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dl |
1.1 |
/* |
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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.*; |
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import java.util.concurrent.locks.*; |
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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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jsr166 |
1.9 |
* contains}, {@link #iterator iterator.remove()}, and the bulk |
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dl |
1.1 |
* 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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jsr166 |
1.9 |
* Iterator} interfaces. |
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* |
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* <p>This class is a member of the |
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jsr166 |
1.18 |
* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
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jsr166 |
1.9 |
* Java Collections Framework</a>. |
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dl |
1.1 |
* |
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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 |
39 |
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*/ |
40 |
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public class LinkedBlockingDeque<E> |
41 |
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extends AbstractQueue<E> |
42 |
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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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|
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jsr166 |
1.9 |
/* |
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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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dl |
1.1 |
private static final long serialVersionUID = -387911632671998426L; |
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58 |
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/** Doubly-linked list node class */ |
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static final class Node<E> { |
60 |
jsr166 |
1.19 |
E item; |
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dl |
1.1 |
Node<E> prev; |
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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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/** Pointer to first node */ |
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private transient Node<E> first; |
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/** Pointer to last node */ |
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private 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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private final ReentrantLock lock = new ReentrantLock(); |
80 |
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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(); |
84 |
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85 |
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/** |
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* Creates a <tt>LinkedBlockingDeque</tt> with a capacity of |
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* {@link Integer#MAX_VALUE}. |
88 |
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*/ |
89 |
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public LinkedBlockingDeque() { |
90 |
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this(Integer.MAX_VALUE); |
91 |
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} |
92 |
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93 |
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/** |
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jsr166 |
1.9 |
* Creates a <tt>LinkedBlockingDeque</tt> with the given (fixed) capacity. |
95 |
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* |
96 |
dl |
1.1 |
* @param capacity the capacity of this deque |
97 |
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* @throws IllegalArgumentException if <tt>capacity</tt> is less than 1 |
98 |
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*/ |
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public LinkedBlockingDeque(int capacity) { |
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if (capacity <= 0) throw new IllegalArgumentException(); |
101 |
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this.capacity = capacity; |
102 |
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} |
103 |
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104 |
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/** |
105 |
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* Creates a <tt>LinkedBlockingDeque</tt> with a capacity of |
106 |
jsr166 |
1.9 |
* {@link Integer#MAX_VALUE}, initially containing the elements of |
107 |
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* the given collection, added in traversal order of the |
108 |
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* collection's iterator. |
109 |
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* |
110 |
dl |
1.1 |
* @param c the collection of elements to initially contain |
111 |
jsr166 |
1.9 |
* @throws NullPointerException if the specified collection or any |
112 |
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* of its elements are null |
113 |
dl |
1.1 |
*/ |
114 |
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public LinkedBlockingDeque(Collection<? extends E> c) { |
115 |
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this(Integer.MAX_VALUE); |
116 |
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for (E e : c) |
117 |
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add(e); |
118 |
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} |
119 |
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120 |
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121 |
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// Basic linking and unlinking operations, called only while holding lock |
122 |
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123 |
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/** |
124 |
jsr166 |
1.3 |
* Links e as first element, or returns false if full. |
125 |
dl |
1.1 |
*/ |
126 |
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private boolean linkFirst(E e) { |
127 |
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if (count >= capacity) |
128 |
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return false; |
129 |
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++count; |
130 |
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Node<E> f = first; |
131 |
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Node<E> x = new Node<E>(e, null, f); |
132 |
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first = x; |
133 |
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if (last == null) |
134 |
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last = x; |
135 |
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else |
136 |
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f.prev = x; |
137 |
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notEmpty.signal(); |
138 |
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return true; |
139 |
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} |
140 |
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141 |
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/** |
142 |
jsr166 |
1.3 |
* Links e as last element, or returns false if full. |
143 |
dl |
1.1 |
*/ |
144 |
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private boolean linkLast(E e) { |
145 |
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if (count >= capacity) |
146 |
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return false; |
147 |
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++count; |
148 |
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Node<E> l = last; |
149 |
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Node<E> x = new Node<E>(e, l, null); |
150 |
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last = x; |
151 |
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if (first == null) |
152 |
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first = x; |
153 |
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else |
154 |
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l.next = x; |
155 |
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notEmpty.signal(); |
156 |
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return true; |
157 |
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} |
158 |
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159 |
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/** |
160 |
jsr166 |
1.3 |
* Removes and returns first element, or null if empty. |
161 |
dl |
1.1 |
*/ |
162 |
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private E unlinkFirst() { |
163 |
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Node<E> f = first; |
164 |
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if (f == null) |
165 |
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return null; |
166 |
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Node<E> n = f.next; |
167 |
dl |
1.20 |
f.next = null; // help GC |
168 |
dl |
1.1 |
first = n; |
169 |
jsr166 |
1.3 |
if (n == null) |
170 |
dl |
1.1 |
last = null; |
171 |
jsr166 |
1.3 |
else |
172 |
dl |
1.1 |
n.prev = null; |
173 |
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--count; |
174 |
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notFull.signal(); |
175 |
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return f.item; |
176 |
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} |
177 |
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178 |
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/** |
179 |
jsr166 |
1.3 |
* Removes and returns last element, or null if empty. |
180 |
dl |
1.1 |
*/ |
181 |
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private E unlinkLast() { |
182 |
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Node<E> l = last; |
183 |
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if (l == null) |
184 |
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return null; |
185 |
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Node<E> p = l.prev; |
186 |
dl |
1.20 |
l.prev = null; // help GC |
187 |
dl |
1.1 |
last = p; |
188 |
jsr166 |
1.3 |
if (p == null) |
189 |
dl |
1.1 |
first = null; |
190 |
jsr166 |
1.3 |
else |
191 |
dl |
1.1 |
p.next = null; |
192 |
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--count; |
193 |
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notFull.signal(); |
194 |
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return l.item; |
195 |
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} |
196 |
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197 |
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/** |
198 |
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* Unlink e |
199 |
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*/ |
200 |
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private void unlink(Node<E> x) { |
201 |
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Node<E> p = x.prev; |
202 |
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Node<E> n = x.next; |
203 |
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if (p == null) { |
204 |
jsr166 |
1.3 |
if (n == null) |
205 |
dl |
1.1 |
first = last = null; |
206 |
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else { |
207 |
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n.prev = null; |
208 |
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first = n; |
209 |
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} |
210 |
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} else if (n == null) { |
211 |
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p.next = null; |
212 |
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last = p; |
213 |
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} else { |
214 |
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p.next = n; |
215 |
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n.prev = p; |
216 |
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} |
217 |
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--count; |
218 |
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notFull.signalAll(); |
219 |
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} |
220 |
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221 |
jsr166 |
1.9 |
// BlockingDeque methods |
222 |
dl |
1.1 |
|
223 |
jsr166 |
1.9 |
/** |
224 |
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* @throws IllegalStateException {@inheritDoc} |
225 |
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* @throws NullPointerException {@inheritDoc} |
226 |
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*/ |
227 |
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public void addFirst(E e) { |
228 |
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if (!offerFirst(e)) |
229 |
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throw new IllegalStateException("Deque full"); |
230 |
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} |
231 |
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232 |
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/** |
233 |
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* @throws IllegalStateException {@inheritDoc} |
234 |
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* @throws NullPointerException {@inheritDoc} |
235 |
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*/ |
236 |
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public void addLast(E e) { |
237 |
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if (!offerLast(e)) |
238 |
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throw new IllegalStateException("Deque full"); |
239 |
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} |
240 |
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241 |
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/** |
242 |
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* @throws NullPointerException {@inheritDoc} |
243 |
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*/ |
244 |
jsr166 |
1.6 |
public boolean offerFirst(E e) { |
245 |
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if (e == null) throw new NullPointerException(); |
246 |
dl |
1.1 |
lock.lock(); |
247 |
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try { |
248 |
jsr166 |
1.6 |
return linkFirst(e); |
249 |
dl |
1.1 |
} finally { |
250 |
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lock.unlock(); |
251 |
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} |
252 |
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} |
253 |
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|
254 |
jsr166 |
1.9 |
/** |
255 |
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* @throws NullPointerException {@inheritDoc} |
256 |
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*/ |
257 |
jsr166 |
1.6 |
public boolean offerLast(E e) { |
258 |
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if (e == null) throw new NullPointerException(); |
259 |
dl |
1.1 |
lock.lock(); |
260 |
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try { |
261 |
jsr166 |
1.6 |
return linkLast(e); |
262 |
dl |
1.1 |
} finally { |
263 |
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lock.unlock(); |
264 |
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} |
265 |
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} |
266 |
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|
267 |
jsr166 |
1.9 |
/** |
268 |
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* @throws NullPointerException {@inheritDoc} |
269 |
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* @throws InterruptedException {@inheritDoc} |
270 |
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*/ |
271 |
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public void putFirst(E e) throws InterruptedException { |
272 |
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if (e == null) throw new NullPointerException(); |
273 |
dl |
1.1 |
lock.lock(); |
274 |
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try { |
275 |
jsr166 |
1.9 |
while (!linkFirst(e)) |
276 |
|
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notFull.await(); |
277 |
dl |
1.1 |
} finally { |
278 |
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lock.unlock(); |
279 |
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} |
280 |
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} |
281 |
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|
282 |
jsr166 |
1.9 |
/** |
283 |
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* @throws NullPointerException {@inheritDoc} |
284 |
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* @throws InterruptedException {@inheritDoc} |
285 |
|
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*/ |
286 |
|
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public void putLast(E e) throws InterruptedException { |
287 |
|
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if (e == null) throw new NullPointerException(); |
288 |
dl |
1.1 |
lock.lock(); |
289 |
|
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try { |
290 |
jsr166 |
1.9 |
while (!linkLast(e)) |
291 |
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notFull.await(); |
292 |
dl |
1.1 |
} finally { |
293 |
|
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lock.unlock(); |
294 |
|
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} |
295 |
|
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} |
296 |
|
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|
297 |
jsr166 |
1.9 |
/** |
298 |
|
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* @throws NullPointerException {@inheritDoc} |
299 |
|
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* @throws InterruptedException {@inheritDoc} |
300 |
|
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*/ |
301 |
|
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public boolean offerFirst(E e, long timeout, TimeUnit unit) |
302 |
|
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throws InterruptedException { |
303 |
|
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if (e == null) throw new NullPointerException(); |
304 |
jsr166 |
1.19 |
long nanos = unit.toNanos(timeout); |
305 |
jsr166 |
1.9 |
lock.lockInterruptibly(); |
306 |
dl |
1.1 |
try { |
307 |
jsr166 |
1.9 |
for (;;) { |
308 |
|
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if (linkFirst(e)) |
309 |
|
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return true; |
310 |
|
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if (nanos <= 0) |
311 |
|
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return false; |
312 |
|
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nanos = notFull.awaitNanos(nanos); |
313 |
|
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} |
314 |
dl |
1.1 |
} finally { |
315 |
|
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lock.unlock(); |
316 |
|
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} |
317 |
|
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} |
318 |
|
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|
319 |
jsr166 |
1.9 |
/** |
320 |
|
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* @throws NullPointerException {@inheritDoc} |
321 |
|
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* @throws InterruptedException {@inheritDoc} |
322 |
|
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*/ |
323 |
|
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public boolean offerLast(E e, long timeout, TimeUnit unit) |
324 |
|
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throws InterruptedException { |
325 |
|
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if (e == null) throw new NullPointerException(); |
326 |
jsr166 |
1.19 |
long nanos = unit.toNanos(timeout); |
327 |
jsr166 |
1.9 |
lock.lockInterruptibly(); |
328 |
dl |
1.1 |
try { |
329 |
jsr166 |
1.9 |
for (;;) { |
330 |
|
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if (linkLast(e)) |
331 |
|
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return true; |
332 |
|
|
if (nanos <= 0) |
333 |
|
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return false; |
334 |
|
|
nanos = notFull.awaitNanos(nanos); |
335 |
|
|
} |
336 |
dl |
1.1 |
} finally { |
337 |
|
|
lock.unlock(); |
338 |
|
|
} |
339 |
|
|
} |
340 |
|
|
|
341 |
jsr166 |
1.9 |
/** |
342 |
|
|
* @throws NoSuchElementException {@inheritDoc} |
343 |
|
|
*/ |
344 |
|
|
public E removeFirst() { |
345 |
|
|
E x = pollFirst(); |
346 |
dl |
1.1 |
if (x == null) throw new NoSuchElementException(); |
347 |
|
|
return x; |
348 |
|
|
} |
349 |
|
|
|
350 |
jsr166 |
1.9 |
/** |
351 |
|
|
* @throws NoSuchElementException {@inheritDoc} |
352 |
|
|
*/ |
353 |
|
|
public E removeLast() { |
354 |
|
|
E x = pollLast(); |
355 |
dl |
1.1 |
if (x == null) throw new NoSuchElementException(); |
356 |
|
|
return x; |
357 |
|
|
} |
358 |
|
|
|
359 |
jsr166 |
1.9 |
public E pollFirst() { |
360 |
dl |
1.1 |
lock.lock(); |
361 |
|
|
try { |
362 |
jsr166 |
1.9 |
return unlinkFirst(); |
363 |
dl |
1.1 |
} finally { |
364 |
|
|
lock.unlock(); |
365 |
|
|
} |
366 |
|
|
} |
367 |
|
|
|
368 |
jsr166 |
1.9 |
public E pollLast() { |
369 |
dl |
1.1 |
lock.lock(); |
370 |
|
|
try { |
371 |
jsr166 |
1.9 |
return unlinkLast(); |
372 |
dl |
1.1 |
} finally { |
373 |
|
|
lock.unlock(); |
374 |
|
|
} |
375 |
|
|
} |
376 |
|
|
|
377 |
|
|
public E takeFirst() throws InterruptedException { |
378 |
|
|
lock.lock(); |
379 |
|
|
try { |
380 |
|
|
E x; |
381 |
|
|
while ( (x = unlinkFirst()) == null) |
382 |
|
|
notEmpty.await(); |
383 |
|
|
return x; |
384 |
|
|
} finally { |
385 |
|
|
lock.unlock(); |
386 |
|
|
} |
387 |
|
|
} |
388 |
|
|
|
389 |
|
|
public E takeLast() throws InterruptedException { |
390 |
|
|
lock.lock(); |
391 |
|
|
try { |
392 |
|
|
E x; |
393 |
|
|
while ( (x = unlinkLast()) == null) |
394 |
|
|
notEmpty.await(); |
395 |
|
|
return x; |
396 |
|
|
} finally { |
397 |
|
|
lock.unlock(); |
398 |
|
|
} |
399 |
|
|
} |
400 |
|
|
|
401 |
jsr166 |
1.9 |
public E pollFirst(long timeout, TimeUnit unit) |
402 |
dl |
1.1 |
throws InterruptedException { |
403 |
jsr166 |
1.19 |
long nanos = unit.toNanos(timeout); |
404 |
dl |
1.1 |
lock.lockInterruptibly(); |
405 |
|
|
try { |
406 |
|
|
for (;;) { |
407 |
jsr166 |
1.9 |
E x = unlinkFirst(); |
408 |
|
|
if (x != null) |
409 |
|
|
return x; |
410 |
dl |
1.1 |
if (nanos <= 0) |
411 |
jsr166 |
1.9 |
return null; |
412 |
|
|
nanos = notEmpty.awaitNanos(nanos); |
413 |
dl |
1.1 |
} |
414 |
|
|
} finally { |
415 |
|
|
lock.unlock(); |
416 |
|
|
} |
417 |
|
|
} |
418 |
jsr166 |
1.3 |
|
419 |
jsr166 |
1.9 |
public E pollLast(long timeout, TimeUnit unit) |
420 |
dl |
1.1 |
throws InterruptedException { |
421 |
jsr166 |
1.19 |
long nanos = unit.toNanos(timeout); |
422 |
dl |
1.1 |
lock.lockInterruptibly(); |
423 |
|
|
try { |
424 |
|
|
for (;;) { |
425 |
jsr166 |
1.9 |
E x = unlinkLast(); |
426 |
|
|
if (x != null) |
427 |
|
|
return x; |
428 |
dl |
1.1 |
if (nanos <= 0) |
429 |
jsr166 |
1.9 |
return null; |
430 |
|
|
nanos = notEmpty.awaitNanos(nanos); |
431 |
dl |
1.1 |
} |
432 |
|
|
} finally { |
433 |
|
|
lock.unlock(); |
434 |
|
|
} |
435 |
|
|
} |
436 |
|
|
|
437 |
jsr166 |
1.9 |
/** |
438 |
|
|
* @throws NoSuchElementException {@inheritDoc} |
439 |
|
|
*/ |
440 |
|
|
public E getFirst() { |
441 |
|
|
E x = peekFirst(); |
442 |
|
|
if (x == null) throw new NoSuchElementException(); |
443 |
|
|
return x; |
444 |
|
|
} |
445 |
|
|
|
446 |
|
|
/** |
447 |
|
|
* @throws NoSuchElementException {@inheritDoc} |
448 |
|
|
*/ |
449 |
|
|
public E getLast() { |
450 |
|
|
E x = peekLast(); |
451 |
|
|
if (x == null) throw new NoSuchElementException(); |
452 |
|
|
return x; |
453 |
|
|
} |
454 |
|
|
|
455 |
|
|
public E peekFirst() { |
456 |
|
|
lock.lock(); |
457 |
|
|
try { |
458 |
|
|
return (first == null) ? null : first.item; |
459 |
|
|
} finally { |
460 |
|
|
lock.unlock(); |
461 |
|
|
} |
462 |
|
|
} |
463 |
|
|
|
464 |
|
|
public E peekLast() { |
465 |
|
|
lock.lock(); |
466 |
|
|
try { |
467 |
|
|
return (last == null) ? null : last.item; |
468 |
|
|
} finally { |
469 |
|
|
lock.unlock(); |
470 |
|
|
} |
471 |
|
|
} |
472 |
|
|
|
473 |
|
|
public boolean removeFirstOccurrence(Object o) { |
474 |
|
|
if (o == null) return false; |
475 |
|
|
lock.lock(); |
476 |
dl |
1.1 |
try { |
477 |
jsr166 |
1.9 |
for (Node<E> p = first; p != null; p = p.next) { |
478 |
|
|
if (o.equals(p.item)) { |
479 |
|
|
unlink(p); |
480 |
|
|
return true; |
481 |
|
|
} |
482 |
dl |
1.1 |
} |
483 |
jsr166 |
1.9 |
return false; |
484 |
dl |
1.1 |
} finally { |
485 |
|
|
lock.unlock(); |
486 |
|
|
} |
487 |
|
|
} |
488 |
|
|
|
489 |
jsr166 |
1.9 |
public boolean removeLastOccurrence(Object o) { |
490 |
|
|
if (o == null) return false; |
491 |
|
|
lock.lock(); |
492 |
dl |
1.1 |
try { |
493 |
jsr166 |
1.9 |
for (Node<E> p = last; p != null; p = p.prev) { |
494 |
|
|
if (o.equals(p.item)) { |
495 |
|
|
unlink(p); |
496 |
|
|
return true; |
497 |
|
|
} |
498 |
dl |
1.1 |
} |
499 |
jsr166 |
1.9 |
return false; |
500 |
dl |
1.1 |
} finally { |
501 |
|
|
lock.unlock(); |
502 |
|
|
} |
503 |
|
|
} |
504 |
|
|
|
505 |
jsr166 |
1.9 |
// BlockingQueue methods |
506 |
dl |
1.1 |
|
507 |
jsr166 |
1.9 |
/** |
508 |
|
|
* Inserts the specified element at the end of this deque unless it would |
509 |
|
|
* violate capacity restrictions. When using a capacity-restricted deque, |
510 |
|
|
* it is generally preferable to use method {@link #offer(Object) offer}. |
511 |
|
|
* |
512 |
jsr166 |
1.13 |
* <p>This method is equivalent to {@link #addLast}. |
513 |
jsr166 |
1.9 |
* |
514 |
|
|
* @throws IllegalStateException if the element cannot be added at this |
515 |
|
|
* time due to capacity restrictions |
516 |
|
|
* @throws NullPointerException if the specified element is null |
517 |
|
|
*/ |
518 |
|
|
public boolean add(E e) { |
519 |
jsr166 |
1.19 |
addLast(e); |
520 |
|
|
return true; |
521 |
jsr166 |
1.9 |
} |
522 |
|
|
|
523 |
|
|
/** |
524 |
|
|
* @throws NullPointerException if the specified element is null |
525 |
|
|
*/ |
526 |
|
|
public boolean offer(E e) { |
527 |
jsr166 |
1.19 |
return offerLast(e); |
528 |
jsr166 |
1.9 |
} |
529 |
dl |
1.1 |
|
530 |
jsr166 |
1.9 |
/** |
531 |
|
|
* @throws NullPointerException {@inheritDoc} |
532 |
|
|
* @throws InterruptedException {@inheritDoc} |
533 |
|
|
*/ |
534 |
|
|
public void put(E e) throws InterruptedException { |
535 |
jsr166 |
1.19 |
putLast(e); |
536 |
jsr166 |
1.9 |
} |
537 |
dl |
1.1 |
|
538 |
jsr166 |
1.9 |
/** |
539 |
|
|
* @throws NullPointerException {@inheritDoc} |
540 |
|
|
* @throws InterruptedException {@inheritDoc} |
541 |
|
|
*/ |
542 |
jsr166 |
1.7 |
public boolean offer(E e, long timeout, TimeUnit unit) |
543 |
jsr166 |
1.9 |
throws InterruptedException { |
544 |
jsr166 |
1.19 |
return offerLast(e, timeout, unit); |
545 |
jsr166 |
1.9 |
} |
546 |
|
|
|
547 |
|
|
/** |
548 |
|
|
* Retrieves and removes the head of the queue represented by this deque. |
549 |
|
|
* This method differs from {@link #poll poll} only in that it throws an |
550 |
|
|
* exception if this deque is empty. |
551 |
|
|
* |
552 |
|
|
* <p>This method is equivalent to {@link #removeFirst() removeFirst}. |
553 |
|
|
* |
554 |
|
|
* @return the head of the queue represented by this deque |
555 |
|
|
* @throws NoSuchElementException if this deque is empty |
556 |
|
|
*/ |
557 |
|
|
public E remove() { |
558 |
jsr166 |
1.19 |
return removeFirst(); |
559 |
jsr166 |
1.9 |
} |
560 |
|
|
|
561 |
|
|
public E poll() { |
562 |
jsr166 |
1.19 |
return pollFirst(); |
563 |
jsr166 |
1.9 |
} |
564 |
|
|
|
565 |
|
|
public E take() throws InterruptedException { |
566 |
jsr166 |
1.19 |
return takeFirst(); |
567 |
jsr166 |
1.9 |
} |
568 |
|
|
|
569 |
|
|
public E poll(long timeout, TimeUnit unit) throws InterruptedException { |
570 |
jsr166 |
1.19 |
return pollFirst(timeout, unit); |
571 |
jsr166 |
1.9 |
} |
572 |
dl |
1.1 |
|
573 |
|
|
/** |
574 |
jsr166 |
1.9 |
* Retrieves, but does not remove, the head of the queue represented by |
575 |
|
|
* this deque. This method differs from {@link #peek peek} only in that |
576 |
|
|
* it throws an exception if this deque is empty. |
577 |
|
|
* |
578 |
|
|
* <p>This method is equivalent to {@link #getFirst() getFirst}. |
579 |
dl |
1.1 |
* |
580 |
jsr166 |
1.9 |
* @return the head of the queue represented by this deque |
581 |
|
|
* @throws NoSuchElementException if this deque is empty |
582 |
dl |
1.1 |
*/ |
583 |
jsr166 |
1.9 |
public E element() { |
584 |
jsr166 |
1.19 |
return getFirst(); |
585 |
jsr166 |
1.9 |
} |
586 |
|
|
|
587 |
|
|
public E peek() { |
588 |
jsr166 |
1.19 |
return peekFirst(); |
589 |
dl |
1.1 |
} |
590 |
|
|
|
591 |
|
|
/** |
592 |
jsr166 |
1.4 |
* Returns the number of additional elements that this deque can ideally |
593 |
|
|
* (in the absence of memory or resource constraints) accept without |
594 |
dl |
1.1 |
* blocking. This is always equal to the initial capacity of this deque |
595 |
|
|
* less the current <tt>size</tt> of this deque. |
596 |
jsr166 |
1.4 |
* |
597 |
|
|
* <p>Note that you <em>cannot</em> always tell if an attempt to insert |
598 |
|
|
* an element will succeed by inspecting <tt>remainingCapacity</tt> |
599 |
|
|
* because it may be the case that another thread is about to |
600 |
jsr166 |
1.9 |
* insert or remove an element. |
601 |
dl |
1.1 |
*/ |
602 |
|
|
public int remainingCapacity() { |
603 |
|
|
lock.lock(); |
604 |
|
|
try { |
605 |
|
|
return capacity - count; |
606 |
|
|
} finally { |
607 |
|
|
lock.unlock(); |
608 |
|
|
} |
609 |
|
|
} |
610 |
|
|
|
611 |
jsr166 |
1.9 |
/** |
612 |
|
|
* @throws UnsupportedOperationException {@inheritDoc} |
613 |
|
|
* @throws ClassCastException {@inheritDoc} |
614 |
|
|
* @throws NullPointerException {@inheritDoc} |
615 |
|
|
* @throws IllegalArgumentException {@inheritDoc} |
616 |
|
|
*/ |
617 |
|
|
public int drainTo(Collection<? super E> c) { |
618 |
|
|
if (c == null) |
619 |
|
|
throw new NullPointerException(); |
620 |
|
|
if (c == this) |
621 |
|
|
throw new IllegalArgumentException(); |
622 |
dl |
1.1 |
lock.lock(); |
623 |
|
|
try { |
624 |
jsr166 |
1.3 |
for (Node<E> p = first; p != null; p = p.next) |
625 |
jsr166 |
1.9 |
c.add(p.item); |
626 |
|
|
int n = count; |
627 |
|
|
count = 0; |
628 |
|
|
first = last = null; |
629 |
|
|
notFull.signalAll(); |
630 |
|
|
return n; |
631 |
dl |
1.1 |
} finally { |
632 |
|
|
lock.unlock(); |
633 |
|
|
} |
634 |
|
|
} |
635 |
|
|
|
636 |
jsr166 |
1.9 |
/** |
637 |
|
|
* @throws UnsupportedOperationException {@inheritDoc} |
638 |
|
|
* @throws ClassCastException {@inheritDoc} |
639 |
|
|
* @throws NullPointerException {@inheritDoc} |
640 |
|
|
* @throws IllegalArgumentException {@inheritDoc} |
641 |
|
|
*/ |
642 |
|
|
public int drainTo(Collection<? super E> c, int maxElements) { |
643 |
|
|
if (c == null) |
644 |
|
|
throw new NullPointerException(); |
645 |
|
|
if (c == this) |
646 |
|
|
throw new IllegalArgumentException(); |
647 |
dl |
1.1 |
lock.lock(); |
648 |
|
|
try { |
649 |
jsr166 |
1.9 |
int n = 0; |
650 |
|
|
while (n < maxElements && first != null) { |
651 |
|
|
c.add(first.item); |
652 |
|
|
first.prev = null; |
653 |
|
|
first = first.next; |
654 |
|
|
--count; |
655 |
|
|
++n; |
656 |
dl |
1.1 |
} |
657 |
jsr166 |
1.9 |
if (first == null) |
658 |
|
|
last = null; |
659 |
|
|
notFull.signalAll(); |
660 |
|
|
return n; |
661 |
|
|
} finally { |
662 |
|
|
lock.unlock(); |
663 |
|
|
} |
664 |
|
|
} |
665 |
|
|
|
666 |
|
|
// Stack methods |
667 |
|
|
|
668 |
|
|
/** |
669 |
|
|
* @throws IllegalStateException {@inheritDoc} |
670 |
|
|
* @throws NullPointerException {@inheritDoc} |
671 |
|
|
*/ |
672 |
|
|
public void push(E e) { |
673 |
jsr166 |
1.19 |
addFirst(e); |
674 |
jsr166 |
1.9 |
} |
675 |
|
|
|
676 |
|
|
/** |
677 |
|
|
* @throws NoSuchElementException {@inheritDoc} |
678 |
|
|
*/ |
679 |
|
|
public E pop() { |
680 |
jsr166 |
1.19 |
return removeFirst(); |
681 |
jsr166 |
1.9 |
} |
682 |
|
|
|
683 |
|
|
// Collection methods |
684 |
|
|
|
685 |
jsr166 |
1.11 |
/** |
686 |
|
|
* Removes the first occurrence of the specified element from this deque. |
687 |
|
|
* If the deque does not contain the element, it is unchanged. |
688 |
|
|
* More formally, removes the first element <tt>e</tt> such that |
689 |
|
|
* <tt>o.equals(e)</tt> (if such an element exists). |
690 |
|
|
* Returns <tt>true</tt> if this deque contained the specified element |
691 |
|
|
* (or equivalently, if this deque changed as a result of the call). |
692 |
|
|
* |
693 |
|
|
* <p>This method is equivalent to |
694 |
|
|
* {@link #removeFirstOccurrence(Object) removeFirstOccurrence}. |
695 |
|
|
* |
696 |
|
|
* @param o element to be removed from this deque, if present |
697 |
|
|
* @return <tt>true</tt> if this deque changed as a result of the call |
698 |
|
|
*/ |
699 |
jsr166 |
1.9 |
public boolean remove(Object o) { |
700 |
jsr166 |
1.19 |
return removeFirstOccurrence(o); |
701 |
jsr166 |
1.9 |
} |
702 |
|
|
|
703 |
|
|
/** |
704 |
|
|
* Returns the number of elements in this deque. |
705 |
|
|
* |
706 |
|
|
* @return the number of elements in this deque |
707 |
|
|
*/ |
708 |
|
|
public int size() { |
709 |
|
|
lock.lock(); |
710 |
|
|
try { |
711 |
|
|
return count; |
712 |
dl |
1.1 |
} finally { |
713 |
|
|
lock.unlock(); |
714 |
|
|
} |
715 |
|
|
} |
716 |
|
|
|
717 |
jsr166 |
1.9 |
/** |
718 |
|
|
* Returns <tt>true</tt> if this deque contains the specified element. |
719 |
|
|
* More formally, returns <tt>true</tt> if and only if this deque contains |
720 |
|
|
* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>. |
721 |
|
|
* |
722 |
|
|
* @param o object to be checked for containment in this deque |
723 |
|
|
* @return <tt>true</tt> if this deque contains the specified element |
724 |
|
|
*/ |
725 |
|
|
public boolean contains(Object o) { |
726 |
|
|
if (o == null) return false; |
727 |
dl |
1.1 |
lock.lock(); |
728 |
|
|
try { |
729 |
jsr166 |
1.9 |
for (Node<E> p = first; p != null; p = p.next) |
730 |
|
|
if (o.equals(p.item)) |
731 |
dl |
1.1 |
return true; |
732 |
|
|
return false; |
733 |
|
|
} finally { |
734 |
|
|
lock.unlock(); |
735 |
|
|
} |
736 |
|
|
} |
737 |
|
|
|
738 |
|
|
/** |
739 |
|
|
* Variant of removeFirstOccurrence needed by iterator.remove. |
740 |
|
|
* Searches for the node, not its contents. |
741 |
|
|
*/ |
742 |
jsr166 |
1.12 |
boolean removeNode(Node<E> e) { |
743 |
dl |
1.1 |
lock.lock(); |
744 |
|
|
try { |
745 |
|
|
for (Node<E> p = first; p != null; p = p.next) { |
746 |
|
|
if (p == e) { |
747 |
|
|
unlink(p); |
748 |
|
|
return true; |
749 |
|
|
} |
750 |
|
|
} |
751 |
|
|
return false; |
752 |
|
|
} finally { |
753 |
|
|
lock.unlock(); |
754 |
|
|
} |
755 |
|
|
} |
756 |
|
|
|
757 |
jsr166 |
1.9 |
/** |
758 |
|
|
* Returns an array containing all of the elements in this deque, in |
759 |
|
|
* proper sequence (from first to last element). |
760 |
|
|
* |
761 |
|
|
* <p>The returned array will be "safe" in that no references to it are |
762 |
|
|
* maintained by this deque. (In other words, this method must allocate |
763 |
|
|
* a new array). The caller is thus free to modify the returned array. |
764 |
jsr166 |
1.10 |
* |
765 |
jsr166 |
1.9 |
* <p>This method acts as bridge between array-based and collection-based |
766 |
|
|
* APIs. |
767 |
|
|
* |
768 |
|
|
* @return an array containing all of the elements in this deque |
769 |
|
|
*/ |
770 |
dl |
1.1 |
public Object[] toArray() { |
771 |
|
|
lock.lock(); |
772 |
|
|
try { |
773 |
|
|
Object[] a = new Object[count]; |
774 |
|
|
int k = 0; |
775 |
jsr166 |
1.3 |
for (Node<E> p = first; p != null; p = p.next) |
776 |
dl |
1.1 |
a[k++] = p.item; |
777 |
|
|
return a; |
778 |
|
|
} finally { |
779 |
|
|
lock.unlock(); |
780 |
|
|
} |
781 |
|
|
} |
782 |
|
|
|
783 |
jsr166 |
1.9 |
/** |
784 |
|
|
* Returns an array containing all of the elements in this deque, in |
785 |
|
|
* proper sequence; the runtime type of the returned array is that of |
786 |
|
|
* the specified array. If the deque fits in the specified array, it |
787 |
|
|
* is returned therein. Otherwise, a new array is allocated with the |
788 |
|
|
* runtime type of the specified array and the size of this deque. |
789 |
|
|
* |
790 |
|
|
* <p>If this deque fits in the specified array with room to spare |
791 |
|
|
* (i.e., the array has more elements than this deque), the element in |
792 |
|
|
* the array immediately following the end of the deque is set to |
793 |
|
|
* <tt>null</tt>. |
794 |
|
|
* |
795 |
|
|
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
796 |
|
|
* array-based and collection-based APIs. Further, this method allows |
797 |
|
|
* precise control over the runtime type of the output array, and may, |
798 |
|
|
* under certain circumstances, be used to save allocation costs. |
799 |
|
|
* |
800 |
|
|
* <p>Suppose <tt>x</tt> is a deque known to contain only strings. |
801 |
|
|
* The following code can be used to dump the deque into a newly |
802 |
|
|
* allocated array of <tt>String</tt>: |
803 |
|
|
* |
804 |
|
|
* <pre> |
805 |
|
|
* String[] y = x.toArray(new String[0]);</pre> |
806 |
|
|
* |
807 |
|
|
* Note that <tt>toArray(new Object[0])</tt> is identical in function to |
808 |
|
|
* <tt>toArray()</tt>. |
809 |
|
|
* |
810 |
|
|
* @param a the array into which the elements of the deque are to |
811 |
|
|
* be stored, if it is big enough; otherwise, a new array of the |
812 |
|
|
* same runtime type is allocated for this purpose |
813 |
|
|
* @return an array containing all of the elements in this deque |
814 |
|
|
* @throws ArrayStoreException if the runtime type of the specified array |
815 |
|
|
* is not a supertype of the runtime type of every element in |
816 |
|
|
* this deque |
817 |
|
|
* @throws NullPointerException if the specified array is null |
818 |
|
|
*/ |
819 |
dl |
1.1 |
public <T> T[] toArray(T[] a) { |
820 |
|
|
lock.lock(); |
821 |
|
|
try { |
822 |
|
|
if (a.length < count) |
823 |
|
|
a = (T[])java.lang.reflect.Array.newInstance( |
824 |
|
|
a.getClass().getComponentType(), |
825 |
|
|
count |
826 |
|
|
); |
827 |
|
|
|
828 |
|
|
int k = 0; |
829 |
jsr166 |
1.3 |
for (Node<E> p = first; p != null; p = p.next) |
830 |
dl |
1.1 |
a[k++] = (T)p.item; |
831 |
|
|
if (a.length > k) |
832 |
|
|
a[k] = null; |
833 |
|
|
return a; |
834 |
|
|
} finally { |
835 |
|
|
lock.unlock(); |
836 |
|
|
} |
837 |
|
|
} |
838 |
|
|
|
839 |
|
|
public String toString() { |
840 |
|
|
lock.lock(); |
841 |
|
|
try { |
842 |
|
|
return super.toString(); |
843 |
|
|
} finally { |
844 |
|
|
lock.unlock(); |
845 |
|
|
} |
846 |
|
|
} |
847 |
|
|
|
848 |
|
|
/** |
849 |
|
|
* Atomically removes all of the elements from this deque. |
850 |
|
|
* The deque will be empty after this call returns. |
851 |
|
|
*/ |
852 |
|
|
public void clear() { |
853 |
|
|
lock.lock(); |
854 |
|
|
try { |
855 |
|
|
first = last = null; |
856 |
|
|
count = 0; |
857 |
|
|
notFull.signalAll(); |
858 |
|
|
} finally { |
859 |
|
|
lock.unlock(); |
860 |
|
|
} |
861 |
|
|
} |
862 |
|
|
|
863 |
|
|
/** |
864 |
|
|
* Returns an iterator over the elements in this deque in proper sequence. |
865 |
jsr166 |
1.9 |
* The elements will be returned in order from first (head) to last (tail). |
866 |
dl |
1.1 |
* The returned <tt>Iterator</tt> is a "weakly consistent" iterator that |
867 |
jsr166 |
1.3 |
* will never throw {@link ConcurrentModificationException}, |
868 |
dl |
1.1 |
* and guarantees to traverse elements as they existed upon |
869 |
|
|
* construction of the iterator, and may (but is not guaranteed to) |
870 |
|
|
* reflect any modifications subsequent to construction. |
871 |
|
|
* |
872 |
jsr166 |
1.9 |
* @return an iterator over the elements in this deque in proper sequence |
873 |
dl |
1.1 |
*/ |
874 |
|
|
public Iterator<E> iterator() { |
875 |
|
|
return new Itr(); |
876 |
|
|
} |
877 |
|
|
|
878 |
|
|
/** |
879 |
dl |
1.14 |
* Returns an iterator over the elements in this deque in reverse |
880 |
|
|
* sequential order. The elements will be returned in order from |
881 |
|
|
* last (tail) to first (head). |
882 |
|
|
* The returned <tt>Iterator</tt> is a "weakly consistent" iterator that |
883 |
|
|
* will never throw {@link ConcurrentModificationException}, |
884 |
|
|
* and guarantees to traverse elements as they existed upon |
885 |
|
|
* construction of the iterator, and may (but is not guaranteed to) |
886 |
|
|
* reflect any modifications subsequent to construction. |
887 |
|
|
*/ |
888 |
|
|
public Iterator<E> descendingIterator() { |
889 |
|
|
return new DescendingItr(); |
890 |
|
|
} |
891 |
|
|
|
892 |
|
|
/** |
893 |
|
|
* Base class for Iterators for LinkedBlockingDeque |
894 |
dl |
1.1 |
*/ |
895 |
dl |
1.16 |
private abstract class AbstractItr implements Iterator<E> { |
896 |
jsr166 |
1.15 |
/** |
897 |
|
|
* The next node to return in next |
898 |
dl |
1.14 |
*/ |
899 |
|
|
Node<E> next; |
900 |
dl |
1.1 |
|
901 |
|
|
/** |
902 |
|
|
* nextItem holds on to item fields because once we claim that |
903 |
|
|
* an element exists in hasNext(), we must return item read |
904 |
|
|
* under lock (in advance()) even if it was in the process of |
905 |
|
|
* being removed when hasNext() was called. |
906 |
jsr166 |
1.3 |
*/ |
907 |
dl |
1.14 |
E nextItem; |
908 |
dl |
1.1 |
|
909 |
|
|
/** |
910 |
|
|
* Node returned by most recent call to next. Needed by remove. |
911 |
|
|
* Reset to null if this element is deleted by a call to remove. |
912 |
|
|
*/ |
913 |
dl |
1.16 |
private Node<E> lastRet; |
914 |
|
|
|
915 |
|
|
AbstractItr() { |
916 |
|
|
advance(); // set to initial position |
917 |
|
|
} |
918 |
dl |
1.1 |
|
919 |
|
|
/** |
920 |
jsr166 |
1.8 |
* Advances next, or if not yet initialized, sets to first node. |
921 |
dl |
1.14 |
* Implemented to move forward vs backward in the two subclasses. |
922 |
dl |
1.1 |
*/ |
923 |
dl |
1.14 |
abstract void advance(); |
924 |
dl |
1.1 |
|
925 |
|
|
public boolean hasNext() { |
926 |
|
|
return next != null; |
927 |
|
|
} |
928 |
|
|
|
929 |
|
|
public E next() { |
930 |
|
|
if (next == null) |
931 |
|
|
throw new NoSuchElementException(); |
932 |
dl |
1.14 |
lastRet = next; |
933 |
dl |
1.1 |
E x = nextItem; |
934 |
|
|
advance(); |
935 |
|
|
return x; |
936 |
|
|
} |
937 |
|
|
|
938 |
|
|
public void remove() { |
939 |
dl |
1.14 |
Node<E> n = lastRet; |
940 |
dl |
1.1 |
if (n == null) |
941 |
|
|
throw new IllegalStateException(); |
942 |
dl |
1.14 |
lastRet = null; |
943 |
dl |
1.1 |
// Note: removeNode rescans looking for this node to make |
944 |
dl |
1.2 |
// sure it was not already removed. Otherwise, trying to |
945 |
dl |
1.1 |
// re-remove could corrupt list. |
946 |
|
|
removeNode(n); |
947 |
|
|
} |
948 |
|
|
} |
949 |
|
|
|
950 |
dl |
1.14 |
/** Forward iterator */ |
951 |
dl |
1.16 |
private class Itr extends AbstractItr { |
952 |
dl |
1.14 |
void advance() { |
953 |
|
|
final ReentrantLock lock = LinkedBlockingDeque.this.lock; |
954 |
|
|
lock.lock(); |
955 |
|
|
try { |
956 |
|
|
next = (next == null)? first : next.next; |
957 |
|
|
nextItem = (next == null)? null : next.item; |
958 |
|
|
} finally { |
959 |
|
|
lock.unlock(); |
960 |
|
|
} |
961 |
|
|
} |
962 |
|
|
} |
963 |
|
|
|
964 |
|
|
/** |
965 |
|
|
* Descending iterator for LinkedBlockingDeque |
966 |
|
|
*/ |
967 |
dl |
1.16 |
private class DescendingItr extends AbstractItr { |
968 |
dl |
1.14 |
void advance() { |
969 |
|
|
final ReentrantLock lock = LinkedBlockingDeque.this.lock; |
970 |
|
|
lock.lock(); |
971 |
|
|
try { |
972 |
|
|
next = (next == null)? last : next.prev; |
973 |
|
|
nextItem = (next == null)? null : next.item; |
974 |
|
|
} finally { |
975 |
|
|
lock.unlock(); |
976 |
|
|
} |
977 |
|
|
} |
978 |
|
|
} |
979 |
|
|
|
980 |
dl |
1.1 |
/** |
981 |
jsr166 |
1.3 |
* Save the state of this deque to a stream (that is, serialize it). |
982 |
dl |
1.1 |
* |
983 |
|
|
* @serialData The capacity (int), followed by elements (each an |
984 |
|
|
* <tt>Object</tt>) in the proper order, followed by a null |
985 |
|
|
* @param s the stream |
986 |
|
|
*/ |
987 |
|
|
private void writeObject(java.io.ObjectOutputStream s) |
988 |
|
|
throws java.io.IOException { |
989 |
|
|
lock.lock(); |
990 |
|
|
try { |
991 |
|
|
// Write out capacity and any hidden stuff |
992 |
|
|
s.defaultWriteObject(); |
993 |
|
|
// Write out all elements in the proper order. |
994 |
|
|
for (Node<E> p = first; p != null; p = p.next) |
995 |
|
|
s.writeObject(p.item); |
996 |
|
|
// Use trailing null as sentinel |
997 |
|
|
s.writeObject(null); |
998 |
|
|
} finally { |
999 |
|
|
lock.unlock(); |
1000 |
|
|
} |
1001 |
|
|
} |
1002 |
|
|
|
1003 |
|
|
/** |
1004 |
jsr166 |
1.3 |
* Reconstitute this deque from a stream (that is, |
1005 |
dl |
1.1 |
* deserialize it). |
1006 |
|
|
* @param s the stream |
1007 |
|
|
*/ |
1008 |
|
|
private void readObject(java.io.ObjectInputStream s) |
1009 |
|
|
throws java.io.IOException, ClassNotFoundException { |
1010 |
|
|
s.defaultReadObject(); |
1011 |
|
|
count = 0; |
1012 |
|
|
first = null; |
1013 |
|
|
last = null; |
1014 |
|
|
// Read in all elements and place in queue |
1015 |
|
|
for (;;) { |
1016 |
|
|
E item = (E)s.readObject(); |
1017 |
|
|
if (item == null) |
1018 |
|
|
break; |
1019 |
|
|
add(item); |
1020 |
|
|
} |
1021 |
|
|
} |
1022 |
jsr166 |
1.3 |
|
1023 |
dl |
1.1 |
} |