1 |
dl |
1.2 |
/* |
2 |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
3 |
dl |
1.33 |
* Expert Group and released to the public domain, as explained at |
4 |
jsr166 |
1.58 |
* http://creativecommons.org/publicdomain/zero/1.0/ |
5 |
dl |
1.2 |
*/ |
6 |
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7 |
tim |
1.1 |
package java.util.concurrent; |
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jsr166 |
1.51 |
|
9 |
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import java.util.concurrent.atomic.AtomicInteger; |
10 |
|
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import java.util.concurrent.locks.Condition; |
11 |
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import java.util.concurrent.locks.ReentrantLock; |
12 |
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import java.util.AbstractQueue; |
13 |
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import java.util.Collection; |
14 |
dl |
1.74 |
import java.util.Collections; |
15 |
jsr166 |
1.51 |
import java.util.Iterator; |
16 |
|
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import java.util.NoSuchElementException; |
17 |
dl |
1.74 |
import java.util.Spliterator; |
18 |
dl |
1.75 |
import java.util.Spliterators; |
19 |
dl |
1.74 |
import java.util.stream.Stream; |
20 |
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import java.util.stream.Streams; |
21 |
|
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import java.util.function.Consumer; |
22 |
tim |
1.1 |
|
23 |
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/** |
24 |
dholmes |
1.14 |
* An optionally-bounded {@linkplain BlockingQueue blocking queue} based on |
25 |
dholmes |
1.8 |
* linked nodes. |
26 |
|
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* This queue orders elements FIFO (first-in-first-out). |
27 |
tim |
1.12 |
* The <em>head</em> of the queue is that element that has been on the |
28 |
dholmes |
1.8 |
* queue the longest time. |
29 |
|
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* The <em>tail</em> of the queue is that element that has been on the |
30 |
dl |
1.20 |
* queue the shortest time. New elements |
31 |
|
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* are inserted at the tail of the queue, and the queue retrieval |
32 |
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* operations obtain elements at the head of the queue. |
33 |
dholmes |
1.8 |
* Linked queues typically have higher throughput than array-based queues but |
34 |
|
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* less predictable performance in most concurrent applications. |
35 |
tim |
1.12 |
* |
36 |
jsr166 |
1.70 |
* <p>The optional capacity bound constructor argument serves as a |
37 |
dholmes |
1.8 |
* way to prevent excessive queue expansion. The capacity, if unspecified, |
38 |
|
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* is equal to {@link Integer#MAX_VALUE}. Linked nodes are |
39 |
dl |
1.3 |
* dynamically created upon each insertion unless this would bring the |
40 |
|
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* queue above capacity. |
41 |
dholmes |
1.8 |
* |
42 |
dl |
1.36 |
* <p>This class and its iterator implement all of the |
43 |
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* <em>optional</em> methods of the {@link Collection} and {@link |
44 |
dl |
1.38 |
* Iterator} interfaces. |
45 |
dl |
1.21 |
* |
46 |
dl |
1.34 |
* <p>This class is a member of the |
47 |
jsr166 |
1.48 |
* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
48 |
dl |
1.34 |
* Java Collections Framework</a>. |
49 |
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* |
50 |
dl |
1.6 |
* @since 1.5 |
51 |
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* @author Doug Lea |
52 |
dl |
1.27 |
* @param <E> the type of elements held in this collection |
53 |
jsr166 |
1.40 |
*/ |
54 |
dl |
1.2 |
public class LinkedBlockingQueue<E> extends AbstractQueue<E> |
55 |
tim |
1.1 |
implements BlockingQueue<E>, java.io.Serializable { |
56 |
dl |
1.18 |
private static final long serialVersionUID = -6903933977591709194L; |
57 |
tim |
1.1 |
|
58 |
dl |
1.2 |
/* |
59 |
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* A variant of the "two lock queue" algorithm. The putLock gates |
60 |
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* entry to put (and offer), and has an associated condition for |
61 |
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* waiting puts. Similarly for the takeLock. The "count" field |
62 |
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* that they both rely on is maintained as an atomic to avoid |
63 |
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* needing to get both locks in most cases. Also, to minimize need |
64 |
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* for puts to get takeLock and vice-versa, cascading notifies are |
65 |
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* used. When a put notices that it has enabled at least one take, |
66 |
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* it signals taker. That taker in turn signals others if more |
67 |
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* items have been entered since the signal. And symmetrically for |
68 |
tim |
1.12 |
* takes signalling puts. Operations such as remove(Object) and |
69 |
dl |
1.2 |
* iterators acquire both locks. |
70 |
jsr166 |
1.51 |
* |
71 |
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* Visibility between writers and readers is provided as follows: |
72 |
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* |
73 |
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* Whenever an element is enqueued, the putLock is acquired and |
74 |
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* count updated. A subsequent reader guarantees visibility to the |
75 |
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* enqueued Node by either acquiring the putLock (via fullyLock) |
76 |
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* or by acquiring the takeLock, and then reading n = count.get(); |
77 |
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* this gives visibility to the first n items. |
78 |
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* |
79 |
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* To implement weakly consistent iterators, it appears we need to |
80 |
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* keep all Nodes GC-reachable from a predecessor dequeued Node. |
81 |
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* That would cause two problems: |
82 |
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* - allow a rogue Iterator to cause unbounded memory retention |
83 |
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* - cause cross-generational linking of old Nodes to new Nodes if |
84 |
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* a Node was tenured while live, which generational GCs have a |
85 |
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* hard time dealing with, causing repeated major collections. |
86 |
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* However, only non-deleted Nodes need to be reachable from |
87 |
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* dequeued Nodes, and reachability does not necessarily have to |
88 |
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* be of the kind understood by the GC. We use the trick of |
89 |
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* linking a Node that has just been dequeued to itself. Such a |
90 |
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* self-link implicitly means to advance to head.next. |
91 |
dl |
1.38 |
*/ |
92 |
dl |
1.2 |
|
93 |
dl |
1.6 |
/** |
94 |
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* Linked list node class |
95 |
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*/ |
96 |
dl |
1.2 |
static class Node<E> { |
97 |
jsr166 |
1.51 |
E item; |
98 |
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99 |
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/** |
100 |
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* One of: |
101 |
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* - the real successor Node |
102 |
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* - this Node, meaning the successor is head.next |
103 |
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* - null, meaning there is no successor (this is the last node) |
104 |
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*/ |
105 |
dl |
1.2 |
Node<E> next; |
106 |
jsr166 |
1.51 |
|
107 |
dl |
1.2 |
Node(E x) { item = x; } |
108 |
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} |
109 |
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|
110 |
dl |
1.6 |
/** The capacity bound, or Integer.MAX_VALUE if none */ |
111 |
dl |
1.2 |
private final int capacity; |
112 |
dl |
1.6 |
|
113 |
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/** Current number of elements */ |
114 |
jsr166 |
1.61 |
private final AtomicInteger count = new AtomicInteger(); |
115 |
dl |
1.2 |
|
116 |
jsr166 |
1.51 |
/** |
117 |
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* Head of linked list. |
118 |
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* Invariant: head.item == null |
119 |
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*/ |
120 |
jsr166 |
1.64 |
transient Node<E> head; |
121 |
dl |
1.6 |
|
122 |
jsr166 |
1.51 |
/** |
123 |
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* Tail of linked list. |
124 |
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* Invariant: last.next == null |
125 |
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*/ |
126 |
dl |
1.6 |
private transient Node<E> last; |
127 |
dl |
1.2 |
|
128 |
dl |
1.6 |
/** Lock held by take, poll, etc */ |
129 |
dl |
1.5 |
private final ReentrantLock takeLock = new ReentrantLock(); |
130 |
dl |
1.6 |
|
131 |
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/** Wait queue for waiting takes */ |
132 |
dl |
1.32 |
private final Condition notEmpty = takeLock.newCondition(); |
133 |
dl |
1.2 |
|
134 |
dl |
1.6 |
/** Lock held by put, offer, etc */ |
135 |
dl |
1.5 |
private final ReentrantLock putLock = new ReentrantLock(); |
136 |
dl |
1.6 |
|
137 |
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/** Wait queue for waiting puts */ |
138 |
dl |
1.32 |
private final Condition notFull = putLock.newCondition(); |
139 |
dl |
1.2 |
|
140 |
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/** |
141 |
jsr166 |
1.40 |
* Signals a waiting take. Called only from put/offer (which do not |
142 |
dl |
1.4 |
* otherwise ordinarily lock takeLock.) |
143 |
dl |
1.2 |
*/ |
144 |
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private void signalNotEmpty() { |
145 |
dl |
1.31 |
final ReentrantLock takeLock = this.takeLock; |
146 |
dl |
1.2 |
takeLock.lock(); |
147 |
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try { |
148 |
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notEmpty.signal(); |
149 |
tim |
1.17 |
} finally { |
150 |
dl |
1.2 |
takeLock.unlock(); |
151 |
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} |
152 |
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} |
153 |
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|
154 |
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/** |
155 |
jsr166 |
1.40 |
* Signals a waiting put. Called only from take/poll. |
156 |
dl |
1.2 |
*/ |
157 |
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private void signalNotFull() { |
158 |
dl |
1.31 |
final ReentrantLock putLock = this.putLock; |
159 |
dl |
1.2 |
putLock.lock(); |
160 |
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try { |
161 |
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notFull.signal(); |
162 |
tim |
1.17 |
} finally { |
163 |
dl |
1.2 |
putLock.unlock(); |
164 |
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} |
165 |
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} |
166 |
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|
167 |
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/** |
168 |
dl |
1.54 |
* Links node at end of queue. |
169 |
jsr166 |
1.51 |
* |
170 |
dl |
1.54 |
* @param node the node |
171 |
dl |
1.2 |
*/ |
172 |
dl |
1.54 |
private void enqueue(Node<E> node) { |
173 |
jsr166 |
1.51 |
// assert putLock.isHeldByCurrentThread(); |
174 |
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// assert last.next == null; |
175 |
dl |
1.54 |
last = last.next = node; |
176 |
dl |
1.2 |
} |
177 |
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|
178 |
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/** |
179 |
jsr166 |
1.51 |
* Removes a node from head of queue. |
180 |
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* |
181 |
dl |
1.6 |
* @return the node |
182 |
dl |
1.2 |
*/ |
183 |
jsr166 |
1.51 |
private E dequeue() { |
184 |
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// assert takeLock.isHeldByCurrentThread(); |
185 |
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// assert head.item == null; |
186 |
dl |
1.50 |
Node<E> h = head; |
187 |
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Node<E> first = h.next; |
188 |
jsr166 |
1.51 |
h.next = h; // help GC |
189 |
dl |
1.2 |
head = first; |
190 |
dl |
1.28 |
E x = first.item; |
191 |
dl |
1.2 |
first.item = null; |
192 |
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return x; |
193 |
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} |
194 |
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|
195 |
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/** |
196 |
jsr166 |
1.71 |
* Locks to prevent both puts and takes. |
197 |
dl |
1.2 |
*/ |
198 |
jsr166 |
1.51 |
void fullyLock() { |
199 |
dl |
1.2 |
putLock.lock(); |
200 |
|
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takeLock.lock(); |
201 |
tim |
1.1 |
} |
202 |
dl |
1.2 |
|
203 |
|
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/** |
204 |
jsr166 |
1.71 |
* Unlocks to allow both puts and takes. |
205 |
dl |
1.2 |
*/ |
206 |
jsr166 |
1.51 |
void fullyUnlock() { |
207 |
dl |
1.2 |
takeLock.unlock(); |
208 |
|
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putLock.unlock(); |
209 |
|
|
} |
210 |
|
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|
211 |
jsr166 |
1.51 |
// /** |
212 |
|
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// * Tells whether both locks are held by current thread. |
213 |
|
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// */ |
214 |
|
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// boolean isFullyLocked() { |
215 |
|
|
// return (putLock.isHeldByCurrentThread() && |
216 |
|
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// takeLock.isHeldByCurrentThread()); |
217 |
|
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// } |
218 |
dl |
1.2 |
|
219 |
|
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/** |
220 |
jsr166 |
1.51 |
* Creates a {@code LinkedBlockingQueue} with a capacity of |
221 |
dholmes |
1.8 |
* {@link Integer#MAX_VALUE}. |
222 |
dl |
1.2 |
*/ |
223 |
|
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public LinkedBlockingQueue() { |
224 |
|
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this(Integer.MAX_VALUE); |
225 |
|
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} |
226 |
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|
227 |
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/** |
228 |
jsr166 |
1.51 |
* Creates a {@code LinkedBlockingQueue} with the given (fixed) capacity. |
229 |
tim |
1.16 |
* |
230 |
jsr166 |
1.43 |
* @param capacity the capacity of this queue |
231 |
jsr166 |
1.51 |
* @throws IllegalArgumentException if {@code capacity} is not greater |
232 |
jsr166 |
1.43 |
* than zero |
233 |
dl |
1.2 |
*/ |
234 |
|
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public LinkedBlockingQueue(int capacity) { |
235 |
dholmes |
1.8 |
if (capacity <= 0) throw new IllegalArgumentException(); |
236 |
dl |
1.2 |
this.capacity = capacity; |
237 |
dl |
1.6 |
last = head = new Node<E>(null); |
238 |
dl |
1.2 |
} |
239 |
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|
240 |
|
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/** |
241 |
jsr166 |
1.51 |
* Creates a {@code LinkedBlockingQueue} with a capacity of |
242 |
dholmes |
1.14 |
* {@link Integer#MAX_VALUE}, initially containing the elements of the |
243 |
tim |
1.12 |
* given collection, |
244 |
dholmes |
1.8 |
* added in traversal order of the collection's iterator. |
245 |
jsr166 |
1.43 |
* |
246 |
dholmes |
1.9 |
* @param c the collection of elements to initially contain |
247 |
jsr166 |
1.43 |
* @throws NullPointerException if the specified collection or any |
248 |
|
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* of its elements are null |
249 |
dl |
1.2 |
*/ |
250 |
dholmes |
1.10 |
public LinkedBlockingQueue(Collection<? extends E> c) { |
251 |
dl |
1.2 |
this(Integer.MAX_VALUE); |
252 |
jsr166 |
1.51 |
final ReentrantLock putLock = this.putLock; |
253 |
|
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putLock.lock(); // Never contended, but necessary for visibility |
254 |
|
|
try { |
255 |
|
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int n = 0; |
256 |
|
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for (E e : c) { |
257 |
|
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if (e == null) |
258 |
|
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throw new NullPointerException(); |
259 |
|
|
if (n == capacity) |
260 |
|
|
throw new IllegalStateException("Queue full"); |
261 |
dl |
1.54 |
enqueue(new Node<E>(e)); |
262 |
jsr166 |
1.51 |
++n; |
263 |
|
|
} |
264 |
|
|
count.set(n); |
265 |
|
|
} finally { |
266 |
|
|
putLock.unlock(); |
267 |
|
|
} |
268 |
dl |
1.2 |
} |
269 |
|
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|
270 |
dholmes |
1.8 |
// this doc comment is overridden to remove the reference to collections |
271 |
|
|
// greater in size than Integer.MAX_VALUE |
272 |
tim |
1.12 |
/** |
273 |
dl |
1.20 |
* Returns the number of elements in this queue. |
274 |
|
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* |
275 |
jsr166 |
1.43 |
* @return the number of elements in this queue |
276 |
dholmes |
1.8 |
*/ |
277 |
dl |
1.2 |
public int size() { |
278 |
|
|
return count.get(); |
279 |
tim |
1.1 |
} |
280 |
dl |
1.2 |
|
281 |
dholmes |
1.8 |
// this doc comment is a modified copy of the inherited doc comment, |
282 |
|
|
// without the reference to unlimited queues. |
283 |
tim |
1.12 |
/** |
284 |
jsr166 |
1.41 |
* Returns the number of additional elements that this queue can ideally |
285 |
|
|
* (in the absence of memory or resource constraints) accept without |
286 |
dholmes |
1.8 |
* blocking. This is always equal to the initial capacity of this queue |
287 |
jsr166 |
1.51 |
* less the current {@code size} of this queue. |
288 |
jsr166 |
1.41 |
* |
289 |
|
|
* <p>Note that you <em>cannot</em> always tell if an attempt to insert |
290 |
jsr166 |
1.51 |
* an element will succeed by inspecting {@code remainingCapacity} |
291 |
jsr166 |
1.41 |
* because it may be the case that another thread is about to |
292 |
jsr166 |
1.43 |
* insert or remove an element. |
293 |
dholmes |
1.8 |
*/ |
294 |
dl |
1.2 |
public int remainingCapacity() { |
295 |
|
|
return capacity - count.get(); |
296 |
|
|
} |
297 |
|
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|
298 |
dholmes |
1.22 |
/** |
299 |
jsr166 |
1.44 |
* Inserts the specified element at the tail of this queue, waiting if |
300 |
dholmes |
1.22 |
* necessary for space to become available. |
301 |
jsr166 |
1.43 |
* |
302 |
|
|
* @throws InterruptedException {@inheritDoc} |
303 |
|
|
* @throws NullPointerException {@inheritDoc} |
304 |
dholmes |
1.22 |
*/ |
305 |
jsr166 |
1.42 |
public void put(E e) throws InterruptedException { |
306 |
|
|
if (e == null) throw new NullPointerException(); |
307 |
jsr166 |
1.51 |
// Note: convention in all put/take/etc is to preset local var |
308 |
|
|
// holding count negative to indicate failure unless set. |
309 |
tim |
1.12 |
int c = -1; |
310 |
jsr166 |
1.60 |
Node<E> node = new Node<E>(e); |
311 |
dl |
1.31 |
final ReentrantLock putLock = this.putLock; |
312 |
|
|
final AtomicInteger count = this.count; |
313 |
dl |
1.2 |
putLock.lockInterruptibly(); |
314 |
|
|
try { |
315 |
|
|
/* |
316 |
|
|
* Note that count is used in wait guard even though it is |
317 |
|
|
* not protected by lock. This works because count can |
318 |
|
|
* only decrease at this point (all other puts are shut |
319 |
|
|
* out by lock), and we (or some other waiting put) are |
320 |
jsr166 |
1.51 |
* signalled if it ever changes from capacity. Similarly |
321 |
|
|
* for all other uses of count in other wait guards. |
322 |
dl |
1.2 |
*/ |
323 |
jsr166 |
1.51 |
while (count.get() == capacity) { |
324 |
|
|
notFull.await(); |
325 |
dl |
1.2 |
} |
326 |
dl |
1.54 |
enqueue(node); |
327 |
dl |
1.2 |
c = count.getAndIncrement(); |
328 |
dl |
1.6 |
if (c + 1 < capacity) |
329 |
dl |
1.2 |
notFull.signal(); |
330 |
tim |
1.17 |
} finally { |
331 |
dl |
1.2 |
putLock.unlock(); |
332 |
|
|
} |
333 |
tim |
1.12 |
if (c == 0) |
334 |
dl |
1.2 |
signalNotEmpty(); |
335 |
tim |
1.1 |
} |
336 |
dl |
1.2 |
|
337 |
dholmes |
1.22 |
/** |
338 |
|
|
* Inserts the specified element at the tail of this queue, waiting if |
339 |
|
|
* necessary up to the specified wait time for space to become available. |
340 |
jsr166 |
1.43 |
* |
341 |
jsr166 |
1.51 |
* @return {@code true} if successful, or {@code false} if |
342 |
jsr166 |
1.73 |
* the specified waiting time elapses before space is available |
343 |
jsr166 |
1.43 |
* @throws InterruptedException {@inheritDoc} |
344 |
|
|
* @throws NullPointerException {@inheritDoc} |
345 |
dholmes |
1.22 |
*/ |
346 |
jsr166 |
1.42 |
public boolean offer(E e, long timeout, TimeUnit unit) |
347 |
dholmes |
1.8 |
throws InterruptedException { |
348 |
tim |
1.12 |
|
349 |
jsr166 |
1.42 |
if (e == null) throw new NullPointerException(); |
350 |
dl |
1.2 |
long nanos = unit.toNanos(timeout); |
351 |
|
|
int c = -1; |
352 |
dl |
1.31 |
final ReentrantLock putLock = this.putLock; |
353 |
|
|
final AtomicInteger count = this.count; |
354 |
dholmes |
1.8 |
putLock.lockInterruptibly(); |
355 |
dl |
1.2 |
try { |
356 |
jsr166 |
1.51 |
while (count.get() == capacity) { |
357 |
dl |
1.2 |
if (nanos <= 0) |
358 |
|
|
return false; |
359 |
jsr166 |
1.51 |
nanos = notFull.awaitNanos(nanos); |
360 |
dl |
1.2 |
} |
361 |
dl |
1.54 |
enqueue(new Node<E>(e)); |
362 |
jsr166 |
1.51 |
c = count.getAndIncrement(); |
363 |
|
|
if (c + 1 < capacity) |
364 |
|
|
notFull.signal(); |
365 |
tim |
1.17 |
} finally { |
366 |
dl |
1.2 |
putLock.unlock(); |
367 |
|
|
} |
368 |
tim |
1.12 |
if (c == 0) |
369 |
dl |
1.2 |
signalNotEmpty(); |
370 |
|
|
return true; |
371 |
tim |
1.1 |
} |
372 |
dl |
1.2 |
|
373 |
dl |
1.23 |
/** |
374 |
jsr166 |
1.44 |
* Inserts the specified element at the tail of this queue if it is |
375 |
|
|
* possible to do so immediately without exceeding the queue's capacity, |
376 |
jsr166 |
1.51 |
* returning {@code true} upon success and {@code false} if this queue |
377 |
jsr166 |
1.44 |
* is full. |
378 |
|
|
* When using a capacity-restricted queue, this method is generally |
379 |
|
|
* preferable to method {@link BlockingQueue#add add}, which can fail to |
380 |
|
|
* insert an element only by throwing an exception. |
381 |
dl |
1.23 |
* |
382 |
jsr166 |
1.43 |
* @throws NullPointerException if the specified element is null |
383 |
dl |
1.23 |
*/ |
384 |
jsr166 |
1.42 |
public boolean offer(E e) { |
385 |
|
|
if (e == null) throw new NullPointerException(); |
386 |
dl |
1.31 |
final AtomicInteger count = this.count; |
387 |
dl |
1.2 |
if (count.get() == capacity) |
388 |
|
|
return false; |
389 |
tim |
1.12 |
int c = -1; |
390 |
jsr166 |
1.60 |
Node<E> node = new Node<E>(e); |
391 |
dl |
1.31 |
final ReentrantLock putLock = this.putLock; |
392 |
dholmes |
1.8 |
putLock.lock(); |
393 |
dl |
1.2 |
try { |
394 |
|
|
if (count.get() < capacity) { |
395 |
dl |
1.54 |
enqueue(node); |
396 |
dl |
1.2 |
c = count.getAndIncrement(); |
397 |
dl |
1.6 |
if (c + 1 < capacity) |
398 |
dl |
1.2 |
notFull.signal(); |
399 |
|
|
} |
400 |
tim |
1.17 |
} finally { |
401 |
dl |
1.2 |
putLock.unlock(); |
402 |
|
|
} |
403 |
tim |
1.12 |
if (c == 0) |
404 |
dl |
1.2 |
signalNotEmpty(); |
405 |
|
|
return c >= 0; |
406 |
tim |
1.1 |
} |
407 |
dl |
1.2 |
|
408 |
|
|
public E take() throws InterruptedException { |
409 |
|
|
E x; |
410 |
|
|
int c = -1; |
411 |
dl |
1.31 |
final AtomicInteger count = this.count; |
412 |
|
|
final ReentrantLock takeLock = this.takeLock; |
413 |
dl |
1.2 |
takeLock.lockInterruptibly(); |
414 |
|
|
try { |
415 |
jsr166 |
1.51 |
while (count.get() == 0) { |
416 |
|
|
notEmpty.await(); |
417 |
dl |
1.2 |
} |
418 |
jsr166 |
1.51 |
x = dequeue(); |
419 |
dl |
1.2 |
c = count.getAndDecrement(); |
420 |
|
|
if (c > 1) |
421 |
|
|
notEmpty.signal(); |
422 |
tim |
1.17 |
} finally { |
423 |
dl |
1.2 |
takeLock.unlock(); |
424 |
|
|
} |
425 |
tim |
1.12 |
if (c == capacity) |
426 |
dl |
1.2 |
signalNotFull(); |
427 |
|
|
return x; |
428 |
|
|
} |
429 |
|
|
|
430 |
|
|
public E poll(long timeout, TimeUnit unit) throws InterruptedException { |
431 |
|
|
E x = null; |
432 |
|
|
int c = -1; |
433 |
dholmes |
1.8 |
long nanos = unit.toNanos(timeout); |
434 |
dl |
1.31 |
final AtomicInteger count = this.count; |
435 |
|
|
final ReentrantLock takeLock = this.takeLock; |
436 |
dl |
1.2 |
takeLock.lockInterruptibly(); |
437 |
|
|
try { |
438 |
jsr166 |
1.51 |
while (count.get() == 0) { |
439 |
dl |
1.2 |
if (nanos <= 0) |
440 |
|
|
return null; |
441 |
jsr166 |
1.51 |
nanos = notEmpty.awaitNanos(nanos); |
442 |
dl |
1.2 |
} |
443 |
jsr166 |
1.51 |
x = dequeue(); |
444 |
|
|
c = count.getAndDecrement(); |
445 |
|
|
if (c > 1) |
446 |
|
|
notEmpty.signal(); |
447 |
tim |
1.17 |
} finally { |
448 |
dl |
1.2 |
takeLock.unlock(); |
449 |
|
|
} |
450 |
tim |
1.12 |
if (c == capacity) |
451 |
dl |
1.2 |
signalNotFull(); |
452 |
|
|
return x; |
453 |
|
|
} |
454 |
|
|
|
455 |
|
|
public E poll() { |
456 |
dl |
1.31 |
final AtomicInteger count = this.count; |
457 |
dl |
1.2 |
if (count.get() == 0) |
458 |
|
|
return null; |
459 |
|
|
E x = null; |
460 |
tim |
1.12 |
int c = -1; |
461 |
dl |
1.31 |
final ReentrantLock takeLock = this.takeLock; |
462 |
dl |
1.30 |
takeLock.lock(); |
463 |
dl |
1.2 |
try { |
464 |
|
|
if (count.get() > 0) { |
465 |
jsr166 |
1.51 |
x = dequeue(); |
466 |
dl |
1.2 |
c = count.getAndDecrement(); |
467 |
|
|
if (c > 1) |
468 |
|
|
notEmpty.signal(); |
469 |
|
|
} |
470 |
tim |
1.17 |
} finally { |
471 |
dl |
1.2 |
takeLock.unlock(); |
472 |
|
|
} |
473 |
tim |
1.12 |
if (c == capacity) |
474 |
dl |
1.2 |
signalNotFull(); |
475 |
|
|
return x; |
476 |
tim |
1.1 |
} |
477 |
dl |
1.2 |
|
478 |
|
|
public E peek() { |
479 |
|
|
if (count.get() == 0) |
480 |
|
|
return null; |
481 |
dl |
1.31 |
final ReentrantLock takeLock = this.takeLock; |
482 |
dholmes |
1.8 |
takeLock.lock(); |
483 |
dl |
1.2 |
try { |
484 |
|
|
Node<E> first = head.next; |
485 |
|
|
if (first == null) |
486 |
|
|
return null; |
487 |
|
|
else |
488 |
|
|
return first.item; |
489 |
tim |
1.17 |
} finally { |
490 |
dl |
1.2 |
takeLock.unlock(); |
491 |
|
|
} |
492 |
tim |
1.1 |
} |
493 |
|
|
|
494 |
dl |
1.35 |
/** |
495 |
jsr166 |
1.51 |
* Unlinks interior Node p with predecessor trail. |
496 |
|
|
*/ |
497 |
|
|
void unlink(Node<E> p, Node<E> trail) { |
498 |
|
|
// assert isFullyLocked(); |
499 |
|
|
// p.next is not changed, to allow iterators that are |
500 |
|
|
// traversing p to maintain their weak-consistency guarantee. |
501 |
|
|
p.item = null; |
502 |
|
|
trail.next = p.next; |
503 |
|
|
if (last == p) |
504 |
|
|
last = trail; |
505 |
|
|
if (count.getAndDecrement() == capacity) |
506 |
|
|
notFull.signal(); |
507 |
|
|
} |
508 |
|
|
|
509 |
|
|
/** |
510 |
jsr166 |
1.44 |
* Removes a single instance of the specified element from this queue, |
511 |
jsr166 |
1.51 |
* if it is present. More formally, removes an element {@code e} such |
512 |
|
|
* that {@code o.equals(e)}, if this queue contains one or more such |
513 |
jsr166 |
1.44 |
* elements. |
514 |
jsr166 |
1.51 |
* Returns {@code true} if this queue contained the specified element |
515 |
jsr166 |
1.44 |
* (or equivalently, if this queue changed as a result of the call). |
516 |
|
|
* |
517 |
|
|
* @param o element to be removed from this queue, if present |
518 |
jsr166 |
1.51 |
* @return {@code true} if this queue changed as a result of the call |
519 |
dl |
1.35 |
*/ |
520 |
dholmes |
1.9 |
public boolean remove(Object o) { |
521 |
|
|
if (o == null) return false; |
522 |
dl |
1.2 |
fullyLock(); |
523 |
|
|
try { |
524 |
jsr166 |
1.51 |
for (Node<E> trail = head, p = trail.next; |
525 |
|
|
p != null; |
526 |
|
|
trail = p, p = p.next) { |
527 |
dholmes |
1.9 |
if (o.equals(p.item)) { |
528 |
jsr166 |
1.51 |
unlink(p, trail); |
529 |
|
|
return true; |
530 |
dl |
1.2 |
} |
531 |
|
|
} |
532 |
jsr166 |
1.51 |
return false; |
533 |
tim |
1.17 |
} finally { |
534 |
dl |
1.2 |
fullyUnlock(); |
535 |
|
|
} |
536 |
tim |
1.1 |
} |
537 |
dl |
1.2 |
|
538 |
jsr166 |
1.43 |
/** |
539 |
jsr166 |
1.56 |
* Returns {@code true} if this queue contains the specified element. |
540 |
|
|
* More formally, returns {@code true} if and only if this queue contains |
541 |
|
|
* at least one element {@code e} such that {@code o.equals(e)}. |
542 |
|
|
* |
543 |
|
|
* @param o object to be checked for containment in this queue |
544 |
|
|
* @return {@code true} if this queue contains the specified element |
545 |
|
|
*/ |
546 |
|
|
public boolean contains(Object o) { |
547 |
|
|
if (o == null) return false; |
548 |
|
|
fullyLock(); |
549 |
|
|
try { |
550 |
|
|
for (Node<E> p = head.next; p != null; p = p.next) |
551 |
|
|
if (o.equals(p.item)) |
552 |
|
|
return true; |
553 |
|
|
return false; |
554 |
|
|
} finally { |
555 |
|
|
fullyUnlock(); |
556 |
|
|
} |
557 |
|
|
} |
558 |
|
|
|
559 |
|
|
/** |
560 |
jsr166 |
1.43 |
* Returns an array containing all of the elements in this queue, in |
561 |
|
|
* proper sequence. |
562 |
|
|
* |
563 |
|
|
* <p>The returned array will be "safe" in that no references to it are |
564 |
|
|
* maintained by this queue. (In other words, this method must allocate |
565 |
|
|
* a new array). The caller is thus free to modify the returned array. |
566 |
jsr166 |
1.45 |
* |
567 |
jsr166 |
1.43 |
* <p>This method acts as bridge between array-based and collection-based |
568 |
|
|
* APIs. |
569 |
|
|
* |
570 |
|
|
* @return an array containing all of the elements in this queue |
571 |
|
|
*/ |
572 |
dl |
1.2 |
public Object[] toArray() { |
573 |
|
|
fullyLock(); |
574 |
|
|
try { |
575 |
|
|
int size = count.get(); |
576 |
tim |
1.12 |
Object[] a = new Object[size]; |
577 |
dl |
1.2 |
int k = 0; |
578 |
tim |
1.12 |
for (Node<E> p = head.next; p != null; p = p.next) |
579 |
dl |
1.2 |
a[k++] = p.item; |
580 |
|
|
return a; |
581 |
tim |
1.17 |
} finally { |
582 |
dl |
1.2 |
fullyUnlock(); |
583 |
|
|
} |
584 |
tim |
1.1 |
} |
585 |
dl |
1.2 |
|
586 |
jsr166 |
1.43 |
/** |
587 |
|
|
* Returns an array containing all of the elements in this queue, in |
588 |
|
|
* proper sequence; the runtime type of the returned array is that of |
589 |
|
|
* the specified array. If the queue fits in the specified array, it |
590 |
|
|
* is returned therein. Otherwise, a new array is allocated with the |
591 |
|
|
* runtime type of the specified array and the size of this queue. |
592 |
|
|
* |
593 |
|
|
* <p>If this queue fits in the specified array with room to spare |
594 |
|
|
* (i.e., the array has more elements than this queue), the element in |
595 |
|
|
* the array immediately following the end of the queue is set to |
596 |
jsr166 |
1.51 |
* {@code null}. |
597 |
jsr166 |
1.43 |
* |
598 |
|
|
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
599 |
|
|
* array-based and collection-based APIs. Further, this method allows |
600 |
|
|
* precise control over the runtime type of the output array, and may, |
601 |
|
|
* under certain circumstances, be used to save allocation costs. |
602 |
|
|
* |
603 |
jsr166 |
1.51 |
* <p>Suppose {@code x} is a queue known to contain only strings. |
604 |
jsr166 |
1.43 |
* The following code can be used to dump the queue into a newly |
605 |
jsr166 |
1.51 |
* allocated array of {@code String}: |
606 |
jsr166 |
1.43 |
* |
607 |
jsr166 |
1.62 |
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre> |
608 |
jsr166 |
1.43 |
* |
609 |
jsr166 |
1.51 |
* Note that {@code toArray(new Object[0])} is identical in function to |
610 |
|
|
* {@code toArray()}. |
611 |
jsr166 |
1.43 |
* |
612 |
|
|
* @param a the array into which the elements of the queue are to |
613 |
|
|
* be stored, if it is big enough; otherwise, a new array of the |
614 |
|
|
* same runtime type is allocated for this purpose |
615 |
|
|
* @return an array containing all of the elements in this queue |
616 |
|
|
* @throws ArrayStoreException if the runtime type of the specified array |
617 |
|
|
* is not a supertype of the runtime type of every element in |
618 |
|
|
* this queue |
619 |
|
|
* @throws NullPointerException if the specified array is null |
620 |
|
|
*/ |
621 |
jsr166 |
1.51 |
@SuppressWarnings("unchecked") |
622 |
dl |
1.2 |
public <T> T[] toArray(T[] a) { |
623 |
|
|
fullyLock(); |
624 |
|
|
try { |
625 |
|
|
int size = count.get(); |
626 |
|
|
if (a.length < size) |
627 |
dl |
1.4 |
a = (T[])java.lang.reflect.Array.newInstance |
628 |
|
|
(a.getClass().getComponentType(), size); |
629 |
tim |
1.12 |
|
630 |
dl |
1.2 |
int k = 0; |
631 |
jsr166 |
1.51 |
for (Node<E> p = head.next; p != null; p = p.next) |
632 |
dl |
1.2 |
a[k++] = (T)p.item; |
633 |
jsr166 |
1.47 |
if (a.length > k) |
634 |
|
|
a[k] = null; |
635 |
dl |
1.2 |
return a; |
636 |
tim |
1.17 |
} finally { |
637 |
dl |
1.2 |
fullyUnlock(); |
638 |
|
|
} |
639 |
tim |
1.1 |
} |
640 |
dl |
1.2 |
|
641 |
|
|
public String toString() { |
642 |
|
|
fullyLock(); |
643 |
|
|
try { |
644 |
jsr166 |
1.55 |
Node<E> p = head.next; |
645 |
|
|
if (p == null) |
646 |
|
|
return "[]"; |
647 |
|
|
|
648 |
|
|
StringBuilder sb = new StringBuilder(); |
649 |
|
|
sb.append('['); |
650 |
|
|
for (;;) { |
651 |
|
|
E e = p.item; |
652 |
|
|
sb.append(e == this ? "(this Collection)" : e); |
653 |
|
|
p = p.next; |
654 |
|
|
if (p == null) |
655 |
|
|
return sb.append(']').toString(); |
656 |
|
|
sb.append(',').append(' '); |
657 |
|
|
} |
658 |
tim |
1.17 |
} finally { |
659 |
dl |
1.2 |
fullyUnlock(); |
660 |
|
|
} |
661 |
tim |
1.1 |
} |
662 |
dl |
1.2 |
|
663 |
dl |
1.35 |
/** |
664 |
|
|
* Atomically removes all of the elements from this queue. |
665 |
|
|
* The queue will be empty after this call returns. |
666 |
|
|
*/ |
667 |
dl |
1.24 |
public void clear() { |
668 |
|
|
fullyLock(); |
669 |
|
|
try { |
670 |
jsr166 |
1.51 |
for (Node<E> p, h = head; (p = h.next) != null; h = p) { |
671 |
|
|
h.next = h; |
672 |
|
|
p.item = null; |
673 |
|
|
} |
674 |
|
|
head = last; |
675 |
|
|
// assert head.item == null && head.next == null; |
676 |
dl |
1.24 |
if (count.getAndSet(0) == capacity) |
677 |
jsr166 |
1.51 |
notFull.signal(); |
678 |
dl |
1.24 |
} finally { |
679 |
|
|
fullyUnlock(); |
680 |
|
|
} |
681 |
|
|
} |
682 |
|
|
|
683 |
jsr166 |
1.43 |
/** |
684 |
|
|
* @throws UnsupportedOperationException {@inheritDoc} |
685 |
|
|
* @throws ClassCastException {@inheritDoc} |
686 |
|
|
* @throws NullPointerException {@inheritDoc} |
687 |
|
|
* @throws IllegalArgumentException {@inheritDoc} |
688 |
|
|
*/ |
689 |
dl |
1.24 |
public int drainTo(Collection<? super E> c) { |
690 |
jsr166 |
1.51 |
return drainTo(c, Integer.MAX_VALUE); |
691 |
dl |
1.24 |
} |
692 |
jsr166 |
1.40 |
|
693 |
jsr166 |
1.43 |
/** |
694 |
|
|
* @throws UnsupportedOperationException {@inheritDoc} |
695 |
|
|
* @throws ClassCastException {@inheritDoc} |
696 |
|
|
* @throws NullPointerException {@inheritDoc} |
697 |
|
|
* @throws IllegalArgumentException {@inheritDoc} |
698 |
|
|
*/ |
699 |
dl |
1.24 |
public int drainTo(Collection<? super E> c, int maxElements) { |
700 |
|
|
if (c == null) |
701 |
|
|
throw new NullPointerException(); |
702 |
|
|
if (c == this) |
703 |
|
|
throw new IllegalArgumentException(); |
704 |
jsr166 |
1.63 |
if (maxElements <= 0) |
705 |
|
|
return 0; |
706 |
jsr166 |
1.51 |
boolean signalNotFull = false; |
707 |
|
|
final ReentrantLock takeLock = this.takeLock; |
708 |
|
|
takeLock.lock(); |
709 |
dl |
1.24 |
try { |
710 |
jsr166 |
1.51 |
int n = Math.min(maxElements, count.get()); |
711 |
|
|
// count.get provides visibility to first n Nodes |
712 |
|
|
Node<E> h = head; |
713 |
|
|
int i = 0; |
714 |
|
|
try { |
715 |
|
|
while (i < n) { |
716 |
|
|
Node<E> p = h.next; |
717 |
|
|
c.add(p.item); |
718 |
|
|
p.item = null; |
719 |
|
|
h.next = h; |
720 |
|
|
h = p; |
721 |
|
|
++i; |
722 |
|
|
} |
723 |
|
|
return n; |
724 |
|
|
} finally { |
725 |
|
|
// Restore invariants even if c.add() threw |
726 |
|
|
if (i > 0) { |
727 |
|
|
// assert h.item == null; |
728 |
|
|
head = h; |
729 |
|
|
signalNotFull = (count.getAndAdd(-i) == capacity); |
730 |
|
|
} |
731 |
dl |
1.24 |
} |
732 |
|
|
} finally { |
733 |
jsr166 |
1.51 |
takeLock.unlock(); |
734 |
|
|
if (signalNotFull) |
735 |
|
|
signalNotFull(); |
736 |
dl |
1.24 |
} |
737 |
|
|
} |
738 |
|
|
|
739 |
dholmes |
1.14 |
/** |
740 |
|
|
* Returns an iterator over the elements in this queue in proper sequence. |
741 |
jsr166 |
1.57 |
* The elements will be returned in order from first (head) to last (tail). |
742 |
|
|
* |
743 |
|
|
* <p>The returned iterator is a "weakly consistent" iterator that |
744 |
jsr166 |
1.52 |
* will never throw {@link java.util.ConcurrentModificationException |
745 |
jsr166 |
1.57 |
* ConcurrentModificationException}, and guarantees to traverse |
746 |
|
|
* elements as they existed upon construction of the iterator, and |
747 |
|
|
* may (but is not guaranteed to) reflect any modifications |
748 |
|
|
* subsequent to construction. |
749 |
dholmes |
1.14 |
* |
750 |
jsr166 |
1.43 |
* @return an iterator over the elements in this queue in proper sequence |
751 |
dholmes |
1.14 |
*/ |
752 |
dl |
1.2 |
public Iterator<E> iterator() { |
753 |
jsr166 |
1.59 |
return new Itr(); |
754 |
tim |
1.1 |
} |
755 |
dl |
1.2 |
|
756 |
|
|
private class Itr implements Iterator<E> { |
757 |
tim |
1.12 |
/* |
758 |
jsr166 |
1.51 |
* Basic weakly-consistent iterator. At all times hold the next |
759 |
dl |
1.4 |
* item to hand out so that if hasNext() reports true, we will |
760 |
|
|
* still have it to return even if lost race with a take etc. |
761 |
|
|
*/ |
762 |
jsr166 |
1.72 |
|
763 |
dl |
1.31 |
private Node<E> current; |
764 |
|
|
private Node<E> lastRet; |
765 |
|
|
private E currentElement; |
766 |
tim |
1.12 |
|
767 |
dl |
1.2 |
Itr() { |
768 |
jsr166 |
1.51 |
fullyLock(); |
769 |
dl |
1.2 |
try { |
770 |
|
|
current = head.next; |
771 |
dl |
1.4 |
if (current != null) |
772 |
|
|
currentElement = current.item; |
773 |
tim |
1.17 |
} finally { |
774 |
jsr166 |
1.51 |
fullyUnlock(); |
775 |
dl |
1.2 |
} |
776 |
|
|
} |
777 |
tim |
1.12 |
|
778 |
|
|
public boolean hasNext() { |
779 |
dl |
1.2 |
return current != null; |
780 |
|
|
} |
781 |
|
|
|
782 |
jsr166 |
1.51 |
/** |
783 |
jsr166 |
1.53 |
* Returns the next live successor of p, or null if no such. |
784 |
|
|
* |
785 |
|
|
* Unlike other traversal methods, iterators need to handle both: |
786 |
jsr166 |
1.51 |
* - dequeued nodes (p.next == p) |
787 |
jsr166 |
1.53 |
* - (possibly multiple) interior removed nodes (p.item == null) |
788 |
jsr166 |
1.51 |
*/ |
789 |
|
|
private Node<E> nextNode(Node<E> p) { |
790 |
jsr166 |
1.53 |
for (;;) { |
791 |
|
|
Node<E> s = p.next; |
792 |
|
|
if (s == p) |
793 |
|
|
return head.next; |
794 |
|
|
if (s == null || s.item != null) |
795 |
|
|
return s; |
796 |
|
|
p = s; |
797 |
|
|
} |
798 |
jsr166 |
1.51 |
} |
799 |
|
|
|
800 |
tim |
1.12 |
public E next() { |
801 |
jsr166 |
1.51 |
fullyLock(); |
802 |
dl |
1.2 |
try { |
803 |
|
|
if (current == null) |
804 |
|
|
throw new NoSuchElementException(); |
805 |
dl |
1.4 |
E x = currentElement; |
806 |
dl |
1.2 |
lastRet = current; |
807 |
jsr166 |
1.51 |
current = nextNode(current); |
808 |
|
|
currentElement = (current == null) ? null : current.item; |
809 |
dl |
1.2 |
return x; |
810 |
tim |
1.17 |
} finally { |
811 |
jsr166 |
1.51 |
fullyUnlock(); |
812 |
dl |
1.2 |
} |
813 |
|
|
} |
814 |
|
|
|
815 |
tim |
1.12 |
public void remove() { |
816 |
dl |
1.2 |
if (lastRet == null) |
817 |
tim |
1.12 |
throw new IllegalStateException(); |
818 |
jsr166 |
1.51 |
fullyLock(); |
819 |
dl |
1.2 |
try { |
820 |
|
|
Node<E> node = lastRet; |
821 |
|
|
lastRet = null; |
822 |
jsr166 |
1.51 |
for (Node<E> trail = head, p = trail.next; |
823 |
|
|
p != null; |
824 |
|
|
trail = p, p = p.next) { |
825 |
|
|
if (p == node) { |
826 |
|
|
unlink(p, trail); |
827 |
|
|
break; |
828 |
|
|
} |
829 |
dl |
1.2 |
} |
830 |
tim |
1.17 |
} finally { |
831 |
jsr166 |
1.51 |
fullyUnlock(); |
832 |
dl |
1.2 |
} |
833 |
|
|
} |
834 |
tim |
1.1 |
} |
835 |
dl |
1.2 |
|
836 |
dl |
1.74 |
static final class LBQSpliterator<E> implements Spliterator<E> { |
837 |
|
|
// Similar idea to ConcurrentLinkedQueue spliterator |
838 |
|
|
static final int MAX_BATCH = 1 << 11; // saturate batch size |
839 |
|
|
final LinkedBlockingQueue<E> queue; |
840 |
|
|
Node<E> current; // current node; null until initialized |
841 |
|
|
int batch; // batch size for splits |
842 |
|
|
boolean exhausted; // true when no more nodes |
843 |
|
|
long est; // size estimate |
844 |
|
|
LBQSpliterator(LinkedBlockingQueue<E> queue) { |
845 |
|
|
this.queue = queue; |
846 |
|
|
this.est = queue.size(); |
847 |
|
|
} |
848 |
|
|
|
849 |
|
|
public long estimateSize() { return est; } |
850 |
|
|
|
851 |
|
|
public Spliterator<E> trySplit() { |
852 |
|
|
int n; |
853 |
|
|
final LinkedBlockingQueue<E> q = this.queue; |
854 |
|
|
if (!exhausted && (n = batch + 1) > 0 && n <= MAX_BATCH) { |
855 |
|
|
Object[] a = new Object[batch = n]; |
856 |
|
|
int i = 0; |
857 |
|
|
Node<E> p = current; |
858 |
|
|
q.fullyLock(); |
859 |
|
|
try { |
860 |
|
|
if (p != null || (p = q.head.next) != null) { |
861 |
|
|
do { |
862 |
|
|
if ((a[i] = p.item) != null) |
863 |
|
|
++i; |
864 |
|
|
} while ((p = p.next) != null && i < n); |
865 |
|
|
} |
866 |
|
|
} finally { |
867 |
|
|
q.fullyUnlock(); |
868 |
|
|
} |
869 |
|
|
if ((current = p) == null) { |
870 |
|
|
est = 0L; |
871 |
|
|
exhausted = true; |
872 |
|
|
} |
873 |
|
|
else if ((est -= i) <= 0L) |
874 |
|
|
est = 1L; |
875 |
dl |
1.75 |
return Spliterators.spliterator |
876 |
dl |
1.74 |
(a, 0, i, Spliterator.ORDERED | Spliterator.NONNULL | |
877 |
|
|
Spliterator.CONCURRENT); |
878 |
|
|
} |
879 |
|
|
return null; |
880 |
|
|
} |
881 |
|
|
|
882 |
|
|
public void forEach(Consumer<? super E> action) { |
883 |
|
|
if (action == null) throw new NullPointerException(); |
884 |
|
|
final LinkedBlockingQueue<E> q = this.queue; |
885 |
|
|
if (!exhausted) { |
886 |
|
|
exhausted = true; |
887 |
|
|
Node<E> p = current; |
888 |
|
|
do { |
889 |
|
|
E e = null; |
890 |
|
|
q.fullyLock(); |
891 |
|
|
try { |
892 |
|
|
if (p == null) |
893 |
|
|
p = q.head.next; |
894 |
|
|
while (p != null) { |
895 |
|
|
e = p.item; |
896 |
|
|
p = p.next; |
897 |
|
|
if (e != null) |
898 |
|
|
break; |
899 |
|
|
} |
900 |
|
|
} finally { |
901 |
|
|
q.fullyUnlock(); |
902 |
|
|
} |
903 |
|
|
if (e != null) |
904 |
|
|
action.accept(e); |
905 |
|
|
} while (p != null); |
906 |
|
|
} |
907 |
|
|
} |
908 |
|
|
|
909 |
|
|
public boolean tryAdvance(Consumer<? super E> action) { |
910 |
|
|
if (action == null) throw new NullPointerException(); |
911 |
|
|
final LinkedBlockingQueue<E> q = this.queue; |
912 |
|
|
if (!exhausted) { |
913 |
|
|
E e = null; |
914 |
|
|
q.fullyLock(); |
915 |
|
|
try { |
916 |
|
|
if (current == null) |
917 |
|
|
current = q.head.next; |
918 |
|
|
while (current != null) { |
919 |
|
|
e = current.item; |
920 |
|
|
current = current.next; |
921 |
|
|
if (e != null) |
922 |
|
|
break; |
923 |
|
|
} |
924 |
|
|
} finally { |
925 |
|
|
q.fullyUnlock(); |
926 |
|
|
} |
927 |
dl |
1.76 |
if (current == null) |
928 |
|
|
exhausted = true; |
929 |
dl |
1.74 |
if (e != null) { |
930 |
|
|
action.accept(e); |
931 |
|
|
return true; |
932 |
|
|
} |
933 |
|
|
} |
934 |
|
|
return false; |
935 |
|
|
} |
936 |
|
|
|
937 |
|
|
public int characteristics() { |
938 |
|
|
return Spliterator.ORDERED | Spliterator.NONNULL | |
939 |
|
|
Spliterator.CONCURRENT; |
940 |
|
|
} |
941 |
|
|
} |
942 |
|
|
|
943 |
dl |
1.76 |
public Spliterator<E> spliterator() { |
944 |
dl |
1.74 |
return new LBQSpliterator<E>(this); |
945 |
|
|
} |
946 |
|
|
|
947 |
dl |
1.2 |
/** |
948 |
jsr166 |
1.68 |
* Saves this queue to a stream (that is, serializes it). |
949 |
dl |
1.2 |
* |
950 |
|
|
* @serialData The capacity is emitted (int), followed by all of |
951 |
jsr166 |
1.51 |
* its elements (each an {@code Object}) in the proper order, |
952 |
dl |
1.2 |
* followed by a null |
953 |
|
|
*/ |
954 |
|
|
private void writeObject(java.io.ObjectOutputStream s) |
955 |
|
|
throws java.io.IOException { |
956 |
|
|
|
957 |
tim |
1.12 |
fullyLock(); |
958 |
dl |
1.2 |
try { |
959 |
|
|
// Write out any hidden stuff, plus capacity |
960 |
|
|
s.defaultWriteObject(); |
961 |
|
|
|
962 |
|
|
// Write out all elements in the proper order. |
963 |
tim |
1.12 |
for (Node<E> p = head.next; p != null; p = p.next) |
964 |
dl |
1.2 |
s.writeObject(p.item); |
965 |
|
|
|
966 |
|
|
// Use trailing null as sentinel |
967 |
|
|
s.writeObject(null); |
968 |
tim |
1.17 |
} finally { |
969 |
dl |
1.2 |
fullyUnlock(); |
970 |
|
|
} |
971 |
tim |
1.1 |
} |
972 |
|
|
|
973 |
dl |
1.2 |
/** |
974 |
jsr166 |
1.65 |
* Reconstitutes this queue from a stream (that is, deserializes it). |
975 |
dl |
1.2 |
*/ |
976 |
|
|
private void readObject(java.io.ObjectInputStream s) |
977 |
|
|
throws java.io.IOException, ClassNotFoundException { |
978 |
tim |
1.12 |
// Read in capacity, and any hidden stuff |
979 |
|
|
s.defaultReadObject(); |
980 |
dl |
1.2 |
|
981 |
dl |
1.19 |
count.set(0); |
982 |
|
|
last = head = new Node<E>(null); |
983 |
|
|
|
984 |
dl |
1.6 |
// Read in all elements and place in queue |
985 |
dl |
1.2 |
for (;;) { |
986 |
jsr166 |
1.51 |
@SuppressWarnings("unchecked") |
987 |
dl |
1.2 |
E item = (E)s.readObject(); |
988 |
|
|
if (item == null) |
989 |
|
|
break; |
990 |
|
|
add(item); |
991 |
|
|
} |
992 |
tim |
1.1 |
} |
993 |
|
|
} |