1 |
dl |
1.2 |
/* |
2 |
|
|
* Written by Doug Lea with assistance from members of JCP JSR-166 |
3 |
|
|
* Expert Group and released to the public domain. Use, modify, and |
4 |
|
|
* redistribute this code in any way without acknowledgement. |
5 |
|
|
*/ |
6 |
|
|
|
7 |
tim |
1.1 |
package java.util.concurrent; |
8 |
dl |
1.2 |
import java.util.concurrent.atomic.*; |
9 |
dl |
1.7 |
import java.util.concurrent.locks.*; |
10 |
tim |
1.1 |
import java.util.*; |
11 |
|
|
|
12 |
|
|
/** |
13 |
dholmes |
1.14 |
* An optionally-bounded {@linkplain BlockingQueue blocking queue} based on |
14 |
dholmes |
1.8 |
* linked nodes. |
15 |
|
|
* This queue orders elements FIFO (first-in-first-out). |
16 |
tim |
1.12 |
* The <em>head</em> of the queue is that element that has been on the |
17 |
dholmes |
1.8 |
* queue the longest time. |
18 |
|
|
* The <em>tail</em> of the queue is that element that has been on the |
19 |
dl |
1.20 |
* queue the shortest time. New elements |
20 |
|
|
* are inserted at the tail of the queue, and the queue retrieval |
21 |
|
|
* operations obtain elements at the head of the queue. |
22 |
dholmes |
1.8 |
* Linked queues typically have higher throughput than array-based queues but |
23 |
|
|
* less predictable performance in most concurrent applications. |
24 |
tim |
1.12 |
* |
25 |
dl |
1.3 |
* <p> The optional capacity bound constructor argument serves as a |
26 |
dholmes |
1.8 |
* way to prevent excessive queue expansion. The capacity, if unspecified, |
27 |
|
|
* is equal to {@link Integer#MAX_VALUE}. Linked nodes are |
28 |
dl |
1.3 |
* dynamically created upon each insertion unless this would bring the |
29 |
|
|
* queue above capacity. |
30 |
dholmes |
1.8 |
* |
31 |
dl |
1.21 |
* <p>This class implements all of the <em>optional</em> methods |
32 |
|
|
* of the {@link Collection} and {@link Iterator} interfaces. |
33 |
|
|
* |
34 |
dl |
1.6 |
* @since 1.5 |
35 |
|
|
* @author Doug Lea |
36 |
dl |
1.27 |
* @param <E> the type of elements held in this collection |
37 |
tim |
1.12 |
* |
38 |
tim |
1.1 |
**/ |
39 |
dl |
1.2 |
public class LinkedBlockingQueue<E> extends AbstractQueue<E> |
40 |
tim |
1.1 |
implements BlockingQueue<E>, java.io.Serializable { |
41 |
dl |
1.18 |
private static final long serialVersionUID = -6903933977591709194L; |
42 |
tim |
1.1 |
|
43 |
dl |
1.2 |
/* |
44 |
|
|
* A variant of the "two lock queue" algorithm. The putLock gates |
45 |
|
|
* entry to put (and offer), and has an associated condition for |
46 |
|
|
* waiting puts. Similarly for the takeLock. The "count" field |
47 |
|
|
* that they both rely on is maintained as an atomic to avoid |
48 |
|
|
* needing to get both locks in most cases. Also, to minimize need |
49 |
|
|
* for puts to get takeLock and vice-versa, cascading notifies are |
50 |
|
|
* used. When a put notices that it has enabled at least one take, |
51 |
|
|
* it signals taker. That taker in turn signals others if more |
52 |
|
|
* items have been entered since the signal. And symmetrically for |
53 |
tim |
1.12 |
* takes signalling puts. Operations such as remove(Object) and |
54 |
dl |
1.2 |
* iterators acquire both locks. |
55 |
|
|
*/ |
56 |
|
|
|
57 |
dl |
1.6 |
/** |
58 |
|
|
* Linked list node class |
59 |
|
|
*/ |
60 |
dl |
1.2 |
static class Node<E> { |
61 |
dl |
1.6 |
/** The item, volatile to ensure barrier separating write and read */ |
62 |
dl |
1.2 |
volatile E item; |
63 |
|
|
Node<E> next; |
64 |
|
|
Node(E x) { item = x; } |
65 |
|
|
} |
66 |
|
|
|
67 |
dl |
1.6 |
/** The capacity bound, or Integer.MAX_VALUE if none */ |
68 |
dl |
1.2 |
private final int capacity; |
69 |
dl |
1.6 |
|
70 |
|
|
/** Current number of elements */ |
71 |
dl |
1.19 |
private final AtomicInteger count = new AtomicInteger(0); |
72 |
dl |
1.2 |
|
73 |
dl |
1.6 |
/** Head of linked list */ |
74 |
|
|
private transient Node<E> head; |
75 |
|
|
|
76 |
dholmes |
1.8 |
/** Tail of linked list */ |
77 |
dl |
1.6 |
private transient Node<E> last; |
78 |
dl |
1.2 |
|
79 |
dl |
1.6 |
/** Lock held by take, poll, etc */ |
80 |
dl |
1.5 |
private final ReentrantLock takeLock = new ReentrantLock(); |
81 |
dl |
1.6 |
|
82 |
|
|
/** Wait queue for waiting takes */ |
83 |
dl |
1.25 |
private final ReentrantLock.ConditionObject notEmpty = takeLock.newCondition(); |
84 |
dl |
1.2 |
|
85 |
dl |
1.6 |
/** Lock held by put, offer, etc */ |
86 |
dl |
1.5 |
private final ReentrantLock putLock = new ReentrantLock(); |
87 |
dl |
1.6 |
|
88 |
|
|
/** Wait queue for waiting puts */ |
89 |
dl |
1.25 |
private final ReentrantLock.ConditionObject notFull = putLock.newCondition(); |
90 |
dl |
1.2 |
|
91 |
|
|
/** |
92 |
|
|
* Signal a waiting take. Called only from put/offer (which do not |
93 |
dl |
1.4 |
* otherwise ordinarily lock takeLock.) |
94 |
dl |
1.2 |
*/ |
95 |
|
|
private void signalNotEmpty() { |
96 |
|
|
takeLock.lock(); |
97 |
|
|
try { |
98 |
|
|
notEmpty.signal(); |
99 |
tim |
1.17 |
} finally { |
100 |
dl |
1.2 |
takeLock.unlock(); |
101 |
|
|
} |
102 |
|
|
} |
103 |
|
|
|
104 |
|
|
/** |
105 |
|
|
* Signal a waiting put. Called only from take/poll. |
106 |
|
|
*/ |
107 |
|
|
private void signalNotFull() { |
108 |
|
|
putLock.lock(); |
109 |
|
|
try { |
110 |
|
|
notFull.signal(); |
111 |
tim |
1.17 |
} finally { |
112 |
dl |
1.2 |
putLock.unlock(); |
113 |
|
|
} |
114 |
|
|
} |
115 |
|
|
|
116 |
|
|
/** |
117 |
dholmes |
1.8 |
* Create a node and link it at end of queue |
118 |
dl |
1.6 |
* @param x the item |
119 |
dl |
1.2 |
*/ |
120 |
|
|
private void insert(E x) { |
121 |
|
|
last = last.next = new Node<E>(x); |
122 |
|
|
} |
123 |
|
|
|
124 |
|
|
/** |
125 |
|
|
* Remove a node from head of queue, |
126 |
dl |
1.6 |
* @return the node |
127 |
dl |
1.2 |
*/ |
128 |
|
|
private E extract() { |
129 |
|
|
Node<E> first = head.next; |
130 |
|
|
head = first; |
131 |
dl |
1.28 |
E x = first.item; |
132 |
dl |
1.2 |
first.item = null; |
133 |
|
|
return x; |
134 |
|
|
} |
135 |
|
|
|
136 |
|
|
/** |
137 |
tim |
1.12 |
* Lock to prevent both puts and takes. |
138 |
dl |
1.2 |
*/ |
139 |
|
|
private void fullyLock() { |
140 |
|
|
putLock.lock(); |
141 |
|
|
takeLock.lock(); |
142 |
tim |
1.1 |
} |
143 |
dl |
1.2 |
|
144 |
|
|
/** |
145 |
tim |
1.12 |
* Unlock to allow both puts and takes. |
146 |
dl |
1.2 |
*/ |
147 |
|
|
private void fullyUnlock() { |
148 |
|
|
takeLock.unlock(); |
149 |
|
|
putLock.unlock(); |
150 |
|
|
} |
151 |
|
|
|
152 |
|
|
|
153 |
|
|
/** |
154 |
dholmes |
1.13 |
* Creates a <tt>LinkedBlockingQueue</tt> with a capacity of |
155 |
dholmes |
1.8 |
* {@link Integer#MAX_VALUE}. |
156 |
dl |
1.2 |
*/ |
157 |
|
|
public LinkedBlockingQueue() { |
158 |
|
|
this(Integer.MAX_VALUE); |
159 |
|
|
} |
160 |
|
|
|
161 |
|
|
/** |
162 |
tim |
1.16 |
* Creates a <tt>LinkedBlockingQueue</tt> with the given (fixed) capacity. |
163 |
|
|
* |
164 |
dholmes |
1.8 |
* @param capacity the capacity of this queue. |
165 |
|
|
* @throws IllegalArgumentException if <tt>capacity</tt> is not greater |
166 |
tim |
1.16 |
* than zero. |
167 |
dl |
1.2 |
*/ |
168 |
|
|
public LinkedBlockingQueue(int capacity) { |
169 |
dholmes |
1.8 |
if (capacity <= 0) throw new IllegalArgumentException(); |
170 |
dl |
1.2 |
this.capacity = capacity; |
171 |
dl |
1.6 |
last = head = new Node<E>(null); |
172 |
dl |
1.2 |
} |
173 |
|
|
|
174 |
|
|
/** |
175 |
dholmes |
1.13 |
* Creates a <tt>LinkedBlockingQueue</tt> with a capacity of |
176 |
dholmes |
1.14 |
* {@link Integer#MAX_VALUE}, initially containing the elements of the |
177 |
tim |
1.12 |
* given collection, |
178 |
dholmes |
1.8 |
* added in traversal order of the collection's iterator. |
179 |
dholmes |
1.9 |
* @param c the collection of elements to initially contain |
180 |
|
|
* @throws NullPointerException if <tt>c</tt> or any element within it |
181 |
|
|
* is <tt>null</tt> |
182 |
dl |
1.2 |
*/ |
183 |
dholmes |
1.10 |
public LinkedBlockingQueue(Collection<? extends E> c) { |
184 |
dl |
1.2 |
this(Integer.MAX_VALUE); |
185 |
tim |
1.12 |
for (Iterator<? extends E> it = c.iterator(); it.hasNext();) |
186 |
|
|
add(it.next()); |
187 |
dl |
1.2 |
} |
188 |
|
|
|
189 |
dholmes |
1.9 |
|
190 |
dholmes |
1.8 |
// this doc comment is overridden to remove the reference to collections |
191 |
|
|
// greater in size than Integer.MAX_VALUE |
192 |
tim |
1.12 |
/** |
193 |
dl |
1.20 |
* Returns the number of elements in this queue. |
194 |
|
|
* |
195 |
|
|
* @return the number of elements in this queue. |
196 |
dholmes |
1.8 |
*/ |
197 |
dl |
1.2 |
public int size() { |
198 |
|
|
return count.get(); |
199 |
tim |
1.1 |
} |
200 |
dl |
1.2 |
|
201 |
dholmes |
1.8 |
// this doc comment is a modified copy of the inherited doc comment, |
202 |
|
|
// without the reference to unlimited queues. |
203 |
tim |
1.12 |
/** |
204 |
dholmes |
1.13 |
* Returns the number of elements that this queue can ideally (in |
205 |
dholmes |
1.8 |
* the absence of memory or resource constraints) accept without |
206 |
|
|
* blocking. This is always equal to the initial capacity of this queue |
207 |
|
|
* less the current <tt>size</tt> of this queue. |
208 |
|
|
* <p>Note that you <em>cannot</em> always tell if |
209 |
|
|
* an attempt to <tt>add</tt> an element will succeed by |
210 |
|
|
* inspecting <tt>remainingCapacity</tt> because it may be the |
211 |
|
|
* case that a waiting consumer is ready to <tt>take</tt> an |
212 |
|
|
* element out of an otherwise full queue. |
213 |
|
|
*/ |
214 |
dl |
1.2 |
public int remainingCapacity() { |
215 |
|
|
return capacity - count.get(); |
216 |
|
|
} |
217 |
|
|
|
218 |
dholmes |
1.22 |
/** |
219 |
|
|
* Adds the specified element to the tail of this queue, waiting if |
220 |
|
|
* necessary for space to become available. |
221 |
dl |
1.23 |
* @param o the element to add |
222 |
|
|
* @throws InterruptedException if interrupted while waiting. |
223 |
dholmes |
1.22 |
* @throws NullPointerException if the specified element is <tt>null</tt>. |
224 |
|
|
*/ |
225 |
dholmes |
1.14 |
public void put(E o) throws InterruptedException { |
226 |
|
|
if (o == null) throw new NullPointerException(); |
227 |
dl |
1.2 |
// Note: convention in all put/take/etc is to preset |
228 |
|
|
// local var holding count negative to indicate failure unless set. |
229 |
tim |
1.12 |
int c = -1; |
230 |
dl |
1.2 |
putLock.lockInterruptibly(); |
231 |
|
|
try { |
232 |
|
|
/* |
233 |
|
|
* Note that count is used in wait guard even though it is |
234 |
|
|
* not protected by lock. This works because count can |
235 |
|
|
* only decrease at this point (all other puts are shut |
236 |
|
|
* out by lock), and we (or some other waiting put) are |
237 |
|
|
* signalled if it ever changes from |
238 |
|
|
* capacity. Similarly for all other uses of count in |
239 |
|
|
* other wait guards. |
240 |
|
|
*/ |
241 |
|
|
try { |
242 |
tim |
1.12 |
while (count.get() == capacity) |
243 |
dl |
1.2 |
notFull.await(); |
244 |
tim |
1.17 |
} catch (InterruptedException ie) { |
245 |
dl |
1.2 |
notFull.signal(); // propagate to a non-interrupted thread |
246 |
|
|
throw ie; |
247 |
|
|
} |
248 |
dholmes |
1.14 |
insert(o); |
249 |
dl |
1.2 |
c = count.getAndIncrement(); |
250 |
dl |
1.6 |
if (c + 1 < capacity) |
251 |
dl |
1.2 |
notFull.signal(); |
252 |
tim |
1.17 |
} finally { |
253 |
dl |
1.2 |
putLock.unlock(); |
254 |
|
|
} |
255 |
tim |
1.12 |
if (c == 0) |
256 |
dl |
1.2 |
signalNotEmpty(); |
257 |
tim |
1.1 |
} |
258 |
dl |
1.2 |
|
259 |
dholmes |
1.22 |
/** |
260 |
|
|
* Inserts the specified element at the tail of this queue, waiting if |
261 |
|
|
* necessary up to the specified wait time for space to become available. |
262 |
dl |
1.23 |
* @param o the element to add |
263 |
|
|
* @param timeout how long to wait before giving up, in units of |
264 |
|
|
* <tt>unit</tt> |
265 |
|
|
* @param unit a <tt>TimeUnit</tt> determining how to interpret the |
266 |
|
|
* <tt>timeout</tt> parameter |
267 |
|
|
* @return <tt>true</tt> if successful, or <tt>false</tt> if |
268 |
|
|
* the specified waiting time elapses before space is available. |
269 |
|
|
* @throws InterruptedException if interrupted while waiting. |
270 |
dholmes |
1.22 |
* @throws NullPointerException if the specified element is <tt>null</tt>. |
271 |
|
|
*/ |
272 |
dholmes |
1.14 |
public boolean offer(E o, long timeout, TimeUnit unit) |
273 |
dholmes |
1.8 |
throws InterruptedException { |
274 |
tim |
1.12 |
|
275 |
dholmes |
1.14 |
if (o == null) throw new NullPointerException(); |
276 |
dl |
1.2 |
long nanos = unit.toNanos(timeout); |
277 |
|
|
int c = -1; |
278 |
dholmes |
1.8 |
putLock.lockInterruptibly(); |
279 |
dl |
1.2 |
try { |
280 |
|
|
for (;;) { |
281 |
|
|
if (count.get() < capacity) { |
282 |
dholmes |
1.14 |
insert(o); |
283 |
dl |
1.2 |
c = count.getAndIncrement(); |
284 |
dl |
1.6 |
if (c + 1 < capacity) |
285 |
dl |
1.2 |
notFull.signal(); |
286 |
|
|
break; |
287 |
|
|
} |
288 |
|
|
if (nanos <= 0) |
289 |
|
|
return false; |
290 |
|
|
try { |
291 |
|
|
nanos = notFull.awaitNanos(nanos); |
292 |
tim |
1.17 |
} catch (InterruptedException ie) { |
293 |
dl |
1.2 |
notFull.signal(); // propagate to a non-interrupted thread |
294 |
|
|
throw ie; |
295 |
|
|
} |
296 |
|
|
} |
297 |
tim |
1.17 |
} finally { |
298 |
dl |
1.2 |
putLock.unlock(); |
299 |
|
|
} |
300 |
tim |
1.12 |
if (c == 0) |
301 |
dl |
1.2 |
signalNotEmpty(); |
302 |
|
|
return true; |
303 |
tim |
1.1 |
} |
304 |
dl |
1.2 |
|
305 |
dl |
1.23 |
/** |
306 |
|
|
* Inserts the specified element at the tail of this queue if possible, |
307 |
|
|
* returning immediately if this queue is full. |
308 |
|
|
* |
309 |
|
|
* @param o the element to add. |
310 |
|
|
* @return <tt>true</tt> if it was possible to add the element to |
311 |
|
|
* this queue, else <tt>false</tt> |
312 |
|
|
* @throws NullPointerException if the specified element is <tt>null</tt> |
313 |
|
|
*/ |
314 |
dholmes |
1.14 |
public boolean offer(E o) { |
315 |
|
|
if (o == null) throw new NullPointerException(); |
316 |
dl |
1.2 |
if (count.get() == capacity) |
317 |
|
|
return false; |
318 |
tim |
1.12 |
int c = -1; |
319 |
dholmes |
1.8 |
putLock.lock(); |
320 |
dl |
1.2 |
try { |
321 |
|
|
if (count.get() < capacity) { |
322 |
dholmes |
1.14 |
insert(o); |
323 |
dl |
1.2 |
c = count.getAndIncrement(); |
324 |
dl |
1.6 |
if (c + 1 < capacity) |
325 |
dl |
1.2 |
notFull.signal(); |
326 |
|
|
} |
327 |
tim |
1.17 |
} finally { |
328 |
dl |
1.2 |
putLock.unlock(); |
329 |
|
|
} |
330 |
tim |
1.12 |
if (c == 0) |
331 |
dl |
1.2 |
signalNotEmpty(); |
332 |
|
|
return c >= 0; |
333 |
tim |
1.1 |
} |
334 |
dl |
1.2 |
|
335 |
|
|
|
336 |
|
|
public E take() throws InterruptedException { |
337 |
|
|
E x; |
338 |
|
|
int c = -1; |
339 |
|
|
takeLock.lockInterruptibly(); |
340 |
|
|
try { |
341 |
|
|
try { |
342 |
tim |
1.12 |
while (count.get() == 0) |
343 |
dl |
1.2 |
notEmpty.await(); |
344 |
tim |
1.17 |
} catch (InterruptedException ie) { |
345 |
dl |
1.2 |
notEmpty.signal(); // propagate to a non-interrupted thread |
346 |
|
|
throw ie; |
347 |
|
|
} |
348 |
|
|
|
349 |
|
|
x = extract(); |
350 |
|
|
c = count.getAndDecrement(); |
351 |
|
|
if (c > 1) |
352 |
|
|
notEmpty.signal(); |
353 |
tim |
1.17 |
} finally { |
354 |
dl |
1.2 |
takeLock.unlock(); |
355 |
|
|
} |
356 |
tim |
1.12 |
if (c == capacity) |
357 |
dl |
1.2 |
signalNotFull(); |
358 |
|
|
return x; |
359 |
|
|
} |
360 |
|
|
|
361 |
|
|
public E poll(long timeout, TimeUnit unit) throws InterruptedException { |
362 |
|
|
E x = null; |
363 |
|
|
int c = -1; |
364 |
dholmes |
1.8 |
long nanos = unit.toNanos(timeout); |
365 |
dl |
1.2 |
takeLock.lockInterruptibly(); |
366 |
|
|
try { |
367 |
|
|
for (;;) { |
368 |
|
|
if (count.get() > 0) { |
369 |
|
|
x = extract(); |
370 |
|
|
c = count.getAndDecrement(); |
371 |
|
|
if (c > 1) |
372 |
|
|
notEmpty.signal(); |
373 |
|
|
break; |
374 |
|
|
} |
375 |
|
|
if (nanos <= 0) |
376 |
|
|
return null; |
377 |
|
|
try { |
378 |
|
|
nanos = notEmpty.awaitNanos(nanos); |
379 |
tim |
1.17 |
} catch (InterruptedException ie) { |
380 |
dl |
1.2 |
notEmpty.signal(); // propagate to a non-interrupted thread |
381 |
|
|
throw ie; |
382 |
|
|
} |
383 |
|
|
} |
384 |
tim |
1.17 |
} finally { |
385 |
dl |
1.2 |
takeLock.unlock(); |
386 |
|
|
} |
387 |
tim |
1.12 |
if (c == capacity) |
388 |
dl |
1.2 |
signalNotFull(); |
389 |
|
|
return x; |
390 |
|
|
} |
391 |
|
|
|
392 |
|
|
public E poll() { |
393 |
|
|
if (count.get() == 0) |
394 |
|
|
return null; |
395 |
|
|
E x = null; |
396 |
tim |
1.12 |
int c = -1; |
397 |
dl |
1.2 |
takeLock.tryLock(); |
398 |
|
|
try { |
399 |
|
|
if (count.get() > 0) { |
400 |
|
|
x = extract(); |
401 |
|
|
c = count.getAndDecrement(); |
402 |
|
|
if (c > 1) |
403 |
|
|
notEmpty.signal(); |
404 |
|
|
} |
405 |
tim |
1.17 |
} finally { |
406 |
dl |
1.2 |
takeLock.unlock(); |
407 |
|
|
} |
408 |
tim |
1.12 |
if (c == capacity) |
409 |
dl |
1.2 |
signalNotFull(); |
410 |
|
|
return x; |
411 |
tim |
1.1 |
} |
412 |
dl |
1.2 |
|
413 |
|
|
|
414 |
|
|
public E peek() { |
415 |
|
|
if (count.get() == 0) |
416 |
|
|
return null; |
417 |
dholmes |
1.8 |
takeLock.lock(); |
418 |
dl |
1.2 |
try { |
419 |
|
|
Node<E> first = head.next; |
420 |
|
|
if (first == null) |
421 |
|
|
return null; |
422 |
|
|
else |
423 |
|
|
return first.item; |
424 |
tim |
1.17 |
} finally { |
425 |
dl |
1.2 |
takeLock.unlock(); |
426 |
|
|
} |
427 |
tim |
1.1 |
} |
428 |
|
|
|
429 |
dholmes |
1.9 |
public boolean remove(Object o) { |
430 |
|
|
if (o == null) return false; |
431 |
dl |
1.2 |
boolean removed = false; |
432 |
|
|
fullyLock(); |
433 |
|
|
try { |
434 |
|
|
Node<E> trail = head; |
435 |
|
|
Node<E> p = head.next; |
436 |
|
|
while (p != null) { |
437 |
dholmes |
1.9 |
if (o.equals(p.item)) { |
438 |
dl |
1.2 |
removed = true; |
439 |
|
|
break; |
440 |
|
|
} |
441 |
|
|
trail = p; |
442 |
|
|
p = p.next; |
443 |
|
|
} |
444 |
|
|
if (removed) { |
445 |
|
|
p.item = null; |
446 |
|
|
trail.next = p.next; |
447 |
|
|
if (count.getAndDecrement() == capacity) |
448 |
|
|
notFull.signalAll(); |
449 |
|
|
} |
450 |
tim |
1.17 |
} finally { |
451 |
dl |
1.2 |
fullyUnlock(); |
452 |
|
|
} |
453 |
|
|
return removed; |
454 |
tim |
1.1 |
} |
455 |
dl |
1.2 |
|
456 |
|
|
public Object[] toArray() { |
457 |
|
|
fullyLock(); |
458 |
|
|
try { |
459 |
|
|
int size = count.get(); |
460 |
tim |
1.12 |
Object[] a = new Object[size]; |
461 |
dl |
1.2 |
int k = 0; |
462 |
tim |
1.12 |
for (Node<E> p = head.next; p != null; p = p.next) |
463 |
dl |
1.2 |
a[k++] = p.item; |
464 |
|
|
return a; |
465 |
tim |
1.17 |
} finally { |
466 |
dl |
1.2 |
fullyUnlock(); |
467 |
|
|
} |
468 |
tim |
1.1 |
} |
469 |
dl |
1.2 |
|
470 |
|
|
public <T> T[] toArray(T[] a) { |
471 |
|
|
fullyLock(); |
472 |
|
|
try { |
473 |
|
|
int size = count.get(); |
474 |
|
|
if (a.length < size) |
475 |
dl |
1.4 |
a = (T[])java.lang.reflect.Array.newInstance |
476 |
|
|
(a.getClass().getComponentType(), size); |
477 |
tim |
1.12 |
|
478 |
dl |
1.2 |
int k = 0; |
479 |
tim |
1.12 |
for (Node p = head.next; p != null; p = p.next) |
480 |
dl |
1.2 |
a[k++] = (T)p.item; |
481 |
|
|
return a; |
482 |
tim |
1.17 |
} finally { |
483 |
dl |
1.2 |
fullyUnlock(); |
484 |
|
|
} |
485 |
tim |
1.1 |
} |
486 |
dl |
1.2 |
|
487 |
|
|
public String toString() { |
488 |
|
|
fullyLock(); |
489 |
|
|
try { |
490 |
|
|
return super.toString(); |
491 |
tim |
1.17 |
} finally { |
492 |
dl |
1.2 |
fullyUnlock(); |
493 |
|
|
} |
494 |
tim |
1.1 |
} |
495 |
dl |
1.2 |
|
496 |
dl |
1.24 |
public void clear() { |
497 |
|
|
fullyLock(); |
498 |
|
|
try { |
499 |
|
|
head.next = null; |
500 |
|
|
if (count.getAndSet(0) == capacity) |
501 |
|
|
notFull.signalAll(); |
502 |
|
|
} finally { |
503 |
|
|
fullyUnlock(); |
504 |
|
|
} |
505 |
|
|
} |
506 |
|
|
|
507 |
|
|
public int drainTo(Collection<? super E> c) { |
508 |
|
|
if (c == null) |
509 |
|
|
throw new NullPointerException(); |
510 |
|
|
if (c == this) |
511 |
|
|
throw new IllegalArgumentException(); |
512 |
|
|
Node first; |
513 |
|
|
fullyLock(); |
514 |
|
|
try { |
515 |
|
|
first = head.next; |
516 |
|
|
head.next = null; |
517 |
|
|
if (count.getAndSet(0) == capacity) |
518 |
|
|
notFull.signalAll(); |
519 |
|
|
} finally { |
520 |
|
|
fullyUnlock(); |
521 |
|
|
} |
522 |
|
|
// Transfer the elements outside of locks |
523 |
|
|
int n = 0; |
524 |
|
|
for (Node p = first; p != null; p = p.next) { |
525 |
|
|
c.add((E)p.item); |
526 |
|
|
p.item = null; |
527 |
|
|
++n; |
528 |
|
|
} |
529 |
|
|
return n; |
530 |
|
|
} |
531 |
|
|
|
532 |
|
|
public int drainTo(Collection<? super E> c, int maxElements) { |
533 |
|
|
if (c == null) |
534 |
|
|
throw new NullPointerException(); |
535 |
|
|
if (c == this) |
536 |
|
|
throw new IllegalArgumentException(); |
537 |
|
|
if (maxElements <= 0) |
538 |
|
|
return 0; |
539 |
|
|
fullyLock(); |
540 |
|
|
try { |
541 |
|
|
int n = 0; |
542 |
|
|
Node p = head.next; |
543 |
|
|
while (p != null && n < maxElements) { |
544 |
|
|
c.add((E)p.item); |
545 |
|
|
p.item = null; |
546 |
|
|
p = p.next; |
547 |
|
|
++n; |
548 |
|
|
} |
549 |
|
|
if (n != 0) { |
550 |
|
|
head.next = p; |
551 |
|
|
if (count.getAndAdd(-n) == capacity) |
552 |
|
|
notFull.signalAll(); |
553 |
|
|
} |
554 |
|
|
return n; |
555 |
|
|
} finally { |
556 |
|
|
fullyUnlock(); |
557 |
|
|
} |
558 |
|
|
} |
559 |
|
|
|
560 |
|
|
|
561 |
|
|
|
562 |
dholmes |
1.14 |
/** |
563 |
|
|
* Returns an iterator over the elements in this queue in proper sequence. |
564 |
dl |
1.15 |
* The returned <tt>Iterator</tt> is a "weakly consistent" iterator that |
565 |
|
|
* will never throw {@link java.util.ConcurrentModificationException}, |
566 |
|
|
* and guarantees to traverse elements as they existed upon |
567 |
|
|
* construction of the iterator, and may (but is not guaranteed to) |
568 |
|
|
* reflect any modifications subsequent to construction. |
569 |
dholmes |
1.14 |
* |
570 |
|
|
* @return an iterator over the elements in this queue in proper sequence. |
571 |
|
|
*/ |
572 |
dl |
1.2 |
public Iterator<E> iterator() { |
573 |
|
|
return new Itr(); |
574 |
tim |
1.1 |
} |
575 |
dl |
1.2 |
|
576 |
|
|
private class Itr implements Iterator<E> { |
577 |
tim |
1.12 |
/* |
578 |
dl |
1.4 |
* Basic weak-consistent iterator. At all times hold the next |
579 |
|
|
* item to hand out so that if hasNext() reports true, we will |
580 |
|
|
* still have it to return even if lost race with a take etc. |
581 |
|
|
*/ |
582 |
dl |
1.2 |
Node<E> current; |
583 |
|
|
Node<E> lastRet; |
584 |
dl |
1.4 |
E currentElement; |
585 |
tim |
1.12 |
|
586 |
dl |
1.2 |
Itr() { |
587 |
|
|
fullyLock(); |
588 |
|
|
try { |
589 |
|
|
current = head.next; |
590 |
dl |
1.4 |
if (current != null) |
591 |
|
|
currentElement = current.item; |
592 |
tim |
1.17 |
} finally { |
593 |
dl |
1.2 |
fullyUnlock(); |
594 |
|
|
} |
595 |
|
|
} |
596 |
tim |
1.12 |
|
597 |
|
|
public boolean hasNext() { |
598 |
dl |
1.2 |
return current != null; |
599 |
|
|
} |
600 |
|
|
|
601 |
tim |
1.12 |
public E next() { |
602 |
dl |
1.2 |
fullyLock(); |
603 |
|
|
try { |
604 |
|
|
if (current == null) |
605 |
|
|
throw new NoSuchElementException(); |
606 |
dl |
1.4 |
E x = currentElement; |
607 |
dl |
1.2 |
lastRet = current; |
608 |
|
|
current = current.next; |
609 |
dl |
1.4 |
if (current != null) |
610 |
|
|
currentElement = current.item; |
611 |
dl |
1.2 |
return x; |
612 |
tim |
1.17 |
} finally { |
613 |
dl |
1.2 |
fullyUnlock(); |
614 |
|
|
} |
615 |
tim |
1.12 |
|
616 |
dl |
1.2 |
} |
617 |
|
|
|
618 |
tim |
1.12 |
public void remove() { |
619 |
dl |
1.2 |
if (lastRet == null) |
620 |
tim |
1.12 |
throw new IllegalStateException(); |
621 |
dl |
1.2 |
fullyLock(); |
622 |
|
|
try { |
623 |
|
|
Node<E> node = lastRet; |
624 |
|
|
lastRet = null; |
625 |
|
|
Node<E> trail = head; |
626 |
|
|
Node<E> p = head.next; |
627 |
|
|
while (p != null && p != node) { |
628 |
|
|
trail = p; |
629 |
|
|
p = p.next; |
630 |
|
|
} |
631 |
|
|
if (p == node) { |
632 |
|
|
p.item = null; |
633 |
|
|
trail.next = p.next; |
634 |
|
|
int c = count.getAndDecrement(); |
635 |
|
|
if (c == capacity) |
636 |
|
|
notFull.signalAll(); |
637 |
|
|
} |
638 |
tim |
1.17 |
} finally { |
639 |
dl |
1.2 |
fullyUnlock(); |
640 |
|
|
} |
641 |
|
|
} |
642 |
tim |
1.1 |
} |
643 |
dl |
1.2 |
|
644 |
|
|
/** |
645 |
|
|
* Save the state to a stream (that is, serialize it). |
646 |
|
|
* |
647 |
|
|
* @serialData The capacity is emitted (int), followed by all of |
648 |
|
|
* its elements (each an <tt>Object</tt>) in the proper order, |
649 |
|
|
* followed by a null |
650 |
dl |
1.6 |
* @param s the stream |
651 |
dl |
1.2 |
*/ |
652 |
|
|
private void writeObject(java.io.ObjectOutputStream s) |
653 |
|
|
throws java.io.IOException { |
654 |
|
|
|
655 |
tim |
1.12 |
fullyLock(); |
656 |
dl |
1.2 |
try { |
657 |
|
|
// Write out any hidden stuff, plus capacity |
658 |
|
|
s.defaultWriteObject(); |
659 |
|
|
|
660 |
|
|
// Write out all elements in the proper order. |
661 |
tim |
1.12 |
for (Node<E> p = head.next; p != null; p = p.next) |
662 |
dl |
1.2 |
s.writeObject(p.item); |
663 |
|
|
|
664 |
|
|
// Use trailing null as sentinel |
665 |
|
|
s.writeObject(null); |
666 |
tim |
1.17 |
} finally { |
667 |
dl |
1.2 |
fullyUnlock(); |
668 |
|
|
} |
669 |
tim |
1.1 |
} |
670 |
|
|
|
671 |
dl |
1.2 |
/** |
672 |
dholmes |
1.8 |
* Reconstitute this queue instance from a stream (that is, |
673 |
dl |
1.2 |
* deserialize it). |
674 |
dl |
1.6 |
* @param s the stream |
675 |
dl |
1.2 |
*/ |
676 |
|
|
private void readObject(java.io.ObjectInputStream s) |
677 |
|
|
throws java.io.IOException, ClassNotFoundException { |
678 |
tim |
1.12 |
// Read in capacity, and any hidden stuff |
679 |
|
|
s.defaultReadObject(); |
680 |
dl |
1.2 |
|
681 |
dl |
1.19 |
count.set(0); |
682 |
|
|
last = head = new Node<E>(null); |
683 |
|
|
|
684 |
dl |
1.6 |
// Read in all elements and place in queue |
685 |
dl |
1.2 |
for (;;) { |
686 |
|
|
E item = (E)s.readObject(); |
687 |
|
|
if (item == null) |
688 |
|
|
break; |
689 |
|
|
add(item); |
690 |
|
|
} |
691 |
tim |
1.1 |
} |
692 |
|
|
} |