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Comparing jsr166/src/test/tck/SemaphoreTest.java (file contents):
Revision 1.9 by dl, Mon Dec 29 19:05:40 2003 UTC vs.
Revision 1.36 by jsr166, Thu Nov 19 03:35:48 2015 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 >
15 > import junit.framework.AssertionFailedError;
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 boolean hasQueuedThread(Thread t) {
37 >            return super.getQueuedThreads().contains(t);
38          }
39 <        public void reducePermits(int p) {
40 <            super.reducePermits(p);
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 AssertionFailedError("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 AssertionFailedError("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 >        },
131 >        tryAcquireTimedN {
132 >            void acquire(Semaphore s, int permits) throws InterruptedException {
133 >                assertTrue(s.tryAcquire(permits, 2 * LONG_DELAY_MS, MILLISECONDS));
134 >            }
135 >        };
136 >
137 >        // Intentionally meta-circular
138 >
139 >        /** Acquires 1 permit. */
140 >        void acquire(Semaphore s) throws InterruptedException {
141 >            acquire(s, 1);
142 >        }
143 >        /** Acquires the given number of permits. */
144 >        void acquire(Semaphore s, int permits) throws InterruptedException {
145 >            for (int i = 0; i < permits; i++)
146 >                acquire(s);
147          }
148      }
149  
150      /**
151       * Zero, negative, and positive initial values are allowed in constructor
152       */
153 <    public void testConstructor() {
154 <        Semaphore s0 = new Semaphore(0, false);
155 <        assertEquals(0, s0.availablePermits());
156 <        assertFalse(s0.isFair());
157 <        Semaphore s1 = new Semaphore(-1, false);
158 <        assertEquals(-1, s1.availablePermits());
159 <        Semaphore s2 = new Semaphore(-1, false);
160 <        assertEquals(-1, s2.availablePermits());
153 >    public void testConstructor()      { testConstructor(false); }
154 >    public void testConstructor_fair() { testConstructor(true); }
155 >    public void testConstructor(boolean fair) {
156 >        for (int permits : new int[] { -42, -1, 0, 1, 42 }) {
157 >            Semaphore s = new Semaphore(permits, fair);
158 >            assertEquals(permits, s.availablePermits());
159 >            assertEquals(fair, s.isFair());
160 >        }
161 >    }
162 >
163 >    /**
164 >     * Constructor without fairness argument behaves as nonfair
165 >     */
166 >    public void testConstructorDefaultsToNonFair() {
167 >        for (int permits : new int[] { -42, -1, 0, 1, 42 }) {
168 >            Semaphore s = new Semaphore(permits);
169 >            assertEquals(permits, s.availablePermits());
170 >            assertFalse(s.isFair());
171 >        }
172      }
173  
174      /**
175       * tryAcquire succeeds when sufficient permits, else fails
176       */
177 <    public void testTryAcquireInSameThread() {
178 <        Semaphore s = new Semaphore(2, false);
177 >    public void testTryAcquireInSameThread()      { testTryAcquireInSameThread(false); }
178 >    public void testTryAcquireInSameThread_fair() { testTryAcquireInSameThread(true); }
179 >    public void testTryAcquireInSameThread(boolean fair) {
180 >        Semaphore s = new Semaphore(2, fair);
181          assertEquals(2, s.availablePermits());
182          assertTrue(s.tryAcquire());
183          assertTrue(s.tryAcquire());
184          assertEquals(0, s.availablePermits());
185          assertFalse(s.tryAcquire());
186 +        assertFalse(s.tryAcquire());
187 +        assertEquals(0, s.availablePermits());
188      }
189  
190      /**
191 <     * Acquire and release of semaphore succeed if initially available
191 >     * timed tryAcquire times out
192       */
193 <    public void testAcquireReleaseInSameThread() {
194 <        Semaphore s = new Semaphore(1, false);
195 <        try {
196 <            s.acquire();
197 <            s.release();
198 <            s.acquire();
199 <            s.release();
200 <            s.acquire();
201 <            s.release();
202 <            s.acquire();
203 <            s.release();
204 <            s.acquire();
205 <            s.release();
206 <            assertEquals(1, s.availablePermits());
207 <        } catch( InterruptedException e){
208 <            unexpectedException();
209 <        }
210 <    }
193 >    public void testTryAcquire_timeout()      { testTryAcquire_timeout(false); }
194 >    public void testTryAcquire_timeout_fair() { testTryAcquire_timeout(true); }
195 >    public void testTryAcquire_timeout(boolean fair) {
196 >        Semaphore s = new Semaphore(0, fair);
197 >        long startTime = System.nanoTime();
198 >        try { assertFalse(s.tryAcquire(timeoutMillis(), MILLISECONDS)); }
199 >        catch (InterruptedException e) { threadUnexpectedException(e); }
200 >        assertTrue(millisElapsedSince(startTime) >= timeoutMillis());
201 >    }
202 >
203 >    /**
204 >     * timed tryAcquire(N) times out
205 >     */
206 >    public void testTryAcquireN_timeout()      { testTryAcquireN_timeout(false); }
207 >    public void testTryAcquireN_timeout_fair() { testTryAcquireN_timeout(true); }
208 >    public void testTryAcquireN_timeout(boolean fair) {
209 >        Semaphore s = new Semaphore(2, fair);
210 >        long startTime = System.nanoTime();
211 >        try { assertFalse(s.tryAcquire(3, timeoutMillis(), MILLISECONDS)); }
212 >        catch (InterruptedException e) { threadUnexpectedException(e); }
213 >        assertTrue(millisElapsedSince(startTime) >= timeoutMillis());
214 >    }
215 >
216 >    /**
217 >     * acquire(), acquire(N), timed tryAcquired, timed tryAcquire(N)
218 >     * are interruptible
219 >     */
220 >    public void testInterruptible_acquire()               { testInterruptible(false, AcquireMethod.acquire); }
221 >    public void testInterruptible_acquire_fair()          { testInterruptible(true,  AcquireMethod.acquire); }
222 >    public void testInterruptible_acquireN()              { testInterruptible(false, AcquireMethod.acquireN); }
223 >    public void testInterruptible_acquireN_fair()         { testInterruptible(true,  AcquireMethod.acquireN); }
224 >    public void testInterruptible_tryAcquireTimed()       { testInterruptible(false, AcquireMethod.tryAcquireTimed); }
225 >    public void testInterruptible_tryAcquireTimed_fair()  { testInterruptible(true,  AcquireMethod.tryAcquireTimed); }
226 >    public void testInterruptible_tryAcquireTimedN()      { testInterruptible(false, AcquireMethod.tryAcquireTimedN); }
227 >    public void testInterruptible_tryAcquireTimedN_fair() { testInterruptible(true,  AcquireMethod.tryAcquireTimedN); }
228 >    public void testInterruptible(boolean fair, final AcquireMethod acquirer) {
229 >        final PublicSemaphore s = new PublicSemaphore(0, fair);
230 >        final Semaphore pleaseInterrupt = new Semaphore(0, fair);
231 >        Thread t = newStartedThread(new CheckedRunnable() {
232 >            public void realRun() {
233 >                // Interrupt before acquire
234 >                Thread.currentThread().interrupt();
235 >                try {
236 >                    acquirer.acquire(s);
237 >                    shouldThrow();
238 >                } catch (InterruptedException success) {}
239 >
240 >                // Interrupt during acquire
241 >                try {
242 >                    acquirer.acquire(s);
243 >                    shouldThrow();
244 >                } catch (InterruptedException success) {}
245 >
246 >                // Interrupt before acquire(N)
247 >                Thread.currentThread().interrupt();
248 >                try {
249 >                    acquirer.acquire(s, 3);
250 >                    shouldThrow();
251 >                } catch (InterruptedException success) {}
252 >
253 >                pleaseInterrupt.release();
254 >
255 >                // Interrupt during acquire(N)
256 >                try {
257 >                    acquirer.acquire(s, 3);
258 >                    shouldThrow();
259 >                } catch (InterruptedException success) {}
260 >            }});
261 >
262 >        waitForQueuedThread(s, t);
263 >        t.interrupt();
264 >        await(pleaseInterrupt);
265 >        waitForQueuedThread(s, t);
266 >        t.interrupt();
267 >        awaitTermination(t);
268 >    }
269 >
270 >    /**
271 >     * acquireUninterruptibly(), acquireUninterruptibly(N) are
272 >     * uninterruptible
273 >     */
274 >    public void testUninterruptible_acquireUninterruptibly()       { testUninterruptible(false, AcquireMethod.acquireUninterruptibly); }
275 >    public void testUninterruptible_acquireUninterruptibly_fair()  { testUninterruptible(true,  AcquireMethod.acquireUninterruptibly); }
276 >    public void testUninterruptible_acquireUninterruptiblyN()      { testUninterruptible(false, AcquireMethod.acquireUninterruptiblyN); }
277 >    public void testUninterruptible_acquireUninterruptiblyN_fair() { testUninterruptible(true,  AcquireMethod.acquireUninterruptiblyN); }
278 >    public void testUninterruptible(boolean fair, final AcquireMethod acquirer) {
279 >        final PublicSemaphore s = new PublicSemaphore(0, fair);
280 >        final Semaphore pleaseInterrupt = new Semaphore(-1, fair);
281 >
282 >        Thread t1 = newStartedThread(new CheckedRunnable() {
283 >            public void realRun() throws InterruptedException {
284 >                // Interrupt before acquire
285 >                pleaseInterrupt.release();
286 >                Thread.currentThread().interrupt();
287 >                acquirer.acquire(s);
288 >                assertTrue(Thread.interrupted());
289 >            }});
290 >
291 >        Thread t2 = newStartedThread(new CheckedRunnable() {
292 >            public void realRun() throws InterruptedException {
293 >                // Interrupt during acquire
294 >                pleaseInterrupt.release();
295 >                acquirer.acquire(s);
296 >                assertTrue(Thread.interrupted());
297 >            }});
298 >
299 >        await(pleaseInterrupt);
300 >        waitForQueuedThread(s, t1);
301 >        waitForQueuedThread(s, t2);
302 >        t2.interrupt();
303  
304 <    /**
305 <     * 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 <        }
131 <    }
304 >        assertThreadStaysAlive(t1);
305 >        assertTrue(t2.isAlive());
306  
307 <    /**
308 <     * Timed Acquire and release of semaphore succeed if
309 <     * initially available
310 <     */
137 <    public void testTimedAcquireReleaseInSameThread() {
138 <        Semaphore s = new Semaphore(1, false);
139 <        try {
140 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
141 <            s.release();
142 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
143 <            s.release();
144 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
145 <            s.release();
146 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
147 <            s.release();
148 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
149 <            s.release();
150 <            assertEquals(1, s.availablePermits());
151 <        } catch( InterruptedException e){
152 <            unexpectedException();
153 <        }
307 >        s.release(2);
308 >
309 >        awaitTermination(t1);
310 >        awaitTermination(t2);
311      }
312  
313      /**
314 <     * A release in one thread enables an acquire in another thread
314 >     * hasQueuedThreads reports whether there are waiting threads
315       */
316 <    public void testAcquireReleaseInDifferentThreads() {
317 <        final Semaphore s = new Semaphore(0, false);
318 <        Thread t = new Thread(new Runnable() {
319 <                public void run() {
320 <                    try {
321 <                        s.acquire();
322 <                        s.release();
323 <                        s.release();
324 <                        s.acquire();
325 <                    } catch(InterruptedException ie){
326 <                        threadUnexpectedException();
327 <                    }
328 <                }
329 <            });
330 <        try {
331 <            t.start();
332 <            Thread.sleep(SHORT_DELAY_MS);
333 <            s.release();
177 <            s.release();
178 <            s.acquire();
179 <            s.acquire();
180 <            s.release();
181 <            t.join();
182 <        } catch( InterruptedException e){
183 <            unexpectedException();
184 <        }
316 >    public void testHasQueuedThreads()      { testHasQueuedThreads(false); }
317 >    public void testHasQueuedThreads_fair() { testHasQueuedThreads(true); }
318 >    public void testHasQueuedThreads(boolean fair) {
319 >        final PublicSemaphore lock = new PublicSemaphore(1, fair);
320 >        assertFalse(lock.hasQueuedThreads());
321 >        lock.acquireUninterruptibly();
322 >        Thread t1 = newStartedThread(new InterruptedLockRunnable(lock));
323 >        waitForQueuedThread(lock, t1);
324 >        assertTrue(lock.hasQueuedThreads());
325 >        Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock));
326 >        waitForQueuedThread(lock, t2);
327 >        assertTrue(lock.hasQueuedThreads());
328 >        t1.interrupt();
329 >        awaitTermination(t1);
330 >        assertTrue(lock.hasQueuedThreads());
331 >        lock.release();
332 >        awaitTermination(t2);
333 >        assertFalse(lock.hasQueuedThreads());
334      }
335  
336      /**
337 <     * A release in one thread enables an uninterruptible acquire in another thread
337 >     * getQueueLength reports number of waiting threads
338       */
339 <    public void testUninterruptibleAcquireReleaseInDifferentThreads() {
340 <        final Semaphore s = new Semaphore(0, false);
341 <        Thread t = new Thread(new Runnable() {
342 <                public void run() {
343 <                    s.acquireUninterruptibly();
344 <                    s.release();
345 <                    s.release();
346 <                    s.acquireUninterruptibly();
347 <                }
348 <            });
349 <        try {
350 <            t.start();
351 <            Thread.sleep(SHORT_DELAY_MS);
352 <            s.release();
353 <            s.release();
354 <            s.acquireUninterruptibly();
355 <            s.acquireUninterruptibly();
356 <            s.release();
208 <            t.join();
209 <        } catch( InterruptedException e){
210 <            unexpectedException();
211 <        }
339 >    public void testGetQueueLength()      { testGetQueueLength(false); }
340 >    public void testGetQueueLength_fair() { testGetQueueLength(true); }
341 >    public void testGetQueueLength(boolean fair) {
342 >        final PublicSemaphore lock = new PublicSemaphore(1, fair);
343 >        assertEquals(0, lock.getQueueLength());
344 >        lock.acquireUninterruptibly();
345 >        Thread t1 = newStartedThread(new InterruptedLockRunnable(lock));
346 >        waitForQueuedThread(lock, t1);
347 >        assertEquals(1, lock.getQueueLength());
348 >        Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock));
349 >        waitForQueuedThread(lock, t2);
350 >        assertEquals(2, lock.getQueueLength());
351 >        t1.interrupt();
352 >        awaitTermination(t1);
353 >        assertEquals(1, lock.getQueueLength());
354 >        lock.release();
355 >        awaitTermination(t2);
356 >        assertEquals(0, lock.getQueueLength());
357      }
358  
214
359      /**
360 <     *  A release in one thread enables a timed acquire in another thread
360 >     * getQueuedThreads includes waiting threads
361       */
362 <    public void testTimedAcquireReleaseInDifferentThreads() {
363 <        final Semaphore s = new Semaphore(1, false);
364 <        Thread t = new Thread(new Runnable() {
365 <                public void run() {
366 <                    try {
367 <                        s.release();
368 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
369 <                        s.release();
370 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
371 <
372 <                    } catch(InterruptedException ie){
373 <                        threadUnexpectedException();
374 <                    }
375 <                }
376 <            });
377 <        try {
378 <            t.start();
379 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
380 <            s.release();
381 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
382 <            s.release();
239 <            s.release();
240 <            t.join();
241 <        } catch( InterruptedException e){
242 <            unexpectedException();
243 <        }
362 >    public void testGetQueuedThreads()      { testGetQueuedThreads(false); }
363 >    public void testGetQueuedThreads_fair() { testGetQueuedThreads(true); }
364 >    public void testGetQueuedThreads(boolean fair) {
365 >        final PublicSemaphore lock = new PublicSemaphore(1, fair);
366 >        assertTrue(lock.getQueuedThreads().isEmpty());
367 >        lock.acquireUninterruptibly();
368 >        assertTrue(lock.getQueuedThreads().isEmpty());
369 >        Thread t1 = newStartedThread(new InterruptedLockRunnable(lock));
370 >        waitForQueuedThread(lock, t1);
371 >        assertTrue(lock.getQueuedThreads().contains(t1));
372 >        Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock));
373 >        waitForQueuedThread(lock, t2);
374 >        assertTrue(lock.getQueuedThreads().contains(t1));
375 >        assertTrue(lock.getQueuedThreads().contains(t2));
376 >        t1.interrupt();
377 >        awaitTermination(t1);
378 >        assertFalse(lock.getQueuedThreads().contains(t1));
379 >        assertTrue(lock.getQueuedThreads().contains(t2));
380 >        lock.release();
381 >        awaitTermination(t2);
382 >        assertTrue(lock.getQueuedThreads().isEmpty());
383      }
384  
385      /**
386 <     * A waiting acquire blocks interruptibly
387 <     */
388 <    public void testAcquire_InterruptedException() {
389 <        final Semaphore s = new Semaphore(0, false);
390 <        Thread t = new Thread(new Runnable() {
391 <                public void run() {
392 <                    try {
393 <                        s.acquire();
394 <                        threadShouldThrow();
395 <                    } catch(InterruptedException success){}
396 <                }
397 <            });
398 <        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 <        }
386 >     * drainPermits reports and removes given number of permits
387 >     */
388 >    public void testDrainPermits()      { testDrainPermits(false); }
389 >    public void testDrainPermits_fair() { testDrainPermits(true); }
390 >    public void testDrainPermits(boolean fair) {
391 >        Semaphore s = new Semaphore(0, fair);
392 >        assertEquals(0, s.availablePermits());
393 >        assertEquals(0, s.drainPermits());
394 >        s.release(10);
395 >        assertEquals(10, s.availablePermits());
396 >        assertEquals(10, s.drainPermits());
397 >        assertEquals(0, s.availablePermits());
398 >        assertEquals(0, s.drainPermits());
399      }
400  
401      /**
402 <     * 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
402 >     * release(-N) throws IllegalArgumentException
403       */
404 <    public void testGetQueueLength() {
405 <        final Semaphore lock = new Semaphore(1, false);
406 <        Thread t1 = new Thread(new InterruptedLockRunnable(lock));
407 <        Thread t2 = new Thread(new InterruptibleLockRunnable(lock));
404 >    public void testReleaseIAE()      { testReleaseIAE(false); }
405 >    public void testReleaseIAE_fair() { testReleaseIAE(true); }
406 >    public void testReleaseIAE(boolean fair) {
407 >        Semaphore s = new Semaphore(10, fair);
408          try {
409 <            assertEquals(0, lock.getQueueLength());
410 <            lock.acquireUninterruptibly();
411 <            t1.start();
412 <            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 <    }
409 >            s.release(-1);
410 >            shouldThrow();
411 >        } catch (IllegalArgumentException success) {}
412 >    }
413  
414      /**
415 <     * getQueuedThreads includes waiting threads
415 >     * reducePermits(-N) throws IllegalArgumentException
416       */
417 <    public void testGetQueuedThreads() {
418 <        final PublicSemaphore lock = new PublicSemaphore(1, false);
419 <        Thread t1 = new Thread(new InterruptedLockRunnable(lock));
420 <        Thread t2 = new Thread(new InterruptibleLockRunnable(lock));
417 >    public void testReducePermitsIAE()      { testReducePermitsIAE(false); }
418 >    public void testReducePermitsIAE_fair() { testReducePermitsIAE(true); }
419 >    public void testReducePermitsIAE(boolean fair) {
420 >        PublicSemaphore s = new PublicSemaphore(10, fair);
421          try {
422 <            assertTrue(lock.getQueuedThreads().isEmpty());
423 <            lock.acquireUninterruptibly();
424 <            assertTrue(lock.getQueuedThreads().isEmpty());
425 <            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 <
422 >            s.reducePermits(-1);
423 >            shouldThrow();
424 >        } catch (IllegalArgumentException success) {}
425 >    }
426  
427      /**
428       * reducePermits reduces number of permits
429       */
430 <    public void testReducePermits() {
431 <        PublicSemaphore s = new PublicSemaphore(10, false);
430 >    public void testReducePermits()      { testReducePermits(false); }
431 >    public void testReducePermits_fair() { testReducePermits(true); }
432 >    public void testReducePermits(boolean fair) {
433 >        PublicSemaphore s = new PublicSemaphore(10, fair);
434 >        assertEquals(10, s.availablePermits());
435 >        s.reducePermits(0);
436          assertEquals(10, s.availablePermits());
437          s.reducePermits(1);
438          assertEquals(9, s.availablePermits());
439          s.reducePermits(10);
440          assertEquals(-1, s.availablePermits());
441 +        s.reducePermits(10);
442 +        assertEquals(-11, s.availablePermits());
443 +        s.reducePermits(0);
444 +        assertEquals(-11, s.availablePermits());
445      }
446  
447      /**
448 <     * a deserialized serialized semaphore has same number of permits
449 <     */
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 sufficient 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 sufficient 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
448 >     * a reserialized semaphore has same number of permits and
449 >     * fairness, but no queued threads
450       */
451 <    public void testAcquireReleaseInSameThread_fair() {
452 <        Semaphore s = new Semaphore(1, true);
451 >    public void testSerialization()      { testSerialization(false); }
452 >    public void testSerialization_fair() { testSerialization(true); }
453 >    public void testSerialization(boolean fair) {
454          try {
455 +            Semaphore s = new Semaphore(3, fair);
456              s.acquire();
465            s.release();
466            s.acquire();
467            s.release();
468            s.acquire();
469            s.release();
470            s.acquire();
471            s.release();
457              s.acquire();
458              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    }
459  
460 <    /**
461 <     * Acquire(n) and release(n) of semaphore succeed if initially available
462 <     */
463 <    public void testAcquireUninterruptiblyReleaseNInSameThread_fair() {
464 <        Semaphore s = new Semaphore(1, true);
465 <        try {
466 <            s.release(1);
467 <            s.acquireUninterruptibly(1);
468 <            s.release(2);
469 <            s.acquireUninterruptibly(2);
470 <            s.release(3);
471 <            s.acquireUninterruptibly(3);
472 <            s.release(4);
473 <            s.acquireUninterruptibly(4);
474 <            s.release(5);
475 <            s.acquireUninterruptibly(5);
476 <            assertEquals(1, s.availablePermits());
477 <        } finally {
460 >            Semaphore clone = serialClone(s);
461 >            assertEquals(fair, s.isFair());
462 >            assertEquals(fair, clone.isFair());
463 >            assertEquals(2, s.availablePermits());
464 >            assertEquals(2, clone.availablePermits());
465 >            clone.acquire();
466 >            clone.acquire();
467 >            clone.release();
468 >            assertEquals(2, s.availablePermits());
469 >            assertEquals(1, clone.availablePermits());
470 >            assertFalse(s.hasQueuedThreads());
471 >            assertFalse(clone.hasQueuedThreads());
472 >        } catch (InterruptedException e) { threadUnexpectedException(e); }
473 >
474 >        {
475 >            PublicSemaphore s = new PublicSemaphore(0, fair);
476 >            Thread t = newStartedThread(new InterruptibleLockRunnable(s));
477 >            // waitForQueuedThreads(s); // suffers from "flicker", so ...
478 >            waitForQueuedThread(s, t);  // ... we use this instead
479 >            PublicSemaphore clone = serialClone(s);
480 >            assertEquals(fair, s.isFair());
481 >            assertEquals(fair, clone.isFair());
482 >            assertEquals(0, s.availablePermits());
483 >            assertEquals(0, clone.availablePermits());
484 >            assertTrue(s.hasQueuedThreads());
485 >            assertFalse(clone.hasQueuedThreads());
486 >            s.release();
487 >            awaitTermination(t);
488 >            assertFalse(s.hasQueuedThreads());
489 >            assertFalse(clone.hasQueuedThreads());
490          }
491      }
492  
493      /**
494 <     * release(n) in one thread enables timed acquire(n) in another thread
494 >     * tryAcquire(n) succeeds when sufficient permits, else fails
495       */
496 <    public void testTimedAcquireReleaseNInSameThread_fair() {
497 <        Semaphore s = new Semaphore(1, true);
498 <        try {
499 <            s.release(1);
500 <            assertTrue(s.tryAcquire(1, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
501 <            s.release(2);
502 <            assertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
503 <            s.release(3);
504 <            assertTrue(s.tryAcquire(3, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
505 <            s.release(4);
506 <            assertTrue(s.tryAcquire(4, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
507 <            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 <        }
496 >    public void testTryAcquireNInSameThread()      { testTryAcquireNInSameThread(false); }
497 >    public void testTryAcquireNInSameThread_fair() { testTryAcquireNInSameThread(true); }
498 >    public void testTryAcquireNInSameThread(boolean fair) {
499 >        Semaphore s = new Semaphore(2, fair);
500 >        assertEquals(2, s.availablePermits());
501 >        assertFalse(s.tryAcquire(3));
502 >        assertEquals(2, s.availablePermits());
503 >        assertTrue(s.tryAcquire(2));
504 >        assertEquals(0, s.availablePermits());
505 >        assertFalse(s.tryAcquire(1));
506 >        assertFalse(s.tryAcquire(2));
507 >        assertEquals(0, s.availablePermits());
508      }
509  
510      /**
511 <     * release in one thread enables timed acquire in another thread
511 >     * acquire succeeds if permits available
512       */
513 <    public void testTimedAcquireReleaseInSameThread_fair() {
514 <        Semaphore s = new Semaphore(1, true);
515 <        try {
516 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
517 <            s.release();
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 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
523 <            s.release();
524 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
525 <            s.release();
513 >    public void testReleaseAcquireSameThread_acquire()       { testReleaseAcquireSameThread(false, AcquireMethod.acquire); }
514 >    public void testReleaseAcquireSameThread_acquire_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.acquire); }
515 >    public void testReleaseAcquireSameThread_acquireN()      { testReleaseAcquireSameThread(false, AcquireMethod.acquireN); }
516 >    public void testReleaseAcquireSameThread_acquireN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.acquireN); }
517 >    public void testReleaseAcquireSameThread_acquireUninterruptibly()       { testReleaseAcquireSameThread(false, AcquireMethod.acquireUninterruptibly); }
518 >    public void testReleaseAcquireSameThread_acquireUninterruptibly_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.acquireUninterruptibly); }
519 >    public void testReleaseAcquireSameThread_acquireUninterruptiblyN()      { testReleaseAcquireSameThread(false, AcquireMethod.acquireUninterruptibly); }
520 >    public void testReleaseAcquireSameThread_acquireUninterruptiblyN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.acquireUninterruptibly); }
521 >    public void testReleaseAcquireSameThread_tryAcquire()       { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquire); }
522 >    public void testReleaseAcquireSameThread_tryAcquire_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquire); }
523 >    public void testReleaseAcquireSameThread_tryAcquireN()      { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireN); }
524 >    public void testReleaseAcquireSameThread_tryAcquireN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireN); }
525 >    public void testReleaseAcquireSameThread_tryAcquireTimed()       { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireTimed); }
526 >    public void testReleaseAcquireSameThread_tryAcquireTimed_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireTimed); }
527 >    public void testReleaseAcquireSameThread_tryAcquireTimedN()      { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireTimedN); }
528 >    public void testReleaseAcquireSameThread_tryAcquireTimedN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireTimedN); }
529 >    public void testReleaseAcquireSameThread(boolean fair,
530 >                                             final AcquireMethod acquirer) {
531 >        Semaphore s = new Semaphore(1, fair);
532 >        for (int i = 1; i < 6; i++) {
533 >            s.release(i);
534 >            assertEquals(1 + i, s.availablePermits());
535 >            try {
536 >                acquirer.acquire(s, i);
537 >            } catch (InterruptedException e) { threadUnexpectedException(e); }
538              assertEquals(1, s.availablePermits());
562        } catch( InterruptedException e){
563            unexpectedException();
539          }
540      }
541  
542      /**
543 <     * A release in one thread enables an acquire in another thread
543 >     * release in one thread enables acquire in another thread
544       */
545 <    public void testAcquireReleaseInDifferentThreads_fair() {
546 <        final Semaphore s = new Semaphore(0, true);
547 <        Thread t = new Thread(new Runnable() {
548 <                public void run() {
549 <                    try {
550 <                        s.acquire();
551 <                        s.acquire();
552 <                        s.acquire();
553 <                        s.acquire();
554 <                    } catch(InterruptedException ie){
555 <                        threadUnexpectedException();
556 <                    }
557 <                }
558 <            });
559 <        try {
560 <            t.start();
561 <            Thread.sleep(SHORT_DELAY_MS);
562 <            s.release();
563 <            s.release();
564 <            s.release();
565 <            s.release();
566 <            s.release();
567 <            s.release();
568 <            t.join();
569 <            assertEquals(2, s.availablePermits());
570 <        } catch( InterruptedException e){
571 <            unexpectedException();
545 >    public void testReleaseAcquireDifferentThreads_acquire()       { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquire); }
546 >    public void testReleaseAcquireDifferentThreads_acquire_fair()  { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquire); }
547 >    public void testReleaseAcquireDifferentThreads_acquireN()      { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireN); }
548 >    public void testReleaseAcquireDifferentThreads_acquireN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireN); }
549 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptibly()       { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireUninterruptibly); }
550 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptibly_fair()  { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireUninterruptibly); }
551 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptiblyN()      { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireUninterruptibly); }
552 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptiblyN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireUninterruptibly); }
553 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimed()       { testReleaseAcquireDifferentThreads(false, AcquireMethod.tryAcquireTimed); }
554 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimed_fair()  { testReleaseAcquireDifferentThreads(true, AcquireMethod.tryAcquireTimed); }
555 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimedN()      { testReleaseAcquireDifferentThreads(false, AcquireMethod.tryAcquireTimedN); }
556 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimedN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.tryAcquireTimedN); }
557 >    public void testReleaseAcquireDifferentThreads(boolean fair,
558 >                                                   final AcquireMethod acquirer) {
559 >        final Semaphore s = new Semaphore(0, fair);
560 >        final int rounds = 4;
561 >        long startTime = System.nanoTime();
562 >        Thread t = newStartedThread(new CheckedRunnable() {
563 >            public void realRun() throws InterruptedException {
564 >                for (int i = 0; i < rounds; i++) {
565 >                    assertFalse(s.hasQueuedThreads());
566 >                    if (i % 2 == 0)
567 >                        acquirer.acquire(s);
568 >                    else
569 >                        acquirer.acquire(s, 3);
570 >                }}});
571 >
572 >        for (int i = 0; i < rounds; i++) {
573 >            while (! (s.availablePermits() == 0 && s.hasQueuedThreads()))
574 >                Thread.yield();
575 >            assertTrue(t.isAlive());
576 >            if (i % 2 == 0)
577 >                s.release();
578 >            else
579 >                s.release(3);
580          }
581 +        awaitTermination(t);
582 +        assertEquals(0, s.availablePermits());
583 +        assertTrue(millisElapsedSince(startTime) < LONG_DELAY_MS);
584      }
585  
586      /**
587 <     * release(n) in one thread enables acquire(n) in another thread
587 >     * fair locks are strictly FIFO
588       */
589 <    public void testAcquireReleaseNInDifferentThreads_fair() {
590 <        final Semaphore s = new Semaphore(0, true);
591 <        Thread t = new Thread(new Runnable() {
592 <                public void run() {
593 <                    try {
594 <                        s.acquire(2);
595 <                        s.acquire(2);
596 <                        s.release(4);
597 <                    } catch(InterruptedException ie){
598 <                        threadUnexpectedException();
599 <                    }
600 <                }
601 <            });
602 <        try {
603 <            t.start();
604 <            Thread.sleep(SHORT_DELAY_MS);
605 <            s.release(6);
606 <            s.acquire(2);
607 <            s.acquire(2);
608 <            s.release(2);
609 <            t.join();
610 <        } catch( InterruptedException e){
611 <            unexpectedException();
612 <        }
613 <    }
614 <
615 <
616 <
617 <    /**
618 <     * release in one thread enables timed acquire in another thread
619 <     */
620 <    public void testTimedAcquireReleaseInDifferentThreads_fair() {
621 <        final Semaphore s = new Semaphore(1, true);
622 <        Thread t = new Thread(new Runnable() {
623 <                public void run() {
638 <                    try {
639 <                        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 <        }
589 >    public void testFairLocksFifo() {
590 >        final PublicSemaphore s = new PublicSemaphore(1, true);
591 >        final CountDownLatch pleaseRelease = new CountDownLatch(1);
592 >        Thread t1 = newStartedThread(new CheckedRunnable() {
593 >            public void realRun() throws InterruptedException {
594 >                // Will block; permits are available, but not three
595 >                s.acquire(3);
596 >            }});
597 >
598 >        waitForQueuedThread(s, t1);
599 >
600 >        Thread t2 = newStartedThread(new CheckedRunnable() {
601 >            public void realRun() throws InterruptedException {
602 >                // Will fail, even though 1 permit is available
603 >                assertFalse(s.tryAcquire(0L, MILLISECONDS));
604 >                assertFalse(s.tryAcquire(1, 0L, MILLISECONDS));
605 >
606 >                // untimed tryAcquire will barge and succeed
607 >                assertTrue(s.tryAcquire());
608 >                s.release(2);
609 >                assertTrue(s.tryAcquire(2));
610 >                s.release();
611 >
612 >                pleaseRelease.countDown();
613 >                // Will queue up behind t1, even though 1 permit is available
614 >                s.acquire();
615 >            }});
616 >
617 >        await(pleaseRelease);
618 >        waitForQueuedThread(s, t2);
619 >        s.release(2);
620 >        awaitTermination(t1);
621 >        assertTrue(t2.isAlive());
622 >        s.release();
623 >        awaitTermination(t2);
624      }
625  
626      /**
627 <     * release(n) in one thread enables timed acquire(n) in another thread
628 <     */
629 <    public void testTimedAcquireReleaseNInDifferentThreads_fair() {
630 <        final Semaphore s = new Semaphore(2, true);
631 <        Thread t = new Thread(new Runnable() {
632 <                public void run() {
633 <                    try {
634 <                        threadAssertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
635 <                        s.release(2);
636 <                        threadAssertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
637 <                        s.release(2);
638 <                    } catch(InterruptedException ie){
639 <                        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 <        }
760 <    }
761 <
762 <    /**
763 <     *  A waiting tryAcquire(n) blocks interruptibly
764 <     */
765 <    public void testTryAcquireN_InterruptedException_fair() {
766 <        final Semaphore s = new Semaphore(1, true);
767 <        Thread t = new Thread(new Runnable() {
768 <                public void run() {
769 <                    try {
770 <                        s.tryAcquire(4, MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS);
771 <                        threadShouldThrow();
772 <                    } catch(InterruptedException success){
773 <                    }
774 <                }
775 <            });
776 <        t.start();
777 <        try {
778 <            Thread.sleep(SHORT_DELAY_MS);
779 <            t.interrupt();
780 <            t.join();
781 <        } catch(InterruptedException e){
782 <            unexpectedException();
783 <        }
627 >     * toString indicates current number of permits
628 >     */
629 >    public void testToString()      { testToString(false); }
630 >    public void testToString_fair() { testToString(true); }
631 >    public void testToString(boolean fair) {
632 >        PublicSemaphore s = new PublicSemaphore(0, fair);
633 >        assertTrue(s.toString().contains("Permits = 0"));
634 >        s.release();
635 >        assertTrue(s.toString().contains("Permits = 1"));
636 >        s.release(2);
637 >        assertTrue(s.toString().contains("Permits = 3"));
638 >        s.reducePermits(5);
639 >        assertTrue(s.toString().contains("Permits = -2"));
640      }
641  
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
642   }

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