops.java	Wed Jul 29 11:19:14 2009 -0700
@@ -0,0 +1,130 @@
+/*
+ * 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.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * Written by Doug Lea with assistance from members of JCP JSR-166
+ * Expert Group and released to the public domain, as explained at
+ * http://creativecommons.org/licenses/publicdomain
+ */
+
+/*
+ * @test
+ * @bug 6805775 6815766
+ * @summary Test concurrent offer vs. drainTo
+ */
+
+import java.util.*;
+import java.util.concurrent.*;
+
+@SuppressWarnings({"unchecked", "rawtypes"})
+public class OfferDrainToLoops {
+    void checkNotContainsNull(Iterable it) {
+        for (Object x : it)
+            check(x != null);
+    }
+
+    abstract class CheckedThread extends Thread {
+        abstract protected void realRun();
+        public void run() {
+            try { realRun(); } catch (Throwable t) { unexpected(t); }
+        }
+        {
+            setDaemon(true);
+            start();
+        }
+    }
+
+    void test(String[] args) throws Throwable {
+        test(new LinkedBlockingQueue());
+        test(new LinkedBlockingQueue(2000));
+        test(new LinkedBlockingDeque());
+        test(new LinkedBlockingDeque(2000));
+        test(new ArrayBlockingQueue(2000));
+    }
+
+    void test(final BlockingQueue q) throws Throwable {
+        System.out.println(q.getClass().getSimpleName());
+        final long testDurationSeconds = 1L;
+        final long testDurationMillis = testDurationSeconds * 1000L;
+        final long quittingTimeNanos
+            = System.nanoTime() + testDurationSeconds * 1000L * 1000L * 1000L;
+
+        Thread offerer = new CheckedThread() {
+            protected void realRun() {
+                for (long i = 0; ; i++) {
+                    if ((i % 1024) == 0 &&
+                        System.nanoTime() - quittingTimeNanos > 0)
+                        break;
+                    while (! q.offer(i))
+                        Thread.yield();
+                }}};
+
+        Thread drainer = new CheckedThread() {
+            protected void realRun() {
+                for (long i = 0; ; i++) {
+                    if (System.nanoTime() - quittingTimeNanos > 0)
+                        break;
+                    List list = new ArrayList();
+                    int n = q.drainTo(list);
+                    equal(list.size(), n);
+                    for (int j = 0; j < n - 1; j++)
+                        equal((Long) list.get(j) + 1L, list.get(j + 1));
+                    Thread.yield();
+                }}};
+
+        Thread scanner = new CheckedThread() {
+            protected void realRun() {
+                for (long i = 0; ; i++) {
+                    if (System.nanoTime() - quittingTimeNanos > 0)
+                        break;
+                    checkNotContainsNull(q);
+                    Thread.yield();
+                }}};
+
+        offerer.join(10 * testDurationMillis);
+        drainer.join(10 * testDurationMillis);
+        check(! offerer.isAlive());
+        check(! drainer.isAlive());
+    }
+
+    //--------------------- Infrastructure ---------------------------
+    volatile int passed = 0, failed = 0;
+    void pass() {passed++;}
+    void fail() {failed++; Thread.dumpStack();}
+    void fail(String msg) {System.err.println(msg); fail();}
+    void unexpected(Throwable t) {failed++; t.printStackTrace();}
+    void check(boolean cond) {if (cond) pass(); else fail();}
+    void equal(Object x, Object y) {
+        if (x == null ? y == null : x.equals(y)) pass();
+        else fail(x + " not equal to " + y);}
+    public static void main(String[] args) throws Throwable {
+        new OfferDrainToLoops().instanceMain(args);}
+    public void instanceMain(String[] args) throws Throwable {
+        try {test(args);} catch (Throwable t) {unexpected(t);}
+        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
+        if (failed > 0) throw new AssertionError("Some tests failed");}
+}
--- a/test/java/util/concurrent/ConcurrentLinkedQueue/ConcurrentQueueLoops.java	Fri Jul 24 11:22:29 2009 -0700
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,146 +0,0 @@
-/*
- * 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.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
- * CA 95054 USA or visit www.sun.com if you need additional information or
- * have any questions.
- */
-
-/*
- * This file is available under and governed by the GNU General Public
- * License version 2 only, as published by the Free Software Foundation.
- * However, the following notice accompanied the original version of this
- * file:
- *
- * Written by Doug Lea with assistance from members of JCP JSR-166
- * Expert Group and released to the public domain, as explained at
- * http://creativecommons.org/licenses/publicdomain
- */
-
-/*
- * @test
- * @bug 4486658
- * @compile -source 1.5 ConcurrentQueueLoops.java
- * @run main/timeout=230 ConcurrentQueueLoops
- * @summary Checks that a set of threads can repeatedly get and modify items
- */
-
-import java.util.*;
-import java.util.concurrent.*;
-import java.util.concurrent.atomic.*;
-
-public class ConcurrentQueueLoops {
-    static final ExecutorService pool = Executors.newCachedThreadPool();
-    static AtomicInteger totalItems;
-    static boolean print = false;
-
-    public static void main(String[] args) throws Exception {
-        int maxStages = 8;
-        int items = 100000;
-
-        if (args.length > 0)
-            maxStages = Integer.parseInt(args[0]);
-
-        print = false;
-        System.out.println("Warmup...");
-        oneRun(1, items);
-        Thread.sleep(100);
-        oneRun(1, items);
-        Thread.sleep(100);
-        print = true;
-
-        for (int i = 1; i <= maxStages; i += (i+1) >>> 1) {
-            oneRun(i, items);
-        }
-        pool.shutdown();
-        if (! pool.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS))
-            throw new Error();
-   }
-
-    static class Stage implements Callable<Integer> {
-        final Queue<Integer> queue;
-        final CyclicBarrier barrier;
-        int items;
-        Stage (Queue<Integer> q, CyclicBarrier b, int items) {
-            queue = q;
-            barrier = b;
-            this.items = items;
-        }
-
-        public Integer call() {
-            // Repeatedly take something from queue if possible,
-            // transform it, and put back in.
-            try {
-                barrier.await();
-                int l = 4321;
-                int takes = 0;
-                for (;;) {
-                    Integer item = queue.poll();
-                    if (item != null) {
-                        ++takes;
-                        l = LoopHelpers.compute2(item.intValue());
-                    }
-                    else if (takes != 0) {
-                        totalItems.getAndAdd(-takes);
-                        takes = 0;
-                    }
-                    else if (totalItems.get() <= 0)
-                        break;
-                    l = LoopHelpers.compute1(l);
-                    if (items > 0) {
-                        --items;
-                        queue.offer(new Integer(l));
-                    }
-                    else if ( (l & (3 << 5)) == 0) // spinwait
-                        Thread.sleep(1);
-                }
-                return new Integer(l);
-            }
-            catch (Exception ie) {
-                ie.printStackTrace();
-                throw new Error("Call loop failed");
-            }
-        }
-    }
-
-    static void oneRun(int n, int items) throws Exception {
-        Queue<Integer> q = new ConcurrentLinkedQueue<Integer>();
-        LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
-        CyclicBarrier barrier = new CyclicBarrier(n + 1, timer);
-        totalItems = new AtomicInteger(n * items);
-        ArrayList<Future<Integer>> results = new ArrayList<Future<Integer>>(n);
-        for (int i = 0; i < n; ++i)
-            results.add(pool.submit(new Stage(q, barrier, items)));
-
-        if (print)
-            System.out.print("Threads: " + n + "\t:");
-        barrier.await();
-        int total = 0;
-        for (int i = 0; i < n; ++i) {
-            Future<Integer> f = results.get(i);
-            Integer r = f.get();
-            total += r.intValue();
-        }
-        long endTime = System.nanoTime();
-        long time = endTime - timer.startTime;
-        if (print)
-            System.out.println(LoopHelpers.rightJustify(time / (items * n)) + " ns per item");
-        if (total == 0) // avoid overoptimization
-            System.out.println("useless result: " + total);
-
-    }
-}
--- a/test/java/util/concurrent/ConcurrentLinkedQueue/LoopHelpers.java	Fri Jul 24 11:22:29 2009 -0700
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,129 +0,0 @@
-/*
- * 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.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
- * CA 95054 USA or visit www.sun.com if you need additional information or
- * have any questions.
- */
-
-/*
- * This file is available under and governed by the GNU General Public
- * License version 2 only, as published by the Free Software Foundation.
- * However, the following notice accompanied the original version of this
- * file:
- *
- * Written by Doug Lea with assistance from members of JCP JSR-166
- * Expert Group and released to the public domain, as explained at
- * http://creativecommons.org/licenses/publicdomain
- */
-
-/**
- * Misc utilities in JSR166 performance tests
- */
-
-import java.util.concurrent.*;
-import java.util.concurrent.atomic.*;
-
-class LoopHelpers {
-
-    // Some mindless computation to do between synchronizations...
-
-    /**
-     * generates 32 bit pseudo-random numbers.
-     * Adapted from http://www.snippets.org
-     */
-    public static int compute1(int x) {
-        int lo = 16807 * (x & 0xFFFF);
-        int hi = 16807 * (x >>> 16);
-        lo += (hi & 0x7FFF) << 16;
-        if ((lo & 0x80000000) != 0) {
-            lo &= 0x7fffffff;
-            ++lo;
-        }
-        lo += hi >>> 15;
-        if (lo == 0 || (lo & 0x80000000) != 0) {
-            lo &= 0x7fffffff;
-            ++lo;
-        }
-        return lo;
-    }
-
-    /**
-     *  Computes a linear congruential random number a random number
-     *  of times.
-     */
-    public static int compute2(int x) {
-        int loops = (x >>> 4) & 7;
-        while (loops-- > 0) {
-            x = (x * 2147483647) % 16807;
-        }
-        return x;
-    }
-
-    /**
-     * An actually useful random number generator, but unsynchronized.
-     * Basically same as java.util.Random.
-     */
-    public static class SimpleRandom {
-        private final static long multiplier = 0x5DEECE66DL;
-        private final static long addend = 0xBL;
-        private final static long mask = (1L << 48) - 1;
-        static final AtomicLong seq = new AtomicLong(1);
-        private long seed = System.nanoTime() + seq.getAndIncrement();
-
-        public void setSeed(long s) {
-            seed = s;
-        }
-
-        public int next() {
-            long nextseed = (seed * multiplier + addend) & mask;
-            seed = nextseed;
-            return ((int)(nextseed >>> 17)) & 0x7FFFFFFF;
-        }
-    }
-
-    public static class BarrierTimer implements Runnable {
-        public volatile long startTime;
-        public volatile long endTime;
-        public void run() {
-            long t = System.nanoTime();
-            if (startTime == 0)
-                startTime = t;
-            else
-                endTime = t;
-        }
-        public void clear() {
-            startTime = 0;
-            endTime = 0;
-        }
-        public long getTime() {
-            return endTime - startTime;
-        }
-    }
-
-    public static String rightJustify(long n) {
-        // There's probably a better way to do this...
-        String field = "         ";
-        String num = Long.toString(n);
-        if (num.length() >= field.length())
-            return num;
-        StringBuffer b = new StringBuffer(field);
-        b.replace(b.length()-num.length(), b.length(), num);
-        return b.toString();
-    }
-
-}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/java/util/concurrent/ConcurrentQueues/ConcurrentQueueLoops.java	Wed Jul 29 11:19:14 2009 -0700
@@ -0,0 +1,198 @@
+/*
+ * 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.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * Written by Doug Lea with assistance from members of JCP JSR-166
+ * Expert Group and released to the public domain, as explained at
+ * http://creativecommons.org/licenses/publicdomain
+ */
+
+/*
+ * @test
+ * @bug 4486658 6785442
+ * @run main ConcurrentQueueLoops 8 123456
+ * @summary Checks that a set of threads can repeatedly get and modify items
+ */
+
+import java.util.*;
+import java.util.concurrent.*;
+import java.util.concurrent.atomic.*;
+
+public class ConcurrentQueueLoops {
+    ExecutorService pool;
+    AtomicInteger totalItems;
+    boolean print;
+
+    // Suitable for benchmarking.  Overriden by args[0] for testing.
+    int maxStages = 20;
+
+    // Suitable for benchmarking.  Overriden by args[1] for testing.
+    int items = 1024 * 1024;
+
+    Collection<Queue<Integer>> concurrentQueues() {
+        List<Queue<Integer>> queues = new ArrayList<Queue<Integer>>();
+        queues.add(new ConcurrentLinkedQueue<Integer>());
+        queues.add(new ArrayBlockingQueue<Integer>(items, false));
+        //queues.add(new ArrayBlockingQueue<Integer>(count, true));
+        queues.add(new LinkedBlockingQueue<Integer>());
+        queues.add(new LinkedBlockingDeque<Integer>());
+
+        try {
+            queues.add((Queue<Integer>)
+                       Class.forName("java.util.concurrent.LinkedTransferQueue")
+                       .newInstance());
+        } catch (IllegalAccessException e) {
+        } catch (InstantiationException e) {
+        } catch (ClassNotFoundException e) {
+            // OK; not yet added to JDK
+        }
+
+        // Following additional implementations are available from:
+        // http://gee.cs.oswego.edu/dl/concurrency-interest/index.html
+        // queues.add(new LinkedTransferQueue<Integer>());
+        // queues.add(new SynchronizedLinkedListQueue<Integer>());
+
+        // Avoid "first fast, second slow" benchmark effect.
+        Collections.shuffle(queues);
+        return queues;
+    }
+
+    void test(String[] args) throws Throwable {
+        if (args.length > 0)
+            maxStages = Integer.parseInt(args[0]);
+        if (args.length > 1)
+            items = Integer.parseInt(args[1]);
+
+        for (Queue<Integer> queue : concurrentQueues())
+            test(queue);
+    }
+
+    void test(final Queue<Integer> q) throws Throwable {
+        System.out.println(q.getClass().getSimpleName());
+        pool = Executors.newCachedThreadPool();
+        print = false;
+
+        print = false;
+        System.out.println("Warmup...");
+        oneRun(1, items, q);
+        //Thread.sleep(100);
+        oneRun(3, items, q);
+        Thread.sleep(100);
+        print = true;
+
+        for (int i = 1; i <= maxStages; i += (i+1) >>> 1) {
+            oneRun(i, items, q);
+        }
+        pool.shutdown();
+        check(pool.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS));
+   }
+
+    class Stage implements Callable<Integer> {
+        final Queue<Integer> queue;
+        final CyclicBarrier barrier;
+        int items;
+        Stage (Queue<Integer> q, CyclicBarrier b, int items) {
+            queue = q;
+            barrier = b;
+            this.items = items;
+        }
+
+        public Integer call() {
+            // Repeatedly take something from queue if possible,
+            // transform it, and put back in.
+            try {
+                barrier.await();
+                int l = 4321;
+                int takes = 0;
+                for (;;) {
+                    Integer item = queue.poll();
+                    if (item != null) {
+                        ++takes;
+                        l = LoopHelpers.compute2(item.intValue());
+                    }
+                    else if (takes != 0) {
+                        totalItems.getAndAdd(-takes);
+                        takes = 0;
+                    }
+                    else if (totalItems.get() <= 0)
+                        break;
+                    l = LoopHelpers.compute1(l);
+                    if (items > 0) {
+                        --items;
+                        queue.offer(new Integer(l));
+                    }
+                    else if ( (l & (3 << 5)) == 0) // spinwait
+                        Thread.sleep(1);
+                }
+                return new Integer(l);
+            }
+            catch (Throwable t) { unexpected(t); return null; }
+        }
+    }
+
+    void oneRun(int n, int items, final Queue<Integer> q) throws Exception {
+        LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
+        CyclicBarrier barrier = new CyclicBarrier(n + 1, timer);
+        totalItems = new AtomicInteger(n * items);
+        ArrayList<Future<Integer>> results = new ArrayList<Future<Integer>>(n);
+        for (int i = 0; i < n; ++i)
+            results.add(pool.submit(new Stage(q, barrier, items)));
+
+        if (print)
+            System.out.print("Threads: " + n + "\t:");
+        barrier.await();
+        int total = 0;
+        for (int i = 0; i < n; ++i) {
+            Future<Integer> f = results.get(i);
+            Integer r = f.get();
+            total += r.intValue();
+        }
+        long endTime = System.nanoTime();
+        long time = endTime - timer.startTime;
+        if (print)
+            System.out.println(LoopHelpers.rightJustify(time / (items * n)) + " ns per item");
+        if (total == 0) // avoid overoptimization
+            System.out.println("useless result: " + total);
+    }
+
+    //--------------------- Infrastructure ---------------------------
+    volatile int passed = 0, failed = 0;
+    void pass() {passed++;}
+    void fail() {failed++; Thread.dumpStack();}
+    void fail(String msg) {System.err.println(msg); fail();}
+    void unexpected(Throwable t) {failed++; t.printStackTrace();}
+    void check(boolean cond) {if (cond) pass(); else fail();}
+    void equal(Object x, Object y) {
+        if (x == null ? y == null : x.equals(y)) pass();
+        else fail(x + " not equal to " + y);}
+    public static void main(String[] args) throws Throwable {
+        new ConcurrentQueueLoops().instanceMain(args);}
+    public void instanceMain(String[] args) throws Throwable {
+        try {test(args);} catch (Throwable t) {unexpected(t);}
+        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
+        if (failed > 0) throw new AssertionError("Some tests failed");}
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/java/util/concurrent/ConcurrentQueues/GCRetention.java	Wed Jul 29 11:19:14 2009 -0700
@@ -0,0 +1,165 @@
+/*
+ * 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.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * Written by Doug Lea with assistance from members of JCP JSR-166
+ * Expert Group and released to the public domain, as explained at
+ * http://creativecommons.org/licenses/publicdomain
+ */
+/*
+ * @test
+ * @bug 6785442
+ * @summary Benchmark that tries to GC-tenure head, followed by
+ * many add/remove operations.
+ * @run main GCRetention 12345
+ */
+
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.LinkedBlockingDeque;
+import java.util.concurrent.PriorityBlockingQueue;
+import java.util.LinkedList;
+import java.util.PriorityQueue;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Queue;
+import java.util.Map;
+
+public class GCRetention {
+    // Suitable for benchmarking.  Overriden by args[0] for testing.
+    int count = 1024 * 1024;
+
+    final Map<String,String> results = new ConcurrentHashMap<String,String>();
+
+    Collection<Queue<Boolean>> queues() {
+        List<Queue<Boolean>> queues = new ArrayList<Queue<Boolean>>();
+        queues.add(new ConcurrentLinkedQueue<Boolean>());
+        queues.add(new ArrayBlockingQueue<Boolean>(count, false));
+        queues.add(new ArrayBlockingQueue<Boolean>(count, true));
+        queues.add(new LinkedBlockingQueue<Boolean>());
+        queues.add(new LinkedBlockingDeque<Boolean>());
+        queues.add(new PriorityBlockingQueue<Boolean>());
+        queues.add(new PriorityQueue<Boolean>());
+        queues.add(new LinkedList<Boolean>());
+
+        try {
+            queues.add((Queue<Boolean>)
+                       Class.forName("java.util.concurrent.LinkedTransferQueue")
+                       .newInstance());
+        } catch (IllegalAccessException e) {
+        } catch (InstantiationException e) {
+        } catch (ClassNotFoundException e) {
+            // OK; not yet added to JDK
+        }
+
+        // Following additional implementations are available from:
+        // http://gee.cs.oswego.edu/dl/concurrency-interest/index.html
+        // queues.add(new LinkedTransferQueue<Boolean>());
+        // queues.add(new SynchronizedLinkedListQueue<Boolean>());
+
+        // Avoid "first fast, second slow" benchmark effect.
+        Collections.shuffle(queues);
+        return queues;
+    }
+
+    void prettyPrintResults() {
+        List<String> classNames = new ArrayList<String>(results.keySet());
+        Collections.sort(classNames);
+        int maxClassNameLength = 0;
+        int maxNanosLength = 0;
+        for (String name : classNames) {
+            if (maxClassNameLength < name.length())
+                maxClassNameLength = name.length();
+            if (maxNanosLength < results.get(name).length())
+                maxNanosLength = results.get(name).length();
+        }
+        String format = String.format("%%%ds %%%ds nanos/item%%n",
+                                      maxClassNameLength, maxNanosLength);
+        for (String name : classNames)
+            System.out.printf(format, name, results.get(name));
+    }
+
+    void test(String[] args) {
+        if (args.length > 0)
+            count = Integer.valueOf(args[0]);
+        // Warmup
+        for (Queue<Boolean> queue : queues())
+            test(queue);
+        results.clear();
+        for (Queue<Boolean> queue : queues())
+            test(queue);
+
+        prettyPrintResults();
+    }
+
+    void test(Queue<Boolean> q) {
+        long t0 = System.nanoTime();
+        for (int i = 0; i < count; i++)
+            check(q.add(Boolean.TRUE));
+        System.gc();
+        System.gc();
+        Boolean x;
+        while ((x = q.poll()) != null)
+            equal(x, Boolean.TRUE);
+        check(q.isEmpty());
+
+        for (int i = 0; i < 10 * count; i++) {
+            for (int k = 0; k < 3; k++)
+                check(q.add(Boolean.TRUE));
+            for (int k = 0; k < 3; k++)
+                if (q.poll() != Boolean.TRUE)
+                    fail();
+        }
+        check(q.isEmpty());
+
+        String className = q.getClass().getSimpleName();
+        long elapsed = System.nanoTime() - t0;
+        int nanos = (int) ((double) elapsed / (10 * 3 * count));
+        results.put(className, String.valueOf(nanos));
+    }
+
+    //--------------------- Infrastructure ---------------------------
+    volatile int passed = 0, failed = 0;
+    void pass() {passed++;}
+    void fail() {failed++; Thread.dumpStack();}
+    void fail(String msg) {System.err.println(msg); fail();}
+    void unexpected(Throwable t) {failed++; t.printStackTrace();}
+    void check(boolean cond) {if (cond) pass(); else fail();}
+    void equal(Object x, Object y) {
+        if (x == null ? y == null : x.equals(y)) pass();
+        else fail(x + " not equal to " + y);}
+    public static void main(String[] args) throws Throwable {
+        new GCRetention().instanceMain(args);}
+    public void instanceMain(String[] args) throws Throwable {
+        try {test(args);} catch (Throwable t) {unexpected(t);}
+        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
+        if (failed > 0) throw new AssertionError("Some tests failed");}
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/java/util/concurrent/ConcurrentQueues/IteratorWeakConsistency.java	Wed Jul 29 11:19:14 2009 -0700
@@ -0,0 +1,93 @@
+/*
+ * 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.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * Written by Doug Lea with assistance from members of JCP JSR-166
+ * Expert Group and released to the public domain, as explained at
+ * http://creativecommons.org/licenses/publicdomain
+ */
+
+import java.util.*;
+import java.util.concurrent.*;
+
+/*
+ * @test
+ * @bug 6805775 6815766
+ * @summary Check weak consistency of concurrent queue iterators
+ */
+
+@SuppressWarnings({"unchecked", "rawtypes"})
+public class IteratorWeakConsistency {
+
+    void test(String[] args) throws Throwable {
+        test(new LinkedBlockingQueue());
+        test(new LinkedBlockingQueue(20));
+        test(new LinkedBlockingDeque());
+        test(new LinkedBlockingDeque(20));
+        test(new ConcurrentLinkedQueue());
+        // Other concurrent queues (e.g. ArrayBlockingQueue) do not
+        // currently have weakly consistent iterators.
+        // test(new ArrayBlockingQueue(20));
+    }
+
+    void test(Queue q) throws Throwable {
+        // TODO: make this more general
+        for (int i = 0; i < 10; i++)
+            q.add(i);
+        Iterator it = q.iterator();
+        q.poll();
+        q.poll();
+        q.poll();
+        q.remove(7);
+        List list = new ArrayList();
+        while (it.hasNext())
+            list.add(it.next());
+        equal(list, Arrays.asList(0, 3, 4, 5, 6, 8, 9));
+        check(! list.contains(null));
+        System.out.printf("%s: %s%n",
+                          q.getClass().getSimpleName(),
+                          list);
+    }
+
+    //--------------------- Infrastructure ---------------------------
+    volatile int passed = 0, failed = 0;
+    void pass() {passed++;}
+    void fail() {failed++; Thread.dumpStack();}
+    void fail(String msg) {System.err.println(msg); fail();}
+    void unexpected(Throwable t) {failed++; t.printStackTrace();}
+    void check(boolean cond) {if (cond) pass(); else fail();}
+    void equal(Object x, Object y) {
+        if (x == null ? y == null : x.equals(y)) pass();
+        else fail(x + " not equal to " + y);}
+    static Class<?> thisClass = new Object(){}.getClass().getEnclosingClass();
+    public static void main(String[] args) throws Throwable {
+        new IteratorWeakConsistency().instanceMain(args);}
+    public void instanceMain(String[] args) throws Throwable {
+        try {test(args);} catch (Throwable t) {unexpected(t);}
+        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
+        if (failed > 0) throw new AssertionError("Some tests failed");}
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/java/util/concurrent/ConcurrentQueues/LoopHelpers.java	Wed Jul 29 11:19:14 2009 -0700
@@ -0,0 +1,129 @@
+/*
+ * 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.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * Written by Doug Lea with assistance from members of JCP JSR-166
+ * Expert Group and released to the public domain, as explained at
+ * http://creativecommons.org/licenses/publicdomain
+ */
+
+/**
+ * Misc utilities in JSR166 performance tests
+ */
+
+import java.util.concurrent.*;
+import java.util.concurrent.atomic.*;
+
+class LoopHelpers {
+
+    // Some mindless computation to do between synchronizations...
+
+    /**
+     * generates 32 bit pseudo-random numbers.
+     * Adapted from http://www.snippets.org
+     */
+    public static int compute1(int x) {
+        int lo = 16807 * (x & 0xFFFF);
+        int hi = 16807 * (x >>> 16);
+        lo += (hi & 0x7FFF) << 16;
+        if ((lo & 0x80000000) != 0) {
+            lo &= 0x7fffffff;
+            ++lo;
+        }
+        lo += hi >>> 15;
+        if (lo == 0 || (lo & 0x80000000) != 0) {
+            lo &= 0x7fffffff;
+            ++lo;
+        }
+        return lo;
+    }
+
+    /**
+     *  Computes a linear congruential random number a random number
+     *  of times.
+     */
+    public static int compute2(int x) {
+        int loops = (x >>> 4) & 7;
+        while (loops-- > 0) {
+            x = (x * 2147483647) % 16807;
+        }
+        return x;
+    }
+
+    /**
+     * An actually useful random number generator, but unsynchronized.
+     * Basically same as java.util.Random.
+     */
+    public static class SimpleRandom {
+        private final static long multiplier = 0x5DEECE66DL;
+        private final static long addend = 0xBL;
+        private final static long mask = (1L << 48) - 1;
+        static final AtomicLong seq = new AtomicLong(1);
+        private long seed = System.nanoTime() + seq.getAndIncrement();
+
+        public void setSeed(long s) {
+            seed = s;
+        }
+
+        public int next() {
+            long nextseed = (seed * multiplier + addend) & mask;
+            seed = nextseed;
+            return ((int)(nextseed >>> 17)) & 0x7FFFFFFF;
+        }
+    }
+
+    public static class BarrierTimer implements Runnable {
+        public volatile long startTime;
+        public volatile long endTime;
+        public void run() {
+            long t = System.nanoTime();
+            if (startTime == 0)
+                startTime = t;
+            else
+                endTime = t;
+        }
+        public void clear() {
+            startTime = 0;
+            endTime = 0;
+        }
+        public long getTime() {
+            return endTime - startTime;
+        }
+    }
+
+    public static String rightJustify(long n) {
+        // There's probably a better way to do this...
+        String field = "         ";
+        String num = Long.toString(n);
+        if (num.length() >= field.length())
+            return num;
+        StringBuffer b = new StringBuffer(field);
+        b.replace(b.length()-num.length(), b.length(), num);
+        return b.toString();
+    }
+
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/java/util/concurrent/ConcurrentQueues/RemovePollRace.java	Wed Jul 29 11:19:14 2009 -0700
@@ -0,0 +1,230 @@
+/*
+ * 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.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * Written by Doug Lea with assistance from members of JCP JSR-166
+ * Expert Group and released to the public domain, as explained at
+ * http://creativecommons.org/licenses/publicdomain
+ */
+
+/*
+ * @test
+ * @bug 6785442
+ * @summary Checks race between poll and remove(Object), while
+ * occasionally moonlighting as a microbenchmark.
+ * @run main RemovePollRace 12345
+ */
+
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.LinkedBlockingDeque;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Queue;
+import java.util.Map;
+
+public class RemovePollRace {
+    // Suitable for benchmarking.  Overriden by args[0] for testing.
+    int count = 1024 * 1024;
+
+    final Map<String,String> results = new ConcurrentHashMap<String,String>();
+
+    Collection<Queue<Boolean>> concurrentQueues() {
+        List<Queue<Boolean>> queues = new ArrayList<Queue<Boolean>>();
+        queues.add(new ConcurrentLinkedQueue<Boolean>());
+        queues.add(new ArrayBlockingQueue<Boolean>(count, false));
+        queues.add(new ArrayBlockingQueue<Boolean>(count, true));
+        queues.add(new LinkedBlockingQueue<Boolean>());
+        queues.add(new LinkedBlockingDeque<Boolean>());
+
+        try {
+            queues.add((Queue<Boolean>)
+                       Class.forName("java.util.concurrent.LinkedTransferQueue")
+                       .newInstance());
+        } catch (IllegalAccessException e) {
+        } catch (InstantiationException e) {
+        } catch (ClassNotFoundException e) {
+            // OK; not yet added to JDK
+        }
+
+        // Following additional implementations are available from:
+        // http://gee.cs.oswego.edu/dl/concurrency-interest/index.html
+        // queues.add(new LinkedTransferQueue<Boolean>());
+        // queues.add(new SynchronizedLinkedListQueue<Boolean>());
+
+        // Avoid "first fast, second slow" benchmark effect.
+        Collections.shuffle(queues);
+        return queues;
+    }
+
+    void prettyPrintResults() {
+        List<String> classNames = new ArrayList<String>(results.keySet());
+        Collections.sort(classNames);
+        int maxClassNameLength = 0;
+        int maxNanosLength = 0;
+        for (String name : classNames) {
+            if (maxClassNameLength < name.length())
+                maxClassNameLength = name.length();
+            if (maxNanosLength < results.get(name).length())
+                maxNanosLength = results.get(name).length();
+        }
+        String format = String.format("%%%ds %%%ds nanos/item%%n",
+                                      maxClassNameLength, maxNanosLength);
+        for (String name : classNames)
+            System.out.printf(format, name, results.get(name));
+    }
+
+    void test(String[] args) throws Throwable {
+        if (args.length > 0)
+            count = Integer.valueOf(args[0]);
+        // Warmup
+        for (Queue<Boolean> queue : concurrentQueues())
+            test(queue);
+        results.clear();
+        for (Queue<Boolean> queue : concurrentQueues())
+            test(queue);
+
+        prettyPrintResults();
+    }
+
+    void await(CountDownLatch latch) {
+        try { latch.await(); }
+        catch (InterruptedException e) { unexpected(e); }
+    }
+
+    void test(final Queue<Boolean> q) throws Throwable {
+        long t0 = System.nanoTime();
+        final int SPINS = 5;
+        final AtomicLong removes = new AtomicLong(0);
+        final AtomicLong polls = new AtomicLong(0);
+        final int adderCount =
+            Math.max(1, Runtime.getRuntime().availableProcessors() / 4);
+        final int removerCount =
+            Math.max(1, Runtime.getRuntime().availableProcessors() / 4);
+        final int pollerCount = removerCount;
+        final int threadCount = adderCount + removerCount + pollerCount;
+        final CountDownLatch startingGate = new CountDownLatch(1);
+        final CountDownLatch addersDone = new CountDownLatch(adderCount);
+        final Runnable remover = new Runnable() {
+            public void run() {
+                await(startingGate);
+                int spins = 0;
+                for (;;) {
+                    boolean quittingTime = (addersDone.getCount() == 0);
+                    if (q.remove(Boolean.TRUE))
+                        removes.getAndIncrement();
+                    else if (quittingTime)
+                        break;
+                    else if (++spins > SPINS) {
+                        Thread.yield();
+                        spins = 0;
+                    }}}};
+        final Runnable poller = new Runnable() {
+            public void run() {
+                await(startingGate);
+                int spins = 0;
+                for (;;) {
+                    boolean quittingTime = (addersDone.getCount() == 0);
+                    if (q.poll() == Boolean.TRUE)
+                        polls.getAndIncrement();
+                    else if (quittingTime)
+                        break;
+                    else if (++spins > SPINS) {
+                        Thread.yield();
+                        spins = 0;
+                    }}}};
+        final Runnable adder = new Runnable() {
+            public void run() {
+                await(startingGate);
+                for (int i = 0; i < count; i++) {
+                    for (;;) {
+                        try { q.add(Boolean.TRUE); break; }
+                        catch (IllegalStateException e) { Thread.yield(); }
+                    }
+                }
+                addersDone.countDown();
+            }};
+
+        final List<Thread> adders   = new ArrayList<Thread>();
+        final List<Thread> removers = new ArrayList<Thread>();
+        final List<Thread> pollers  = new ArrayList<Thread>();
+        for (int i = 0; i < adderCount; i++)
+            adders.add(checkedThread(adder));
+        for (int i = 0; i < removerCount; i++)
+            removers.add(checkedThread(remover));
+        for (int i = 0; i < pollerCount; i++)
+            pollers.add(checkedThread(poller));
+
+        final List<Thread> allThreads = new ArrayList<Thread>();
+        allThreads.addAll(removers);
+        allThreads.addAll(pollers);
+        allThreads.addAll(adders);
+
+        for (Thread t : allThreads)
+            t.start();
+        startingGate.countDown();
+        for (Thread t : allThreads)
+            t.join();
+
+        String className = q.getClass().getSimpleName();
+        long elapsed = System.nanoTime() - t0;
+        int nanos = (int) ((double) elapsed / (adderCount * count));
+        results.put(className, String.valueOf(nanos));
+        if (removes.get() + polls.get() != adderCount * count) {
+            String msg = String.format
+                ("class=%s removes=%s polls=%d count=%d",
+                 className, removes.get(), polls.get(), count);
+            fail(msg);
+        }
+    }
+
+    //--------------------- Infrastructure ---------------------------
+    volatile int passed = 0, failed = 0;
+    void pass() {passed++;}
+    void fail() {failed++; Thread.dumpStack();}
+    void fail(String msg) {System.err.println(msg); fail();}
+    void unexpected(Throwable t) {failed++; t.printStackTrace();}
+    void check(boolean cond) {if (cond) pass(); else fail();}
+    void equal(Object x, Object y) {
+        if (x == null ? y == null : x.equals(y)) pass();
+        else fail(x + " not equal to " + y);}
+    public static void main(String[] args) throws Throwable {
+        new RemovePollRace().instanceMain(args);}
+    public void instanceMain(String[] args) throws Throwable {
+        try {test(args);} catch (Throwable t) {unexpected(t);}
+        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
+        if (failed > 0) throw new AssertionError("Some tests failed");}
+    Thread checkedThread(final Runnable r) {
+        return new Thread() {public void run() {
+            try {r.run();} catch (Throwable t) {unexpected(t);}}};}
+}
--- a/test/java/util/concurrent/LinkedBlockingQueue/OfferRemoveLoops.java	Fri Jul 24 11:22:29 2009 -0700
+++ b/test/java/util/concurrent/LinkedBlockingQueue/OfferRemoveLoops.java	Wed Jul 29 11:19:14 2009 -0700
@@ -28,62 +28,74 @@
  * @author Martin Buchholz
  */
 
+import java.util.*;
 import java.util.concurrent.*;
 
 public class OfferRemoveLoops {
-    private static void realMain(String[] args) throws Throwable {
+    void test(String[] args) throws Throwable {
         testQueue(new LinkedBlockingQueue<String>(10));
         testQueue(new LinkedBlockingQueue<String>());
         testQueue(new LinkedBlockingDeque<String>(10));
         testQueue(new LinkedBlockingDeque<String>());
         testQueue(new ArrayBlockingQueue<String>(10));
         testQueue(new PriorityBlockingQueue<String>(10));
+        testQueue(new ConcurrentLinkedQueue<String>());
     }
 
-    private abstract static class ControlledThread extends Thread {
+    abstract class CheckedThread extends Thread {
         abstract protected void realRun();
         public void run() {
             try { realRun(); } catch (Throwable t) { unexpected(t); }
         }
     }
 
-    private static void testQueue(final BlockingQueue<String> q) throws Throwable {
-        System.out.println(q.getClass());
-        final int count = 10000;
-        final long quittingTime = System.nanoTime() + 1L * 1000L * 1000L * 1000L;
-        Thread t1 = new ControlledThread() {
-                protected void realRun() {
-                    for (int i = 0, j = 0; i < count; i++)
-                        while (! q.remove(String.valueOf(i))
-                               && System.nanoTime() - quittingTime < 0)
-                            Thread.yield();}};
-        Thread t2 = new ControlledThread() {
-                protected void realRun() {
-                    for (int i = 0, j = 0; i < count; i++)
-                        while (! q.offer(String.valueOf(i))
-                               && System.nanoTime() - quittingTime < 0)
-                            Thread.yield();}};
+    void testQueue(final Queue<String> q) throws Throwable {
+        System.out.println(q.getClass().getSimpleName());
+        final int count = 1000 * 1000;
+        final long testDurationSeconds = 1L;
+        final long testDurationMillis = testDurationSeconds * 1000L;
+        final long quittingTimeNanos
+            = System.nanoTime() + testDurationSeconds * 1000L * 1000L * 1000L;
+        Thread t1 = new CheckedThread() {
+            protected void realRun() {
+                for (int i = 0; i < count; i++) {
+                    if ((i % 1024) == 0 &&
+                        System.nanoTime() - quittingTimeNanos > 0)
+                        return;
+                    while (! q.remove(String.valueOf(i)))
+                        Thread.yield();
+                }}};
+        Thread t2 = new CheckedThread() {
+            protected void realRun() {
+                for (int i = 0; i < count; i++) {
+                    if ((i % 1024) == 0 &&
+                        System.nanoTime() - quittingTimeNanos > 0)
+                        return;
+                    while (! q.offer(String.valueOf(i)))
+                        Thread.yield();
+                    }}};
         t1.setDaemon(true); t2.setDaemon(true);
         t1.start(); t2.start();
-        t1.join(10000); t2.join(10000);
+        t1.join(10 * testDurationMillis);
+        t2.join(10 * testDurationMillis);
         check(! t1.isAlive());
         check(! t2.isAlive());
     }
 
     //--------------------- Infrastructure ---------------------------
-    static volatile int passed = 0, failed = 0;
-    static void pass() { passed++; }
-    static void fail() { failed++; Thread.dumpStack(); }
-    static void unexpected(Throwable t) { failed++; t.printStackTrace(); }
-    static void check(boolean cond) { if (cond) pass(); else fail(); }
-    static void equal(Object x, Object y) {
+    volatile int passed = 0, failed = 0;
+    void pass() {passed++;}
+    void fail() {failed++; Thread.dumpStack();}
+    void fail(String msg) {System.err.println(msg); fail();}
+    void unexpected(Throwable t) {failed++; t.printStackTrace();}
+    void check(boolean cond) {if (cond) pass(); else fail();}
+    void equal(Object x, Object y) {
         if (x == null ? y == null : x.equals(y)) pass();
-        else {System.out.println(x + " not equal to " + y); fail(); }}
-
+        else fail(x + " not equal to " + y);}
     public static void main(String[] args) throws Throwable {
-        try { realMain(args); } catch (Throwable t) { unexpected(t); }
-
+        new OfferRemoveLoops().instanceMain(args);}
+    public void instanceMain(String[] args) throws Throwable {
+        try {test(args);} catch (Throwable t) {unexpected(t);}
         System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
-        if (failed > 0) throw new Exception("Some tests failed");
-    }
+        if (failed > 0) throw new AssertionError("Some tests failed");}
 }