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Comparing jsr166/src/test/tck/SemaphoreTest.java (file contents):
Revision 1.2 by dl, Sun Sep 7 20:39:11 2003 UTC vs.
Revision 1.30 by jsr166, Fri Jun 3 05:07:14 2011 UTC

# Line 1 | Line 1
1   /*
2 < * Written by members of JCP JSR-166 Expert Group and released to the
3 < * public domain. Use, modify, and redistribute this code in any way
4 < * without acknowledgement. Other contributors include Andrew Wright,
5 < * Jeffrey Hayes, Pat Fischer, Mike Judd.
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 junit.framework.*;
10   import java.util.*;
11 < import java.util.concurrent.*;
12 < import java.io.*;
13 <
13 < public class SemaphoreTest extends TestCase{
11 > import java.util.concurrent.CountDownLatch;
12 > import java.util.concurrent.Semaphore;
13 > import static java.util.concurrent.TimeUnit.MILLISECONDS;
14  
15 + public class SemaphoreTest extends JSR166TestCase {
16      public static void main(String[] args) {
17 <        junit.textui.TestRunner.run (suite());  
17 >        junit.textui.TestRunner.run(suite());
18      }
18    
19      public static Test suite() {
20 <        return new TestSuite(SemaphoreTest.class);
20 >        return new TestSuite(SemaphoreTest.class);
21      }
22  
23 <    private static long SHORT_DELAY_MS = 100;
24 <    private static long MEDIUM_DELAY_MS = 1000;
25 <    private static long LONG_DELAY_MS = 10000;
23 >    /**
24 >     * Subclass to expose protected methods
25 >     */
26 >    static class PublicSemaphore extends Semaphore {
27 >        PublicSemaphore(int permits) { super(permits); }
28 >        PublicSemaphore(int permits, boolean fair) { super(permits, fair); }
29 >        public Collection<Thread> getQueuedThreads() {
30 >            return super.getQueuedThreads();
31 >        }
32 >        public boolean hasQueuedThread(Thread t) {
33 >            return super.getQueuedThreads().contains(t);
34 >        }
35 >        public void reducePermits(int reduction) {
36 >            super.reducePermits(reduction);
37 >        }
38 >    }
39  
40 +    /**
41 +     * A runnable calling acquire
42 +     */
43 +    class InterruptibleLockRunnable extends CheckedRunnable {
44 +        final Semaphore lock;
45 +        InterruptibleLockRunnable(Semaphore s) { lock = s; }
46 +        public void realRun() {
47 +            try {
48 +                lock.acquire();
49 +            }
50 +            catch (InterruptedException ignored) {}
51 +        }
52 +    }
53  
54 <    public void testConstructor1() {
55 <        Semaphore s = new Semaphore(0);
56 <        assertEquals(0, s.availablePermits());
54 >    /**
55 >     * A runnable calling acquire that expects to be interrupted
56 >     */
57 >    class InterruptedLockRunnable extends CheckedInterruptedRunnable {
58 >        final Semaphore lock;
59 >        InterruptedLockRunnable(Semaphore s) { lock = s; }
60 >        public void realRun() throws InterruptedException {
61 >            lock.acquire();
62 >        }
63      }
64  
65 <    public void testConstructor2() {
66 <        Semaphore s = new Semaphore(-1);
67 <        assertEquals(-1, s.availablePermits());
65 >    /**
66 >     * Spin-waits until s.hasQueuedThread(t) becomes true.
67 >     */
68 >    void waitForQueuedThread(PublicSemaphore s, Thread t) {
69 >        long startTime = System.nanoTime();
70 >        while (!s.hasQueuedThread(t)) {
71 >            if (millisElapsedSince(startTime) > LONG_DELAY_MS)
72 >                throw new AssertionFailedError("timed out");
73 >            Thread.yield();
74 >        }
75 >        assert(s.hasQueuedThreads());
76 >        assertTrue(t.isAlive());
77 >    }
78 >
79 >    /**
80 >     * Spin-waits until s.hasQueuedThreads() becomes true.
81 >     */
82 >    void waitForQueuedThreads(Semaphore s) {
83 >        long startTime = System.nanoTime();
84 >        while (!s.hasQueuedThreads()) {
85 >            if (millisElapsedSince(startTime) > LONG_DELAY_MS)
86 >                throw new AssertionFailedError("timed out");
87 >            Thread.yield();
88 >        }
89 >    }
90 >
91 >    enum AcquireMethod {
92 >        acquire() {
93 >            void acquire(Semaphore s) throws InterruptedException {
94 >                s.acquire();
95 >            }
96 >        },
97 >        acquireN() {
98 >            void acquire(Semaphore s, int permits) throws InterruptedException {
99 >                s.acquire(permits);
100 >            }
101 >        },
102 >        acquireUninterruptibly() {
103 >            void acquire(Semaphore s) {
104 >                s.acquireUninterruptibly();
105 >            }
106 >        },
107 >        acquireUninterruptiblyN() {
108 >            void acquire(Semaphore s, int permits) {
109 >                s.acquireUninterruptibly(permits);
110 >            }
111 >        },
112 >        tryAcquire() {
113 >            void acquire(Semaphore s) {
114 >                assertTrue(s.tryAcquire());
115 >            }
116 >        },
117 >        tryAcquireN() {
118 >            void acquire(Semaphore s, int permits) {
119 >                assertTrue(s.tryAcquire(permits));
120 >            }
121 >        },
122 >        tryAcquireTimed() {
123 >            void acquire(Semaphore s) throws InterruptedException {
124 >                assertTrue(s.tryAcquire(2 * LONG_DELAY_MS, MILLISECONDS));
125 >            }
126 >        },
127 >        tryAcquireTimedN {
128 >            void acquire(Semaphore s, int permits) throws InterruptedException {
129 >                assertTrue(s.tryAcquire(permits, 2 * LONG_DELAY_MS, MILLISECONDS));
130 >            }
131 >        };
132 >
133 >        // Intentionally meta-circular
134 >
135 >        /** Acquires 1 permit. */
136 >        void acquire(Semaphore s) throws InterruptedException {
137 >            acquire(s, 1);
138 >        }
139 >        /** Acquires the given number of permits. */
140 >        void acquire(Semaphore s, int permits) throws InterruptedException {
141 >            for (int i = 0; i < permits; i++)
142 >                acquire(s);
143 >        }
144 >    }
145 >
146 >    /**
147 >     * Zero, negative, and positive initial values are allowed in constructor
148 >     */
149 >    public void testConstructor()      { testConstructor(false); }
150 >    public void testConstructor_fair() { testConstructor(true); }
151 >    public void testConstructor(boolean fair) {
152 >        for (int permits : new int[] { -42, -1, 0, 1, 42 }) {
153 >            Semaphore s = new Semaphore(permits, fair);
154 >            assertEquals(permits, s.availablePermits());
155 >            assertEquals(fair, s.isFair());
156 >        }
157 >    }
158 >
159 >    /**
160 >     * Constructor without fairness argument behaves as nonfair
161 >     */
162 >    public void testConstructorDefaultsToNonFair() {
163 >        for (int permits : new int[] { -42, -1, 0, 1, 42 }) {
164 >            Semaphore s = new Semaphore(permits);
165 >            assertEquals(permits, s.availablePermits());
166 >            assertFalse(s.isFair());
167 >        }
168      }
169  
170 <    public void testTryAcquireInSameThread() {
171 <        Semaphore s = new Semaphore(2);
170 >    /**
171 >     * tryAcquire succeeds when sufficient permits, else fails
172 >     */
173 >    public void testTryAcquireInSameThread()      { testTryAcquireInSameThread(false); }
174 >    public void testTryAcquireInSameThread_fair() { testTryAcquireInSameThread(true); }
175 >    public void testTryAcquireInSameThread(boolean fair) {
176 >        Semaphore s = new Semaphore(2, fair);
177          assertEquals(2, s.availablePermits());
178          assertTrue(s.tryAcquire());
179          assertTrue(s.tryAcquire());
180          assertEquals(0, s.availablePermits());
181          assertFalse(s.tryAcquire());
182 +        assertFalse(s.tryAcquire());
183 +        assertEquals(0, s.availablePermits());
184      }
185  
186 <    public void testAcquireReleaseInSameThread(){
187 <        Semaphore s = new Semaphore(1);
188 <        try {
189 <            s.acquire();
190 <            s.release();
191 <            s.acquire();
192 <            s.release();
193 <            s.acquire();
194 <            s.release();
195 <            s.acquire();
196 <            s.release();
197 <            s.acquire();
198 <            s.release();
199 <            assertEquals(1, s.availablePermits());
200 <        } catch( InterruptedException e){
201 <            fail("unexpected exception");
202 <        }
186 >    /**
187 >     * timed tryAcquire times out
188 >     */
189 >    public void testTryAcquire_timeout()      { testTryAcquire_timeout(false); }
190 >    public void testTryAcquire_timeout_fair() { testTryAcquire_timeout(true); }
191 >    public void testTryAcquire_timeout(boolean fair) {
192 >        Semaphore s = new Semaphore(0, fair);
193 >        long startTime = System.nanoTime();
194 >        try { assertFalse(s.tryAcquire(timeoutMillis(), MILLISECONDS)); }
195 >        catch (InterruptedException e) { threadUnexpectedException(e); }
196 >        assertTrue(millisElapsedSince(startTime) >= timeoutMillis());
197 >    }
198 >
199 >    /**
200 >     * timed tryAcquire(N) times out
201 >     */
202 >    public void testTryAcquireN_timeout()      { testTryAcquireN_timeout(false); }
203 >    public void testTryAcquireN_timeout_fair() { testTryAcquireN_timeout(true); }
204 >    public void testTryAcquireN_timeout(boolean fair) {
205 >        Semaphore s = new Semaphore(2, fair);
206 >        long startTime = System.nanoTime();
207 >        try { assertFalse(s.tryAcquire(3, timeoutMillis(), MILLISECONDS)); }
208 >        catch (InterruptedException e) { threadUnexpectedException(e); }
209 >        assertTrue(millisElapsedSince(startTime) >= timeoutMillis());
210 >    }
211 >
212 >    /**
213 >     * acquire(), acquire(N), timed tryAcquired, timed tryAcquire(N)
214 >     * are interruptible
215 >     */
216 >    public void testInterruptible_acquire()               { testInterruptible(false, AcquireMethod.acquire); }
217 >    public void testInterruptible_acquire_fair()          { testInterruptible(true,  AcquireMethod.acquire); }
218 >    public void testInterruptible_acquireN()              { testInterruptible(false, AcquireMethod.acquireN); }
219 >    public void testInterruptible_acquireN_fair()         { testInterruptible(true,  AcquireMethod.acquireN); }
220 >    public void testInterruptible_tryAcquireTimed()       { testInterruptible(false, AcquireMethod.tryAcquireTimed); }
221 >    public void testInterruptible_tryAcquireTimed_fair()  { testInterruptible(true,  AcquireMethod.tryAcquireTimed); }
222 >    public void testInterruptible_tryAcquireTimedN()      { testInterruptible(false, AcquireMethod.tryAcquireTimedN); }
223 >    public void testInterruptible_tryAcquireTimedN_fair() { testInterruptible(true,  AcquireMethod.tryAcquireTimedN); }
224 >    public void testInterruptible(boolean fair, final AcquireMethod acquirer) {
225 >        final PublicSemaphore s = new PublicSemaphore(0, fair);
226 >        final Semaphore pleaseInterrupt = new Semaphore(0, fair);
227 >        Thread t = newStartedThread(new CheckedRunnable() {
228 >            public void realRun() {
229 >                // Interrupt before acquire
230 >                Thread.currentThread().interrupt();
231 >                try {
232 >                    acquirer.acquire(s);
233 >                    shouldThrow();
234 >                } catch (InterruptedException success) {}
235 >
236 >                // Interrupt during acquire
237 >                try {
238 >                    acquirer.acquire(s);
239 >                    shouldThrow();
240 >                } catch (InterruptedException success) {}
241 >
242 >                // Interrupt before acquire(N)
243 >                Thread.currentThread().interrupt();
244 >                try {
245 >                    acquirer.acquire(s, 3);
246 >                    shouldThrow();
247 >                } catch (InterruptedException success) {}
248 >
249 >                pleaseInterrupt.release();
250 >
251 >                // Interrupt during acquire(N)
252 >                try {
253 >                    acquirer.acquire(s, 3);
254 >                    shouldThrow();
255 >                } catch (InterruptedException success) {}
256 >            }});
257 >
258 >        waitForQueuedThread(s, t);
259 >        t.interrupt();
260 >        await(pleaseInterrupt);
261 >        waitForQueuedThread(s, t);
262 >        t.interrupt();
263 >        awaitTermination(t);
264 >    }
265 >
266 >    /**
267 >     * acquireUninterruptibly(), acquireUninterruptibly(N) are
268 >     * uninterruptible
269 >     */
270 >    public void testUninterruptible_acquireUninterruptibly()       { testUninterruptible(false, AcquireMethod.acquireUninterruptibly); }
271 >    public void testUninterruptible_acquireUninterruptibly_fair()  { testUninterruptible(true,  AcquireMethod.acquireUninterruptibly); }
272 >    public void testUninterruptible_acquireUninterruptiblyN()      { testUninterruptible(false, AcquireMethod.acquireUninterruptiblyN); }
273 >    public void testUninterruptible_acquireUninterruptiblyN_fair() { testUninterruptible(true,  AcquireMethod.acquireUninterruptiblyN); }
274 >    public void testUninterruptible(boolean fair, final AcquireMethod acquirer) {
275 >        final PublicSemaphore s = new PublicSemaphore(0, fair);
276 >        final Semaphore pleaseInterrupt = new Semaphore(-1, fair);
277 >
278 >        Thread t1 = newStartedThread(new CheckedRunnable() {
279 >            public void realRun() throws InterruptedException {
280 >                // Interrupt before acquire
281 >                pleaseInterrupt.release();
282 >                Thread.currentThread().interrupt();
283 >                acquirer.acquire(s);
284 >                assertTrue(Thread.interrupted());
285 >            }});
286 >
287 >        Thread t2 = newStartedThread(new CheckedRunnable() {
288 >            public void realRun() throws InterruptedException {
289 >                // Interrupt during acquire
290 >                pleaseInterrupt.release();
291 >                acquirer.acquire(s);
292 >                assertTrue(Thread.interrupted());
293 >            }});
294 >
295 >        await(pleaseInterrupt);
296 >        waitForQueuedThread(s, t1);
297 >        waitForQueuedThread(s, t2);
298 >        t2.interrupt();
299 >
300 >        assertThreadStaysAlive(t1);
301 >        assertTrue(t2.isAlive());
302 >
303 >        s.release(2);
304 >
305 >        awaitTermination(t1);
306 >        awaitTermination(t2);
307 >    }
308 >
309 >    /**
310 >     * hasQueuedThreads reports whether there are waiting threads
311 >     */
312 >    public void testHasQueuedThreads()      { testHasQueuedThreads(false); }
313 >    public void testHasQueuedThreads_fair() { testHasQueuedThreads(true); }
314 >    public void testHasQueuedThreads(boolean fair) {
315 >        final PublicSemaphore lock = new PublicSemaphore(1, fair);
316 >        assertFalse(lock.hasQueuedThreads());
317 >        lock.acquireUninterruptibly();
318 >        Thread t1 = newStartedThread(new InterruptedLockRunnable(lock));
319 >        waitForQueuedThread(lock, t1);
320 >        assertTrue(lock.hasQueuedThreads());
321 >        Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock));
322 >        waitForQueuedThread(lock, t2);
323 >        assertTrue(lock.hasQueuedThreads());
324 >        t1.interrupt();
325 >        awaitTermination(t1);
326 >        assertTrue(lock.hasQueuedThreads());
327 >        lock.release();
328 >        awaitTermination(t2);
329 >        assertFalse(lock.hasQueuedThreads());
330 >    }
331 >
332 >    /**
333 >     * getQueueLength reports number of waiting threads
334 >     */
335 >    public void testGetQueueLength()      { testGetQueueLength(false); }
336 >    public void testGetQueueLength_fair() { testGetQueueLength(true); }
337 >    public void testGetQueueLength(boolean fair) {
338 >        final PublicSemaphore lock = new PublicSemaphore(1, fair);
339 >        assertEquals(0, lock.getQueueLength());
340 >        lock.acquireUninterruptibly();
341 >        Thread t1 = newStartedThread(new InterruptedLockRunnable(lock));
342 >        waitForQueuedThread(lock, t1);
343 >        assertEquals(1, lock.getQueueLength());
344 >        Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock));
345 >        waitForQueuedThread(lock, t2);
346 >        assertEquals(2, lock.getQueueLength());
347 >        t1.interrupt();
348 >        awaitTermination(t1);
349 >        assertEquals(1, lock.getQueueLength());
350 >        lock.release();
351 >        awaitTermination(t2);
352 >        assertEquals(0, lock.getQueueLength());
353 >    }
354 >
355 >    /**
356 >     * getQueuedThreads includes waiting threads
357 >     */
358 >    public void testGetQueuedThreads()      { testGetQueuedThreads(false); }
359 >    public void testGetQueuedThreads_fair() { testGetQueuedThreads(true); }
360 >    public void testGetQueuedThreads(boolean fair) {
361 >        final PublicSemaphore lock = new PublicSemaphore(1, fair);
362 >        assertTrue(lock.getQueuedThreads().isEmpty());
363 >        lock.acquireUninterruptibly();
364 >        assertTrue(lock.getQueuedThreads().isEmpty());
365 >        Thread t1 = newStartedThread(new InterruptedLockRunnable(lock));
366 >        waitForQueuedThread(lock, t1);
367 >        assertTrue(lock.getQueuedThreads().contains(t1));
368 >        Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock));
369 >        waitForQueuedThread(lock, t2);
370 >        assertTrue(lock.getQueuedThreads().contains(t1));
371 >        assertTrue(lock.getQueuedThreads().contains(t2));
372 >        t1.interrupt();
373 >        awaitTermination(t1);
374 >        assertFalse(lock.getQueuedThreads().contains(t1));
375 >        assertTrue(lock.getQueuedThreads().contains(t2));
376 >        lock.release();
377 >        awaitTermination(t2);
378 >        assertTrue(lock.getQueuedThreads().isEmpty());
379 >    }
380 >
381 >    /**
382 >     * drainPermits reports and removes given number of permits
383 >     */
384 >    public void testDrainPermits()      { testDrainPermits(false); }
385 >    public void testDrainPermits_fair() { testDrainPermits(true); }
386 >    public void testDrainPermits(boolean fair) {
387 >        Semaphore s = new Semaphore(0, fair);
388 >        assertEquals(0, s.availablePermits());
389 >        assertEquals(0, s.drainPermits());
390 >        s.release(10);
391 >        assertEquals(10, s.availablePermits());
392 >        assertEquals(10, s.drainPermits());
393 >        assertEquals(0, s.availablePermits());
394 >        assertEquals(0, s.drainPermits());
395      }
396  
397 <    public void testAcquireUninterruptiblyReleaseInSameThread(){
398 <        Semaphore s = new Semaphore(1);
397 >    /**
398 >     * release(-N) throws IllegalArgumentException
399 >     */
400 >    public void testReleaseIAE()      { testReleaseIAE(false); }
401 >    public void testReleaseIAE_fair() { testReleaseIAE(true); }
402 >    public void testReleaseIAE(boolean fair) {
403 >        Semaphore s = new Semaphore(10, fair);
404          try {
405 <            s.acquireUninterruptibly();
406 <            s.release();
407 <            s.acquireUninterruptibly();
72 <            s.release();
73 <            s.acquireUninterruptibly();
74 <            s.release();
75 <            s.acquireUninterruptibly();
76 <            s.release();
77 <            s.acquireUninterruptibly();
78 <            s.release();
79 <            assertEquals(1, s.availablePermits());
80 <        } finally {
81 <        }
405 >            s.release(-1);
406 >            shouldThrow();
407 >        } catch (IllegalArgumentException success) {}
408      }
409  
410 <
411 <    public void testAcquireReleaseInDifferentThreads() {
412 <        final Semaphore s = new Semaphore(1);
413 <        Thread t = new Thread(new Runnable(){
414 <                public void run(){
415 <                    try{
416 <                        s.acquire();
91 <                        s.release();
92 <                        s.release();
93 <                        s.acquire();
94 <                    }catch(InterruptedException ie){
95 <                        fail("unexpected exception");
96 <                    }
97 <                }
98 <            });
99 <        t.start();
410 >    /**
411 >     * reducePermits(-N) throws IllegalArgumentException
412 >     */
413 >    public void testReducePermitsIAE()      { testReducePermitsIAE(false); }
414 >    public void testReducePermitsIAE_fair() { testReducePermitsIAE(true); }
415 >    public void testReducePermitsIAE(boolean fair) {
416 >        PublicSemaphore s = new PublicSemaphore(10, fair);
417          try {
418 <            s.release();
419 <            s.release();
420 <            s.acquire();
421 <            s.acquire();
422 <            t.join();
423 <        } catch( InterruptedException e){
424 <            fail("unexpected exception");
425 <        }
418 >            s.reducePermits(-1);
419 >            shouldThrow();
420 >        } catch (IllegalArgumentException success) {}
421 >    }
422 >
423 >    /**
424 >     * reducePermits reduces number of permits
425 >     */
426 >    public void testReducePermits()      { testReducePermits(false); }
427 >    public void testReducePermits_fair() { testReducePermits(true); }
428 >    public void testReducePermits(boolean fair) {
429 >        PublicSemaphore s = new PublicSemaphore(10, fair);
430 >        assertEquals(10, s.availablePermits());
431 >        s.reducePermits(0);
432 >        assertEquals(10, s.availablePermits());
433 >        s.reducePermits(1);
434 >        assertEquals(9, s.availablePermits());
435 >        s.reducePermits(10);
436 >        assertEquals(-1, s.availablePermits());
437 >        s.reducePermits(10);
438 >        assertEquals(-11, s.availablePermits());
439 >        s.reducePermits(0);
440 >        assertEquals(-11, s.availablePermits());
441      }
442  
443 <    public void testTimedAcquireReleaseInSameThread(){
444 <        Semaphore s = new Semaphore(1);
443 >    /**
444 >     * a reserialized semaphore has same number of permits and
445 >     * fairness, but no queued threads
446 >     */
447 >    public void testSerialization()      { testSerialization(false); }
448 >    public void testSerialization_fair() { testSerialization(true); }
449 >    public void testSerialization(boolean fair) {
450          try {
451 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
452 <            s.release();
453 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
117 <            s.release();
118 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
119 <            s.release();
120 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
121 <            s.release();
122 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
451 >            Semaphore s = new Semaphore(3, fair);
452 >            s.acquire();
453 >            s.acquire();
454              s.release();
455 <            assertEquals(1, s.availablePermits());
456 <        } catch( InterruptedException e){
457 <            fail("unexpected exception");
458 <        }
455 >
456 >            Semaphore clone = serialClone(s);
457 >            assertEquals(fair, s.isFair());
458 >            assertEquals(fair, clone.isFair());
459 >            assertEquals(2, s.availablePermits());
460 >            assertEquals(2, clone.availablePermits());
461 >            clone.acquire();
462 >            clone.acquire();
463 >            clone.release();
464 >            assertEquals(2, s.availablePermits());
465 >            assertEquals(1, clone.availablePermits());
466 >
467 >            s = new Semaphore(0, fair);
468 >            Thread t = newStartedThread(new InterruptibleLockRunnable(s));
469 >            waitForQueuedThreads(s);
470 >            clone = serialClone(s);
471 >            assertEquals(fair, s.isFair());
472 >            assertEquals(fair, clone.isFair());
473 >            assertEquals(0, s.availablePermits());
474 >            assertEquals(0, clone.availablePermits());
475 >            assertTrue(s.hasQueuedThreads());
476 >            assertFalse(clone.hasQueuedThreads());
477 >            s.release();
478 >            awaitTermination(t);
479 >            assertFalse(s.hasQueuedThreads());
480 >            assertFalse(clone.hasQueuedThreads());
481 >        } catch (InterruptedException e) { threadUnexpectedException(e); }
482 >    }
483 >
484 >    /**
485 >     * tryAcquire(n) succeeds when sufficient permits, else fails
486 >     */
487 >    public void testTryAcquireNInSameThread()      { testTryAcquireNInSameThread(false); }
488 >    public void testTryAcquireNInSameThread_fair() { testTryAcquireNInSameThread(true); }
489 >    public void testTryAcquireNInSameThread(boolean fair) {
490 >        Semaphore s = new Semaphore(2, fair);
491 >        assertEquals(2, s.availablePermits());
492 >        assertFalse(s.tryAcquire(3));
493 >        assertEquals(2, s.availablePermits());
494 >        assertTrue(s.tryAcquire(2));
495 >        assertEquals(0, s.availablePermits());
496 >        assertFalse(s.tryAcquire(1));
497 >        assertFalse(s.tryAcquire(2));
498 >        assertEquals(0, s.availablePermits());
499      }
500  
501 <    public void testTimedAcquireReleaseInDifferentThreads() {
502 <        final Semaphore s = new Semaphore(1);
503 <        Thread t = new Thread(new Runnable(){
504 <                public void run(){
505 <                    try{
506 <                        s.release();
507 <                        assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
508 <                        s.release();
509 <                        assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
510 <
511 <                    }catch(InterruptedException ie){
512 <                        fail("unexpected exception");
513 <                    }
514 <                }
515 <            });
516 <        t.start();
517 <        try {
518 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
519 <            s.release();
520 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
521 <            s.release();
522 <            t.join();
523 <        } catch( InterruptedException e){
524 <            fail("unexpected exception");
501 >    /**
502 >     * acquire succeeds if permits available
503 >     */
504 >    public void testReleaseAcquireSameThread_acquire()       { testReleaseAcquireSameThread(false, AcquireMethod.acquire); }
505 >    public void testReleaseAcquireSameThread_acquire_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.acquire); }
506 >    public void testReleaseAcquireSameThread_acquireN()      { testReleaseAcquireSameThread(false, AcquireMethod.acquireN); }
507 >    public void testReleaseAcquireSameThread_acquireN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.acquireN); }
508 >    public void testReleaseAcquireSameThread_acquireUninterruptibly()       { testReleaseAcquireSameThread(false, AcquireMethod.acquireUninterruptibly); }
509 >    public void testReleaseAcquireSameThread_acquireUninterruptibly_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.acquireUninterruptibly); }
510 >    public void testReleaseAcquireSameThread_acquireUninterruptiblyN()      { testReleaseAcquireSameThread(false, AcquireMethod.acquireUninterruptibly); }
511 >    public void testReleaseAcquireSameThread_acquireUninterruptiblyN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.acquireUninterruptibly); }
512 >    public void testReleaseAcquireSameThread_tryAcquire()       { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquire); }
513 >    public void testReleaseAcquireSameThread_tryAcquire_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquire); }
514 >    public void testReleaseAcquireSameThread_tryAcquireN()      { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireN); }
515 >    public void testReleaseAcquireSameThread_tryAcquireN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireN); }
516 >    public void testReleaseAcquireSameThread_tryAcquireTimed()       { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireTimed); }
517 >    public void testReleaseAcquireSameThread_tryAcquireTimed_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireTimed); }
518 >    public void testReleaseAcquireSameThread_tryAcquireTimedN()      { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireTimedN); }
519 >    public void testReleaseAcquireSameThread_tryAcquireTimedN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireTimedN); }
520 >    public void testReleaseAcquireSameThread(boolean fair,
521 >                                             final AcquireMethod acquirer) {
522 >        Semaphore s = new Semaphore(1, fair);
523 >        for (int i = 1; i < 6; i++) {
524 >            s.release(i);
525 >            assertEquals(1 + i, s.availablePermits());
526 >            try {
527 >                acquirer.acquire(s, i);
528 >            } catch (InterruptedException e) { threadUnexpectedException(e); }
529 >            assertEquals(1, s.availablePermits());
530          }
531      }
532  
533 <    public void testAcquire_InterruptedException(){
534 <        final Semaphore s = new Semaphore(0);
535 <        Thread t = new Thread(new Runnable(){
536 <                public void run(){
537 <                    try{
538 <                        s.acquire();
539 <                        fail("should throw");
540 <                    }catch(InterruptedException success){}
541 <                }
542 <            });
543 <        t.start();
544 <        try{
545 <            Thread.sleep(SHORT_DELAY_MS);
546 <            t.interrupt();
547 <            t.join();
548 <        } catch(InterruptedException e){
549 <            fail("unexpected exception");
550 <        }
551 <    }
552 <    
553 <    public void testTryAcquire_InterruptedException(){
554 <        final Semaphore s = new Semaphore(0);
555 <        Thread t = new Thread(new Runnable(){
556 <                public void run(){
557 <                    try{
558 <                        s.tryAcquire(MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS);
559 <                        fail("should throw");
560 <                    }catch(InterruptedException success){
561 <                    }
562 <                }
563 <            });
564 <        t.start();
565 <        try{
566 <            Thread.sleep(SHORT_DELAY_MS);
567 <            t.interrupt();
568 <            t.join();
569 <        } catch(InterruptedException e){
570 <            fail("unexpected exception");
533 >    /**
534 >     * release in one thread enables acquire in another thread
535 >     */
536 >    public void testReleaseAcquireDifferentThreads_acquire()       { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquire); }
537 >    public void testReleaseAcquireDifferentThreads_acquire_fair()  { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquire); }
538 >    public void testReleaseAcquireDifferentThreads_acquireN()      { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireN); }
539 >    public void testReleaseAcquireDifferentThreads_acquireN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireN); }
540 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptibly()       { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireUninterruptibly); }
541 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptibly_fair()  { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireUninterruptibly); }
542 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptiblyN()      { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireUninterruptibly); }
543 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptiblyN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireUninterruptibly); }
544 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimed()       { testReleaseAcquireDifferentThreads(false, AcquireMethod.tryAcquireTimed); }
545 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimed_fair()  { testReleaseAcquireDifferentThreads(true, AcquireMethod.tryAcquireTimed); }
546 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimedN()      { testReleaseAcquireDifferentThreads(false, AcquireMethod.tryAcquireTimedN); }
547 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimedN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.tryAcquireTimedN); }
548 >    public void testReleaseAcquireDifferentThreads(boolean fair,
549 >                                                   final AcquireMethod acquirer) {
550 >        final Semaphore s = new Semaphore(0, fair);
551 >        final int rounds = 4;
552 >        long startTime = System.nanoTime();
553 >        Thread t = newStartedThread(new CheckedRunnable() {
554 >            public void realRun() throws InterruptedException {
555 >                for (int i = 0; i < rounds; i++) {
556 >                    assertFalse(s.hasQueuedThreads());
557 >                    if (i % 2 == 0)
558 >                        acquirer.acquire(s);
559 >                    else
560 >                        acquirer.acquire(s, 3);
561 >                }}});
562 >
563 >        for (int i = 0; i < rounds; i++) {
564 >            while (! (s.availablePermits() == 0 && s.hasQueuedThreads()))
565 >                Thread.yield();
566 >            assertTrue(t.isAlive());
567 >            if (i % 2 == 0)
568 >                s.release();
569 >            else
570 >                s.release(3);
571          }
572 +        awaitTermination(t);
573 +        assertEquals(0, s.availablePermits());
574 +        assertTrue(millisElapsedSince(startTime) < LONG_DELAY_MS);
575      }
576  
577 <    public void testSerialization() {
578 <        Semaphore l = new Semaphore(3);
579 <
580 <        try {
581 <            l.acquire();
582 <            l.release();
583 <            ByteArrayOutputStream bout = new ByteArrayOutputStream(10000);
584 <            ObjectOutputStream out = new ObjectOutputStream(new BufferedOutputStream(bout));
585 <            out.writeObject(l);
586 <            out.close();
587 <
588 <            ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());
589 <            ObjectInputStream in = new ObjectInputStream(new BufferedInputStream(bin));
590 <            Semaphore r = (Semaphore) in.readObject();
591 <            assertEquals(3, r.availablePermits());
592 <            r.acquire();
593 <            r.release();
594 <        } catch(Exception e){
595 <            e.printStackTrace();
596 <            fail("unexpected exception");
597 <        }
577 >    /**
578 >     * fair locks are strictly FIFO
579 >     */
580 >    public void testFairLocksFifo() {
581 >        final PublicSemaphore s = new PublicSemaphore(1, true);
582 >        final CountDownLatch pleaseRelease = new CountDownLatch(1);
583 >        Thread t1 = newStartedThread(new CheckedRunnable() {
584 >            public void realRun() throws InterruptedException {
585 >                // Will block; permits are available, but not three
586 >                s.acquire(3);
587 >            }});
588 >
589 >        waitForQueuedThreads(s);
590 >
591 >        Thread t2 = newStartedThread(new CheckedRunnable() {
592 >            public void realRun() throws InterruptedException {
593 >                // Will fail, even though 1 permit is available
594 >                assertFalse(s.tryAcquire(0L, MILLISECONDS));
595 >                assertFalse(s.tryAcquire(1, 0L, MILLISECONDS));
596 >
597 >                // untimed tryAcquire will barge and succeed
598 >                assertTrue(s.tryAcquire());
599 >                s.release(2);
600 >                assertTrue(s.tryAcquire(2));
601 >                s.release();
602 >
603 >                pleaseRelease.countDown();
604 >                // Will queue up behind t1, even though 1 permit is available
605 >                s.acquire();
606 >            }});
607 >
608 >        await(pleaseRelease);
609 >        waitForQueuedThread(s, t2);
610 >        s.release(2);
611 >        awaitTermination(t1);
612 >        assertTrue(t2.isAlive());
613 >        s.release();
614 >        awaitTermination(t2);
615 >   }
616 >
617 >    /**
618 >     * toString indicates current number of permits
619 >     */
620 >    public void testToString()      { testToString(false); }
621 >    public void testToString_fair() { testToString(true); }
622 >    public void testToString(boolean fair) {
623 >        PublicSemaphore s = new PublicSemaphore(0, fair);
624 >        assertTrue(s.toString().contains("Permits = 0"));
625 >        s.release();
626 >        assertTrue(s.toString().contains("Permits = 1"));
627 >        s.release(2);
628 >        assertTrue(s.toString().contains("Permits = 3"));
629 >        s.reducePermits(5);
630 >        assertTrue(s.toString().contains("Permits = -2"));
631      }
632  
633   }

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