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; |
8 |
jsr166 |
1.51 |
|
9 |
|
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import java.util.AbstractQueue; |
10 |
|
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import java.util.Collection; |
11 |
|
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import java.util.Iterator; |
12 |
|
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import java.util.NoSuchElementException; |
13 |
jsr166 |
1.101 |
import java.util.Objects; |
14 |
dl |
1.74 |
import java.util.Spliterator; |
15 |
dl |
1.75 |
import java.util.Spliterators; |
16 |
jsr166 |
1.89 |
import java.util.concurrent.atomic.AtomicInteger; |
17 |
|
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import java.util.concurrent.locks.Condition; |
18 |
|
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import java.util.concurrent.locks.ReentrantLock; |
19 |
|
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import java.util.function.Consumer; |
20 |
jsr166 |
1.107 |
import java.util.function.Predicate; |
21 |
tim |
1.1 |
|
22 |
|
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/** |
23 |
dholmes |
1.14 |
* An optionally-bounded {@linkplain BlockingQueue blocking queue} based on |
24 |
dholmes |
1.8 |
* linked nodes. |
25 |
|
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* This queue orders elements FIFO (first-in-first-out). |
26 |
tim |
1.12 |
* The <em>head</em> of the queue is that element that has been on the |
27 |
dholmes |
1.8 |
* queue the longest time. |
28 |
|
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* The <em>tail</em> of the queue is that element that has been on the |
29 |
dl |
1.20 |
* queue the shortest time. New elements |
30 |
|
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* are inserted at the tail of the queue, and the queue retrieval |
31 |
|
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* operations obtain elements at the head of the queue. |
32 |
dholmes |
1.8 |
* Linked queues typically have higher throughput than array-based queues but |
33 |
|
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* less predictable performance in most concurrent applications. |
34 |
tim |
1.12 |
* |
35 |
jsr166 |
1.70 |
* <p>The optional capacity bound constructor argument serves as a |
36 |
dholmes |
1.8 |
* way to prevent excessive queue expansion. The capacity, if unspecified, |
37 |
|
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* is equal to {@link Integer#MAX_VALUE}. Linked nodes are |
38 |
dl |
1.3 |
* dynamically created upon each insertion unless this would bring the |
39 |
|
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* queue above capacity. |
40 |
dholmes |
1.8 |
* |
41 |
jsr166 |
1.109 |
* <p>This class and its iterator implement all of the <em>optional</em> |
42 |
|
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* methods of the {@link Collection} and {@link Iterator} interfaces. |
43 |
dl |
1.21 |
* |
44 |
dl |
1.34 |
* <p>This class is a member of the |
45 |
jsr166 |
1.111 |
* <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework"> |
46 |
dl |
1.34 |
* Java Collections Framework</a>. |
47 |
|
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* |
48 |
dl |
1.6 |
* @since 1.5 |
49 |
|
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* @author Doug Lea |
50 |
jsr166 |
1.88 |
* @param <E> the type of elements held in this queue |
51 |
jsr166 |
1.40 |
*/ |
52 |
dl |
1.2 |
public class LinkedBlockingQueue<E> extends AbstractQueue<E> |
53 |
tim |
1.1 |
implements BlockingQueue<E>, java.io.Serializable { |
54 |
dl |
1.18 |
private static final long serialVersionUID = -6903933977591709194L; |
55 |
tim |
1.1 |
|
56 |
dl |
1.2 |
/* |
57 |
|
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* A variant of the "two lock queue" algorithm. The putLock gates |
58 |
|
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* entry to put (and offer), and has an associated condition for |
59 |
|
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* waiting puts. Similarly for the takeLock. The "count" field |
60 |
|
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* that they both rely on is maintained as an atomic to avoid |
61 |
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* needing to get both locks in most cases. Also, to minimize need |
62 |
|
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* for puts to get takeLock and vice-versa, cascading notifies are |
63 |
|
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* used. When a put notices that it has enabled at least one take, |
64 |
|
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* it signals taker. That taker in turn signals others if more |
65 |
|
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* items have been entered since the signal. And symmetrically for |
66 |
tim |
1.12 |
* takes signalling puts. Operations such as remove(Object) and |
67 |
dl |
1.2 |
* iterators acquire both locks. |
68 |
jsr166 |
1.51 |
* |
69 |
|
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* Visibility between writers and readers is provided as follows: |
70 |
|
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* |
71 |
|
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* Whenever an element is enqueued, the putLock is acquired and |
72 |
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* count updated. A subsequent reader guarantees visibility to the |
73 |
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* enqueued Node by either acquiring the putLock (via fullyLock) |
74 |
|
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* or by acquiring the takeLock, and then reading n = count.get(); |
75 |
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* this gives visibility to the first n items. |
76 |
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* |
77 |
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* To implement weakly consistent iterators, it appears we need to |
78 |
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* keep all Nodes GC-reachable from a predecessor dequeued Node. |
79 |
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* That would cause two problems: |
80 |
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* - allow a rogue Iterator to cause unbounded memory retention |
81 |
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* - cause cross-generational linking of old Nodes to new Nodes if |
82 |
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* a Node was tenured while live, which generational GCs have a |
83 |
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* hard time dealing with, causing repeated major collections. |
84 |
|
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* However, only non-deleted Nodes need to be reachable from |
85 |
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* dequeued Nodes, and reachability does not necessarily have to |
86 |
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* be of the kind understood by the GC. We use the trick of |
87 |
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* linking a Node that has just been dequeued to itself. Such a |
88 |
|
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* self-link implicitly means to advance to head.next. |
89 |
dl |
1.38 |
*/ |
90 |
dl |
1.2 |
|
91 |
dl |
1.6 |
/** |
92 |
jsr166 |
1.97 |
* Linked list node class. |
93 |
dl |
1.6 |
*/ |
94 |
dl |
1.2 |
static class Node<E> { |
95 |
jsr166 |
1.51 |
E item; |
96 |
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|
97 |
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/** |
98 |
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* One of: |
99 |
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* - the real successor Node |
100 |
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* - this Node, meaning the successor is head.next |
101 |
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* - null, meaning there is no successor (this is the last node) |
102 |
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*/ |
103 |
dl |
1.2 |
Node<E> next; |
104 |
jsr166 |
1.51 |
|
105 |
dl |
1.2 |
Node(E x) { item = x; } |
106 |
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} |
107 |
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|
108 |
dl |
1.6 |
/** The capacity bound, or Integer.MAX_VALUE if none */ |
109 |
dl |
1.2 |
private final int capacity; |
110 |
dl |
1.6 |
|
111 |
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/** Current number of elements */ |
112 |
jsr166 |
1.61 |
private final AtomicInteger count = new AtomicInteger(); |
113 |
dl |
1.2 |
|
114 |
jsr166 |
1.51 |
/** |
115 |
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* Head of linked list. |
116 |
|
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* Invariant: head.item == null |
117 |
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*/ |
118 |
jsr166 |
1.64 |
transient Node<E> head; |
119 |
dl |
1.6 |
|
120 |
jsr166 |
1.51 |
/** |
121 |
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* Tail of linked list. |
122 |
|
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* Invariant: last.next == null |
123 |
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*/ |
124 |
dl |
1.6 |
private transient Node<E> last; |
125 |
dl |
1.2 |
|
126 |
dl |
1.6 |
/** Lock held by take, poll, etc */ |
127 |
dl |
1.5 |
private final ReentrantLock takeLock = new ReentrantLock(); |
128 |
dl |
1.6 |
|
129 |
|
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/** Wait queue for waiting takes */ |
130 |
dl |
1.32 |
private final Condition notEmpty = takeLock.newCondition(); |
131 |
dl |
1.2 |
|
132 |
dl |
1.6 |
/** Lock held by put, offer, etc */ |
133 |
dl |
1.5 |
private final ReentrantLock putLock = new ReentrantLock(); |
134 |
dl |
1.6 |
|
135 |
|
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/** Wait queue for waiting puts */ |
136 |
dl |
1.32 |
private final Condition notFull = putLock.newCondition(); |
137 |
dl |
1.2 |
|
138 |
|
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/** |
139 |
jsr166 |
1.40 |
* Signals a waiting take. Called only from put/offer (which do not |
140 |
dl |
1.4 |
* otherwise ordinarily lock takeLock.) |
141 |
dl |
1.2 |
*/ |
142 |
|
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private void signalNotEmpty() { |
143 |
dl |
1.31 |
final ReentrantLock takeLock = this.takeLock; |
144 |
dl |
1.2 |
takeLock.lock(); |
145 |
|
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try { |
146 |
|
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notEmpty.signal(); |
147 |
tim |
1.17 |
} finally { |
148 |
dl |
1.2 |
takeLock.unlock(); |
149 |
|
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} |
150 |
|
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} |
151 |
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|
152 |
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/** |
153 |
jsr166 |
1.40 |
* Signals a waiting put. Called only from take/poll. |
154 |
dl |
1.2 |
*/ |
155 |
|
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private void signalNotFull() { |
156 |
dl |
1.31 |
final ReentrantLock putLock = this.putLock; |
157 |
dl |
1.2 |
putLock.lock(); |
158 |
|
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try { |
159 |
|
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notFull.signal(); |
160 |
tim |
1.17 |
} finally { |
161 |
dl |
1.2 |
putLock.unlock(); |
162 |
|
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} |
163 |
|
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} |
164 |
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|
165 |
|
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/** |
166 |
dl |
1.54 |
* Links node at end of queue. |
167 |
jsr166 |
1.51 |
* |
168 |
dl |
1.54 |
* @param node the node |
169 |
dl |
1.2 |
*/ |
170 |
dl |
1.54 |
private void enqueue(Node<E> node) { |
171 |
jsr166 |
1.51 |
// assert putLock.isHeldByCurrentThread(); |
172 |
|
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// assert last.next == null; |
173 |
dl |
1.54 |
last = last.next = node; |
174 |
dl |
1.2 |
} |
175 |
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|
176 |
|
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/** |
177 |
jsr166 |
1.51 |
* Removes a node from head of queue. |
178 |
|
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* |
179 |
dl |
1.6 |
* @return the node |
180 |
dl |
1.2 |
*/ |
181 |
jsr166 |
1.51 |
private E dequeue() { |
182 |
|
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// assert takeLock.isHeldByCurrentThread(); |
183 |
|
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// assert head.item == null; |
184 |
dl |
1.50 |
Node<E> h = head; |
185 |
|
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Node<E> first = h.next; |
186 |
jsr166 |
1.51 |
h.next = h; // help GC |
187 |
dl |
1.2 |
head = first; |
188 |
dl |
1.28 |
E x = first.item; |
189 |
dl |
1.2 |
first.item = null; |
190 |
|
|
return x; |
191 |
|
|
} |
192 |
|
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|
193 |
|
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/** |
194 |
jsr166 |
1.71 |
* Locks to prevent both puts and takes. |
195 |
dl |
1.2 |
*/ |
196 |
jsr166 |
1.51 |
void fullyLock() { |
197 |
dl |
1.2 |
putLock.lock(); |
198 |
|
|
takeLock.lock(); |
199 |
tim |
1.1 |
} |
200 |
dl |
1.2 |
|
201 |
|
|
/** |
202 |
jsr166 |
1.71 |
* Unlocks to allow both puts and takes. |
203 |
dl |
1.2 |
*/ |
204 |
jsr166 |
1.51 |
void fullyUnlock() { |
205 |
dl |
1.2 |
takeLock.unlock(); |
206 |
|
|
putLock.unlock(); |
207 |
|
|
} |
208 |
|
|
|
209 |
|
|
/** |
210 |
jsr166 |
1.51 |
* Creates a {@code LinkedBlockingQueue} with a capacity of |
211 |
dholmes |
1.8 |
* {@link Integer#MAX_VALUE}. |
212 |
dl |
1.2 |
*/ |
213 |
|
|
public LinkedBlockingQueue() { |
214 |
|
|
this(Integer.MAX_VALUE); |
215 |
|
|
} |
216 |
|
|
|
217 |
|
|
/** |
218 |
jsr166 |
1.51 |
* Creates a {@code LinkedBlockingQueue} with the given (fixed) capacity. |
219 |
tim |
1.16 |
* |
220 |
jsr166 |
1.43 |
* @param capacity the capacity of this queue |
221 |
jsr166 |
1.51 |
* @throws IllegalArgumentException if {@code capacity} is not greater |
222 |
jsr166 |
1.43 |
* than zero |
223 |
dl |
1.2 |
*/ |
224 |
|
|
public LinkedBlockingQueue(int capacity) { |
225 |
dholmes |
1.8 |
if (capacity <= 0) throw new IllegalArgumentException(); |
226 |
dl |
1.2 |
this.capacity = capacity; |
227 |
dl |
1.6 |
last = head = new Node<E>(null); |
228 |
dl |
1.2 |
} |
229 |
|
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|
230 |
|
|
/** |
231 |
jsr166 |
1.51 |
* Creates a {@code LinkedBlockingQueue} with a capacity of |
232 |
dholmes |
1.14 |
* {@link Integer#MAX_VALUE}, initially containing the elements of the |
233 |
tim |
1.12 |
* given collection, |
234 |
dholmes |
1.8 |
* added in traversal order of the collection's iterator. |
235 |
jsr166 |
1.43 |
* |
236 |
dholmes |
1.9 |
* @param c the collection of elements to initially contain |
237 |
jsr166 |
1.43 |
* @throws NullPointerException if the specified collection or any |
238 |
|
|
* of its elements are null |
239 |
dl |
1.2 |
*/ |
240 |
dholmes |
1.10 |
public LinkedBlockingQueue(Collection<? extends E> c) { |
241 |
dl |
1.2 |
this(Integer.MAX_VALUE); |
242 |
jsr166 |
1.51 |
final ReentrantLock putLock = this.putLock; |
243 |
|
|
putLock.lock(); // Never contended, but necessary for visibility |
244 |
|
|
try { |
245 |
|
|
int n = 0; |
246 |
|
|
for (E e : c) { |
247 |
|
|
if (e == null) |
248 |
|
|
throw new NullPointerException(); |
249 |
|
|
if (n == capacity) |
250 |
|
|
throw new IllegalStateException("Queue full"); |
251 |
dl |
1.54 |
enqueue(new Node<E>(e)); |
252 |
jsr166 |
1.51 |
++n; |
253 |
|
|
} |
254 |
|
|
count.set(n); |
255 |
|
|
} finally { |
256 |
|
|
putLock.unlock(); |
257 |
|
|
} |
258 |
dl |
1.2 |
} |
259 |
|
|
|
260 |
dholmes |
1.8 |
// this doc comment is overridden to remove the reference to collections |
261 |
|
|
// greater in size than Integer.MAX_VALUE |
262 |
tim |
1.12 |
/** |
263 |
dl |
1.20 |
* Returns the number of elements in this queue. |
264 |
|
|
* |
265 |
jsr166 |
1.43 |
* @return the number of elements in this queue |
266 |
dholmes |
1.8 |
*/ |
267 |
dl |
1.2 |
public int size() { |
268 |
|
|
return count.get(); |
269 |
tim |
1.1 |
} |
270 |
dl |
1.2 |
|
271 |
dholmes |
1.8 |
// this doc comment is a modified copy of the inherited doc comment, |
272 |
|
|
// without the reference to unlimited queues. |
273 |
tim |
1.12 |
/** |
274 |
jsr166 |
1.41 |
* Returns the number of additional elements that this queue can ideally |
275 |
|
|
* (in the absence of memory or resource constraints) accept without |
276 |
dholmes |
1.8 |
* blocking. This is always equal to the initial capacity of this queue |
277 |
jsr166 |
1.51 |
* less the current {@code size} of this queue. |
278 |
jsr166 |
1.41 |
* |
279 |
|
|
* <p>Note that you <em>cannot</em> always tell if an attempt to insert |
280 |
jsr166 |
1.51 |
* an element will succeed by inspecting {@code remainingCapacity} |
281 |
jsr166 |
1.41 |
* because it may be the case that another thread is about to |
282 |
jsr166 |
1.43 |
* insert or remove an element. |
283 |
dholmes |
1.8 |
*/ |
284 |
dl |
1.2 |
public int remainingCapacity() { |
285 |
|
|
return capacity - count.get(); |
286 |
|
|
} |
287 |
|
|
|
288 |
dholmes |
1.22 |
/** |
289 |
jsr166 |
1.44 |
* Inserts the specified element at the tail of this queue, waiting if |
290 |
dholmes |
1.22 |
* necessary for space to become available. |
291 |
jsr166 |
1.43 |
* |
292 |
|
|
* @throws InterruptedException {@inheritDoc} |
293 |
|
|
* @throws NullPointerException {@inheritDoc} |
294 |
dholmes |
1.22 |
*/ |
295 |
jsr166 |
1.42 |
public void put(E e) throws InterruptedException { |
296 |
|
|
if (e == null) throw new NullPointerException(); |
297 |
jsr166 |
1.113 |
final int c; |
298 |
|
|
final Node<E> node = new Node<E>(e); |
299 |
dl |
1.31 |
final ReentrantLock putLock = this.putLock; |
300 |
|
|
final AtomicInteger count = this.count; |
301 |
dl |
1.2 |
putLock.lockInterruptibly(); |
302 |
|
|
try { |
303 |
|
|
/* |
304 |
|
|
* Note that count is used in wait guard even though it is |
305 |
|
|
* not protected by lock. This works because count can |
306 |
|
|
* only decrease at this point (all other puts are shut |
307 |
|
|
* out by lock), and we (or some other waiting put) are |
308 |
jsr166 |
1.51 |
* signalled if it ever changes from capacity. Similarly |
309 |
|
|
* for all other uses of count in other wait guards. |
310 |
dl |
1.2 |
*/ |
311 |
jsr166 |
1.51 |
while (count.get() == capacity) { |
312 |
|
|
notFull.await(); |
313 |
dl |
1.2 |
} |
314 |
dl |
1.54 |
enqueue(node); |
315 |
dl |
1.2 |
c = count.getAndIncrement(); |
316 |
dl |
1.6 |
if (c + 1 < capacity) |
317 |
dl |
1.2 |
notFull.signal(); |
318 |
tim |
1.17 |
} finally { |
319 |
dl |
1.2 |
putLock.unlock(); |
320 |
|
|
} |
321 |
tim |
1.12 |
if (c == 0) |
322 |
dl |
1.2 |
signalNotEmpty(); |
323 |
tim |
1.1 |
} |
324 |
dl |
1.2 |
|
325 |
dholmes |
1.22 |
/** |
326 |
|
|
* Inserts the specified element at the tail of this queue, waiting if |
327 |
|
|
* necessary up to the specified wait time for space to become available. |
328 |
jsr166 |
1.43 |
* |
329 |
jsr166 |
1.51 |
* @return {@code true} if successful, or {@code false} if |
330 |
jsr166 |
1.73 |
* the specified waiting time elapses before space is available |
331 |
jsr166 |
1.43 |
* @throws InterruptedException {@inheritDoc} |
332 |
|
|
* @throws NullPointerException {@inheritDoc} |
333 |
dholmes |
1.22 |
*/ |
334 |
jsr166 |
1.42 |
public boolean offer(E e, long timeout, TimeUnit unit) |
335 |
dholmes |
1.8 |
throws InterruptedException { |
336 |
tim |
1.12 |
|
337 |
jsr166 |
1.42 |
if (e == null) throw new NullPointerException(); |
338 |
dl |
1.2 |
long nanos = unit.toNanos(timeout); |
339 |
jsr166 |
1.113 |
final int c; |
340 |
dl |
1.31 |
final ReentrantLock putLock = this.putLock; |
341 |
|
|
final AtomicInteger count = this.count; |
342 |
dholmes |
1.8 |
putLock.lockInterruptibly(); |
343 |
dl |
1.2 |
try { |
344 |
jsr166 |
1.51 |
while (count.get() == capacity) { |
345 |
jsr166 |
1.98 |
if (nanos <= 0L) |
346 |
dl |
1.2 |
return false; |
347 |
jsr166 |
1.51 |
nanos = notFull.awaitNanos(nanos); |
348 |
dl |
1.2 |
} |
349 |
dl |
1.54 |
enqueue(new Node<E>(e)); |
350 |
jsr166 |
1.51 |
c = count.getAndIncrement(); |
351 |
|
|
if (c + 1 < capacity) |
352 |
|
|
notFull.signal(); |
353 |
tim |
1.17 |
} finally { |
354 |
dl |
1.2 |
putLock.unlock(); |
355 |
|
|
} |
356 |
tim |
1.12 |
if (c == 0) |
357 |
dl |
1.2 |
signalNotEmpty(); |
358 |
|
|
return true; |
359 |
tim |
1.1 |
} |
360 |
dl |
1.2 |
|
361 |
dl |
1.23 |
/** |
362 |
jsr166 |
1.44 |
* Inserts the specified element at the tail of this queue if it is |
363 |
|
|
* possible to do so immediately without exceeding the queue's capacity, |
364 |
jsr166 |
1.51 |
* returning {@code true} upon success and {@code false} if this queue |
365 |
jsr166 |
1.44 |
* is full. |
366 |
|
|
* When using a capacity-restricted queue, this method is generally |
367 |
|
|
* preferable to method {@link BlockingQueue#add add}, which can fail to |
368 |
|
|
* insert an element only by throwing an exception. |
369 |
dl |
1.23 |
* |
370 |
jsr166 |
1.43 |
* @throws NullPointerException if the specified element is null |
371 |
dl |
1.23 |
*/ |
372 |
jsr166 |
1.42 |
public boolean offer(E e) { |
373 |
|
|
if (e == null) throw new NullPointerException(); |
374 |
dl |
1.31 |
final AtomicInteger count = this.count; |
375 |
dl |
1.2 |
if (count.get() == capacity) |
376 |
|
|
return false; |
377 |
jsr166 |
1.113 |
final int c; |
378 |
|
|
final Node<E> node = new Node<E>(e); |
379 |
dl |
1.31 |
final ReentrantLock putLock = this.putLock; |
380 |
dholmes |
1.8 |
putLock.lock(); |
381 |
dl |
1.2 |
try { |
382 |
jsr166 |
1.113 |
if (count.get() == capacity) |
383 |
|
|
return false; |
384 |
|
|
enqueue(node); |
385 |
|
|
c = count.getAndIncrement(); |
386 |
|
|
if (c + 1 < capacity) |
387 |
|
|
notFull.signal(); |
388 |
tim |
1.17 |
} finally { |
389 |
dl |
1.2 |
putLock.unlock(); |
390 |
|
|
} |
391 |
tim |
1.12 |
if (c == 0) |
392 |
dl |
1.2 |
signalNotEmpty(); |
393 |
jsr166 |
1.113 |
return true; |
394 |
tim |
1.1 |
} |
395 |
dl |
1.2 |
|
396 |
|
|
public E take() throws InterruptedException { |
397 |
jsr166 |
1.113 |
final E x; |
398 |
|
|
final int c; |
399 |
dl |
1.31 |
final AtomicInteger count = this.count; |
400 |
|
|
final ReentrantLock takeLock = this.takeLock; |
401 |
dl |
1.2 |
takeLock.lockInterruptibly(); |
402 |
|
|
try { |
403 |
jsr166 |
1.51 |
while (count.get() == 0) { |
404 |
|
|
notEmpty.await(); |
405 |
dl |
1.2 |
} |
406 |
jsr166 |
1.51 |
x = dequeue(); |
407 |
dl |
1.2 |
c = count.getAndDecrement(); |
408 |
|
|
if (c > 1) |
409 |
|
|
notEmpty.signal(); |
410 |
tim |
1.17 |
} finally { |
411 |
dl |
1.2 |
takeLock.unlock(); |
412 |
|
|
} |
413 |
tim |
1.12 |
if (c == capacity) |
414 |
dl |
1.2 |
signalNotFull(); |
415 |
|
|
return x; |
416 |
|
|
} |
417 |
|
|
|
418 |
|
|
public E poll(long timeout, TimeUnit unit) throws InterruptedException { |
419 |
jsr166 |
1.113 |
final E x; |
420 |
|
|
final int c; |
421 |
dholmes |
1.8 |
long nanos = unit.toNanos(timeout); |
422 |
dl |
1.31 |
final AtomicInteger count = this.count; |
423 |
|
|
final ReentrantLock takeLock = this.takeLock; |
424 |
dl |
1.2 |
takeLock.lockInterruptibly(); |
425 |
|
|
try { |
426 |
jsr166 |
1.51 |
while (count.get() == 0) { |
427 |
jsr166 |
1.98 |
if (nanos <= 0L) |
428 |
dl |
1.2 |
return null; |
429 |
jsr166 |
1.51 |
nanos = notEmpty.awaitNanos(nanos); |
430 |
dl |
1.2 |
} |
431 |
jsr166 |
1.51 |
x = dequeue(); |
432 |
|
|
c = count.getAndDecrement(); |
433 |
|
|
if (c > 1) |
434 |
|
|
notEmpty.signal(); |
435 |
tim |
1.17 |
} finally { |
436 |
dl |
1.2 |
takeLock.unlock(); |
437 |
|
|
} |
438 |
tim |
1.12 |
if (c == capacity) |
439 |
dl |
1.2 |
signalNotFull(); |
440 |
|
|
return x; |
441 |
|
|
} |
442 |
|
|
|
443 |
|
|
public E poll() { |
444 |
dl |
1.31 |
final AtomicInteger count = this.count; |
445 |
dl |
1.2 |
if (count.get() == 0) |
446 |
|
|
return null; |
447 |
jsr166 |
1.113 |
final E x; |
448 |
|
|
final int c; |
449 |
dl |
1.31 |
final ReentrantLock takeLock = this.takeLock; |
450 |
dl |
1.30 |
takeLock.lock(); |
451 |
dl |
1.2 |
try { |
452 |
jsr166 |
1.113 |
if (count.get() == 0) |
453 |
|
|
return null; |
454 |
|
|
x = dequeue(); |
455 |
|
|
c = count.getAndDecrement(); |
456 |
|
|
if (c > 1) |
457 |
|
|
notEmpty.signal(); |
458 |
tim |
1.17 |
} finally { |
459 |
dl |
1.2 |
takeLock.unlock(); |
460 |
|
|
} |
461 |
tim |
1.12 |
if (c == capacity) |
462 |
dl |
1.2 |
signalNotFull(); |
463 |
|
|
return x; |
464 |
tim |
1.1 |
} |
465 |
dl |
1.2 |
|
466 |
|
|
public E peek() { |
467 |
jsr166 |
1.113 |
final AtomicInteger count = this.count; |
468 |
dl |
1.2 |
if (count.get() == 0) |
469 |
|
|
return null; |
470 |
dl |
1.31 |
final ReentrantLock takeLock = this.takeLock; |
471 |
dholmes |
1.8 |
takeLock.lock(); |
472 |
dl |
1.2 |
try { |
473 |
jsr166 |
1.96 |
return (count.get() > 0) ? head.next.item : null; |
474 |
tim |
1.17 |
} finally { |
475 |
dl |
1.2 |
takeLock.unlock(); |
476 |
|
|
} |
477 |
tim |
1.1 |
} |
478 |
|
|
|
479 |
dl |
1.35 |
/** |
480 |
jsr166 |
1.105 |
* Unlinks interior Node p with predecessor pred. |
481 |
jsr166 |
1.51 |
*/ |
482 |
jsr166 |
1.105 |
void unlink(Node<E> p, Node<E> pred) { |
483 |
jsr166 |
1.100 |
// assert putLock.isHeldByCurrentThread(); |
484 |
|
|
// assert takeLock.isHeldByCurrentThread(); |
485 |
jsr166 |
1.51 |
// p.next is not changed, to allow iterators that are |
486 |
|
|
// traversing p to maintain their weak-consistency guarantee. |
487 |
|
|
p.item = null; |
488 |
jsr166 |
1.105 |
pred.next = p.next; |
489 |
jsr166 |
1.51 |
if (last == p) |
490 |
jsr166 |
1.105 |
last = pred; |
491 |
jsr166 |
1.51 |
if (count.getAndDecrement() == capacity) |
492 |
|
|
notFull.signal(); |
493 |
|
|
} |
494 |
|
|
|
495 |
|
|
/** |
496 |
jsr166 |
1.44 |
* Removes a single instance of the specified element from this queue, |
497 |
jsr166 |
1.51 |
* if it is present. More formally, removes an element {@code e} such |
498 |
|
|
* that {@code o.equals(e)}, if this queue contains one or more such |
499 |
jsr166 |
1.44 |
* elements. |
500 |
jsr166 |
1.51 |
* Returns {@code true} if this queue contained the specified element |
501 |
jsr166 |
1.44 |
* (or equivalently, if this queue changed as a result of the call). |
502 |
|
|
* |
503 |
|
|
* @param o element to be removed from this queue, if present |
504 |
jsr166 |
1.51 |
* @return {@code true} if this queue changed as a result of the call |
505 |
dl |
1.35 |
*/ |
506 |
dholmes |
1.9 |
public boolean remove(Object o) { |
507 |
|
|
if (o == null) return false; |
508 |
dl |
1.2 |
fullyLock(); |
509 |
|
|
try { |
510 |
jsr166 |
1.105 |
for (Node<E> pred = head, p = pred.next; |
511 |
jsr166 |
1.51 |
p != null; |
512 |
jsr166 |
1.105 |
pred = p, p = p.next) { |
513 |
dholmes |
1.9 |
if (o.equals(p.item)) { |
514 |
jsr166 |
1.105 |
unlink(p, pred); |
515 |
jsr166 |
1.51 |
return true; |
516 |
dl |
1.2 |
} |
517 |
|
|
} |
518 |
jsr166 |
1.51 |
return false; |
519 |
tim |
1.17 |
} finally { |
520 |
dl |
1.2 |
fullyUnlock(); |
521 |
|
|
} |
522 |
tim |
1.1 |
} |
523 |
dl |
1.2 |
|
524 |
jsr166 |
1.43 |
/** |
525 |
jsr166 |
1.56 |
* Returns {@code true} if this queue contains the specified element. |
526 |
|
|
* More formally, returns {@code true} if and only if this queue contains |
527 |
|
|
* at least one element {@code e} such that {@code o.equals(e)}. |
528 |
|
|
* |
529 |
|
|
* @param o object to be checked for containment in this queue |
530 |
|
|
* @return {@code true} if this queue contains the specified element |
531 |
|
|
*/ |
532 |
|
|
public boolean contains(Object o) { |
533 |
|
|
if (o == null) return false; |
534 |
|
|
fullyLock(); |
535 |
|
|
try { |
536 |
|
|
for (Node<E> p = head.next; p != null; p = p.next) |
537 |
|
|
if (o.equals(p.item)) |
538 |
|
|
return true; |
539 |
|
|
return false; |
540 |
|
|
} finally { |
541 |
|
|
fullyUnlock(); |
542 |
|
|
} |
543 |
|
|
} |
544 |
|
|
|
545 |
|
|
/** |
546 |
jsr166 |
1.43 |
* Returns an array containing all of the elements in this queue, in |
547 |
|
|
* proper sequence. |
548 |
|
|
* |
549 |
|
|
* <p>The returned array will be "safe" in that no references to it are |
550 |
|
|
* maintained by this queue. (In other words, this method must allocate |
551 |
|
|
* a new array). The caller is thus free to modify the returned array. |
552 |
jsr166 |
1.45 |
* |
553 |
jsr166 |
1.43 |
* <p>This method acts as bridge between array-based and collection-based |
554 |
|
|
* APIs. |
555 |
|
|
* |
556 |
|
|
* @return an array containing all of the elements in this queue |
557 |
|
|
*/ |
558 |
dl |
1.2 |
public Object[] toArray() { |
559 |
|
|
fullyLock(); |
560 |
|
|
try { |
561 |
|
|
int size = count.get(); |
562 |
tim |
1.12 |
Object[] a = new Object[size]; |
563 |
dl |
1.2 |
int k = 0; |
564 |
tim |
1.12 |
for (Node<E> p = head.next; p != null; p = p.next) |
565 |
dl |
1.2 |
a[k++] = p.item; |
566 |
|
|
return a; |
567 |
tim |
1.17 |
} finally { |
568 |
dl |
1.2 |
fullyUnlock(); |
569 |
|
|
} |
570 |
tim |
1.1 |
} |
571 |
dl |
1.2 |
|
572 |
jsr166 |
1.43 |
/** |
573 |
|
|
* Returns an array containing all of the elements in this queue, in |
574 |
|
|
* proper sequence; the runtime type of the returned array is that of |
575 |
|
|
* the specified array. If the queue fits in the specified array, it |
576 |
|
|
* is returned therein. Otherwise, a new array is allocated with the |
577 |
|
|
* runtime type of the specified array and the size of this queue. |
578 |
|
|
* |
579 |
|
|
* <p>If this queue fits in the specified array with room to spare |
580 |
|
|
* (i.e., the array has more elements than this queue), the element in |
581 |
|
|
* the array immediately following the end of the queue is set to |
582 |
jsr166 |
1.51 |
* {@code null}. |
583 |
jsr166 |
1.43 |
* |
584 |
|
|
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
585 |
|
|
* array-based and collection-based APIs. Further, this method allows |
586 |
|
|
* precise control over the runtime type of the output array, and may, |
587 |
|
|
* under certain circumstances, be used to save allocation costs. |
588 |
|
|
* |
589 |
jsr166 |
1.51 |
* <p>Suppose {@code x} is a queue known to contain only strings. |
590 |
jsr166 |
1.43 |
* The following code can be used to dump the queue into a newly |
591 |
jsr166 |
1.51 |
* allocated array of {@code String}: |
592 |
jsr166 |
1.43 |
* |
593 |
jsr166 |
1.92 |
* <pre> {@code String[] y = x.toArray(new String[0]);}</pre> |
594 |
jsr166 |
1.43 |
* |
595 |
jsr166 |
1.51 |
* Note that {@code toArray(new Object[0])} is identical in function to |
596 |
|
|
* {@code toArray()}. |
597 |
jsr166 |
1.43 |
* |
598 |
|
|
* @param a the array into which the elements of the queue are to |
599 |
|
|
* be stored, if it is big enough; otherwise, a new array of the |
600 |
|
|
* same runtime type is allocated for this purpose |
601 |
|
|
* @return an array containing all of the elements in this queue |
602 |
|
|
* @throws ArrayStoreException if the runtime type of the specified array |
603 |
|
|
* is not a supertype of the runtime type of every element in |
604 |
|
|
* this queue |
605 |
|
|
* @throws NullPointerException if the specified array is null |
606 |
|
|
*/ |
607 |
jsr166 |
1.51 |
@SuppressWarnings("unchecked") |
608 |
dl |
1.2 |
public <T> T[] toArray(T[] a) { |
609 |
|
|
fullyLock(); |
610 |
|
|
try { |
611 |
|
|
int size = count.get(); |
612 |
|
|
if (a.length < size) |
613 |
dl |
1.4 |
a = (T[])java.lang.reflect.Array.newInstance |
614 |
|
|
(a.getClass().getComponentType(), size); |
615 |
tim |
1.12 |
|
616 |
dl |
1.2 |
int k = 0; |
617 |
jsr166 |
1.51 |
for (Node<E> p = head.next; p != null; p = p.next) |
618 |
dl |
1.2 |
a[k++] = (T)p.item; |
619 |
jsr166 |
1.47 |
if (a.length > k) |
620 |
|
|
a[k] = null; |
621 |
dl |
1.2 |
return a; |
622 |
tim |
1.17 |
} finally { |
623 |
dl |
1.2 |
fullyUnlock(); |
624 |
|
|
} |
625 |
tim |
1.1 |
} |
626 |
dl |
1.2 |
|
627 |
|
|
public String toString() { |
628 |
jsr166 |
1.94 |
return Helpers.collectionToString(this); |
629 |
tim |
1.1 |
} |
630 |
dl |
1.2 |
|
631 |
dl |
1.35 |
/** |
632 |
|
|
* Atomically removes all of the elements from this queue. |
633 |
|
|
* The queue will be empty after this call returns. |
634 |
|
|
*/ |
635 |
dl |
1.24 |
public void clear() { |
636 |
|
|
fullyLock(); |
637 |
|
|
try { |
638 |
jsr166 |
1.51 |
for (Node<E> p, h = head; (p = h.next) != null; h = p) { |
639 |
|
|
h.next = h; |
640 |
|
|
p.item = null; |
641 |
|
|
} |
642 |
|
|
head = last; |
643 |
|
|
// assert head.item == null && head.next == null; |
644 |
dl |
1.24 |
if (count.getAndSet(0) == capacity) |
645 |
jsr166 |
1.51 |
notFull.signal(); |
646 |
dl |
1.24 |
} finally { |
647 |
|
|
fullyUnlock(); |
648 |
|
|
} |
649 |
|
|
} |
650 |
|
|
|
651 |
jsr166 |
1.43 |
/** |
652 |
|
|
* @throws UnsupportedOperationException {@inheritDoc} |
653 |
|
|
* @throws ClassCastException {@inheritDoc} |
654 |
|
|
* @throws NullPointerException {@inheritDoc} |
655 |
|
|
* @throws IllegalArgumentException {@inheritDoc} |
656 |
|
|
*/ |
657 |
dl |
1.24 |
public int drainTo(Collection<? super E> c) { |
658 |
jsr166 |
1.51 |
return drainTo(c, Integer.MAX_VALUE); |
659 |
dl |
1.24 |
} |
660 |
jsr166 |
1.40 |
|
661 |
jsr166 |
1.43 |
/** |
662 |
|
|
* @throws UnsupportedOperationException {@inheritDoc} |
663 |
|
|
* @throws ClassCastException {@inheritDoc} |
664 |
|
|
* @throws NullPointerException {@inheritDoc} |
665 |
|
|
* @throws IllegalArgumentException {@inheritDoc} |
666 |
|
|
*/ |
667 |
dl |
1.24 |
public int drainTo(Collection<? super E> c, int maxElements) { |
668 |
jsr166 |
1.101 |
Objects.requireNonNull(c); |
669 |
dl |
1.24 |
if (c == this) |
670 |
|
|
throw new IllegalArgumentException(); |
671 |
jsr166 |
1.63 |
if (maxElements <= 0) |
672 |
|
|
return 0; |
673 |
jsr166 |
1.51 |
boolean signalNotFull = false; |
674 |
|
|
final ReentrantLock takeLock = this.takeLock; |
675 |
|
|
takeLock.lock(); |
676 |
dl |
1.24 |
try { |
677 |
jsr166 |
1.51 |
int n = Math.min(maxElements, count.get()); |
678 |
|
|
// count.get provides visibility to first n Nodes |
679 |
|
|
Node<E> h = head; |
680 |
|
|
int i = 0; |
681 |
|
|
try { |
682 |
|
|
while (i < n) { |
683 |
|
|
Node<E> p = h.next; |
684 |
|
|
c.add(p.item); |
685 |
|
|
p.item = null; |
686 |
|
|
h.next = h; |
687 |
|
|
h = p; |
688 |
|
|
++i; |
689 |
|
|
} |
690 |
|
|
return n; |
691 |
|
|
} finally { |
692 |
|
|
// Restore invariants even if c.add() threw |
693 |
|
|
if (i > 0) { |
694 |
|
|
// assert h.item == null; |
695 |
|
|
head = h; |
696 |
|
|
signalNotFull = (count.getAndAdd(-i) == capacity); |
697 |
|
|
} |
698 |
dl |
1.24 |
} |
699 |
|
|
} finally { |
700 |
jsr166 |
1.51 |
takeLock.unlock(); |
701 |
|
|
if (signalNotFull) |
702 |
|
|
signalNotFull(); |
703 |
dl |
1.24 |
} |
704 |
|
|
} |
705 |
|
|
|
706 |
dholmes |
1.14 |
/** |
707 |
jsr166 |
1.101 |
* Used for any element traversal that is not entirely under lock. |
708 |
|
|
* Such traversals must handle both: |
709 |
|
|
* - dequeued nodes (p.next == p) |
710 |
|
|
* - (possibly multiple) interior removed nodes (p.item == null) |
711 |
|
|
*/ |
712 |
|
|
Node<E> succ(Node<E> p) { |
713 |
jsr166 |
1.106 |
if (p == (p = p.next)) |
714 |
|
|
p = head.next; |
715 |
|
|
return p; |
716 |
jsr166 |
1.101 |
} |
717 |
|
|
|
718 |
|
|
/** |
719 |
dholmes |
1.14 |
* Returns an iterator over the elements in this queue in proper sequence. |
720 |
jsr166 |
1.57 |
* The elements will be returned in order from first (head) to last (tail). |
721 |
|
|
* |
722 |
jsr166 |
1.87 |
* <p>The returned iterator is |
723 |
|
|
* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>. |
724 |
dholmes |
1.14 |
* |
725 |
jsr166 |
1.43 |
* @return an iterator over the elements in this queue in proper sequence |
726 |
dholmes |
1.14 |
*/ |
727 |
dl |
1.2 |
public Iterator<E> iterator() { |
728 |
jsr166 |
1.59 |
return new Itr(); |
729 |
tim |
1.1 |
} |
730 |
dl |
1.2 |
|
731 |
jsr166 |
1.108 |
/** |
732 |
|
|
* Weakly-consistent iterator. |
733 |
|
|
* |
734 |
|
|
* Lazily updated ancestor field provides expected O(1) remove(), |
735 |
|
|
* but still O(n) in the worst case, whenever the saved ancestor |
736 |
|
|
* is concurrently deleted. |
737 |
|
|
*/ |
738 |
dl |
1.2 |
private class Itr implements Iterator<E> { |
739 |
jsr166 |
1.108 |
private Node<E> next; // Node holding nextItem |
740 |
|
|
private E nextItem; // next item to hand out |
741 |
dl |
1.31 |
private Node<E> lastRet; |
742 |
jsr166 |
1.108 |
private Node<E> ancestor; // Helps unlink lastRet on remove() |
743 |
tim |
1.12 |
|
744 |
dl |
1.2 |
Itr() { |
745 |
jsr166 |
1.51 |
fullyLock(); |
746 |
dl |
1.2 |
try { |
747 |
jsr166 |
1.102 |
if ((next = head.next) != null) |
748 |
|
|
nextItem = next.item; |
749 |
tim |
1.17 |
} finally { |
750 |
jsr166 |
1.51 |
fullyUnlock(); |
751 |
dl |
1.2 |
} |
752 |
|
|
} |
753 |
tim |
1.12 |
|
754 |
|
|
public boolean hasNext() { |
755 |
jsr166 |
1.102 |
return next != null; |
756 |
dl |
1.2 |
} |
757 |
|
|
|
758 |
tim |
1.12 |
public E next() { |
759 |
jsr166 |
1.101 |
Node<E> p; |
760 |
jsr166 |
1.102 |
if ((p = next) == null) |
761 |
jsr166 |
1.100 |
throw new NoSuchElementException(); |
762 |
jsr166 |
1.101 |
lastRet = p; |
763 |
jsr166 |
1.102 |
E x = nextItem; |
764 |
jsr166 |
1.51 |
fullyLock(); |
765 |
dl |
1.2 |
try { |
766 |
jsr166 |
1.102 |
E e = null; |
767 |
|
|
for (p = p.next; p != null && (e = p.item) == null; ) |
768 |
|
|
p = succ(p); |
769 |
|
|
next = p; |
770 |
|
|
nextItem = e; |
771 |
tim |
1.17 |
} finally { |
772 |
jsr166 |
1.51 |
fullyUnlock(); |
773 |
dl |
1.2 |
} |
774 |
jsr166 |
1.102 |
return x; |
775 |
jsr166 |
1.101 |
} |
776 |
|
|
|
777 |
|
|
public void forEachRemaining(Consumer<? super E> action) { |
778 |
|
|
// A variant of forEachFrom |
779 |
|
|
Objects.requireNonNull(action); |
780 |
|
|
Node<E> p; |
781 |
jsr166 |
1.102 |
if ((p = next) == null) return; |
782 |
|
|
lastRet = p; |
783 |
|
|
next = null; |
784 |
jsr166 |
1.110 |
final int batchSize = 64; |
785 |
jsr166 |
1.101 |
Object[] es = null; |
786 |
|
|
int n, len = 1; |
787 |
|
|
do { |
788 |
|
|
fullyLock(); |
789 |
|
|
try { |
790 |
|
|
if (es == null) { |
791 |
|
|
p = p.next; |
792 |
|
|
for (Node<E> q = p; q != null; q = succ(q)) |
793 |
|
|
if (q.item != null && ++len == batchSize) |
794 |
|
|
break; |
795 |
|
|
es = new Object[len]; |
796 |
jsr166 |
1.102 |
es[0] = nextItem; |
797 |
|
|
nextItem = null; |
798 |
jsr166 |
1.101 |
n = 1; |
799 |
|
|
} else |
800 |
|
|
n = 0; |
801 |
|
|
for (; p != null && n < len; p = succ(p)) |
802 |
|
|
if ((es[n] = p.item) != null) { |
803 |
|
|
lastRet = p; |
804 |
|
|
n++; |
805 |
|
|
} |
806 |
|
|
} finally { |
807 |
|
|
fullyUnlock(); |
808 |
|
|
} |
809 |
|
|
for (int i = 0; i < n; i++) { |
810 |
|
|
@SuppressWarnings("unchecked") E e = (E) es[i]; |
811 |
|
|
action.accept(e); |
812 |
|
|
} |
813 |
|
|
} while (n > 0 && p != null); |
814 |
dl |
1.2 |
} |
815 |
|
|
|
816 |
tim |
1.12 |
public void remove() { |
817 |
jsr166 |
1.108 |
Node<E> p = lastRet; |
818 |
|
|
if (p == null) |
819 |
tim |
1.12 |
throw new IllegalStateException(); |
820 |
jsr166 |
1.108 |
lastRet = null; |
821 |
jsr166 |
1.51 |
fullyLock(); |
822 |
dl |
1.2 |
try { |
823 |
jsr166 |
1.108 |
if (p.item != null) { |
824 |
|
|
if (ancestor == null) |
825 |
|
|
ancestor = head; |
826 |
|
|
ancestor = findPred(p, ancestor); |
827 |
|
|
unlink(p, ancestor); |
828 |
dl |
1.2 |
} |
829 |
tim |
1.17 |
} finally { |
830 |
jsr166 |
1.51 |
fullyUnlock(); |
831 |
dl |
1.2 |
} |
832 |
|
|
} |
833 |
tim |
1.1 |
} |
834 |
dl |
1.2 |
|
835 |
jsr166 |
1.100 |
/** |
836 |
|
|
* A customized variant of Spliterators.IteratorSpliterator. |
837 |
|
|
* Keep this class in sync with (very similar) LBDSpliterator. |
838 |
|
|
*/ |
839 |
|
|
private final class LBQSpliterator implements Spliterator<E> { |
840 |
dl |
1.80 |
static final int MAX_BATCH = 1 << 25; // max batch array size; |
841 |
dl |
1.74 |
Node<E> current; // current node; null until initialized |
842 |
|
|
int batch; // batch size for splits |
843 |
|
|
boolean exhausted; // true when no more nodes |
844 |
jsr166 |
1.100 |
long est = size(); // size estimate |
845 |
jsr166 |
1.99 |
|
846 |
jsr166 |
1.100 |
LBQSpliterator() {} |
847 |
|
|
|
848 |
dl |
1.74 |
public long estimateSize() { return est; } |
849 |
|
|
|
850 |
|
|
public Spliterator<E> trySplit() { |
851 |
dl |
1.80 |
Node<E> h; |
852 |
jsr166 |
1.78 |
if (!exhausted && |
853 |
jsr166 |
1.100 |
((h = current) != null || (h = head.next) != null) |
854 |
|
|
&& h.next != null) { |
855 |
jsr166 |
1.104 |
int n = batch = Math.min(batch + 1, MAX_BATCH); |
856 |
dl |
1.83 |
Object[] a = new Object[n]; |
857 |
dl |
1.74 |
int i = 0; |
858 |
|
|
Node<E> p = current; |
859 |
jsr166 |
1.99 |
fullyLock(); |
860 |
dl |
1.74 |
try { |
861 |
jsr166 |
1.100 |
if (p != null || (p = head.next) != null) |
862 |
|
|
for (; p != null && i < n; p = succ(p)) |
863 |
dl |
1.74 |
if ((a[i] = p.item) != null) |
864 |
jsr166 |
1.100 |
i++; |
865 |
dl |
1.74 |
} finally { |
866 |
jsr166 |
1.99 |
fullyUnlock(); |
867 |
dl |
1.74 |
} |
868 |
|
|
if ((current = p) == null) { |
869 |
|
|
est = 0L; |
870 |
|
|
exhausted = true; |
871 |
|
|
} |
872 |
dl |
1.77 |
else if ((est -= i) < 0L) |
873 |
|
|
est = 0L; |
874 |
jsr166 |
1.104 |
if (i > 0) |
875 |
dl |
1.80 |
return Spliterators.spliterator |
876 |
jsr166 |
1.95 |
(a, 0, i, (Spliterator.ORDERED | |
877 |
|
|
Spliterator.NONNULL | |
878 |
|
|
Spliterator.CONCURRENT)); |
879 |
dl |
1.74 |
} |
880 |
|
|
return null; |
881 |
|
|
} |
882 |
|
|
|
883 |
|
|
public boolean tryAdvance(Consumer<? super E> action) { |
884 |
jsr166 |
1.101 |
Objects.requireNonNull(action); |
885 |
dl |
1.74 |
if (!exhausted) { |
886 |
|
|
E e = null; |
887 |
jsr166 |
1.99 |
fullyLock(); |
888 |
dl |
1.74 |
try { |
889 |
jsr166 |
1.102 |
Node<E> p; |
890 |
|
|
if ((p = current) != null || (p = head.next) != null) |
891 |
jsr166 |
1.100 |
do { |
892 |
|
|
e = p.item; |
893 |
|
|
p = succ(p); |
894 |
|
|
} while (e == null && p != null); |
895 |
jsr166 |
1.103 |
if ((current = p) == null) |
896 |
|
|
exhausted = true; |
897 |
dl |
1.74 |
} finally { |
898 |
jsr166 |
1.99 |
fullyUnlock(); |
899 |
dl |
1.74 |
} |
900 |
|
|
if (e != null) { |
901 |
|
|
action.accept(e); |
902 |
|
|
return true; |
903 |
|
|
} |
904 |
|
|
} |
905 |
|
|
return false; |
906 |
|
|
} |
907 |
|
|
|
908 |
jsr166 |
1.101 |
public void forEachRemaining(Consumer<? super E> action) { |
909 |
|
|
Objects.requireNonNull(action); |
910 |
|
|
if (!exhausted) { |
911 |
|
|
exhausted = true; |
912 |
|
|
Node<E> p = current; |
913 |
|
|
current = null; |
914 |
|
|
forEachFrom(action, p); |
915 |
|
|
} |
916 |
|
|
} |
917 |
|
|
|
918 |
dl |
1.74 |
public int characteristics() { |
919 |
jsr166 |
1.100 |
return (Spliterator.ORDERED | |
920 |
|
|
Spliterator.NONNULL | |
921 |
|
|
Spliterator.CONCURRENT); |
922 |
dl |
1.74 |
} |
923 |
|
|
} |
924 |
|
|
|
925 |
jsr166 |
1.86 |
/** |
926 |
|
|
* Returns a {@link Spliterator} over the elements in this queue. |
927 |
|
|
* |
928 |
jsr166 |
1.87 |
* <p>The returned spliterator is |
929 |
|
|
* <a href="package-summary.html#Weakly"><i>weakly consistent</i></a>. |
930 |
|
|
* |
931 |
jsr166 |
1.86 |
* <p>The {@code Spliterator} reports {@link Spliterator#CONCURRENT}, |
932 |
|
|
* {@link Spliterator#ORDERED}, and {@link Spliterator#NONNULL}. |
933 |
|
|
* |
934 |
|
|
* @implNote |
935 |
|
|
* The {@code Spliterator} implements {@code trySplit} to permit limited |
936 |
|
|
* parallelism. |
937 |
|
|
* |
938 |
|
|
* @return a {@code Spliterator} over the elements in this queue |
939 |
|
|
* @since 1.8 |
940 |
|
|
*/ |
941 |
dl |
1.76 |
public Spliterator<E> spliterator() { |
942 |
jsr166 |
1.99 |
return new LBQSpliterator(); |
943 |
dl |
1.74 |
} |
944 |
|
|
|
945 |
dl |
1.2 |
/** |
946 |
jsr166 |
1.101 |
* @throws NullPointerException {@inheritDoc} |
947 |
|
|
*/ |
948 |
|
|
public void forEach(Consumer<? super E> action) { |
949 |
|
|
Objects.requireNonNull(action); |
950 |
|
|
forEachFrom(action, null); |
951 |
|
|
} |
952 |
|
|
|
953 |
|
|
/** |
954 |
|
|
* Runs action on each element found during a traversal starting at p. |
955 |
|
|
* If p is null, traversal starts at head. |
956 |
|
|
*/ |
957 |
|
|
void forEachFrom(Consumer<? super E> action, Node<E> p) { |
958 |
|
|
// Extract batches of elements while holding the lock; then |
959 |
|
|
// run the action on the elements while not |
960 |
jsr166 |
1.110 |
final int batchSize = 64; // max number of elements per batch |
961 |
jsr166 |
1.101 |
Object[] es = null; // container for batch of elements |
962 |
|
|
int n, len = 0; |
963 |
|
|
do { |
964 |
|
|
fullyLock(); |
965 |
|
|
try { |
966 |
|
|
if (es == null) { |
967 |
|
|
if (p == null) p = head.next; |
968 |
|
|
for (Node<E> q = p; q != null; q = succ(q)) |
969 |
|
|
if (q.item != null && ++len == batchSize) |
970 |
|
|
break; |
971 |
|
|
es = new Object[len]; |
972 |
|
|
} |
973 |
|
|
for (n = 0; p != null && n < len; p = succ(p)) |
974 |
|
|
if ((es[n] = p.item) != null) |
975 |
|
|
n++; |
976 |
|
|
} finally { |
977 |
|
|
fullyUnlock(); |
978 |
|
|
} |
979 |
|
|
for (int i = 0; i < n; i++) { |
980 |
|
|
@SuppressWarnings("unchecked") E e = (E) es[i]; |
981 |
|
|
action.accept(e); |
982 |
|
|
} |
983 |
|
|
} while (n > 0 && p != null); |
984 |
|
|
} |
985 |
|
|
|
986 |
|
|
/** |
987 |
jsr166 |
1.107 |
* @throws NullPointerException {@inheritDoc} |
988 |
|
|
*/ |
989 |
|
|
public boolean removeIf(Predicate<? super E> filter) { |
990 |
|
|
Objects.requireNonNull(filter); |
991 |
|
|
return bulkRemove(filter); |
992 |
|
|
} |
993 |
|
|
|
994 |
|
|
/** |
995 |
|
|
* @throws NullPointerException {@inheritDoc} |
996 |
|
|
*/ |
997 |
|
|
public boolean removeAll(Collection<?> c) { |
998 |
|
|
Objects.requireNonNull(c); |
999 |
|
|
return bulkRemove(e -> c.contains(e)); |
1000 |
|
|
} |
1001 |
|
|
|
1002 |
|
|
/** |
1003 |
|
|
* @throws NullPointerException {@inheritDoc} |
1004 |
|
|
*/ |
1005 |
|
|
public boolean retainAll(Collection<?> c) { |
1006 |
|
|
Objects.requireNonNull(c); |
1007 |
|
|
return bulkRemove(e -> !c.contains(e)); |
1008 |
|
|
} |
1009 |
|
|
|
1010 |
|
|
/** |
1011 |
|
|
* Returns the predecessor of live node p, given a node that was |
1012 |
|
|
* once a live ancestor of p (or head); allows unlinking of p. |
1013 |
|
|
*/ |
1014 |
jsr166 |
1.108 |
Node<E> findPred(Node<E> p, Node<E> ancestor) { |
1015 |
jsr166 |
1.107 |
// assert p.item != null; |
1016 |
|
|
if (ancestor.item == null) |
1017 |
|
|
ancestor = head; |
1018 |
|
|
// Fails with NPE if precondition not satisfied |
1019 |
|
|
for (Node<E> q; (q = ancestor.next) != p; ) |
1020 |
|
|
ancestor = q; |
1021 |
|
|
return ancestor; |
1022 |
|
|
} |
1023 |
|
|
|
1024 |
|
|
/** Implementation of bulk remove methods. */ |
1025 |
|
|
@SuppressWarnings("unchecked") |
1026 |
|
|
private boolean bulkRemove(Predicate<? super E> filter) { |
1027 |
|
|
boolean removed = false; |
1028 |
|
|
Node<E> p = null, ancestor = head; |
1029 |
|
|
Node<E>[] nodes = null; |
1030 |
|
|
int n, len = 0; |
1031 |
|
|
do { |
1032 |
|
|
// 1. Extract batch of up to 64 elements while holding the lock. |
1033 |
|
|
fullyLock(); |
1034 |
|
|
try { |
1035 |
jsr166 |
1.112 |
if (nodes == null) { // first batch; initialize |
1036 |
|
|
p = head.next; |
1037 |
jsr166 |
1.107 |
for (Node<E> q = p; q != null; q = succ(q)) |
1038 |
|
|
if (q.item != null && ++len == 64) |
1039 |
|
|
break; |
1040 |
|
|
nodes = (Node<E>[]) new Node<?>[len]; |
1041 |
|
|
} |
1042 |
|
|
for (n = 0; p != null && n < len; p = succ(p)) |
1043 |
|
|
nodes[n++] = p; |
1044 |
|
|
} finally { |
1045 |
|
|
fullyUnlock(); |
1046 |
|
|
} |
1047 |
|
|
|
1048 |
|
|
// 2. Run the filter on the elements while lock is free. |
1049 |
jsr166 |
1.112 |
long deathRow = 0L; // "bitset" of size 64 |
1050 |
jsr166 |
1.107 |
for (int i = 0; i < n; i++) { |
1051 |
|
|
final E e; |
1052 |
|
|
if ((e = nodes[i].item) != null && filter.test(e)) |
1053 |
|
|
deathRow |= 1L << i; |
1054 |
|
|
} |
1055 |
|
|
|
1056 |
|
|
// 3. Remove any filtered elements while holding the lock. |
1057 |
|
|
if (deathRow != 0) { |
1058 |
|
|
fullyLock(); |
1059 |
|
|
try { |
1060 |
|
|
for (int i = 0; i < n; i++) { |
1061 |
|
|
final Node<E> q; |
1062 |
|
|
if ((deathRow & (1L << i)) != 0L |
1063 |
|
|
&& (q = nodes[i]).item != null) { |
1064 |
|
|
ancestor = findPred(q, ancestor); |
1065 |
|
|
unlink(q, ancestor); |
1066 |
|
|
removed = true; |
1067 |
|
|
} |
1068 |
jsr166 |
1.112 |
nodes[i] = null; // help GC |
1069 |
jsr166 |
1.107 |
} |
1070 |
|
|
} finally { |
1071 |
|
|
fullyUnlock(); |
1072 |
|
|
} |
1073 |
|
|
} |
1074 |
|
|
} while (n > 0 && p != null); |
1075 |
|
|
return removed; |
1076 |
|
|
} |
1077 |
|
|
|
1078 |
|
|
/** |
1079 |
jsr166 |
1.68 |
* Saves this queue to a stream (that is, serializes it). |
1080 |
dl |
1.2 |
* |
1081 |
jsr166 |
1.84 |
* @param s the stream |
1082 |
jsr166 |
1.85 |
* @throws java.io.IOException if an I/O error occurs |
1083 |
dl |
1.2 |
* @serialData The capacity is emitted (int), followed by all of |
1084 |
jsr166 |
1.51 |
* its elements (each an {@code Object}) in the proper order, |
1085 |
dl |
1.2 |
* followed by a null |
1086 |
|
|
*/ |
1087 |
|
|
private void writeObject(java.io.ObjectOutputStream s) |
1088 |
|
|
throws java.io.IOException { |
1089 |
|
|
|
1090 |
tim |
1.12 |
fullyLock(); |
1091 |
dl |
1.2 |
try { |
1092 |
|
|
// Write out any hidden stuff, plus capacity |
1093 |
|
|
s.defaultWriteObject(); |
1094 |
|
|
|
1095 |
|
|
// Write out all elements in the proper order. |
1096 |
tim |
1.12 |
for (Node<E> p = head.next; p != null; p = p.next) |
1097 |
dl |
1.2 |
s.writeObject(p.item); |
1098 |
|
|
|
1099 |
|
|
// Use trailing null as sentinel |
1100 |
|
|
s.writeObject(null); |
1101 |
tim |
1.17 |
} finally { |
1102 |
dl |
1.2 |
fullyUnlock(); |
1103 |
|
|
} |
1104 |
tim |
1.1 |
} |
1105 |
|
|
|
1106 |
dl |
1.2 |
/** |
1107 |
jsr166 |
1.65 |
* Reconstitutes this queue from a stream (that is, deserializes it). |
1108 |
jsr166 |
1.84 |
* @param s the stream |
1109 |
jsr166 |
1.85 |
* @throws ClassNotFoundException if the class of a serialized object |
1110 |
|
|
* could not be found |
1111 |
|
|
* @throws java.io.IOException if an I/O error occurs |
1112 |
dl |
1.2 |
*/ |
1113 |
|
|
private void readObject(java.io.ObjectInputStream s) |
1114 |
|
|
throws java.io.IOException, ClassNotFoundException { |
1115 |
tim |
1.12 |
// Read in capacity, and any hidden stuff |
1116 |
|
|
s.defaultReadObject(); |
1117 |
dl |
1.2 |
|
1118 |
dl |
1.19 |
count.set(0); |
1119 |
|
|
last = head = new Node<E>(null); |
1120 |
|
|
|
1121 |
dl |
1.6 |
// Read in all elements and place in queue |
1122 |
dl |
1.2 |
for (;;) { |
1123 |
jsr166 |
1.51 |
@SuppressWarnings("unchecked") |
1124 |
dl |
1.2 |
E item = (E)s.readObject(); |
1125 |
|
|
if (item == null) |
1126 |
|
|
break; |
1127 |
|
|
add(item); |
1128 |
|
|
} |
1129 |
tim |
1.1 |
} |
1130 |
|
|
} |