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Comparing jsr166/src/test/tck/SemaphoreTest.java (file contents):
Revision 1.8 by dl, Sun Dec 28 21:56:18 2003 UTC vs.
Revision 1.43 by jsr166, Tue Jan 23 20:44:11 2018 UTC

# Line 1 | Line 1
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/licenses/publicdomain
5 < * Other contributors include Andrew Wright, Jeffrey Hayes,
6 < * Pat Fisher, Mike Judd.
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.*;
9 > import static java.util.concurrent.TimeUnit.MILLISECONDS;
10 >
11 > import java.util.Collection;
12 > import java.util.concurrent.CountDownLatch;
13 > import java.util.concurrent.Semaphore;
14 > import java.util.concurrent.ThreadLocalRandom;
15 >
16 > import junit.framework.Test;
17 > import junit.framework.TestSuite;
18  
19   public class SemaphoreTest extends JSR166TestCase {
20      public static void main(String[] args) {
21 <        junit.textui.TestRunner.run (suite());  
21 >        main(suite(), args);
22      }
23      public static Test suite() {
24 <        return new TestSuite(SemaphoreTest.class);
24 >        return new TestSuite(SemaphoreTest.class);
25      }
26  
27      /**
28       * Subclass to expose protected methods
29       */
30      static class PublicSemaphore extends Semaphore {
31 <        PublicSemaphore(int p, boolean f) { super(p, f); }
32 <        public Collection<Thread> getQueuedThreads() {
33 <            return super.getQueuedThreads();
31 >        PublicSemaphore(int permits) { super(permits); }
32 >        PublicSemaphore(int permits, boolean fair) { super(permits, fair); }
33 >        public Collection<Thread> getQueuedThreads() {
34 >            return super.getQueuedThreads();
35          }
36 <        public void reducePermits(int p) {
37 <            super.reducePermits(p);
36 >        public boolean hasQueuedThread(Thread t) {
37 >            return super.getQueuedThreads().contains(t);
38 >        }
39 >        public void reducePermits(int reduction) {
40 >            super.reducePermits(reduction);
41          }
42      }
43  
44      /**
45       * A runnable calling acquire
46       */
47 <    class InterruptibleLockRunnable implements Runnable {
47 >    class InterruptibleLockRunnable extends CheckedRunnable {
48          final Semaphore lock;
49 <        InterruptibleLockRunnable(Semaphore l) { lock = l; }
50 <        public void run() {
49 >        InterruptibleLockRunnable(Semaphore s) { lock = s; }
50 >        public void realRun() {
51              try {
52                  lock.acquire();
53 <            } catch(InterruptedException success){}
53 >            }
54 >            catch (InterruptedException ignored) {}
55          }
56      }
57  
48
58      /**
59 <     * A runnable calling acquire that expects to be
51 <     * interrupted
59 >     * A runnable calling acquire that expects to be interrupted
60       */
61 <    class InterruptedLockRunnable implements Runnable {
61 >    class InterruptedLockRunnable extends CheckedInterruptedRunnable {
62          final Semaphore lock;
63 <        InterruptedLockRunnable(Semaphore l) { lock = l; }
64 <        public void run() {
65 <            try {
66 <                lock.acquire();
67 <                threadShouldThrow();
68 <            } catch(InterruptedException success){}
63 >        InterruptedLockRunnable(Semaphore s) { lock = s; }
64 >        public void realRun() throws InterruptedException {
65 >            lock.acquire();
66 >        }
67 >    }
68 >
69 >    /**
70 >     * Spin-waits until s.hasQueuedThread(t) becomes true.
71 >     */
72 >    void waitForQueuedThread(PublicSemaphore s, Thread t) {
73 >        long startTime = System.nanoTime();
74 >        while (!s.hasQueuedThread(t)) {
75 >            if (millisElapsedSince(startTime) > LONG_DELAY_MS)
76 >                throw new AssertionError("timed out");
77 >            Thread.yield();
78 >        }
79 >        assertTrue(s.hasQueuedThreads());
80 >        assertTrue(t.isAlive());
81 >    }
82 >
83 >    /**
84 >     * Spin-waits until s.hasQueuedThreads() becomes true.
85 >     */
86 >    void waitForQueuedThreads(Semaphore s) {
87 >        long startTime = System.nanoTime();
88 >        while (!s.hasQueuedThreads()) {
89 >            if (millisElapsedSince(startTime) > LONG_DELAY_MS)
90 >                throw new AssertionError("timed out");
91 >            Thread.yield();
92 >        }
93 >    }
94 >
95 >    enum AcquireMethod {
96 >        acquire() {
97 >            void acquire(Semaphore s) throws InterruptedException {
98 >                s.acquire();
99 >            }
100 >        },
101 >        acquireN() {
102 >            void acquire(Semaphore s, int permits) throws InterruptedException {
103 >                s.acquire(permits);
104 >            }
105 >        },
106 >        acquireUninterruptibly() {
107 >            void acquire(Semaphore s) {
108 >                s.acquireUninterruptibly();
109 >            }
110 >        },
111 >        acquireUninterruptiblyN() {
112 >            void acquire(Semaphore s, int permits) {
113 >                s.acquireUninterruptibly(permits);
114 >            }
115 >        },
116 >        tryAcquire() {
117 >            void acquire(Semaphore s) {
118 >                assertTrue(s.tryAcquire());
119 >            }
120 >        },
121 >        tryAcquireN() {
122 >            void acquire(Semaphore s, int permits) {
123 >                assertTrue(s.tryAcquire(permits));
124 >            }
125 >        },
126 >        tryAcquireTimed() {
127 >            void acquire(Semaphore s) throws InterruptedException {
128 >                assertTrue(s.tryAcquire(2 * LONG_DELAY_MS, MILLISECONDS));
129 >            }
130 >            Thread.State parkedState() { return Thread.State.TIMED_WAITING; }
131 >        },
132 >        tryAcquireTimedN {
133 >            void acquire(Semaphore s, int permits) throws InterruptedException {
134 >                assertTrue(s.tryAcquire(permits, 2 * LONG_DELAY_MS, MILLISECONDS));
135 >            }
136 >            Thread.State parkedState() { return Thread.State.TIMED_WAITING; }
137 >        };
138 >
139 >        // Intentionally meta-circular
140 >
141 >        /** Acquires 1 permit. */
142 >        void acquire(Semaphore s) throws InterruptedException {
143 >            acquire(s, 1);
144 >        }
145 >        /** Acquires the given number of permits. */
146 >        void acquire(Semaphore s, int permits) throws InterruptedException {
147 >            for (int i = 0; i < permits; i++)
148 >                acquire(s);
149          }
150 +        Thread.State parkedState() { return Thread.State.WAITING; }
151      }
152  
153      /**
154       * Zero, negative, and positive initial values are allowed in constructor
155       */
156 <    public void testConstructor() {
157 <        Semaphore s0 = new Semaphore(0, false);
158 <        assertEquals(0, s0.availablePermits());
159 <        assertFalse(s0.isFair());
160 <        Semaphore s1 = new Semaphore(-1, false);
161 <        assertEquals(-1, s1.availablePermits());
162 <        Semaphore s2 = new Semaphore(-1, false);
163 <        assertEquals(-1, s2.availablePermits());
156 >    public void testConstructor()      { testConstructor(false); }
157 >    public void testConstructor_fair() { testConstructor(true); }
158 >    public void testConstructor(boolean fair) {
159 >        for (int permits : new int[] { -42, -1, 0, 1, 42 }) {
160 >            Semaphore s = new Semaphore(permits, fair);
161 >            assertEquals(permits, s.availablePermits());
162 >            assertEquals(fair, s.isFair());
163 >        }
164 >    }
165 >
166 >    /**
167 >     * Constructor without fairness argument behaves as nonfair
168 >     */
169 >    public void testConstructorDefaultsToNonFair() {
170 >        for (int permits : new int[] { -42, -1, 0, 1, 42 }) {
171 >            Semaphore s = new Semaphore(permits);
172 >            assertEquals(permits, s.availablePermits());
173 >            assertFalse(s.isFair());
174 >        }
175      }
176  
177      /**
178 <     * tryAcquire succeeds when sufficent permits, else fails
178 >     * tryAcquire succeeds when sufficient permits, else fails
179       */
180 <    public void testTryAcquireInSameThread() {
181 <        Semaphore s = new Semaphore(2, false);
180 >    public void testTryAcquireInSameThread()      { testTryAcquireInSameThread(false); }
181 >    public void testTryAcquireInSameThread_fair() { testTryAcquireInSameThread(true); }
182 >    public void testTryAcquireInSameThread(boolean fair) {
183 >        Semaphore s = new Semaphore(2, fair);
184          assertEquals(2, s.availablePermits());
185          assertTrue(s.tryAcquire());
186          assertTrue(s.tryAcquire());
187          assertEquals(0, s.availablePermits());
188          assertFalse(s.tryAcquire());
189 +        assertFalse(s.tryAcquire());
190 +        assertEquals(0, s.availablePermits());
191      }
192  
193      /**
194 <     * Acquire and release of semaphore succeed if initially available
194 >     * timed tryAcquire times out
195       */
196 <    public void testAcquireReleaseInSameThread() {
197 <        Semaphore s = new Semaphore(1, false);
198 <        try {
199 <            s.acquire();
200 <            s.release();
201 <            s.acquire();
202 <            s.release();
203 <            s.acquire();
204 <            s.release();
205 <            s.acquire();
206 <            s.release();
207 <            s.acquire();
208 <            s.release();
209 <            assertEquals(1, s.availablePermits());
210 <        } catch( InterruptedException e){
211 <            unexpectedException();
196 >    public void testTryAcquire_timeout() {
197 >        final boolean fair = ThreadLocalRandom.current().nextBoolean();
198 >        final Semaphore s = new Semaphore(0, fair);
199 >        final long startTime = System.nanoTime();
200 >        try { assertFalse(s.tryAcquire(timeoutMillis(), MILLISECONDS)); }
201 >        catch (InterruptedException e) { threadUnexpectedException(e); }
202 >        assertTrue(millisElapsedSince(startTime) >= timeoutMillis());
203 >    }
204 >
205 >    /**
206 >     * timed tryAcquire(N) times out
207 >     */
208 >    public void testTryAcquireN_timeout() {
209 >        final boolean fair = ThreadLocalRandom.current().nextBoolean();
210 >        final Semaphore s = new Semaphore(2, fair);
211 >        final long startTime = System.nanoTime();
212 >        try { assertFalse(s.tryAcquire(3, timeoutMillis(), MILLISECONDS)); }
213 >        catch (InterruptedException e) { threadUnexpectedException(e); }
214 >        assertTrue(millisElapsedSince(startTime) >= timeoutMillis());
215 >    }
216 >
217 >    /**
218 >     * acquire(), acquire(N), timed tryAcquired, timed tryAcquire(N)
219 >     * are interruptible
220 >     */
221 >    public void testInterruptible_acquire()               { testInterruptible(false, AcquireMethod.acquire); }
222 >    public void testInterruptible_acquire_fair()          { testInterruptible(true,  AcquireMethod.acquire); }
223 >    public void testInterruptible_acquireN()              { testInterruptible(false, AcquireMethod.acquireN); }
224 >    public void testInterruptible_acquireN_fair()         { testInterruptible(true,  AcquireMethod.acquireN); }
225 >    public void testInterruptible_tryAcquireTimed()       { testInterruptible(false, AcquireMethod.tryAcquireTimed); }
226 >    public void testInterruptible_tryAcquireTimed_fair()  { testInterruptible(true,  AcquireMethod.tryAcquireTimed); }
227 >    public void testInterruptible_tryAcquireTimedN()      { testInterruptible(false, AcquireMethod.tryAcquireTimedN); }
228 >    public void testInterruptible_tryAcquireTimedN_fair() { testInterruptible(true,  AcquireMethod.tryAcquireTimedN); }
229 >    public void testInterruptible(boolean fair, final AcquireMethod acquirer) {
230 >        final PublicSemaphore s = new PublicSemaphore(0, fair);
231 >        final java.util.concurrent.CyclicBarrier pleaseInterrupt
232 >            = new java.util.concurrent.CyclicBarrier(2);
233 >        Thread t = newStartedThread(new CheckedRunnable() {
234 >            public void realRun() {
235 >                // Interrupt before acquire
236 >                Thread.currentThread().interrupt();
237 >                try {
238 >                    acquirer.acquire(s);
239 >                    shouldThrow();
240 >                } catch (InterruptedException success) {}
241 >                assertFalse(Thread.interrupted());
242 >
243 >                // Interrupt before acquire(N)
244 >                Thread.currentThread().interrupt();
245 >                try {
246 >                    acquirer.acquire(s, 3);
247 >                    shouldThrow();
248 >                } catch (InterruptedException success) {}
249 >                assertFalse(Thread.interrupted());
250 >
251 >                // Interrupt during acquire
252 >                await(pleaseInterrupt);
253 >                try {
254 >                    acquirer.acquire(s);
255 >                    shouldThrow();
256 >                } catch (InterruptedException success) {}
257 >                assertFalse(Thread.interrupted());
258 >
259 >                // Interrupt during acquire(N)
260 >                await(pleaseInterrupt);
261 >                try {
262 >                    acquirer.acquire(s, 3);
263 >                    shouldThrow();
264 >                } catch (InterruptedException success) {}
265 >                assertFalse(Thread.interrupted());
266 >            }});
267 >
268 >        for (int n = 2; n-->0; ) {
269 >            await(pleaseInterrupt);
270 >            assertThreadBlocks(t, acquirer.parkedState());
271 >            t.interrupt();
272          }
109    }
273  
274 <    /**
112 <     * Uninterruptible acquire and release of semaphore succeed if
113 <     * initially available
114 <     */
115 <    public void testAcquireUninterruptiblyReleaseInSameThread() {
116 <        Semaphore s = new Semaphore(1, false);
117 <        try {
118 <            s.acquireUninterruptibly();
119 <            s.release();
120 <            s.acquireUninterruptibly();
121 <            s.release();
122 <            s.acquireUninterruptibly();
123 <            s.release();
124 <            s.acquireUninterruptibly();
125 <            s.release();
126 <            s.acquireUninterruptibly();
127 <            s.release();
128 <            assertEquals(1, s.availablePermits());
129 <        } finally {
130 <        }
274 >        awaitTermination(t);
275      }
276  
277      /**
278 <     * Timed Acquire and release of semaphore succeed if
279 <     * initially available
278 >     * acquireUninterruptibly(), acquireUninterruptibly(N) are
279 >     * uninterruptible
280       */
281 <    public void testTimedAcquireReleaseInSameThread() {
282 <        Semaphore s = new Semaphore(1, false);
283 <        try {
284 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
285 <            s.release();
286 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
287 <            s.release();
288 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
289 <            s.release();
290 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
291 <            s.release();
292 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
293 <            s.release();
294 <            assertEquals(1, s.availablePermits());
295 <        } catch( InterruptedException e){
296 <            unexpectedException();
297 <        }
281 >    public void testUninterruptible_acquireUninterruptibly()       { testUninterruptible(false, AcquireMethod.acquireUninterruptibly); }
282 >    public void testUninterruptible_acquireUninterruptibly_fair()  { testUninterruptible(true,  AcquireMethod.acquireUninterruptibly); }
283 >    public void testUninterruptible_acquireUninterruptiblyN()      { testUninterruptible(false, AcquireMethod.acquireUninterruptiblyN); }
284 >    public void testUninterruptible_acquireUninterruptiblyN_fair() { testUninterruptible(true,  AcquireMethod.acquireUninterruptiblyN); }
285 >    public void testUninterruptible(boolean fair, final AcquireMethod acquirer) {
286 >        final PublicSemaphore s = new PublicSemaphore(0, fair);
287 >        final Semaphore pleaseInterrupt = new Semaphore(-1, fair);
288 >
289 >        Thread t1 = newStartedThread(new CheckedRunnable() {
290 >            public void realRun() throws InterruptedException {
291 >                // Interrupt before acquire
292 >                pleaseInterrupt.release();
293 >                Thread.currentThread().interrupt();
294 >                acquirer.acquire(s);
295 >                assertTrue(Thread.interrupted());
296 >            }});
297 >
298 >        Thread t2 = newStartedThread(new CheckedRunnable() {
299 >            public void realRun() throws InterruptedException {
300 >                // Interrupt during acquire
301 >                pleaseInterrupt.release();
302 >                acquirer.acquire(s);
303 >                assertTrue(Thread.interrupted());
304 >            }});
305 >
306 >        await(pleaseInterrupt);
307 >        waitForQueuedThread(s, t1);
308 >        waitForQueuedThread(s, t2);
309 >        t2.interrupt();
310 >
311 >        assertThreadBlocks(t1, Thread.State.WAITING);
312 >        assertThreadBlocks(t2, Thread.State.WAITING);
313 >
314 >        s.release(2);
315 >
316 >        awaitTermination(t1);
317 >        awaitTermination(t2);
318      }
319  
320      /**
321 <     * A release in one thread enables an acquire in another thread
321 >     * hasQueuedThreads reports whether there are waiting threads
322       */
323 <    public void testAcquireReleaseInDifferentThreads() {
324 <        final Semaphore s = new Semaphore(0, false);
325 <        Thread t = new Thread(new Runnable() {
326 <                public void run() {
327 <                    try {
328 <                        s.acquire();
329 <                        s.release();
330 <                        s.release();
331 <                        s.acquire();
332 <                    } catch(InterruptedException ie){
333 <                        threadUnexpectedException();
334 <                    }
335 <                }
336 <            });
337 <        try {
338 <            t.start();
339 <            Thread.sleep(SHORT_DELAY_MS);
340 <            s.release();
177 <            s.release();
178 <            s.acquire();
179 <            s.acquire();
180 <            s.release();
181 <            t.join();
182 <        } catch( InterruptedException e){
183 <            unexpectedException();
184 <        }
323 >    public void testHasQueuedThreads()      { testHasQueuedThreads(false); }
324 >    public void testHasQueuedThreads_fair() { testHasQueuedThreads(true); }
325 >    public void testHasQueuedThreads(boolean fair) {
326 >        final PublicSemaphore lock = new PublicSemaphore(1, fair);
327 >        assertFalse(lock.hasQueuedThreads());
328 >        lock.acquireUninterruptibly();
329 >        Thread t1 = newStartedThread(new InterruptedLockRunnable(lock));
330 >        waitForQueuedThread(lock, t1);
331 >        assertTrue(lock.hasQueuedThreads());
332 >        Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock));
333 >        waitForQueuedThread(lock, t2);
334 >        assertTrue(lock.hasQueuedThreads());
335 >        t1.interrupt();
336 >        awaitTermination(t1);
337 >        assertTrue(lock.hasQueuedThreads());
338 >        lock.release();
339 >        awaitTermination(t2);
340 >        assertFalse(lock.hasQueuedThreads());
341      }
342  
343      /**
344 <     * A release in one thread enables an uninterruptible acquire in another thread
344 >     * getQueueLength reports number of waiting threads
345       */
346 <    public void testUninterruptibleAcquireReleaseInDifferentThreads() {
347 <        final Semaphore s = new Semaphore(0, false);
348 <        Thread t = new Thread(new Runnable() {
349 <                public void run() {
350 <                    s.acquireUninterruptibly();
351 <                    s.release();
352 <                    s.release();
353 <                    s.acquireUninterruptibly();
354 <                }
355 <            });
356 <        try {
357 <            t.start();
358 <            Thread.sleep(SHORT_DELAY_MS);
359 <            s.release();
360 <            s.release();
361 <            s.acquireUninterruptibly();
362 <            s.acquireUninterruptibly();
363 <            s.release();
208 <            t.join();
209 <        } catch( InterruptedException e){
210 <            unexpectedException();
211 <        }
346 >    public void testGetQueueLength()      { testGetQueueLength(false); }
347 >    public void testGetQueueLength_fair() { testGetQueueLength(true); }
348 >    public void testGetQueueLength(boolean fair) {
349 >        final PublicSemaphore lock = new PublicSemaphore(1, fair);
350 >        assertEquals(0, lock.getQueueLength());
351 >        lock.acquireUninterruptibly();
352 >        Thread t1 = newStartedThread(new InterruptedLockRunnable(lock));
353 >        waitForQueuedThread(lock, t1);
354 >        assertEquals(1, lock.getQueueLength());
355 >        Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock));
356 >        waitForQueuedThread(lock, t2);
357 >        assertEquals(2, lock.getQueueLength());
358 >        t1.interrupt();
359 >        awaitTermination(t1);
360 >        assertEquals(1, lock.getQueueLength());
361 >        lock.release();
362 >        awaitTermination(t2);
363 >        assertEquals(0, lock.getQueueLength());
364      }
365  
214
366      /**
367 <     *  A release in one thread enables a timed acquire in another thread
367 >     * getQueuedThreads includes waiting threads
368       */
369 <    public void testTimedAcquireReleaseInDifferentThreads() {
370 <        final Semaphore s = new Semaphore(1, false);
371 <        Thread t = new Thread(new Runnable() {
372 <                public void run() {
373 <                    try {
374 <                        s.release();
375 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
376 <                        s.release();
377 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
378 <
379 <                    } catch(InterruptedException ie){
380 <                        threadUnexpectedException();
381 <                    }
382 <                }
383 <            });
384 <        try {
385 <            t.start();
386 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
387 <            s.release();
388 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
389 <            s.release();
239 <            s.release();
240 <            t.join();
241 <        } catch( InterruptedException e){
242 <            unexpectedException();
243 <        }
369 >    public void testGetQueuedThreads()      { testGetQueuedThreads(false); }
370 >    public void testGetQueuedThreads_fair() { testGetQueuedThreads(true); }
371 >    public void testGetQueuedThreads(boolean fair) {
372 >        final PublicSemaphore lock = new PublicSemaphore(1, fair);
373 >        assertTrue(lock.getQueuedThreads().isEmpty());
374 >        lock.acquireUninterruptibly();
375 >        assertTrue(lock.getQueuedThreads().isEmpty());
376 >        Thread t1 = newStartedThread(new InterruptedLockRunnable(lock));
377 >        waitForQueuedThread(lock, t1);
378 >        assertTrue(lock.getQueuedThreads().contains(t1));
379 >        Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock));
380 >        waitForQueuedThread(lock, t2);
381 >        assertTrue(lock.getQueuedThreads().contains(t1));
382 >        assertTrue(lock.getQueuedThreads().contains(t2));
383 >        t1.interrupt();
384 >        awaitTermination(t1);
385 >        assertFalse(lock.getQueuedThreads().contains(t1));
386 >        assertTrue(lock.getQueuedThreads().contains(t2));
387 >        lock.release();
388 >        awaitTermination(t2);
389 >        assertTrue(lock.getQueuedThreads().isEmpty());
390      }
391  
392      /**
393 <     * A waiting acquire blocks interruptibly
394 <     */
395 <    public void testAcquire_InterruptedException() {
396 <        final Semaphore s = new Semaphore(0, false);
397 <        Thread t = new Thread(new Runnable() {
398 <                public void run() {
399 <                    try {
400 <                        s.acquire();
401 <                        threadShouldThrow();
402 <                    } catch(InterruptedException success){}
403 <                }
404 <            });
405 <        t.start();
260 <        try {
261 <            Thread.sleep(SHORT_DELAY_MS);
262 <            t.interrupt();
263 <            t.join();
264 <        } catch(InterruptedException e){
265 <            unexpectedException();
266 <        }
267 <    }
268 <    
269 <    /**
270 <     *  A waiting timed acquire blocks interruptibly
271 <     */
272 <    public void testTryAcquire_InterruptedException() {
273 <        final Semaphore s = new Semaphore(0, false);
274 <        Thread t = new Thread(new Runnable() {
275 <                public void run() {
276 <                    try {
277 <                        s.tryAcquire(MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS);
278 <                        threadShouldThrow();
279 <                    } catch(InterruptedException success){
280 <                    }
281 <                }
282 <            });
283 <        t.start();
284 <        try {
285 <            Thread.sleep(SHORT_DELAY_MS);
286 <            t.interrupt();
287 <            t.join();
288 <        } catch(InterruptedException e){
289 <            unexpectedException();
290 <        }
393 >     * drainPermits reports and removes given number of permits
394 >     */
395 >    public void testDrainPermits()      { testDrainPermits(false); }
396 >    public void testDrainPermits_fair() { testDrainPermits(true); }
397 >    public void testDrainPermits(boolean fair) {
398 >        Semaphore s = new Semaphore(0, fair);
399 >        assertEquals(0, s.availablePermits());
400 >        assertEquals(0, s.drainPermits());
401 >        s.release(10);
402 >        assertEquals(10, s.availablePermits());
403 >        assertEquals(10, s.drainPermits());
404 >        assertEquals(0, s.availablePermits());
405 >        assertEquals(0, s.drainPermits());
406      }
407  
408      /**
409 <     * hasQueuedThreads reports whether there are waiting threads
295 <     */
296 <    public void testHasQueuedThreads() {
297 <        final Semaphore lock = new Semaphore(1, false);
298 <        Thread t1 = new Thread(new InterruptedLockRunnable(lock));
299 <        Thread t2 = new Thread(new InterruptibleLockRunnable(lock));
300 <        try {
301 <            assertFalse(lock.hasQueuedThreads());
302 <            lock.acquireUninterruptibly();
303 <            t1.start();
304 <            Thread.sleep(SHORT_DELAY_MS);
305 <            assertTrue(lock.hasQueuedThreads());
306 <            t2.start();
307 <            Thread.sleep(SHORT_DELAY_MS);
308 <            assertTrue(lock.hasQueuedThreads());
309 <            t1.interrupt();
310 <            Thread.sleep(SHORT_DELAY_MS);
311 <            assertTrue(lock.hasQueuedThreads());
312 <            lock.release();
313 <            Thread.sleep(SHORT_DELAY_MS);
314 <            assertFalse(lock.hasQueuedThreads());
315 <            t1.join();
316 <            t2.join();
317 <        } catch(Exception e){
318 <            unexpectedException();
319 <        }
320 <    }
321 <
322 <    /**
323 <     * getQueueLength reports number of waiting threads
409 >     * release(-N) throws IllegalArgumentException
410       */
411 <    public void testGetQueueLength() {
412 <        final Semaphore lock = new Semaphore(1, false);
413 <        Thread t1 = new Thread(new InterruptedLockRunnable(lock));
414 <        Thread t2 = new Thread(new InterruptibleLockRunnable(lock));
411 >    public void testReleaseIAE()      { testReleaseIAE(false); }
412 >    public void testReleaseIAE_fair() { testReleaseIAE(true); }
413 >    public void testReleaseIAE(boolean fair) {
414 >        Semaphore s = new Semaphore(10, fair);
415          try {
416 <            assertEquals(0, lock.getQueueLength());
417 <            lock.acquireUninterruptibly();
418 <            t1.start();
419 <            Thread.sleep(SHORT_DELAY_MS);
334 <            assertEquals(1, lock.getQueueLength());
335 <            t2.start();
336 <            Thread.sleep(SHORT_DELAY_MS);
337 <            assertEquals(2, lock.getQueueLength());
338 <            t1.interrupt();
339 <            Thread.sleep(SHORT_DELAY_MS);
340 <            assertEquals(1, lock.getQueueLength());
341 <            lock.release();
342 <            Thread.sleep(SHORT_DELAY_MS);
343 <            assertEquals(0, lock.getQueueLength());
344 <            t1.join();
345 <            t2.join();
346 <        } catch(Exception e){
347 <            unexpectedException();
348 <        }
349 <    }
416 >            s.release(-1);
417 >            shouldThrow();
418 >        } catch (IllegalArgumentException success) {}
419 >    }
420  
421      /**
422 <     * getQueuedThreads includes waiting threads
422 >     * reducePermits(-N) throws IllegalArgumentException
423       */
424 <    public void testGetQueuedThreads() {
425 <        final PublicSemaphore lock = new PublicSemaphore(1, false);
426 <        Thread t1 = new Thread(new InterruptedLockRunnable(lock));
427 <        Thread t2 = new Thread(new InterruptibleLockRunnable(lock));
424 >    public void testReducePermitsIAE()      { testReducePermitsIAE(false); }
425 >    public void testReducePermitsIAE_fair() { testReducePermitsIAE(true); }
426 >    public void testReducePermitsIAE(boolean fair) {
427 >        PublicSemaphore s = new PublicSemaphore(10, fair);
428          try {
429 <            assertTrue(lock.getQueuedThreads().isEmpty());
430 <            lock.acquireUninterruptibly();
431 <            assertTrue(lock.getQueuedThreads().isEmpty());
432 <            t1.start();
363 <            Thread.sleep(SHORT_DELAY_MS);
364 <            assertTrue(lock.getQueuedThreads().contains(t1));
365 <            t2.start();
366 <            Thread.sleep(SHORT_DELAY_MS);
367 <            assertTrue(lock.getQueuedThreads().contains(t1));
368 <            assertTrue(lock.getQueuedThreads().contains(t2));
369 <            t1.interrupt();
370 <            Thread.sleep(SHORT_DELAY_MS);
371 <            assertFalse(lock.getQueuedThreads().contains(t1));
372 <            assertTrue(lock.getQueuedThreads().contains(t2));
373 <            lock.release();
374 <            Thread.sleep(SHORT_DELAY_MS);
375 <            assertTrue(lock.getQueuedThreads().isEmpty());
376 <            t1.join();
377 <            t2.join();
378 <        } catch(Exception e){
379 <            unexpectedException();
380 <        }
381 <    }
382 <
429 >            s.reducePermits(-1);
430 >            shouldThrow();
431 >        } catch (IllegalArgumentException success) {}
432 >    }
433  
434      /**
435       * reducePermits reduces number of permits
436       */
437 <    public void testReducePermits() {
438 <        PublicSemaphore s = new PublicSemaphore(10, false);
437 >    public void testReducePermits()      { testReducePermits(false); }
438 >    public void testReducePermits_fair() { testReducePermits(true); }
439 >    public void testReducePermits(boolean fair) {
440 >        PublicSemaphore s = new PublicSemaphore(10, fair);
441 >        assertEquals(10, s.availablePermits());
442 >        s.reducePermits(0);
443          assertEquals(10, s.availablePermits());
444          s.reducePermits(1);
445          assertEquals(9, s.availablePermits());
446          s.reducePermits(10);
447          assertEquals(-1, s.availablePermits());
448 +        s.reducePermits(10);
449 +        assertEquals(-11, s.availablePermits());
450 +        s.reducePermits(0);
451 +        assertEquals(-11, s.availablePermits());
452      }
453  
454      /**
455 <     * a deserialized serialized semaphore has same number of permits
456 <     */
399 <    public void testSerialization() {
400 <        Semaphore l = new Semaphore(3, false);
401 <        try {
402 <            l.acquire();
403 <            l.release();
404 <            ByteArrayOutputStream bout = new ByteArrayOutputStream(10000);
405 <            ObjectOutputStream out = new ObjectOutputStream(new BufferedOutputStream(bout));
406 <            out.writeObject(l);
407 <            out.close();
408 <
409 <            ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());
410 <            ObjectInputStream in = new ObjectInputStream(new BufferedInputStream(bin));
411 <            Semaphore r = (Semaphore) in.readObject();
412 <            assertEquals(3, r.availablePermits());
413 <            assertFalse(r.isFair());
414 <            r.acquire();
415 <            r.release();
416 <        } catch(Exception e){
417 <            unexpectedException();
418 <        }
419 <    }
420 <
421 <
422 <    /**
423 <     * Zero, negative, and positive initial values are allowed in constructor
424 <     */
425 <    public void testConstructor_fair() {
426 <        Semaphore s0 = new Semaphore(0, true);
427 <        assertEquals(0, s0.availablePermits());
428 <        assertTrue(s0.isFair());
429 <        Semaphore s1 = new Semaphore(-1, true);
430 <        assertEquals(-1, s1.availablePermits());
431 <        Semaphore s2 = new Semaphore(-1, true);
432 <        assertEquals(-1, s2.availablePermits());
433 <    }
434 <
435 <    /**
436 <     * tryAcquire succeeds when sufficent permits, else fails
437 <     */
438 <    public void testTryAcquireInSameThread_fair() {
439 <        Semaphore s = new Semaphore(2, true);
440 <        assertEquals(2, s.availablePermits());
441 <        assertTrue(s.tryAcquire());
442 <        assertTrue(s.tryAcquire());
443 <        assertEquals(0, s.availablePermits());
444 <        assertFalse(s.tryAcquire());
445 <    }
446 <
447 <    /**
448 <     * tryAcquire(n) succeeds when sufficent permits, else fails
449 <     */
450 <    public void testTryAcquireNInSameThread_fair() {
451 <        Semaphore s = new Semaphore(2, true);
452 <        assertEquals(2, s.availablePermits());
453 <        assertTrue(s.tryAcquire(2));
454 <        assertEquals(0, s.availablePermits());
455 <        assertFalse(s.tryAcquire());
456 <    }
457 <
458 <    /**
459 <     * Acquire and release of semaphore succeed if initially available
455 >     * a reserialized semaphore has same number of permits and
456 >     * fairness, but no queued threads
457       */
458 <    public void testAcquireReleaseInSameThread_fair() {
459 <        Semaphore s = new Semaphore(1, true);
458 >    public void testSerialization()      { testSerialization(false); }
459 >    public void testSerialization_fair() { testSerialization(true); }
460 >    public void testSerialization(boolean fair) {
461          try {
462 +            Semaphore s = new Semaphore(3, fair);
463              s.acquire();
465            s.release();
464              s.acquire();
465              s.release();
468            s.acquire();
469            s.release();
470            s.acquire();
471            s.release();
472            s.acquire();
473            s.release();
474            assertEquals(1, s.availablePermits());
475        } catch( InterruptedException e){
476            unexpectedException();
477        }
478    }
479
480    /**
481     * Acquire(n) and release(n) of semaphore succeed if initially available
482     */
483    public void testAcquireReleaseNInSameThread_fair() {
484        Semaphore s = new Semaphore(1, true);
485        try {
486            s.release(1);
487            s.acquire(1);
488            s.release(2);
489            s.acquire(2);
490            s.release(3);
491            s.acquire(3);
492            s.release(4);
493            s.acquire(4);
494            s.release(5);
495            s.acquire(5);
496            assertEquals(1, s.availablePermits());
497        } catch( InterruptedException e){
498            unexpectedException();
499        }
500    }
466  
467 <    /**
468 <     * Acquire(n) and release(n) of semaphore succeed if initially available
469 <     */
470 <    public void testAcquireUninterruptiblyReleaseNInSameThread_fair() {
471 <        Semaphore s = new Semaphore(1, true);
472 <        try {
473 <            s.release(1);
474 <            s.acquireUninterruptibly(1);
475 <            s.release(2);
476 <            s.acquireUninterruptibly(2);
477 <            s.release(3);
478 <            s.acquireUninterruptibly(3);
479 <            s.release(4);
480 <            s.acquireUninterruptibly(4);
481 <            s.release(5);
482 <            s.acquireUninterruptibly(5);
483 <            assertEquals(1, s.availablePermits());
484 <        } finally {
467 >            Semaphore clone = serialClone(s);
468 >            assertEquals(fair, s.isFair());
469 >            assertEquals(fair, clone.isFair());
470 >            assertEquals(2, s.availablePermits());
471 >            assertEquals(2, clone.availablePermits());
472 >            clone.acquire();
473 >            clone.acquire();
474 >            clone.release();
475 >            assertEquals(2, s.availablePermits());
476 >            assertEquals(1, clone.availablePermits());
477 >            assertFalse(s.hasQueuedThreads());
478 >            assertFalse(clone.hasQueuedThreads());
479 >        } catch (InterruptedException e) { threadUnexpectedException(e); }
480 >
481 >        {
482 >            PublicSemaphore s = new PublicSemaphore(0, fair);
483 >            Thread t = newStartedThread(new InterruptibleLockRunnable(s));
484 >            // waitForQueuedThreads(s); // suffers from "flicker", so ...
485 >            waitForQueuedThread(s, t);  // ... we use this instead
486 >            PublicSemaphore clone = serialClone(s);
487 >            assertEquals(fair, s.isFair());
488 >            assertEquals(fair, clone.isFair());
489 >            assertEquals(0, s.availablePermits());
490 >            assertEquals(0, clone.availablePermits());
491 >            assertTrue(s.hasQueuedThreads());
492 >            assertFalse(clone.hasQueuedThreads());
493 >            s.release();
494 >            awaitTermination(t);
495 >            assertFalse(s.hasQueuedThreads());
496 >            assertFalse(clone.hasQueuedThreads());
497          }
498      }
499  
500      /**
501 <     * release(n) in one thread enables timed acquire(n) in another thread
502 <     */
503 <    public void testTimedAcquireReleaseNInSameThread_fair() {
504 <        Semaphore s = new Semaphore(1, true);
505 <        try {
506 <            s.release(1);
507 <            assertTrue(s.tryAcquire(1, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
508 <            s.release(2);
509 <            assertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
510 <            s.release(3);
511 <            assertTrue(s.tryAcquire(3, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
512 <            s.release(4);
513 <            assertTrue(s.tryAcquire(4, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
514 <            s.release(5);
538 <            assertTrue(s.tryAcquire(5, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
539 <            assertEquals(1, s.availablePermits());
540 <        } catch( InterruptedException e){
541 <            unexpectedException();
542 <        }
501 >     * tryAcquire(n) succeeds when sufficient permits, else fails
502 >     */
503 >    public void testTryAcquireNInSameThread()      { testTryAcquireNInSameThread(false); }
504 >    public void testTryAcquireNInSameThread_fair() { testTryAcquireNInSameThread(true); }
505 >    public void testTryAcquireNInSameThread(boolean fair) {
506 >        Semaphore s = new Semaphore(2, fair);
507 >        assertEquals(2, s.availablePermits());
508 >        assertFalse(s.tryAcquire(3));
509 >        assertEquals(2, s.availablePermits());
510 >        assertTrue(s.tryAcquire(2));
511 >        assertEquals(0, s.availablePermits());
512 >        assertFalse(s.tryAcquire(1));
513 >        assertFalse(s.tryAcquire(2));
514 >        assertEquals(0, s.availablePermits());
515      }
516  
517      /**
518 <     * release in one thread enables timed acquire in another thread
518 >     * acquire succeeds if permits available
519       */
520 <    public void testTimedAcquireReleaseInSameThread_fair() {
521 <        Semaphore s = new Semaphore(1, true);
522 <        try {
523 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
524 <            s.release();
525 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
526 <            s.release();
527 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
528 <            s.release();
529 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
530 <            s.release();
531 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
532 <            s.release();
520 >    public void testReleaseAcquireSameThread_acquire()       { testReleaseAcquireSameThread(false, AcquireMethod.acquire); }
521 >    public void testReleaseAcquireSameThread_acquire_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.acquire); }
522 >    public void testReleaseAcquireSameThread_acquireN()      { testReleaseAcquireSameThread(false, AcquireMethod.acquireN); }
523 >    public void testReleaseAcquireSameThread_acquireN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.acquireN); }
524 >    public void testReleaseAcquireSameThread_acquireUninterruptibly()       { testReleaseAcquireSameThread(false, AcquireMethod.acquireUninterruptibly); }
525 >    public void testReleaseAcquireSameThread_acquireUninterruptibly_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.acquireUninterruptibly); }
526 >    public void testReleaseAcquireSameThread_acquireUninterruptiblyN()      { testReleaseAcquireSameThread(false, AcquireMethod.acquireUninterruptibly); }
527 >    public void testReleaseAcquireSameThread_acquireUninterruptiblyN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.acquireUninterruptibly); }
528 >    public void testReleaseAcquireSameThread_tryAcquire()       { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquire); }
529 >    public void testReleaseAcquireSameThread_tryAcquire_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquire); }
530 >    public void testReleaseAcquireSameThread_tryAcquireN()      { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireN); }
531 >    public void testReleaseAcquireSameThread_tryAcquireN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireN); }
532 >    public void testReleaseAcquireSameThread_tryAcquireTimed()       { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireTimed); }
533 >    public void testReleaseAcquireSameThread_tryAcquireTimed_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireTimed); }
534 >    public void testReleaseAcquireSameThread_tryAcquireTimedN()      { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireTimedN); }
535 >    public void testReleaseAcquireSameThread_tryAcquireTimedN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireTimedN); }
536 >    public void testReleaseAcquireSameThread(boolean fair,
537 >                                             final AcquireMethod acquirer) {
538 >        Semaphore s = new Semaphore(1, fair);
539 >        for (int i = 1; i < 6; i++) {
540 >            s.release(i);
541 >            assertEquals(1 + i, s.availablePermits());
542 >            try {
543 >                acquirer.acquire(s, i);
544 >            } catch (InterruptedException e) { threadUnexpectedException(e); }
545              assertEquals(1, s.availablePermits());
562        } catch( InterruptedException e){
563            unexpectedException();
546          }
547      }
548  
549      /**
550 <     * A release in one thread enables an acquire in another thread
550 >     * release in one thread enables acquire in another thread
551       */
552 <    public void testAcquireReleaseInDifferentThreads_fair() {
553 <        final Semaphore s = new Semaphore(0, true);
554 <        Thread t = new Thread(new Runnable() {
555 <                public void run() {
556 <                    try {
557 <                        s.acquire();
558 <                        s.acquire();
559 <                        s.acquire();
560 <                        s.acquire();
561 <                    } catch(InterruptedException ie){
562 <                        threadUnexpectedException();
563 <                    }
564 <                }
565 <            });
566 <        try {
567 <            t.start();
568 <            Thread.sleep(SHORT_DELAY_MS);
569 <            s.release();
570 <            s.release();
571 <            s.release();
572 <            s.release();
573 <            s.release();
574 <            s.release();
575 <            t.join();
576 <            assertEquals(2, s.availablePermits());
577 <        } catch( InterruptedException e){
578 <            unexpectedException();
552 >    public void testReleaseAcquireDifferentThreads_acquire()       { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquire); }
553 >    public void testReleaseAcquireDifferentThreads_acquire_fair()  { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquire); }
554 >    public void testReleaseAcquireDifferentThreads_acquireN()      { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireN); }
555 >    public void testReleaseAcquireDifferentThreads_acquireN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireN); }
556 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptibly()       { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireUninterruptibly); }
557 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptibly_fair()  { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireUninterruptibly); }
558 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptiblyN()      { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireUninterruptibly); }
559 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptiblyN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireUninterruptibly); }
560 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimed()       { testReleaseAcquireDifferentThreads(false, AcquireMethod.tryAcquireTimed); }
561 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimed_fair()  { testReleaseAcquireDifferentThreads(true, AcquireMethod.tryAcquireTimed); }
562 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimedN()      { testReleaseAcquireDifferentThreads(false, AcquireMethod.tryAcquireTimedN); }
563 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimedN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.tryAcquireTimedN); }
564 >    public void testReleaseAcquireDifferentThreads(boolean fair,
565 >                                                   final AcquireMethod acquirer) {
566 >        final Semaphore s = new Semaphore(0, fair);
567 >        final int rounds = 4;
568 >        long startTime = System.nanoTime();
569 >        Thread t = newStartedThread(new CheckedRunnable() {
570 >            public void realRun() throws InterruptedException {
571 >                for (int i = 0; i < rounds; i++) {
572 >                    assertFalse(s.hasQueuedThreads());
573 >                    if (i % 2 == 0)
574 >                        acquirer.acquire(s);
575 >                    else
576 >                        acquirer.acquire(s, 3);
577 >                }}});
578 >
579 >        for (int i = 0; i < rounds; i++) {
580 >            while (! (s.availablePermits() == 0 && s.hasQueuedThreads()))
581 >                Thread.yield();
582 >            assertTrue(t.isAlive());
583 >            if (i % 2 == 0)
584 >                s.release();
585 >            else
586 >                s.release(3);
587          }
588 +        awaitTermination(t);
589 +        assertEquals(0, s.availablePermits());
590 +        assertTrue(millisElapsedSince(startTime) < LONG_DELAY_MS);
591      }
592  
593      /**
594 <     * release(n) in one thread enables acquire(n) in another thread
594 >     * fair locks are strictly FIFO
595       */
596 <    public void testAcquireReleaseNInDifferentThreads_fair() {
597 <        final Semaphore s = new Semaphore(0, true);
598 <        Thread t = new Thread(new Runnable() {
599 <                public void run() {
600 <                    try {
601 <                        s.acquire(2);
602 <                        s.acquire(2);
603 <                        s.release(4);
604 <                    } catch(InterruptedException ie){
605 <                        threadUnexpectedException();
606 <                    }
607 <                }
608 <            });
609 <        try {
610 <            t.start();
611 <            Thread.sleep(SHORT_DELAY_MS);
612 <            s.release(6);
613 <            s.acquire(2);
614 <            s.acquire(2);
615 <            s.release(2);
616 <            t.join();
617 <        } catch( InterruptedException e){
618 <            unexpectedException();
619 <        }
620 <    }
621 <
622 <
623 <
624 <    /**
625 <     * release in one thread enables timed acquire in another thread
626 <     */
627 <    public void testTimedAcquireReleaseInDifferentThreads_fair() {
628 <        final Semaphore s = new Semaphore(1, true);
629 <        Thread t = new Thread(new Runnable() {
630 <                public void run() {
631 <                    try {
632 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
640 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
641 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
642 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
643 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
644 <
645 <                    } catch(InterruptedException ie){
646 <                        threadUnexpectedException();
647 <                    }
648 <                }
649 <            });
650 <        t.start();
651 <        try {
652 <            s.release();
653 <            s.release();
654 <            s.release();
655 <            s.release();
656 <            s.release();
657 <            t.join();
658 <        } catch( InterruptedException e){
659 <            unexpectedException();
660 <        }
661 <    }
662 <
663 <    /**
664 <     * release(n) in one thread enables timed acquire(n) in another thread
665 <     */
666 <    public void testTimedAcquireReleaseNInDifferentThreads_fair() {
667 <        final Semaphore s = new Semaphore(2, true);
668 <        Thread t = new Thread(new Runnable() {
669 <                public void run() {
670 <                    try {
671 <                        threadAssertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
672 <                        s.release(2);
673 <                        threadAssertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
674 <                        s.release(2);
675 <                    } catch(InterruptedException ie){
676 <                        threadUnexpectedException();
677 <                    }
678 <                }
679 <            });
680 <        t.start();
681 <        try {
682 <            assertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
683 <            s.release(2);
684 <            assertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
685 <            s.release(2);
686 <            t.join();
687 <        } catch( InterruptedException e){
688 <            unexpectedException();
689 <        }
690 <    }
691 <
692 <    /**
693 <     * A waiting acquire blocks interruptibly
694 <     */
695 <    public void testAcquire_InterruptedException_fair() {
696 <        final Semaphore s = new Semaphore(0, true);
697 <        Thread t = new Thread(new Runnable() {
698 <                public void run() {
699 <                    try {
700 <                        s.acquire();
701 <                        threadShouldThrow();
702 <                    } catch(InterruptedException success){}
703 <                }
704 <            });
705 <        t.start();
706 <        try {
707 <            Thread.sleep(SHORT_DELAY_MS);
708 <            t.interrupt();
709 <            t.join();
710 <        } catch(InterruptedException e){
711 <            unexpectedException();
712 <        }
713 <    }
714 <
715 <    /**
716 <     * A waiting acquire(n) blocks interruptibly
717 <     */
718 <    public void testAcquireN_InterruptedException_fair() {
719 <        final Semaphore s = new Semaphore(2, true);
720 <        Thread t = new Thread(new Runnable() {
721 <                public void run() {
722 <                    try {
723 <                        s.acquire(3);
724 <                        threadShouldThrow();
725 <                    } catch(InterruptedException success){}
726 <                }
727 <            });
728 <        t.start();
729 <        try {
730 <            Thread.sleep(SHORT_DELAY_MS);
731 <            t.interrupt();
732 <            t.join();
733 <        } catch(InterruptedException e){
734 <            unexpectedException();
735 <        }
736 <    }
737 <    
738 <    /**
739 <     *  A waiting tryAcquire blocks interruptibly
740 <     */
741 <    public void testTryAcquire_InterruptedException_fair() {
742 <        final Semaphore s = new Semaphore(0, true);
743 <        Thread t = new Thread(new Runnable() {
744 <                public void run() {
745 <                    try {
746 <                        s.tryAcquire(MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS);
747 <                        threadShouldThrow();
748 <                    } catch(InterruptedException success){
749 <                    }
750 <                }
751 <            });
752 <        t.start();
753 <        try {
754 <            Thread.sleep(SHORT_DELAY_MS);
755 <            t.interrupt();
756 <            t.join();
757 <        } catch(InterruptedException e){
758 <            unexpectedException();
759 <        }
596 >    public void testFairLocksFifo() {
597 >        final PublicSemaphore s = new PublicSemaphore(1, true);
598 >        final CountDownLatch pleaseRelease = new CountDownLatch(1);
599 >        Thread t1 = newStartedThread(new CheckedRunnable() {
600 >            public void realRun() throws InterruptedException {
601 >                // Will block; permits are available, but not three
602 >                s.acquire(3);
603 >            }});
604 >
605 >        waitForQueuedThread(s, t1);
606 >
607 >        Thread t2 = newStartedThread(new CheckedRunnable() {
608 >            public void realRun() throws InterruptedException {
609 >                // Will fail, even though 1 permit is available
610 >                assertFalse(
611 >                    s.tryAcquire(randomExpiredTimeout(), randomTimeUnit()));
612 >                assertFalse(
613 >                    s.tryAcquire(1, randomExpiredTimeout(), randomTimeUnit()));
614 >
615 >                // untimed tryAcquire will barge and succeed
616 >                assertTrue(s.tryAcquire());
617 >                s.release(2);
618 >                assertTrue(s.tryAcquire(2));
619 >                s.release();
620 >
621 >                pleaseRelease.countDown();
622 >                // Will queue up behind t1, even though 1 permit is available
623 >                s.acquire();
624 >            }});
625 >
626 >        await(pleaseRelease);
627 >        waitForQueuedThread(s, t2);
628 >        s.release(2);
629 >        awaitTermination(t1);
630 >        assertTrue(t2.isAlive());
631 >        s.release();
632 >        awaitTermination(t2);
633      }
634  
635      /**
636 <     *  A waiting tryAcquire(n) blocks interruptibly
637 <     */
638 <    public void testTryAcquireN_InterruptedException_fair() {
639 <        final Semaphore s = new Semaphore(1, true);
640 <        Thread t = new Thread(new Runnable() {
641 <                public void run() {
642 <                    try {
643 <                        s.tryAcquire(4, MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS);
644 <                        threadShouldThrow();
645 <                    } catch(InterruptedException success){
646 <                    }
647 <                }
648 <            });
776 <        t.start();
777 <        try {
778 <            Thread.sleep(SHORT_DELAY_MS);
779 <            t.interrupt();
780 <            t.join();
781 <        } catch(InterruptedException e){
782 <            unexpectedException();
783 <        }
636 >     * toString indicates current number of permits
637 >     */
638 >    public void testToString()      { testToString(false); }
639 >    public void testToString_fair() { testToString(true); }
640 >    public void testToString(boolean fair) {
641 >        PublicSemaphore s = new PublicSemaphore(0, fair);
642 >        assertTrue(s.toString().contains("Permits = 0"));
643 >        s.release();
644 >        assertTrue(s.toString().contains("Permits = 1"));
645 >        s.release(2);
646 >        assertTrue(s.toString().contains("Permits = 3"));
647 >        s.reducePermits(5);
648 >        assertTrue(s.toString().contains("Permits = -2"));
649      }
650  
786    /**
787     * getQueueLength reports number of waiting threads
788     */
789    public void testGetQueueLength_fair() {
790        final Semaphore lock = new Semaphore(1, true);
791        Thread t1 = new Thread(new InterruptedLockRunnable(lock));
792        Thread t2 = new Thread(new InterruptibleLockRunnable(lock));
793        try {
794            assertEquals(0, lock.getQueueLength());
795            lock.acquireUninterruptibly();
796            t1.start();
797            Thread.sleep(SHORT_DELAY_MS);
798            assertEquals(1, lock.getQueueLength());
799            t2.start();
800            Thread.sleep(SHORT_DELAY_MS);
801            assertEquals(2, lock.getQueueLength());
802            t1.interrupt();
803            Thread.sleep(SHORT_DELAY_MS);
804            assertEquals(1, lock.getQueueLength());
805            lock.release();
806            Thread.sleep(SHORT_DELAY_MS);
807            assertEquals(0, lock.getQueueLength());
808            t1.join();
809            t2.join();
810        } catch(Exception e){
811            unexpectedException();
812        }
813    }
814
815
816    /**
817     * a deserialized serialized semaphore has same number of permits
818     */
819    public void testSerialization_fair() {
820        Semaphore l = new Semaphore(3, true);
821
822        try {
823            l.acquire();
824            l.release();
825            ByteArrayOutputStream bout = new ByteArrayOutputStream(10000);
826            ObjectOutputStream out = new ObjectOutputStream(new BufferedOutputStream(bout));
827            out.writeObject(l);
828            out.close();
829
830            ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());
831            ObjectInputStream in = new ObjectInputStream(new BufferedInputStream(bin));
832            Semaphore r = (Semaphore) in.readObject();
833            assertEquals(3, r.availablePermits());
834            assertTrue(r.isFair());
835            r.acquire();
836            r.release();
837        } catch(Exception e){
838            unexpectedException();
839        }
840    }
841
842
651   }

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