author | martin |
Wed, 29 Jul 2009 13:56:15 -0700 | |
changeset 3419 | 3ae6dc68c20d |
parent 3415 | 79309d6eab38 |
child 5506 | 202f599c92aa |
permissions | -rw-r--r-- |
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/* |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Sun designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Sun in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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* CA 95054 USA or visit www.sun.com if you need additional information or |
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* have any questions. |
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*/ |
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/* |
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* This file is available under and governed by the GNU General Public |
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* License version 2 only, as published by the Free Software Foundation. |
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* However, the following notice accompanied the original version of this |
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* file: |
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* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/licenses/publicdomain |
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*/ |
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package java.util.concurrent; |
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import java.util.AbstractQueue; |
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import java.util.Collection; |
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import java.util.Iterator; |
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import java.util.NoSuchElementException; |
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import java.util.concurrent.locks.Condition; |
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import java.util.concurrent.locks.ReentrantLock; |
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/** |
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* An optionally-bounded {@linkplain BlockingDeque blocking deque} based on |
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* linked nodes. |
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* |
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* <p> The optional capacity bound constructor argument serves as a |
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* way to prevent excessive expansion. The capacity, if unspecified, |
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* is equal to {@link Integer#MAX_VALUE}. Linked nodes are |
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* dynamically created upon each insertion unless this would bring the |
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* deque above capacity. |
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* |
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* <p>Most operations run in constant time (ignoring time spent |
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* blocking). Exceptions include {@link #remove(Object) remove}, |
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* {@link #removeFirstOccurrence removeFirstOccurrence}, {@link |
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* #removeLastOccurrence removeLastOccurrence}, {@link #contains |
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* contains}, {@link #iterator iterator.remove()}, and the bulk |
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* operations, all of which run in linear time. |
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* |
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* <p>This class and its iterator implement all of the |
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* <em>optional</em> methods of the {@link Collection} and {@link |
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* Iterator} interfaces. |
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* |
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* <p>This class is a member of the |
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* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
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* Java Collections Framework</a>. |
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* |
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* @since 1.6 |
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* @author Doug Lea |
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* @param <E> the type of elements held in this collection |
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*/ |
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public class LinkedBlockingDeque<E> |
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extends AbstractQueue<E> |
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implements BlockingDeque<E>, java.io.Serializable { |
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/* |
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* Implemented as a simple doubly-linked list protected by a |
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* single lock and using conditions to manage blocking. |
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* |
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* To implement weakly consistent iterators, it appears we need to |
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* keep all Nodes GC-reachable from a predecessor dequeued Node. |
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* That would cause two problems: |
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* - allow a rogue Iterator to cause unbounded memory retention |
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* - cause cross-generational linking of old Nodes to new Nodes if |
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* a Node was tenured while live, which generational GCs have a |
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* hard time dealing with, causing repeated major collections. |
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* However, only non-deleted Nodes need to be reachable from |
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* dequeued Nodes, and reachability does not necessarily have to |
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* be of the kind understood by the GC. We use the trick of |
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* linking a Node that has just been dequeued to itself. Such a |
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* self-link implicitly means to jump to "first" (for next links) |
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* or "last" (for prev links). |
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*/ |
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/* |
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* We have "diamond" multiple interface/abstract class inheritance |
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* here, and that introduces ambiguities. Often we want the |
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* BlockingDeque javadoc combined with the AbstractQueue |
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* implementation, so a lot of method specs are duplicated here. |
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*/ |
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private static final long serialVersionUID = -387911632671998426L; |
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/** Doubly-linked list node class */ |
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static final class Node<E> { |
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/** |
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* The item, or null if this node has been removed. |
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*/ |
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E item; |
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/** |
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* One of: |
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* - the real predecessor Node |
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* - this Node, meaning the predecessor is tail |
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* - null, meaning there is no predecessor |
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*/ |
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Node<E> prev; |
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/** |
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* One of: |
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* - the real successor Node |
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* - this Node, meaning the successor is head |
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* - null, meaning there is no successor |
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*/ |
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Node<E> next; |
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Node(E x, Node<E> p, Node<E> n) { |
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item = x; |
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prev = p; |
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next = n; |
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} |
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} |
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/** |
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* Pointer to first node. |
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* Invariant: (first == null && last == null) || |
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* (first.prev == null && first.item != null) |
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*/ |
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transient Node<E> first; |
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/** |
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* Pointer to last node. |
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* Invariant: (first == null && last == null) || |
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* (last.next == null && last.item != null) |
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*/ |
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transient Node<E> last; |
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/** Number of items in the deque */ |
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private transient int count; |
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/** Maximum number of items in the deque */ |
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private final int capacity; |
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/** Main lock guarding all access */ |
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final ReentrantLock lock = new ReentrantLock(); |
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/** Condition for waiting takes */ |
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private final Condition notEmpty = lock.newCondition(); |
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/** Condition for waiting puts */ |
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private final Condition notFull = lock.newCondition(); |
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/** |
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* Creates a {@code LinkedBlockingDeque} with a capacity of |
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* {@link Integer#MAX_VALUE}. |
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*/ |
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public LinkedBlockingDeque() { |
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this(Integer.MAX_VALUE); |
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} |
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/** |
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* Creates a {@code LinkedBlockingDeque} with the given (fixed) capacity. |
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* |
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* @param capacity the capacity of this deque |
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* @throws IllegalArgumentException if {@code capacity} is less than 1 |
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*/ |
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public LinkedBlockingDeque(int capacity) { |
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if (capacity <= 0) throw new IllegalArgumentException(); |
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this.capacity = capacity; |
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} |
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/** |
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* Creates a {@code LinkedBlockingDeque} with a capacity of |
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* {@link Integer#MAX_VALUE}, initially containing the elements of |
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* the given collection, added in traversal order of the |
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* collection's iterator. |
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* |
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* @param c the collection of elements to initially contain |
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* @throws NullPointerException if the specified collection or any |
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* of its elements are null |
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*/ |
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public LinkedBlockingDeque(Collection<? extends E> c) { |
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this(Integer.MAX_VALUE); |
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final ReentrantLock lock = this.lock; |
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lock.lock(); // Never contended, but necessary for visibility |
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try { |
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for (E e : c) { |
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if (e == null) |
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throw new NullPointerException(); |
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if (!linkLast(e)) |
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throw new IllegalStateException("Deque full"); |
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} |
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} finally { |
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lock.unlock(); |
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} |
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} |
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// Basic linking and unlinking operations, called only while holding lock |
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/** |
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* Links e as first element, or returns false if full. |
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*/ |
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private boolean linkFirst(E e) { |
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// assert lock.isHeldByCurrentThread(); |
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if (count >= capacity) |
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return false; |
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Node<E> f = first; |
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Node<E> x = new Node<E>(e, null, f); |
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first = x; |
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if (last == null) |
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last = x; |
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else |
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f.prev = x; |
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++count; |
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notEmpty.signal(); |
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return true; |
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} |
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/** |
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* Links e as last element, or returns false if full. |
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*/ |
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private boolean linkLast(E e) { |
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// assert lock.isHeldByCurrentThread(); |
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if (count >= capacity) |
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return false; |
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Node<E> l = last; |
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Node<E> x = new Node<E>(e, l, null); |
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last = x; |
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if (first == null) |
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first = x; |
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else |
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l.next = x; |
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++count; |
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notEmpty.signal(); |
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return true; |
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} |
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/** |
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* Removes and returns first element, or null if empty. |
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*/ |
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private E unlinkFirst() { |
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// assert lock.isHeldByCurrentThread(); |
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Node<E> f = first; |
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if (f == null) |
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return null; |
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Node<E> n = f.next; |
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E item = f.item; |
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261 |
f.item = null; |
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262 |
f.next = f; // help GC |
2 | 263 |
first = n; |
264 |
if (n == null) |
|
265 |
last = null; |
|
266 |
else |
|
267 |
n.prev = null; |
|
268 |
--count; |
|
269 |
notFull.signal(); |
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270 |
return item; |
2 | 271 |
} |
272 |
||
273 |
/** |
|
274 |
* Removes and returns last element, or null if empty. |
|
275 |
*/ |
|
276 |
private E unlinkLast() { |
|
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277 |
// assert lock.isHeldByCurrentThread(); |
2 | 278 |
Node<E> l = last; |
279 |
if (l == null) |
|
280 |
return null; |
|
281 |
Node<E> p = l.prev; |
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E item = l.item; |
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283 |
l.item = null; |
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284 |
l.prev = l; // help GC |
2 | 285 |
last = p; |
286 |
if (p == null) |
|
287 |
first = null; |
|
288 |
else |
|
289 |
p.next = null; |
|
290 |
--count; |
|
291 |
notFull.signal(); |
|
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292 |
return item; |
2 | 293 |
} |
294 |
||
295 |
/** |
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296 |
* Unlinks x. |
2 | 297 |
*/ |
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298 |
void unlink(Node<E> x) { |
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|
299 |
// assert lock.isHeldByCurrentThread(); |
2 | 300 |
Node<E> p = x.prev; |
301 |
Node<E> n = x.next; |
|
302 |
if (p == null) { |
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303 |
unlinkFirst(); |
2 | 304 |
} else if (n == null) { |
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305 |
unlinkLast(); |
2 | 306 |
} else { |
307 |
p.next = n; |
|
308 |
n.prev = p; |
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309 |
x.item = null; |
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310 |
// Don't mess with x's links. They may still be in use by |
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311 |
// an iterator. |
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312 |
--count; |
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|
313 |
notFull.signal(); |
2 | 314 |
} |
315 |
} |
|
316 |
||
317 |
// BlockingDeque methods |
|
318 |
||
319 |
/** |
|
320 |
* @throws IllegalStateException {@inheritDoc} |
|
321 |
* @throws NullPointerException {@inheritDoc} |
|
322 |
*/ |
|
323 |
public void addFirst(E e) { |
|
324 |
if (!offerFirst(e)) |
|
325 |
throw new IllegalStateException("Deque full"); |
|
326 |
} |
|
327 |
||
328 |
/** |
|
329 |
* @throws IllegalStateException {@inheritDoc} |
|
330 |
* @throws NullPointerException {@inheritDoc} |
|
331 |
*/ |
|
332 |
public void addLast(E e) { |
|
333 |
if (!offerLast(e)) |
|
334 |
throw new IllegalStateException("Deque full"); |
|
335 |
} |
|
336 |
||
337 |
/** |
|
338 |
* @throws NullPointerException {@inheritDoc} |
|
339 |
*/ |
|
340 |
public boolean offerFirst(E e) { |
|
341 |
if (e == null) throw new NullPointerException(); |
|
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342 |
final ReentrantLock lock = this.lock; |
2 | 343 |
lock.lock(); |
344 |
try { |
|
345 |
return linkFirst(e); |
|
346 |
} finally { |
|
347 |
lock.unlock(); |
|
348 |
} |
|
349 |
} |
|
350 |
||
351 |
/** |
|
352 |
* @throws NullPointerException {@inheritDoc} |
|
353 |
*/ |
|
354 |
public boolean offerLast(E e) { |
|
355 |
if (e == null) throw new NullPointerException(); |
|
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|
356 |
final ReentrantLock lock = this.lock; |
2 | 357 |
lock.lock(); |
358 |
try { |
|
359 |
return linkLast(e); |
|
360 |
} finally { |
|
361 |
lock.unlock(); |
|
362 |
} |
|
363 |
} |
|
364 |
||
365 |
/** |
|
366 |
* @throws NullPointerException {@inheritDoc} |
|
367 |
* @throws InterruptedException {@inheritDoc} |
|
368 |
*/ |
|
369 |
public void putFirst(E e) throws InterruptedException { |
|
370 |
if (e == null) throw new NullPointerException(); |
|
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|
371 |
final ReentrantLock lock = this.lock; |
2 | 372 |
lock.lock(); |
373 |
try { |
|
374 |
while (!linkFirst(e)) |
|
375 |
notFull.await(); |
|
376 |
} finally { |
|
377 |
lock.unlock(); |
|
378 |
} |
|
379 |
} |
|
380 |
||
381 |
/** |
|
382 |
* @throws NullPointerException {@inheritDoc} |
|
383 |
* @throws InterruptedException {@inheritDoc} |
|
384 |
*/ |
|
385 |
public void putLast(E e) throws InterruptedException { |
|
386 |
if (e == null) throw new NullPointerException(); |
|
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|
387 |
final ReentrantLock lock = this.lock; |
2 | 388 |
lock.lock(); |
389 |
try { |
|
390 |
while (!linkLast(e)) |
|
391 |
notFull.await(); |
|
392 |
} finally { |
|
393 |
lock.unlock(); |
|
394 |
} |
|
395 |
} |
|
396 |
||
397 |
/** |
|
398 |
* @throws NullPointerException {@inheritDoc} |
|
399 |
* @throws InterruptedException {@inheritDoc} |
|
400 |
*/ |
|
401 |
public boolean offerFirst(E e, long timeout, TimeUnit unit) |
|
402 |
throws InterruptedException { |
|
403 |
if (e == null) throw new NullPointerException(); |
|
404 |
long nanos = unit.toNanos(timeout); |
|
3415
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|
405 |
final ReentrantLock lock = this.lock; |
2 | 406 |
lock.lockInterruptibly(); |
407 |
try { |
|
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|
408 |
while (!linkFirst(e)) { |
2 | 409 |
if (nanos <= 0) |
410 |
return false; |
|
411 |
nanos = notFull.awaitNanos(nanos); |
|
412 |
} |
|
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|
413 |
return true; |
2 | 414 |
} finally { |
415 |
lock.unlock(); |
|
416 |
} |
|
417 |
} |
|
418 |
||
419 |
/** |
|
420 |
* @throws NullPointerException {@inheritDoc} |
|
421 |
* @throws InterruptedException {@inheritDoc} |
|
422 |
*/ |
|
423 |
public boolean offerLast(E e, long timeout, TimeUnit unit) |
|
424 |
throws InterruptedException { |
|
425 |
if (e == null) throw new NullPointerException(); |
|
426 |
long nanos = unit.toNanos(timeout); |
|
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|
427 |
final ReentrantLock lock = this.lock; |
2 | 428 |
lock.lockInterruptibly(); |
429 |
try { |
|
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|
430 |
while (!linkLast(e)) { |
2 | 431 |
if (nanos <= 0) |
432 |
return false; |
|
433 |
nanos = notFull.awaitNanos(nanos); |
|
434 |
} |
|
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|
435 |
return true; |
2 | 436 |
} finally { |
437 |
lock.unlock(); |
|
438 |
} |
|
439 |
} |
|
440 |
||
441 |
/** |
|
442 |
* @throws NoSuchElementException {@inheritDoc} |
|
443 |
*/ |
|
444 |
public E removeFirst() { |
|
445 |
E x = pollFirst(); |
|
446 |
if (x == null) throw new NoSuchElementException(); |
|
447 |
return x; |
|
448 |
} |
|
449 |
||
450 |
/** |
|
451 |
* @throws NoSuchElementException {@inheritDoc} |
|
452 |
*/ |
|
453 |
public E removeLast() { |
|
454 |
E x = pollLast(); |
|
455 |
if (x == null) throw new NoSuchElementException(); |
|
456 |
return x; |
|
457 |
} |
|
458 |
||
459 |
public E pollFirst() { |
|
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|
460 |
final ReentrantLock lock = this.lock; |
2 | 461 |
lock.lock(); |
462 |
try { |
|
463 |
return unlinkFirst(); |
|
464 |
} finally { |
|
465 |
lock.unlock(); |
|
466 |
} |
|
467 |
} |
|
468 |
||
469 |
public E pollLast() { |
|
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|
470 |
final ReentrantLock lock = this.lock; |
2 | 471 |
lock.lock(); |
472 |
try { |
|
473 |
return unlinkLast(); |
|
474 |
} finally { |
|
475 |
lock.unlock(); |
|
476 |
} |
|
477 |
} |
|
478 |
||
479 |
public E takeFirst() throws InterruptedException { |
|
3415
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|
480 |
final ReentrantLock lock = this.lock; |
2 | 481 |
lock.lock(); |
482 |
try { |
|
483 |
E x; |
|
484 |
while ( (x = unlinkFirst()) == null) |
|
485 |
notEmpty.await(); |
|
486 |
return x; |
|
487 |
} finally { |
|
488 |
lock.unlock(); |
|
489 |
} |
|
490 |
} |
|
491 |
||
492 |
public E takeLast() throws InterruptedException { |
|
3415
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|
493 |
final ReentrantLock lock = this.lock; |
2 | 494 |
lock.lock(); |
495 |
try { |
|
496 |
E x; |
|
497 |
while ( (x = unlinkLast()) == null) |
|
498 |
notEmpty.await(); |
|
499 |
return x; |
|
500 |
} finally { |
|
501 |
lock.unlock(); |
|
502 |
} |
|
503 |
} |
|
504 |
||
505 |
public E pollFirst(long timeout, TimeUnit unit) |
|
506 |
throws InterruptedException { |
|
507 |
long nanos = unit.toNanos(timeout); |
|
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changeset
|
508 |
final ReentrantLock lock = this.lock; |
2 | 509 |
lock.lockInterruptibly(); |
510 |
try { |
|
3415
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changeset
|
511 |
E x; |
79309d6eab38
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diff
changeset
|
512 |
while ( (x = unlinkFirst()) == null) { |
2 | 513 |
if (nanos <= 0) |
514 |
return null; |
|
515 |
nanos = notEmpty.awaitNanos(nanos); |
|
516 |
} |
|
3415
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changeset
|
517 |
return x; |
2 | 518 |
} finally { |
519 |
lock.unlock(); |
|
520 |
} |
|
521 |
} |
|
522 |
||
523 |
public E pollLast(long timeout, TimeUnit unit) |
|
524 |
throws InterruptedException { |
|
525 |
long nanos = unit.toNanos(timeout); |
|
3415
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changeset
|
526 |
final ReentrantLock lock = this.lock; |
2 | 527 |
lock.lockInterruptibly(); |
528 |
try { |
|
3415
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changeset
|
529 |
E x; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
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parents:
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diff
changeset
|
530 |
while ( (x = unlinkLast()) == null) { |
2 | 531 |
if (nanos <= 0) |
532 |
return null; |
|
533 |
nanos = notEmpty.awaitNanos(nanos); |
|
534 |
} |
|
3415
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|
535 |
return x; |
2 | 536 |
} finally { |
537 |
lock.unlock(); |
|
538 |
} |
|
539 |
} |
|
540 |
||
541 |
/** |
|
542 |
* @throws NoSuchElementException {@inheritDoc} |
|
543 |
*/ |
|
544 |
public E getFirst() { |
|
545 |
E x = peekFirst(); |
|
546 |
if (x == null) throw new NoSuchElementException(); |
|
547 |
return x; |
|
548 |
} |
|
549 |
||
550 |
/** |
|
551 |
* @throws NoSuchElementException {@inheritDoc} |
|
552 |
*/ |
|
553 |
public E getLast() { |
|
554 |
E x = peekLast(); |
|
555 |
if (x == null) throw new NoSuchElementException(); |
|
556 |
return x; |
|
557 |
} |
|
558 |
||
559 |
public E peekFirst() { |
|
3415
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changeset
|
560 |
final ReentrantLock lock = this.lock; |
2 | 561 |
lock.lock(); |
562 |
try { |
|
563 |
return (first == null) ? null : first.item; |
|
564 |
} finally { |
|
565 |
lock.unlock(); |
|
566 |
} |
|
567 |
} |
|
568 |
||
569 |
public E peekLast() { |
|
3415
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changeset
|
570 |
final ReentrantLock lock = this.lock; |
2 | 571 |
lock.lock(); |
572 |
try { |
|
573 |
return (last == null) ? null : last.item; |
|
574 |
} finally { |
|
575 |
lock.unlock(); |
|
576 |
} |
|
577 |
} |
|
578 |
||
579 |
public boolean removeFirstOccurrence(Object o) { |
|
580 |
if (o == null) return false; |
|
3415
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changeset
|
581 |
final ReentrantLock lock = this.lock; |
2 | 582 |
lock.lock(); |
583 |
try { |
|
584 |
for (Node<E> p = first; p != null; p = p.next) { |
|
585 |
if (o.equals(p.item)) { |
|
586 |
unlink(p); |
|
587 |
return true; |
|
588 |
} |
|
589 |
} |
|
590 |
return false; |
|
591 |
} finally { |
|
592 |
lock.unlock(); |
|
593 |
} |
|
594 |
} |
|
595 |
||
596 |
public boolean removeLastOccurrence(Object o) { |
|
597 |
if (o == null) return false; |
|
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changeset
|
598 |
final ReentrantLock lock = this.lock; |
2 | 599 |
lock.lock(); |
600 |
try { |
|
601 |
for (Node<E> p = last; p != null; p = p.prev) { |
|
602 |
if (o.equals(p.item)) { |
|
603 |
unlink(p); |
|
604 |
return true; |
|
605 |
} |
|
606 |
} |
|
607 |
return false; |
|
608 |
} finally { |
|
609 |
lock.unlock(); |
|
610 |
} |
|
611 |
} |
|
612 |
||
613 |
// BlockingQueue methods |
|
614 |
||
615 |
/** |
|
616 |
* Inserts the specified element at the end of this deque unless it would |
|
617 |
* violate capacity restrictions. When using a capacity-restricted deque, |
|
618 |
* it is generally preferable to use method {@link #offer(Object) offer}. |
|
619 |
* |
|
620 |
* <p>This method is equivalent to {@link #addLast}. |
|
621 |
* |
|
622 |
* @throws IllegalStateException if the element cannot be added at this |
|
623 |
* time due to capacity restrictions |
|
624 |
* @throws NullPointerException if the specified element is null |
|
625 |
*/ |
|
626 |
public boolean add(E e) { |
|
627 |
addLast(e); |
|
628 |
return true; |
|
629 |
} |
|
630 |
||
631 |
/** |
|
632 |
* @throws NullPointerException if the specified element is null |
|
633 |
*/ |
|
634 |
public boolean offer(E e) { |
|
635 |
return offerLast(e); |
|
636 |
} |
|
637 |
||
638 |
/** |
|
639 |
* @throws NullPointerException {@inheritDoc} |
|
640 |
* @throws InterruptedException {@inheritDoc} |
|
641 |
*/ |
|
642 |
public void put(E e) throws InterruptedException { |
|
643 |
putLast(e); |
|
644 |
} |
|
645 |
||
646 |
/** |
|
647 |
* @throws NullPointerException {@inheritDoc} |
|
648 |
* @throws InterruptedException {@inheritDoc} |
|
649 |
*/ |
|
650 |
public boolean offer(E e, long timeout, TimeUnit unit) |
|
651 |
throws InterruptedException { |
|
652 |
return offerLast(e, timeout, unit); |
|
653 |
} |
|
654 |
||
655 |
/** |
|
656 |
* Retrieves and removes the head of the queue represented by this deque. |
|
657 |
* This method differs from {@link #poll poll} only in that it throws an |
|
658 |
* exception if this deque is empty. |
|
659 |
* |
|
660 |
* <p>This method is equivalent to {@link #removeFirst() removeFirst}. |
|
661 |
* |
|
662 |
* @return the head of the queue represented by this deque |
|
663 |
* @throws NoSuchElementException if this deque is empty |
|
664 |
*/ |
|
665 |
public E remove() { |
|
666 |
return removeFirst(); |
|
667 |
} |
|
668 |
||
669 |
public E poll() { |
|
670 |
return pollFirst(); |
|
671 |
} |
|
672 |
||
673 |
public E take() throws InterruptedException { |
|
674 |
return takeFirst(); |
|
675 |
} |
|
676 |
||
677 |
public E poll(long timeout, TimeUnit unit) throws InterruptedException { |
|
678 |
return pollFirst(timeout, unit); |
|
679 |
} |
|
680 |
||
681 |
/** |
|
682 |
* Retrieves, but does not remove, the head of the queue represented by |
|
683 |
* this deque. This method differs from {@link #peek peek} only in that |
|
684 |
* it throws an exception if this deque is empty. |
|
685 |
* |
|
686 |
* <p>This method is equivalent to {@link #getFirst() getFirst}. |
|
687 |
* |
|
688 |
* @return the head of the queue represented by this deque |
|
689 |
* @throws NoSuchElementException if this deque is empty |
|
690 |
*/ |
|
691 |
public E element() { |
|
692 |
return getFirst(); |
|
693 |
} |
|
694 |
||
695 |
public E peek() { |
|
696 |
return peekFirst(); |
|
697 |
} |
|
698 |
||
699 |
/** |
|
700 |
* Returns the number of additional elements that this deque can ideally |
|
701 |
* (in the absence of memory or resource constraints) accept without |
|
702 |
* blocking. This is always equal to the initial capacity of this deque |
|
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|
703 |
* less the current {@code size} of this deque. |
2 | 704 |
* |
705 |
* <p>Note that you <em>cannot</em> always tell if an attempt to insert |
|
3415
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changeset
|
706 |
* an element will succeed by inspecting {@code remainingCapacity} |
2 | 707 |
* because it may be the case that another thread is about to |
708 |
* insert or remove an element. |
|
709 |
*/ |
|
710 |
public int remainingCapacity() { |
|
3415
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changeset
|
711 |
final ReentrantLock lock = this.lock; |
2 | 712 |
lock.lock(); |
713 |
try { |
|
714 |
return capacity - count; |
|
715 |
} finally { |
|
716 |
lock.unlock(); |
|
717 |
} |
|
718 |
} |
|
719 |
||
720 |
/** |
|
721 |
* @throws UnsupportedOperationException {@inheritDoc} |
|
722 |
* @throws ClassCastException {@inheritDoc} |
|
723 |
* @throws NullPointerException {@inheritDoc} |
|
724 |
* @throws IllegalArgumentException {@inheritDoc} |
|
725 |
*/ |
|
726 |
public int drainTo(Collection<? super E> c) { |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
727 |
return drainTo(c, Integer.MAX_VALUE); |
2 | 728 |
} |
729 |
||
730 |
/** |
|
731 |
* @throws UnsupportedOperationException {@inheritDoc} |
|
732 |
* @throws ClassCastException {@inheritDoc} |
|
733 |
* @throws NullPointerException {@inheritDoc} |
|
734 |
* @throws IllegalArgumentException {@inheritDoc} |
|
735 |
*/ |
|
736 |
public int drainTo(Collection<? super E> c, int maxElements) { |
|
737 |
if (c == null) |
|
738 |
throw new NullPointerException(); |
|
739 |
if (c == this) |
|
740 |
throw new IllegalArgumentException(); |
|
3415
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dl
parents:
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diff
changeset
|
741 |
final ReentrantLock lock = this.lock; |
2 | 742 |
lock.lock(); |
743 |
try { |
|
3415
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6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
744 |
int n = Math.min(maxElements, count); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
745 |
for (int i = 0; i < n; i++) { |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
746 |
c.add(first.item); // In this order, in case add() throws. |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
747 |
unlinkFirst(); |
2 | 748 |
} |
749 |
return n; |
|
750 |
} finally { |
|
751 |
lock.unlock(); |
|
752 |
} |
|
753 |
} |
|
754 |
||
755 |
// Stack methods |
|
756 |
||
757 |
/** |
|
758 |
* @throws IllegalStateException {@inheritDoc} |
|
759 |
* @throws NullPointerException {@inheritDoc} |
|
760 |
*/ |
|
761 |
public void push(E e) { |
|
762 |
addFirst(e); |
|
763 |
} |
|
764 |
||
765 |
/** |
|
766 |
* @throws NoSuchElementException {@inheritDoc} |
|
767 |
*/ |
|
768 |
public E pop() { |
|
769 |
return removeFirst(); |
|
770 |
} |
|
771 |
||
772 |
// Collection methods |
|
773 |
||
774 |
/** |
|
775 |
* Removes the first occurrence of the specified element from this deque. |
|
776 |
* If the deque does not contain the element, it is unchanged. |
|
3415
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dl
parents:
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diff
changeset
|
777 |
* More formally, removes the first element {@code e} such that |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
778 |
* {@code o.equals(e)} (if such an element exists). |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
779 |
* Returns {@code true} if this deque contained the specified element |
2 | 780 |
* (or equivalently, if this deque changed as a result of the call). |
781 |
* |
|
782 |
* <p>This method is equivalent to |
|
783 |
* {@link #removeFirstOccurrence(Object) removeFirstOccurrence}. |
|
784 |
* |
|
785 |
* @param o element to be removed from this deque, if present |
|
3415
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dl
parents:
2
diff
changeset
|
786 |
* @return {@code true} if this deque changed as a result of the call |
2 | 787 |
*/ |
788 |
public boolean remove(Object o) { |
|
789 |
return removeFirstOccurrence(o); |
|
790 |
} |
|
791 |
||
792 |
/** |
|
793 |
* Returns the number of elements in this deque. |
|
794 |
* |
|
795 |
* @return the number of elements in this deque |
|
796 |
*/ |
|
797 |
public int size() { |
|
3415
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dl
parents:
2
diff
changeset
|
798 |
final ReentrantLock lock = this.lock; |
2 | 799 |
lock.lock(); |
800 |
try { |
|
801 |
return count; |
|
802 |
} finally { |
|
803 |
lock.unlock(); |
|
804 |
} |
|
805 |
} |
|
806 |
||
807 |
/** |
|
3415
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6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
808 |
* Returns {@code true} if this deque contains the specified element. |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
809 |
* More formally, returns {@code true} if and only if this deque contains |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
810 |
* at least one element {@code e} such that {@code o.equals(e)}. |
2 | 811 |
* |
812 |
* @param o object to be checked for containment in this deque |
|
3415
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dl
parents:
2
diff
changeset
|
813 |
* @return {@code true} if this deque contains the specified element |
2 | 814 |
*/ |
815 |
public boolean contains(Object o) { |
|
816 |
if (o == null) return false; |
|
3415
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dl
parents:
2
diff
changeset
|
817 |
final ReentrantLock lock = this.lock; |
2 | 818 |
lock.lock(); |
819 |
try { |
|
820 |
for (Node<E> p = first; p != null; p = p.next) |
|
821 |
if (o.equals(p.item)) |
|
822 |
return true; |
|
823 |
return false; |
|
824 |
} finally { |
|
825 |
lock.unlock(); |
|
826 |
} |
|
827 |
} |
|
828 |
||
3415
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6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
829 |
/* |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
830 |
* TODO: Add support for more efficient bulk operations. |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
831 |
* |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
832 |
* We don't want to acquire the lock for every iteration, but we |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
833 |
* also want other threads a chance to interact with the |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
834 |
* collection, especially when count is close to capacity. |
2 | 835 |
*/ |
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
836 |
|
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
837 |
// /** |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
838 |
// * Adds all of the elements in the specified collection to this |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
839 |
// * queue. Attempts to addAll of a queue to itself result in |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
840 |
// * {@code IllegalArgumentException}. Further, the behavior of |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
841 |
// * this operation is undefined if the specified collection is |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
842 |
// * modified while the operation is in progress. |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
843 |
// * |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
844 |
// * @param c collection containing elements to be added to this queue |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
845 |
// * @return {@code true} if this queue changed as a result of the call |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
846 |
// * @throws ClassCastException {@inheritDoc} |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
847 |
// * @throws NullPointerException {@inheritDoc} |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
848 |
// * @throws IllegalArgumentException {@inheritDoc} |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
849 |
// * @throws IllegalStateException {@inheritDoc} |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
850 |
// * @see #add(Object) |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
851 |
// */ |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
852 |
// public boolean addAll(Collection<? extends E> c) { |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
853 |
// if (c == null) |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
854 |
// throw new NullPointerException(); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
855 |
// if (c == this) |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
856 |
// throw new IllegalArgumentException(); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
857 |
// final ReentrantLock lock = this.lock; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
858 |
// lock.lock(); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
859 |
// try { |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
860 |
// boolean modified = false; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
861 |
// for (E e : c) |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
862 |
// if (linkLast(e)) |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
863 |
// modified = true; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
864 |
// return modified; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
865 |
// } finally { |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
866 |
// lock.unlock(); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
867 |
// } |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
868 |
// } |
2 | 869 |
|
870 |
/** |
|
871 |
* Returns an array containing all of the elements in this deque, in |
|
872 |
* proper sequence (from first to last element). |
|
873 |
* |
|
874 |
* <p>The returned array will be "safe" in that no references to it are |
|
875 |
* maintained by this deque. (In other words, this method must allocate |
|
876 |
* a new array). The caller is thus free to modify the returned array. |
|
877 |
* |
|
878 |
* <p>This method acts as bridge between array-based and collection-based |
|
879 |
* APIs. |
|
880 |
* |
|
881 |
* @return an array containing all of the elements in this deque |
|
882 |
*/ |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
883 |
@SuppressWarnings("unchecked") |
2 | 884 |
public Object[] toArray() { |
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
885 |
final ReentrantLock lock = this.lock; |
2 | 886 |
lock.lock(); |
887 |
try { |
|
888 |
Object[] a = new Object[count]; |
|
889 |
int k = 0; |
|
890 |
for (Node<E> p = first; p != null; p = p.next) |
|
891 |
a[k++] = p.item; |
|
892 |
return a; |
|
893 |
} finally { |
|
894 |
lock.unlock(); |
|
895 |
} |
|
896 |
} |
|
897 |
||
898 |
/** |
|
899 |
* Returns an array containing all of the elements in this deque, in |
|
900 |
* proper sequence; the runtime type of the returned array is that of |
|
901 |
* the specified array. If the deque fits in the specified array, it |
|
902 |
* is returned therein. Otherwise, a new array is allocated with the |
|
903 |
* runtime type of the specified array and the size of this deque. |
|
904 |
* |
|
905 |
* <p>If this deque fits in the specified array with room to spare |
|
906 |
* (i.e., the array has more elements than this deque), the element in |
|
907 |
* the array immediately following the end of the deque is set to |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
908 |
* {@code null}. |
2 | 909 |
* |
910 |
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
|
911 |
* array-based and collection-based APIs. Further, this method allows |
|
912 |
* precise control over the runtime type of the output array, and may, |
|
913 |
* under certain circumstances, be used to save allocation costs. |
|
914 |
* |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
915 |
* <p>Suppose {@code x} is a deque known to contain only strings. |
2 | 916 |
* The following code can be used to dump the deque into a newly |
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
917 |
* allocated array of {@code String}: |
2 | 918 |
* |
919 |
* <pre> |
|
920 |
* String[] y = x.toArray(new String[0]);</pre> |
|
921 |
* |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
922 |
* Note that {@code toArray(new Object[0])} is identical in function to |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
923 |
* {@code toArray()}. |
2 | 924 |
* |
925 |
* @param a the array into which the elements of the deque are to |
|
926 |
* be stored, if it is big enough; otherwise, a new array of the |
|
927 |
* same runtime type is allocated for this purpose |
|
928 |
* @return an array containing all of the elements in this deque |
|
929 |
* @throws ArrayStoreException if the runtime type of the specified array |
|
930 |
* is not a supertype of the runtime type of every element in |
|
931 |
* this deque |
|
932 |
* @throws NullPointerException if the specified array is null |
|
933 |
*/ |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
934 |
@SuppressWarnings("unchecked") |
2 | 935 |
public <T> T[] toArray(T[] a) { |
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
936 |
final ReentrantLock lock = this.lock; |
2 | 937 |
lock.lock(); |
938 |
try { |
|
939 |
if (a.length < count) |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
940 |
a = (T[])java.lang.reflect.Array.newInstance |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
941 |
(a.getClass().getComponentType(), count); |
2 | 942 |
|
943 |
int k = 0; |
|
944 |
for (Node<E> p = first; p != null; p = p.next) |
|
945 |
a[k++] = (T)p.item; |
|
946 |
if (a.length > k) |
|
947 |
a[k] = null; |
|
948 |
return a; |
|
949 |
} finally { |
|
950 |
lock.unlock(); |
|
951 |
} |
|
952 |
} |
|
953 |
||
954 |
public String toString() { |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
955 |
final ReentrantLock lock = this.lock; |
2 | 956 |
lock.lock(); |
957 |
try { |
|
958 |
return super.toString(); |
|
959 |
} finally { |
|
960 |
lock.unlock(); |
|
961 |
} |
|
962 |
} |
|
963 |
||
964 |
/** |
|
965 |
* Atomically removes all of the elements from this deque. |
|
966 |
* The deque will be empty after this call returns. |
|
967 |
*/ |
|
968 |
public void clear() { |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
969 |
final ReentrantLock lock = this.lock; |
2 | 970 |
lock.lock(); |
971 |
try { |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
972 |
for (Node<E> f = first; f != null; ) { |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
973 |
f.item = null; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
974 |
Node<E> n = f.next; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
975 |
f.prev = null; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
976 |
f.next = null; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
977 |
f = n; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
978 |
} |
2 | 979 |
first = last = null; |
980 |
count = 0; |
|
981 |
notFull.signalAll(); |
|
982 |
} finally { |
|
983 |
lock.unlock(); |
|
984 |
} |
|
985 |
} |
|
986 |
||
987 |
/** |
|
988 |
* Returns an iterator over the elements in this deque in proper sequence. |
|
989 |
* The elements will be returned in order from first (head) to last (tail). |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
990 |
* The returned {@code Iterator} is a "weakly consistent" iterator that |
3419 | 991 |
* will never throw {@link java.util.ConcurrentModificationException |
992 |
* ConcurrentModificationException}, |
|
2 | 993 |
* and guarantees to traverse elements as they existed upon |
994 |
* construction of the iterator, and may (but is not guaranteed to) |
|
995 |
* reflect any modifications subsequent to construction. |
|
996 |
* |
|
997 |
* @return an iterator over the elements in this deque in proper sequence |
|
998 |
*/ |
|
999 |
public Iterator<E> iterator() { |
|
1000 |
return new Itr(); |
|
1001 |
} |
|
1002 |
||
1003 |
/** |
|
1004 |
* Returns an iterator over the elements in this deque in reverse |
|
1005 |
* sequential order. The elements will be returned in order from |
|
1006 |
* last (tail) to first (head). |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1007 |
* The returned {@code Iterator} is a "weakly consistent" iterator that |
3419 | 1008 |
* will never throw {@link java.util.ConcurrentModificationException |
1009 |
* ConcurrentModificationException}, |
|
2 | 1010 |
* and guarantees to traverse elements as they existed upon |
1011 |
* construction of the iterator, and may (but is not guaranteed to) |
|
1012 |
* reflect any modifications subsequent to construction. |
|
1013 |
*/ |
|
1014 |
public Iterator<E> descendingIterator() { |
|
1015 |
return new DescendingItr(); |
|
1016 |
} |
|
1017 |
||
1018 |
/** |
|
1019 |
* Base class for Iterators for LinkedBlockingDeque |
|
1020 |
*/ |
|
1021 |
private abstract class AbstractItr implements Iterator<E> { |
|
1022 |
/** |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1023 |
* The next node to return in next() |
2 | 1024 |
*/ |
1025 |
Node<E> next; |
|
1026 |
||
1027 |
/** |
|
1028 |
* nextItem holds on to item fields because once we claim that |
|
1029 |
* an element exists in hasNext(), we must return item read |
|
1030 |
* under lock (in advance()) even if it was in the process of |
|
1031 |
* being removed when hasNext() was called. |
|
1032 |
*/ |
|
1033 |
E nextItem; |
|
1034 |
||
1035 |
/** |
|
1036 |
* Node returned by most recent call to next. Needed by remove. |
|
1037 |
* Reset to null if this element is deleted by a call to remove. |
|
1038 |
*/ |
|
1039 |
private Node<E> lastRet; |
|
1040 |
||
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1041 |
abstract Node<E> firstNode(); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1042 |
abstract Node<E> nextNode(Node<E> n); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1043 |
|
2 | 1044 |
AbstractItr() { |
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1045 |
// set to initial position |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1046 |
final ReentrantLock lock = LinkedBlockingDeque.this.lock; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1047 |
lock.lock(); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1048 |
try { |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1049 |
next = firstNode(); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1050 |
nextItem = (next == null) ? null : next.item; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1051 |
} finally { |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1052 |
lock.unlock(); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1053 |
} |
2 | 1054 |
} |
1055 |
||
1056 |
/** |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1057 |
* Advances next. |
2 | 1058 |
*/ |
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1059 |
void advance() { |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1060 |
final ReentrantLock lock = LinkedBlockingDeque.this.lock; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1061 |
lock.lock(); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1062 |
try { |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1063 |
// assert next != null; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1064 |
Node<E> s = nextNode(next); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1065 |
if (s == next) { |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1066 |
next = firstNode(); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1067 |
} else { |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1068 |
// Skip over removed nodes. |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1069 |
// May be necessary if multiple interior Nodes are removed. |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1070 |
while (s != null && s.item == null) |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1071 |
s = nextNode(s); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1072 |
next = s; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1073 |
} |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1074 |
nextItem = (next == null) ? null : next.item; |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1075 |
} finally { |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1076 |
lock.unlock(); |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1077 |
} |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1078 |
} |
2 | 1079 |
|
1080 |
public boolean hasNext() { |
|
1081 |
return next != null; |
|
1082 |
} |
|
1083 |
||
1084 |
public E next() { |
|
1085 |
if (next == null) |
|
1086 |
throw new NoSuchElementException(); |
|
1087 |
lastRet = next; |
|
1088 |
E x = nextItem; |
|
1089 |
advance(); |
|
1090 |
return x; |
|
1091 |
} |
|
1092 |
||
1093 |
public void remove() { |
|
1094 |
Node<E> n = lastRet; |
|
1095 |
if (n == null) |
|
1096 |
throw new IllegalStateException(); |
|
1097 |
lastRet = null; |
|
1098 |
final ReentrantLock lock = LinkedBlockingDeque.this.lock; |
|
1099 |
lock.lock(); |
|
1100 |
try { |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1101 |
if (n.item != null) |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1102 |
unlink(n); |
2 | 1103 |
} finally { |
1104 |
lock.unlock(); |
|
1105 |
} |
|
1106 |
} |
|
1107 |
} |
|
1108 |
||
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1109 |
/** Forward iterator */ |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1110 |
private class Itr extends AbstractItr { |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1111 |
Node<E> firstNode() { return first; } |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1112 |
Node<E> nextNode(Node<E> n) { return n.next; } |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1113 |
} |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1114 |
|
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1115 |
/** Descending iterator */ |
2 | 1116 |
private class DescendingItr extends AbstractItr { |
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1117 |
Node<E> firstNode() { return last; } |
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1118 |
Node<E> nextNode(Node<E> n) { return n.prev; } |
2 | 1119 |
} |
1120 |
||
1121 |
/** |
|
1122 |
* Save the state of this deque to a stream (that is, serialize it). |
|
1123 |
* |
|
1124 |
* @serialData The capacity (int), followed by elements (each an |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1125 |
* {@code Object}) in the proper order, followed by a null |
2 | 1126 |
* @param s the stream |
1127 |
*/ |
|
1128 |
private void writeObject(java.io.ObjectOutputStream s) |
|
1129 |
throws java.io.IOException { |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1130 |
final ReentrantLock lock = this.lock; |
2 | 1131 |
lock.lock(); |
1132 |
try { |
|
1133 |
// Write out capacity and any hidden stuff |
|
1134 |
s.defaultWriteObject(); |
|
1135 |
// Write out all elements in the proper order. |
|
1136 |
for (Node<E> p = first; p != null; p = p.next) |
|
1137 |
s.writeObject(p.item); |
|
1138 |
// Use trailing null as sentinel |
|
1139 |
s.writeObject(null); |
|
1140 |
} finally { |
|
1141 |
lock.unlock(); |
|
1142 |
} |
|
1143 |
} |
|
1144 |
||
1145 |
/** |
|
1146 |
* Reconstitute this deque from a stream (that is, |
|
1147 |
* deserialize it). |
|
1148 |
* @param s the stream |
|
1149 |
*/ |
|
1150 |
private void readObject(java.io.ObjectInputStream s) |
|
1151 |
throws java.io.IOException, ClassNotFoundException { |
|
1152 |
s.defaultReadObject(); |
|
1153 |
count = 0; |
|
1154 |
first = null; |
|
1155 |
last = null; |
|
1156 |
// Read in all elements and place in queue |
|
1157 |
for (;;) { |
|
3415
79309d6eab38
6805775: LinkedBlockingQueue Nodes should unlink themselves before becoming garbage
dl
parents:
2
diff
changeset
|
1158 |
@SuppressWarnings("unchecked") |
2 | 1159 |
E item = (E)s.readObject(); |
1160 |
if (item == null) |
|
1161 |
break; |
|
1162 |
add(item); |
|
1163 |
} |
|
1164 |
} |
|
1165 |
||
1166 |
} |