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root/jsr166/jsr166/src/test/tck/PriorityBlockingQueueTest.java
Revision: 1.87
Committed: Wed Jan 27 02:55:18 2021 UTC (3 years, 2 months ago) by jsr166
Branch: MAIN
CVS Tags: HEAD
Changes since 1.86: +2 -1 lines
Log Message:
Suppress all new errorprone "errors"

File Contents

# Content
1 /*
2 * Written by Doug Lea with assistance from members of JCP JSR-166
3 * Expert Group and released to the public domain, as explained at
4 * http://creativecommons.org/publicdomain/zero/1.0/
5 * Other contributors include Andrew Wright, Jeffrey Hayes,
6 * Pat Fisher, Mike Judd.
7 */
8
9 import static java.util.concurrent.TimeUnit.MILLISECONDS;
10
11 import java.util.ArrayList;
12 import java.util.Arrays;
13 import java.util.Collection;
14 import java.util.Comparator;
15 import java.util.Iterator;
16 import java.util.NoSuchElementException;
17 import java.util.Queue;
18 import java.util.concurrent.BlockingQueue;
19 import java.util.concurrent.CountDownLatch;
20 import java.util.concurrent.Executors;
21 import java.util.concurrent.ExecutorService;
22 import java.util.concurrent.PriorityBlockingQueue;
23 import java.util.concurrent.ThreadLocalRandom;
24
25 import junit.framework.Test;
26
27 public class PriorityBlockingQueueTest extends JSR166TestCase {
28
29 public static class Generic extends BlockingQueueTest {
30 protected BlockingQueue emptyCollection() {
31 return new PriorityBlockingQueue();
32 }
33 }
34
35 public static class InitialCapacity extends BlockingQueueTest {
36 protected BlockingQueue emptyCollection() {
37 ThreadLocalRandom rnd = ThreadLocalRandom.current();
38 int initialCapacity = rnd.nextInt(1, SIZE);
39 return new PriorityBlockingQueue(initialCapacity);
40 }
41 }
42
43 public static void main(String[] args) {
44 main(suite(), args);
45 }
46
47 public static Test suite() {
48 class Implementation implements CollectionImplementation {
49 public Class<?> klazz() { return PriorityBlockingQueue.class; }
50 public Collection emptyCollection() {
51 return new PriorityBlockingQueue();
52 }
53 public Object makeElement(int i) { return JSR166TestCase.itemFor(i); }
54 public boolean isConcurrent() { return true; }
55 public boolean permitsNulls() { return false; }
56 }
57 class ComparatorImplementation implements CollectionImplementation {
58 public Class<?> klazz() { return PriorityBlockingQueue.class; }
59 @SuppressWarnings("unchecked")
60 public Collection emptyCollection() {
61 ThreadLocalRandom rnd = ThreadLocalRandom.current();
62 int initialCapacity = rnd.nextInt(1, 10);
63 return new PriorityBlockingQueue(
64 initialCapacity, new MyReverseComparator());
65 }
66 public Object makeElement(int i) { return JSR166TestCase.itemFor(i); }
67 public boolean isConcurrent() { return true; }
68 public boolean permitsNulls() { return false; }
69 }
70 return newTestSuite(
71 PriorityBlockingQueueTest.class,
72 new Generic().testSuite(),
73 new InitialCapacity().testSuite(),
74 CollectionTest.testSuite(new Implementation()),
75 CollectionTest.testSuite(new ComparatorImplementation()));
76 }
77
78 /** Sample Comparator */
79 static class MyReverseComparator implements Comparator, java.io.Serializable {
80 @SuppressWarnings("unchecked")
81 public int compare(Object x, Object y) {
82 return ((Comparable)y).compareTo(x);
83 }
84 }
85
86 /**
87 * Returns a new queue of given size containing consecutive
88 * Items 0 ... n - 1.
89 */
90 private static PriorityBlockingQueue<Item> populatedQueue(int n) {
91 PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(n);
92 assertTrue(q.isEmpty());
93 for (int i = n - 1; i >= 0; i -= 2)
94 mustOffer(q, i);
95 for (int i = (n & 1); i < n; i += 2)
96 mustOffer(q, i);
97 assertFalse(q.isEmpty());
98 mustEqual(Integer.MAX_VALUE, q.remainingCapacity());
99 mustEqual(n, q.size());
100 mustEqual(0, q.peek());
101 return q;
102 }
103
104 /**
105 * A new queue has unbounded capacity
106 */
107 public void testConstructor1() {
108 mustEqual(Integer.MAX_VALUE,
109 new PriorityBlockingQueue<Item>(SIZE).remainingCapacity());
110 }
111
112 /**
113 * Constructor throws IllegalArgumentException if capacity argument nonpositive
114 */
115 public void testConstructor2() {
116 try {
117 new PriorityBlockingQueue<Item>(0);
118 shouldThrow();
119 } catch (IllegalArgumentException success) {}
120 }
121
122 /**
123 * Initializing from null Collection throws NPE
124 */
125 public void testConstructor3() {
126 try {
127 new PriorityBlockingQueue<Item>(null);
128 shouldThrow();
129 } catch (NullPointerException success) {}
130 }
131
132 /**
133 * Initializing from Collection of null elements throws NPE
134 */
135 public void testConstructor4() {
136 Collection<Item> elements = Arrays.asList(new Item[SIZE]);
137 try {
138 new PriorityBlockingQueue<Item>(elements);
139 shouldThrow();
140 } catch (NullPointerException success) {}
141 }
142
143 /**
144 * Initializing from Collection with some null elements throws NPE
145 */
146 public void testConstructor5() {
147 Item[] items = new Item[2]; items[0] = zero;
148 Collection<Item> elements = Arrays.asList(items);
149 try {
150 new PriorityBlockingQueue<Item>(elements);
151 shouldThrow();
152 } catch (NullPointerException success) {}
153 }
154
155 /**
156 * Queue contains all elements of collection used to initialize
157 */
158 public void testConstructor6() {
159 Item[] items = defaultItems;
160 PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(Arrays.asList(items));
161 for (int i = 0; i < SIZE; ++i)
162 mustEqual(items[i], q.poll());
163 }
164
165 /**
166 * The comparator used in constructor is used
167 */
168 public void testConstructor7() {
169 MyReverseComparator cmp = new MyReverseComparator();
170 @SuppressWarnings("unchecked")
171 PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(SIZE, cmp);
172 mustEqual(cmp, q.comparator());
173 Item[] items = defaultItems;
174 q.addAll(Arrays.asList(items));
175 for (int i = SIZE - 1; i >= 0; --i)
176 mustEqual(items[i], q.poll());
177 }
178
179 /**
180 * isEmpty is true before add, false after
181 */
182 public void testEmpty() {
183 PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(2);
184 assertTrue(q.isEmpty());
185 mustEqual(Integer.MAX_VALUE, q.remainingCapacity());
186 q.add(one);
187 assertFalse(q.isEmpty());
188 q.add(two);
189 q.remove();
190 q.remove();
191 assertTrue(q.isEmpty());
192 }
193
194 /**
195 * remainingCapacity() always returns Integer.MAX_VALUE
196 */
197 public void testRemainingCapacity() {
198 BlockingQueue<Item> q = populatedQueue(SIZE);
199 for (int i = 0; i < SIZE; ++i) {
200 mustEqual(Integer.MAX_VALUE, q.remainingCapacity());
201 mustEqual(SIZE - i, q.size());
202 mustEqual(i, q.remove());
203 }
204 for (int i = 0; i < SIZE; ++i) {
205 mustEqual(Integer.MAX_VALUE, q.remainingCapacity());
206 mustEqual(i, q.size());
207 mustAdd(q, i);
208 }
209 }
210
211 /**
212 * Offer of comparable element succeeds
213 */
214 public void testOffer() {
215 PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(1);
216 assertTrue(q.offer(zero));
217 assertTrue(q.offer(one));
218 }
219
220 /**
221 * Offer of non-Comparable throws CCE
222 */
223 public void testOfferNonComparable() {
224 PriorityBlockingQueue<Object> q = new PriorityBlockingQueue<>(1);
225 try {
226 q.offer(new Object());
227 shouldThrow();
228 } catch (ClassCastException success) {
229 assertTrue(q.isEmpty());
230 mustEqual(0, q.size());
231 assertNull(q.poll());
232 }
233 }
234
235 /**
236 * add of comparable succeeds
237 */
238 public void testAdd() {
239 PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(SIZE);
240 for (int i = 0; i < SIZE; ++i) {
241 mustEqual(i, q.size());
242 mustAdd(q, i);
243 }
244 }
245
246 /**
247 * addAll(this) throws IllegalArgumentException
248 */
249 public void testAddAllSelf() {
250 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
251 try {
252 q.addAll(q);
253 shouldThrow();
254 } catch (IllegalArgumentException success) {}
255 }
256
257 /**
258 * addAll of a collection with any null elements throws NPE after
259 * possibly adding some elements
260 */
261 public void testAddAll3() {
262 PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(SIZE);
263 Item[] items = new Item[2];
264 items[0] = zero;
265 try {
266 q.addAll(Arrays.asList(items));
267 shouldThrow();
268 } catch (NullPointerException success) {}
269 }
270
271 /**
272 * Queue contains all elements of successful addAll
273 */
274 public void testAddAll5() {
275 Item[] empty = new Item[0];
276 Item[] items = defaultItems;
277 PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(SIZE);
278 assertFalse(q.addAll(Arrays.asList(empty)));
279 assertTrue(q.addAll(Arrays.asList(items)));
280 for (int i = 0; i < SIZE; ++i)
281 mustEqual(items[i], q.poll());
282 }
283
284 /**
285 * all elements successfully put are contained
286 */
287 public void testPut() {
288 PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(SIZE);
289 for (int i = 0; i < SIZE; ++i) {
290 Item x = itemFor(i);
291 q.put(x);
292 mustContain(q, x);
293 }
294 mustEqual(SIZE, q.size());
295 }
296
297 /**
298 * put doesn't block waiting for take
299 */
300 public void testPutWithTake() throws InterruptedException {
301 final PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(2);
302 final int size = 4;
303 Thread t = newStartedThread(new CheckedRunnable() {
304 public void realRun() {
305 for (int i = 0; i < size; i++)
306 q.put(zero);
307 }});
308
309 awaitTermination(t);
310 mustEqual(size, q.size());
311 q.take();
312 }
313
314 /**
315 * Queue is unbounded, so timed offer never times out
316 */
317 public void testTimedOffer() {
318 final PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(2);
319 Thread t = newStartedThread(new CheckedRunnable() {
320 public void realRun() {
321 q.put(one);
322 q.put(two);
323 assertTrue(q.offer(zero, SHORT_DELAY_MS, MILLISECONDS));
324 assertTrue(q.offer(zero, LONG_DELAY_MS, MILLISECONDS));
325 }});
326
327 awaitTermination(t);
328 }
329
330 /**
331 * take retrieves elements in priority order
332 */
333 public void testTake() throws InterruptedException {
334 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
335 for (int i = 0; i < SIZE; ++i) {
336 mustEqual(i, q.take());
337 }
338 }
339
340 /**
341 * Take removes existing elements until empty, then blocks interruptibly
342 */
343 public void testBlockingTake() throws InterruptedException {
344 final PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
345 final CountDownLatch pleaseInterrupt = new CountDownLatch(1);
346 Thread t = newStartedThread(new CheckedRunnable() {
347 public void realRun() throws InterruptedException {
348 for (int i = 0; i < SIZE; i++) mustEqual(i, q.take());
349
350 Thread.currentThread().interrupt();
351 try {
352 q.take();
353 shouldThrow();
354 } catch (InterruptedException success) {}
355 assertFalse(Thread.interrupted());
356
357 pleaseInterrupt.countDown();
358 try {
359 q.take();
360 shouldThrow();
361 } catch (InterruptedException success) {}
362 assertFalse(Thread.interrupted());
363 }});
364
365 await(pleaseInterrupt);
366 if (randomBoolean()) assertThreadBlocks(t, Thread.State.WAITING);
367 t.interrupt();
368 awaitTermination(t);
369 }
370
371 /**
372 * poll succeeds unless empty
373 */
374 public void testPoll() {
375 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
376 for (int i = 0; i < SIZE; ++i) {
377 mustEqual(i, q.poll());
378 }
379 assertNull(q.poll());
380 }
381
382 /**
383 * timed poll with zero timeout succeeds when non-empty, else times out
384 */
385 public void testTimedPoll0() throws InterruptedException {
386 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
387 for (int i = 0; i < SIZE; ++i) {
388 mustEqual(i, q.poll(0, MILLISECONDS));
389 }
390 assertNull(q.poll(0, MILLISECONDS));
391 }
392
393 /**
394 * timed poll with nonzero timeout succeeds when non-empty, else times out
395 */
396 public void testTimedPoll() throws InterruptedException {
397 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
398 for (int i = 0; i < SIZE; ++i) {
399 long startTime = System.nanoTime();
400 mustEqual(i, q.poll(LONG_DELAY_MS, MILLISECONDS));
401 assertTrue(millisElapsedSince(startTime) < LONG_DELAY_MS);
402 }
403 long startTime = System.nanoTime();
404 assertNull(q.poll(timeoutMillis(), MILLISECONDS));
405 assertTrue(millisElapsedSince(startTime) >= timeoutMillis());
406 checkEmpty(q);
407 }
408
409 /**
410 * Interrupted timed poll throws InterruptedException instead of
411 * returning timeout status
412 */
413 public void testInterruptedTimedPoll() throws InterruptedException {
414 final BlockingQueue<Item> q = populatedQueue(SIZE);
415 final CountDownLatch pleaseInterrupt = new CountDownLatch(1);
416 Thread t = newStartedThread(new CheckedRunnable() {
417 public void realRun() throws InterruptedException {
418 for (int i = 0; i < SIZE; i++)
419 mustEqual(i, q.poll(LONG_DELAY_MS, MILLISECONDS));
420
421 Thread.currentThread().interrupt();
422 try {
423 q.poll(randomTimeout(), randomTimeUnit());
424 shouldThrow();
425 } catch (InterruptedException success) {}
426 assertFalse(Thread.interrupted());
427
428 pleaseInterrupt.countDown();
429 try {
430 q.poll(LONGER_DELAY_MS, MILLISECONDS);
431 shouldThrow();
432 } catch (InterruptedException success) {}
433 assertFalse(Thread.interrupted());
434 }});
435
436 await(pleaseInterrupt);
437 if (randomBoolean()) assertThreadBlocks(t, Thread.State.TIMED_WAITING);
438 t.interrupt();
439 awaitTermination(t);
440 }
441
442 /**
443 * peek returns next element, or null if empty
444 */
445 public void testPeek() {
446 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
447 for (int i = 0; i < SIZE; ++i) {
448 mustEqual(i, q.peek());
449 mustEqual(i, q.poll());
450 assertTrue(q.peek() == null ||
451 !q.peek().equals(i));
452 }
453 assertNull(q.peek());
454 }
455
456 /**
457 * element returns next element, or throws NSEE if empty
458 */
459 public void testElement() {
460 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
461 for (int i = 0; i < SIZE; ++i) {
462 mustEqual(i, q.element());
463 mustEqual(i, q.poll());
464 }
465 try {
466 q.element();
467 shouldThrow();
468 } catch (NoSuchElementException success) {}
469 }
470
471 /**
472 * remove removes next element, or throws NSEE if empty
473 */
474 public void testRemove() {
475 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
476 for (int i = 0; i < SIZE; ++i) {
477 mustEqual(i, q.remove());
478 }
479 try {
480 q.remove();
481 shouldThrow();
482 } catch (NoSuchElementException success) {}
483 }
484
485 /**
486 * contains(x) reports true when elements added but not yet removed
487 */
488 public void testContains() {
489 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
490 for (int i = 0; i < SIZE; ++i) {
491 mustContain(q, i);
492 q.poll();
493 mustNotContain(q, i);
494 }
495 }
496
497 /**
498 * clear removes all elements
499 */
500 public void testClear() {
501 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
502 q.clear();
503 assertTrue(q.isEmpty());
504 mustEqual(0, q.size());
505 q.add(one);
506 assertFalse(q.isEmpty());
507 mustContain(q, one);
508 q.clear();
509 assertTrue(q.isEmpty());
510 }
511
512 /**
513 * containsAll(c) is true when c contains a subset of elements
514 */
515 public void testContainsAll() {
516 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
517 PriorityBlockingQueue<Item> p = new PriorityBlockingQueue<>(SIZE);
518 for (int i = 0; i < SIZE; ++i) {
519 assertTrue(q.containsAll(p));
520 assertFalse(p.containsAll(q));
521 mustAdd(p, i);
522 }
523 assertTrue(p.containsAll(q));
524 }
525
526 /**
527 * retainAll(c) retains only those elements of c and reports true if changed
528 */
529 public void testRetainAll() {
530 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
531 PriorityBlockingQueue<Item> p = populatedQueue(SIZE);
532 for (int i = 0; i < SIZE; ++i) {
533 boolean changed = q.retainAll(p);
534 if (i == 0)
535 assertFalse(changed);
536 else
537 assertTrue(changed);
538
539 assertTrue(q.containsAll(p));
540 mustEqual(SIZE - i, q.size());
541 p.remove();
542 }
543 }
544
545 /**
546 * removeAll(c) removes only those elements of c and reports true if changed
547 */
548 public void testRemoveAll() {
549 for (int i = 1; i < SIZE; ++i) {
550 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
551 PriorityBlockingQueue<Item> p = populatedQueue(i);
552 assertTrue(q.removeAll(p));
553 mustEqual(SIZE - i, q.size());
554 for (int j = 0; j < i; ++j) {
555 Item x = p.remove();
556 mustNotContain(q, x);
557 }
558 }
559 }
560
561 /**
562 * toArray contains all elements
563 */
564 public void testToArray() throws InterruptedException {
565 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
566 Object[] a = q.toArray();
567 assertSame(Object[].class, a.getClass());
568 Arrays.sort(a);
569 for (Object o : a)
570 assertSame(o, q.take());
571 assertTrue(q.isEmpty());
572 }
573
574 /**
575 * toArray(a) contains all elements
576 */
577 public void testToArray2() throws InterruptedException {
578 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
579 Item[] items = new Item[SIZE];
580 Item[] array = q.toArray(items);
581 assertSame(items, array);
582 Arrays.sort(items);
583 for (Item o : items)
584 assertSame(o, q.take());
585 assertTrue(q.isEmpty());
586 }
587
588 /**
589 * toArray(incompatible array type) throws ArrayStoreException
590 */
591 @SuppressWarnings("CollectionToArraySafeParameter")
592 public void testToArray_incompatibleArrayType() {
593 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
594 try {
595 q.toArray(new String[10]);
596 shouldThrow();
597 } catch (ArrayStoreException success) {}
598 }
599
600 /**
601 * iterator iterates through all elements
602 */
603 public void testIterator() {
604 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
605 Iterator<? extends Item> it = q.iterator();
606 int i;
607 for (i = 0; it.hasNext(); i++)
608 mustContain(q, it.next());
609 mustEqual(i, SIZE);
610 assertIteratorExhausted(it);
611 }
612
613 /**
614 * iterator of empty collection has no elements
615 */
616 public void testEmptyIterator() {
617 assertIteratorExhausted(new PriorityBlockingQueue<>().iterator());
618 }
619
620 /**
621 * iterator.remove removes current element
622 */
623 public void testIteratorRemove() {
624 final PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(3);
625 q.add(two);
626 q.add(one);
627 q.add(three);
628
629 Iterator<? extends Item> it = q.iterator();
630 it.next();
631 it.remove();
632
633 it = q.iterator();
634 mustEqual(it.next(), two);
635 mustEqual(it.next(), three);
636 assertFalse(it.hasNext());
637 }
638
639 /**
640 * toString contains toStrings of elements
641 */
642 public void testToString() {
643 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
644 String s = q.toString();
645 for (int i = 0; i < SIZE; ++i) {
646 assertTrue(s.contains(String.valueOf(i)));
647 }
648 }
649
650 /**
651 * timed poll transfers elements across Executor tasks
652 */
653 public void testPollInExecutor() {
654 final PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(2);
655 final CheckedBarrier threadsStarted = new CheckedBarrier(2);
656 final ExecutorService executor = Executors.newFixedThreadPool(2);
657 try (PoolCleaner cleaner = cleaner(executor)) {
658 executor.execute(new CheckedRunnable() {
659 public void realRun() throws InterruptedException {
660 assertNull(q.poll());
661 threadsStarted.await();
662 assertSame(one, q.poll(LONG_DELAY_MS, MILLISECONDS));
663 checkEmpty(q);
664 }});
665
666 executor.execute(new CheckedRunnable() {
667 public void realRun() throws InterruptedException {
668 threadsStarted.await();
669 q.put(one);
670 }});
671 }
672 }
673
674 /**
675 * A deserialized/reserialized queue has same elements
676 */
677 public void testSerialization() throws Exception {
678 Queue<Item> x = populatedQueue(SIZE);
679 Queue<Item> y = serialClone(x);
680
681 assertNotSame(x, y);
682 mustEqual(x.size(), y.size());
683 while (!x.isEmpty()) {
684 assertFalse(y.isEmpty());
685 mustEqual(x.remove(), y.remove());
686 }
687 assertTrue(y.isEmpty());
688 }
689
690 /**
691 * drainTo(c) empties queue into another collection c
692 */
693 public void testDrainTo() {
694 PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
695 ArrayList<Item> l = new ArrayList<>();
696 q.drainTo(l);
697 mustEqual(0, q.size());
698 mustEqual(SIZE, l.size());
699 for (int i = 0; i < SIZE; ++i)
700 mustEqual(l.get(i), i);
701 q.add(zero);
702 q.add(one);
703 assertFalse(q.isEmpty());
704 mustContain(q, one);
705 l.clear();
706 q.drainTo(l);
707 mustEqual(0, q.size());
708 mustEqual(2, l.size());
709 for (int i = 0; i < 2; ++i)
710 mustEqual(l.get(i), i);
711 }
712
713 /**
714 * drainTo empties queue
715 */
716 public void testDrainToWithActivePut() throws InterruptedException {
717 final PriorityBlockingQueue<Item> q = populatedQueue(SIZE);
718 Thread t = new Thread(new CheckedRunnable() {
719 public void realRun() {
720 q.put(new Item(SIZE + 1));
721 }});
722
723 t.start();
724 ArrayList<Item> l = new ArrayList<>();
725 q.drainTo(l);
726 assertTrue(l.size() >= SIZE);
727 for (int i = 0; i < SIZE; ++i)
728 mustEqual(l.get(i), i);
729 t.join();
730 assertTrue(q.size() + l.size() >= SIZE);
731 }
732
733 /**
734 * drainTo(c, n) empties first min(n, size) elements of queue into c
735 */
736 public void testDrainToN() {
737 PriorityBlockingQueue<Item> q = new PriorityBlockingQueue<>(SIZE * 2);
738 for (int i = 0; i < SIZE + 2; ++i) {
739 for (int j = 0; j < SIZE; j++)
740 mustOffer(q, j);
741 ArrayList<Item> l = new ArrayList<>();
742 q.drainTo(l, i);
743 int k = (i < SIZE) ? i : SIZE;
744 mustEqual(k, l.size());
745 mustEqual(SIZE - k, q.size());
746 for (int j = 0; j < k; ++j)
747 mustEqual(l.get(j), j);
748 do {} while (q.poll() != null);
749 }
750 }
751
752 /**
753 * remove(null), contains(null) always return false
754 */
755 public void testNeverContainsNull() {
756 Collection<?>[] qs = {
757 new PriorityBlockingQueue<>(),
758 populatedQueue(2),
759 };
760
761 for (Collection<?> q : qs) {
762 assertFalse(q.contains(null));
763 assertFalse(q.remove(null));
764 }
765 }
766
767 }