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Comparing jsr166/src/test/tck/SemaphoreTest.java (file contents):
Revision 1.6 by dl, Mon Nov 3 13:50:07 2003 UTC vs.
Revision 1.41 by jsr166, Sun May 14 04:18:31 2017 UTC

# Line 1 | Line 1
1   /*
2 < * Written by members of JCP JSR-166 Expert Group and released to the
3 < * public domain. Use, modify, and redistribute this code in any way
4 < * without acknowledgement. Other contributors include Andrew Wright,
5 < * Jeffrey Hayes, Pat Fischer, Mike Judd.
2 > * Written by Doug Lea with assistance from members of JCP JSR-166
3 > * Expert Group and released to the public domain, as explained at
4 > * http://creativecommons.org/publicdomain/zero/1.0/
5 > * Other contributors include Andrew Wright, Jeffrey Hayes,
6 > * Pat Fisher, Mike Judd.
7   */
8  
9 < import junit.framework.*;
10 < import java.util.*;
11 < import java.util.concurrent.*;
12 < import java.io.*;
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.AssertionFailedError;
17 > import junit.framework.Test;
18 > import junit.framework.TestSuite;
19  
20   public class SemaphoreTest extends JSR166TestCase {
21      public static void main(String[] args) {
22 <        junit.textui.TestRunner.run (suite());  
22 >        main(suite(), args);
23      }
24      public static Test suite() {
25 <        return new TestSuite(SemaphoreTest.class);
25 >        return new TestSuite(SemaphoreTest.class);
26      }
27  
28      /**
29       * Subclass to expose protected methods
30       */
31      static class PublicSemaphore extends Semaphore {
32 <        PublicSemaphore(int p, boolean f) { super(p, f); }
33 <        public Collection<Thread> getQueuedThreads() {
34 <            return super.getQueuedThreads();
32 >        PublicSemaphore(int permits) { super(permits); }
33 >        PublicSemaphore(int permits, boolean fair) { super(permits, fair); }
34 >        public Collection<Thread> getQueuedThreads() {
35 >            return super.getQueuedThreads();
36 >        }
37 >        public boolean hasQueuedThread(Thread t) {
38 >            return super.getQueuedThreads().contains(t);
39          }
40 <        public void reducePermits(int p) {
41 <            super.reducePermits(p);
40 >        public void reducePermits(int reduction) {
41 >            super.reducePermits(reduction);
42          }
43      }
44  
45      /**
46       * A runnable calling acquire
47       */
48 <    class InterruptibleLockRunnable implements Runnable {
48 >    class InterruptibleLockRunnable extends CheckedRunnable {
49          final Semaphore lock;
50 <        InterruptibleLockRunnable(Semaphore l) { lock = l; }
51 <        public void run() {
50 >        InterruptibleLockRunnable(Semaphore s) { lock = s; }
51 >        public void realRun() {
52              try {
53                  lock.acquire();
54 <            } catch(InterruptedException success){}
54 >            }
55 >            catch (InterruptedException ignored) {}
56          }
57      }
58  
47
59      /**
60 <     * A runnable calling acquire that expects to be
50 <     * interrupted
60 >     * A runnable calling acquire that expects to be interrupted
61       */
62 <    class InterruptedLockRunnable implements Runnable {
62 >    class InterruptedLockRunnable extends CheckedInterruptedRunnable {
63          final Semaphore lock;
64 <        InterruptedLockRunnable(Semaphore l) { lock = l; }
65 <        public void run() {
66 <            try {
67 <                lock.acquire();
68 <                threadShouldThrow();
69 <            } catch(InterruptedException success){}
64 >        InterruptedLockRunnable(Semaphore s) { lock = s; }
65 >        public void realRun() throws InterruptedException {
66 >            lock.acquire();
67 >        }
68 >    }
69 >
70 >    /**
71 >     * Spin-waits until s.hasQueuedThread(t) becomes true.
72 >     */
73 >    void waitForQueuedThread(PublicSemaphore s, Thread t) {
74 >        long startTime = System.nanoTime();
75 >        while (!s.hasQueuedThread(t)) {
76 >            if (millisElapsedSince(startTime) > LONG_DELAY_MS)
77 >                throw new AssertionFailedError("timed out");
78 >            Thread.yield();
79 >        }
80 >        assertTrue(s.hasQueuedThreads());
81 >        assertTrue(t.isAlive());
82 >    }
83 >
84 >    /**
85 >     * Spin-waits until s.hasQueuedThreads() becomes true.
86 >     */
87 >    void waitForQueuedThreads(Semaphore s) {
88 >        long startTime = System.nanoTime();
89 >        while (!s.hasQueuedThreads()) {
90 >            if (millisElapsedSince(startTime) > LONG_DELAY_MS)
91 >                throw new AssertionFailedError("timed out");
92 >            Thread.yield();
93 >        }
94 >    }
95 >
96 >    enum AcquireMethod {
97 >        acquire() {
98 >            void acquire(Semaphore s) throws InterruptedException {
99 >                s.acquire();
100 >            }
101 >        },
102 >        acquireN() {
103 >            void acquire(Semaphore s, int permits) throws InterruptedException {
104 >                s.acquire(permits);
105 >            }
106 >        },
107 >        acquireUninterruptibly() {
108 >            void acquire(Semaphore s) {
109 >                s.acquireUninterruptibly();
110 >            }
111 >        },
112 >        acquireUninterruptiblyN() {
113 >            void acquire(Semaphore s, int permits) {
114 >                s.acquireUninterruptibly(permits);
115 >            }
116 >        },
117 >        tryAcquire() {
118 >            void acquire(Semaphore s) {
119 >                assertTrue(s.tryAcquire());
120 >            }
121 >        },
122 >        tryAcquireN() {
123 >            void acquire(Semaphore s, int permits) {
124 >                assertTrue(s.tryAcquire(permits));
125 >            }
126 >        },
127 >        tryAcquireTimed() {
128 >            void acquire(Semaphore s) throws InterruptedException {
129 >                assertTrue(s.tryAcquire(2 * LONG_DELAY_MS, MILLISECONDS));
130 >            }
131 >            Thread.State parkedState() { return Thread.State.TIMED_WAITING; }
132 >        },
133 >        tryAcquireTimedN {
134 >            void acquire(Semaphore s, int permits) throws InterruptedException {
135 >                assertTrue(s.tryAcquire(permits, 2 * LONG_DELAY_MS, MILLISECONDS));
136 >            }
137 >            Thread.State parkedState() { return Thread.State.TIMED_WAITING; }
138 >        };
139 >
140 >        // Intentionally meta-circular
141 >
142 >        /** Acquires 1 permit. */
143 >        void acquire(Semaphore s) throws InterruptedException {
144 >            acquire(s, 1);
145 >        }
146 >        /** Acquires the given number of permits. */
147 >        void acquire(Semaphore s, int permits) throws InterruptedException {
148 >            for (int i = 0; i < permits; i++)
149 >                acquire(s);
150          }
151 +        Thread.State parkedState() { return Thread.State.WAITING; }
152      }
153  
154      /**
155       * Zero, negative, and positive initial values are allowed in constructor
156       */
157 <    public void testConstructor() {
158 <        Semaphore s0 = new Semaphore(0, false);
159 <        assertEquals(0, s0.availablePermits());
160 <        assertFalse(s0.isFair());
161 <        Semaphore s1 = new Semaphore(-1, false);
162 <        assertEquals(-1, s1.availablePermits());
163 <        Semaphore s2 = new Semaphore(-1, false);
164 <        assertEquals(-1, s2.availablePermits());
157 >    public void testConstructor()      { testConstructor(false); }
158 >    public void testConstructor_fair() { testConstructor(true); }
159 >    public void testConstructor(boolean fair) {
160 >        for (int permits : new int[] { -42, -1, 0, 1, 42 }) {
161 >            Semaphore s = new Semaphore(permits, fair);
162 >            assertEquals(permits, s.availablePermits());
163 >            assertEquals(fair, s.isFair());
164 >        }
165 >    }
166 >
167 >    /**
168 >     * Constructor without fairness argument behaves as nonfair
169 >     */
170 >    public void testConstructorDefaultsToNonFair() {
171 >        for (int permits : new int[] { -42, -1, 0, 1, 42 }) {
172 >            Semaphore s = new Semaphore(permits);
173 >            assertEquals(permits, s.availablePermits());
174 >            assertFalse(s.isFair());
175 >        }
176      }
177  
178      /**
179 <     * tryAcquire succeeds when sufficent permits, else fails
179 >     * tryAcquire succeeds when sufficient permits, else fails
180       */
181 <    public void testTryAcquireInSameThread() {
182 <        Semaphore s = new Semaphore(2, false);
181 >    public void testTryAcquireInSameThread()      { testTryAcquireInSameThread(false); }
182 >    public void testTryAcquireInSameThread_fair() { testTryAcquireInSameThread(true); }
183 >    public void testTryAcquireInSameThread(boolean fair) {
184 >        Semaphore s = new Semaphore(2, fair);
185          assertEquals(2, s.availablePermits());
186          assertTrue(s.tryAcquire());
187          assertTrue(s.tryAcquire());
188          assertEquals(0, s.availablePermits());
189          assertFalse(s.tryAcquire());
190 +        assertFalse(s.tryAcquire());
191 +        assertEquals(0, s.availablePermits());
192      }
193  
194      /**
195 <     * Acquire and release of semaphore succeed if initially available
195 >     * timed tryAcquire times out
196       */
197 <    public void testAcquireReleaseInSameThread() {
198 <        Semaphore s = new Semaphore(1, false);
199 <        try {
200 <            s.acquire();
201 <            s.release();
202 <            s.acquire();
203 <            s.release();
204 <            s.acquire();
205 <            s.release();
206 <            s.acquire();
207 <            s.release();
208 <            s.acquire();
209 <            s.release();
210 <            assertEquals(1, s.availablePermits());
211 <        } catch( InterruptedException e){
212 <            unexpectedException();
197 >    public void testTryAcquire_timeout() {
198 >        final boolean fair = ThreadLocalRandom.current().nextBoolean();
199 >        final Semaphore s = new Semaphore(0, fair);
200 >        final long startTime = System.nanoTime();
201 >        try { assertFalse(s.tryAcquire(timeoutMillis(), MILLISECONDS)); }
202 >        catch (InterruptedException e) { threadUnexpectedException(e); }
203 >        assertTrue(millisElapsedSince(startTime) >= timeoutMillis());
204 >    }
205 >
206 >    /**
207 >     * timed tryAcquire(N) times out
208 >     */
209 >    public void testTryAcquireN_timeout() {
210 >        final boolean fair = ThreadLocalRandom.current().nextBoolean();
211 >        final Semaphore s = new Semaphore(2, fair);
212 >        final long startTime = System.nanoTime();
213 >        try { assertFalse(s.tryAcquire(3, timeoutMillis(), MILLISECONDS)); }
214 >        catch (InterruptedException e) { threadUnexpectedException(e); }
215 >        assertTrue(millisElapsedSince(startTime) >= timeoutMillis());
216 >    }
217 >
218 >    /**
219 >     * acquire(), acquire(N), timed tryAcquired, timed tryAcquire(N)
220 >     * are interruptible
221 >     */
222 >    public void testInterruptible_acquire()               { testInterruptible(false, AcquireMethod.acquire); }
223 >    public void testInterruptible_acquire_fair()          { testInterruptible(true,  AcquireMethod.acquire); }
224 >    public void testInterruptible_acquireN()              { testInterruptible(false, AcquireMethod.acquireN); }
225 >    public void testInterruptible_acquireN_fair()         { testInterruptible(true,  AcquireMethod.acquireN); }
226 >    public void testInterruptible_tryAcquireTimed()       { testInterruptible(false, AcquireMethod.tryAcquireTimed); }
227 >    public void testInterruptible_tryAcquireTimed_fair()  { testInterruptible(true,  AcquireMethod.tryAcquireTimed); }
228 >    public void testInterruptible_tryAcquireTimedN()      { testInterruptible(false, AcquireMethod.tryAcquireTimedN); }
229 >    public void testInterruptible_tryAcquireTimedN_fair() { testInterruptible(true,  AcquireMethod.tryAcquireTimedN); }
230 >    public void testInterruptible(boolean fair, final AcquireMethod acquirer) {
231 >        final PublicSemaphore s = new PublicSemaphore(0, fair);
232 >        final java.util.concurrent.CyclicBarrier pleaseInterrupt
233 >            = new java.util.concurrent.CyclicBarrier(2);
234 >        Thread t = newStartedThread(new CheckedRunnable() {
235 >            public void realRun() {
236 >                // Interrupt before acquire
237 >                Thread.currentThread().interrupt();
238 >                try {
239 >                    acquirer.acquire(s);
240 >                    shouldThrow();
241 >                } catch (InterruptedException success) {}
242 >                assertFalse(Thread.interrupted());
243 >
244 >                // Interrupt before acquire(N)
245 >                Thread.currentThread().interrupt();
246 >                try {
247 >                    acquirer.acquire(s, 3);
248 >                    shouldThrow();
249 >                } catch (InterruptedException success) {}
250 >                assertFalse(Thread.interrupted());
251 >
252 >                // Interrupt during acquire
253 >                await(pleaseInterrupt);
254 >                try {
255 >                    acquirer.acquire(s);
256 >                    shouldThrow();
257 >                } catch (InterruptedException success) {}
258 >                assertFalse(Thread.interrupted());
259 >
260 >                // Interrupt during acquire(N)
261 >                await(pleaseInterrupt);
262 >                try {
263 >                    acquirer.acquire(s, 3);
264 >                    shouldThrow();
265 >                } catch (InterruptedException success) {}
266 >                assertFalse(Thread.interrupted());
267 >            }});
268 >
269 >        for (int n = 2; n-->0; ) {
270 >            await(pleaseInterrupt);
271 >            assertThreadBlocks(t, acquirer.parkedState());
272 >            t.interrupt();
273          }
108    }
274  
275 <    /**
111 <     * Uninterruptible acquire and release of semaphore succeed if
112 <     * initially available
113 <     */
114 <    public void testAcquireUninterruptiblyReleaseInSameThread() {
115 <        Semaphore s = new Semaphore(1, false);
116 <        try {
117 <            s.acquireUninterruptibly();
118 <            s.release();
119 <            s.acquireUninterruptibly();
120 <            s.release();
121 <            s.acquireUninterruptibly();
122 <            s.release();
123 <            s.acquireUninterruptibly();
124 <            s.release();
125 <            s.acquireUninterruptibly();
126 <            s.release();
127 <            assertEquals(1, s.availablePermits());
128 <        } finally {
129 <        }
275 >        awaitTermination(t);
276      }
277  
278      /**
279 <     * Timed Acquire and release of semaphore succeed if
280 <     * initially available
279 >     * acquireUninterruptibly(), acquireUninterruptibly(N) are
280 >     * uninterruptible
281       */
282 <    public void testTimedAcquireReleaseInSameThread() {
283 <        Semaphore s = new Semaphore(1, false);
284 <        try {
285 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
286 <            s.release();
287 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
288 <            s.release();
289 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
290 <            s.release();
291 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
292 <            s.release();
293 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
294 <            s.release();
295 <            assertEquals(1, s.availablePermits());
296 <        } catch( InterruptedException e){
297 <            unexpectedException();
298 <        }
282 >    public void testUninterruptible_acquireUninterruptibly()       { testUninterruptible(false, AcquireMethod.acquireUninterruptibly); }
283 >    public void testUninterruptible_acquireUninterruptibly_fair()  { testUninterruptible(true,  AcquireMethod.acquireUninterruptibly); }
284 >    public void testUninterruptible_acquireUninterruptiblyN()      { testUninterruptible(false, AcquireMethod.acquireUninterruptiblyN); }
285 >    public void testUninterruptible_acquireUninterruptiblyN_fair() { testUninterruptible(true,  AcquireMethod.acquireUninterruptiblyN); }
286 >    public void testUninterruptible(boolean fair, final AcquireMethod acquirer) {
287 >        final PublicSemaphore s = new PublicSemaphore(0, fair);
288 >        final Semaphore pleaseInterrupt = new Semaphore(-1, fair);
289 >
290 >        Thread t1 = newStartedThread(new CheckedRunnable() {
291 >            public void realRun() throws InterruptedException {
292 >                // Interrupt before acquire
293 >                pleaseInterrupt.release();
294 >                Thread.currentThread().interrupt();
295 >                acquirer.acquire(s);
296 >                assertTrue(Thread.interrupted());
297 >            }});
298 >
299 >        Thread t2 = newStartedThread(new CheckedRunnable() {
300 >            public void realRun() throws InterruptedException {
301 >                // Interrupt during acquire
302 >                pleaseInterrupt.release();
303 >                acquirer.acquire(s);
304 >                assertTrue(Thread.interrupted());
305 >            }});
306 >
307 >        await(pleaseInterrupt);
308 >        waitForQueuedThread(s, t1);
309 >        waitForQueuedThread(s, t2);
310 >        t2.interrupt();
311 >
312 >        assertThreadBlocks(t1, Thread.State.WAITING);
313 >        assertThreadBlocks(t2, Thread.State.WAITING);
314 >
315 >        s.release(2);
316 >
317 >        awaitTermination(t1);
318 >        awaitTermination(t2);
319 >    }
320 >
321 >    /**
322 >     * hasQueuedThreads reports whether there are waiting threads
323 >     */
324 >    public void testHasQueuedThreads()      { testHasQueuedThreads(false); }
325 >    public void testHasQueuedThreads_fair() { testHasQueuedThreads(true); }
326 >    public void testHasQueuedThreads(boolean fair) {
327 >        final PublicSemaphore lock = new PublicSemaphore(1, fair);
328 >        assertFalse(lock.hasQueuedThreads());
329 >        lock.acquireUninterruptibly();
330 >        Thread t1 = newStartedThread(new InterruptedLockRunnable(lock));
331 >        waitForQueuedThread(lock, t1);
332 >        assertTrue(lock.hasQueuedThreads());
333 >        Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock));
334 >        waitForQueuedThread(lock, t2);
335 >        assertTrue(lock.hasQueuedThreads());
336 >        t1.interrupt();
337 >        awaitTermination(t1);
338 >        assertTrue(lock.hasQueuedThreads());
339 >        lock.release();
340 >        awaitTermination(t2);
341 >        assertFalse(lock.hasQueuedThreads());
342      }
343  
344      /**
345 <     * A release in one thread enables an acquire in another thread
157 <     */
158 <    public void testAcquireReleaseInDifferentThreads() {
159 <        final Semaphore s = new Semaphore(0, false);
160 <        Thread t = new Thread(new Runnable() {
161 <                public void run() {
162 <                    try {
163 <                        s.acquire();
164 <                        s.release();
165 <                        s.release();
166 <                        s.acquire();
167 <                    } catch(InterruptedException ie){
168 <                        threadUnexpectedException();
169 <                    }
170 <                }
171 <            });
172 <        try {
173 <            t.start();
174 <            Thread.sleep(SHORT_DELAY_MS);
175 <            s.release();
176 <            s.release();
177 <            s.acquire();
178 <            s.acquire();
179 <            s.release();
180 <            t.join();
181 <        } catch( InterruptedException e){
182 <            unexpectedException();
183 <        }
184 <    }
185 <
186 <    /**
187 <     * A release in one thread enables an uninterruptible acquire in another thread
345 >     * getQueueLength reports number of waiting threads
346       */
347 <    public void testUninterruptibleAcquireReleaseInDifferentThreads() {
348 <        final Semaphore s = new Semaphore(0, false);
349 <        Thread t = new Thread(new Runnable() {
350 <                public void run() {
351 <                    s.acquireUninterruptibly();
352 <                    s.release();
353 <                    s.release();
354 <                    s.acquireUninterruptibly();
355 <                }
356 <            });
357 <        try {
358 <            t.start();
359 <            Thread.sleep(SHORT_DELAY_MS);
360 <            s.release();
361 <            s.release();
362 <            s.acquireUninterruptibly();
363 <            s.acquireUninterruptibly();
364 <            s.release();
207 <            t.join();
208 <        } catch( InterruptedException e){
209 <            unexpectedException();
210 <        }
347 >    public void testGetQueueLength()      { testGetQueueLength(false); }
348 >    public void testGetQueueLength_fair() { testGetQueueLength(true); }
349 >    public void testGetQueueLength(boolean fair) {
350 >        final PublicSemaphore lock = new PublicSemaphore(1, fair);
351 >        assertEquals(0, lock.getQueueLength());
352 >        lock.acquireUninterruptibly();
353 >        Thread t1 = newStartedThread(new InterruptedLockRunnable(lock));
354 >        waitForQueuedThread(lock, t1);
355 >        assertEquals(1, lock.getQueueLength());
356 >        Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock));
357 >        waitForQueuedThread(lock, t2);
358 >        assertEquals(2, lock.getQueueLength());
359 >        t1.interrupt();
360 >        awaitTermination(t1);
361 >        assertEquals(1, lock.getQueueLength());
362 >        lock.release();
363 >        awaitTermination(t2);
364 >        assertEquals(0, lock.getQueueLength());
365      }
366  
213
367      /**
368 <     *  A release in one thread enables a timed acquire in another thread
368 >     * getQueuedThreads includes waiting threads
369       */
370 <    public void testTimedAcquireReleaseInDifferentThreads() {
371 <        final Semaphore s = new Semaphore(1, false);
372 <        Thread t = new Thread(new Runnable() {
373 <                public void run() {
374 <                    try {
375 <                        s.release();
376 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
377 <                        s.release();
378 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
379 <
380 <                    } catch(InterruptedException ie){
381 <                        threadUnexpectedException();
382 <                    }
383 <                }
384 <            });
385 <        try {
386 <            t.start();
387 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
388 <            s.release();
389 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
390 <            s.release();
238 <            s.release();
239 <            t.join();
240 <        } catch( InterruptedException e){
241 <            unexpectedException();
242 <        }
370 >    public void testGetQueuedThreads()      { testGetQueuedThreads(false); }
371 >    public void testGetQueuedThreads_fair() { testGetQueuedThreads(true); }
372 >    public void testGetQueuedThreads(boolean fair) {
373 >        final PublicSemaphore lock = new PublicSemaphore(1, fair);
374 >        assertTrue(lock.getQueuedThreads().isEmpty());
375 >        lock.acquireUninterruptibly();
376 >        assertTrue(lock.getQueuedThreads().isEmpty());
377 >        Thread t1 = newStartedThread(new InterruptedLockRunnable(lock));
378 >        waitForQueuedThread(lock, t1);
379 >        assertTrue(lock.getQueuedThreads().contains(t1));
380 >        Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock));
381 >        waitForQueuedThread(lock, t2);
382 >        assertTrue(lock.getQueuedThreads().contains(t1));
383 >        assertTrue(lock.getQueuedThreads().contains(t2));
384 >        t1.interrupt();
385 >        awaitTermination(t1);
386 >        assertFalse(lock.getQueuedThreads().contains(t1));
387 >        assertTrue(lock.getQueuedThreads().contains(t2));
388 >        lock.release();
389 >        awaitTermination(t2);
390 >        assertTrue(lock.getQueuedThreads().isEmpty());
391      }
392  
393      /**
394 <     * A waiting acquire blocks interruptibly
395 <     */
396 <    public void testAcquire_InterruptedException() {
397 <        final Semaphore s = new Semaphore(0, false);
398 <        Thread t = new Thread(new Runnable() {
399 <                public void run() {
400 <                    try {
401 <                        s.acquire();
402 <                        threadShouldThrow();
403 <                    } catch(InterruptedException success){}
404 <                }
405 <            });
406 <        t.start();
259 <        try {
260 <            Thread.sleep(SHORT_DELAY_MS);
261 <            t.interrupt();
262 <            t.join();
263 <        } catch(InterruptedException e){
264 <            unexpectedException();
265 <        }
266 <    }
267 <    
268 <    /**
269 <     *  A waiting timed acquire blocks interruptibly
270 <     */
271 <    public void testTryAcquire_InterruptedException() {
272 <        final Semaphore s = new Semaphore(0, false);
273 <        Thread t = new Thread(new Runnable() {
274 <                public void run() {
275 <                    try {
276 <                        s.tryAcquire(MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS);
277 <                        threadShouldThrow();
278 <                    } catch(InterruptedException success){
279 <                    }
280 <                }
281 <            });
282 <        t.start();
283 <        try {
284 <            Thread.sleep(SHORT_DELAY_MS);
285 <            t.interrupt();
286 <            t.join();
287 <        } catch(InterruptedException e){
288 <            unexpectedException();
289 <        }
394 >     * drainPermits reports and removes given number of permits
395 >     */
396 >    public void testDrainPermits()      { testDrainPermits(false); }
397 >    public void testDrainPermits_fair() { testDrainPermits(true); }
398 >    public void testDrainPermits(boolean fair) {
399 >        Semaphore s = new Semaphore(0, fair);
400 >        assertEquals(0, s.availablePermits());
401 >        assertEquals(0, s.drainPermits());
402 >        s.release(10);
403 >        assertEquals(10, s.availablePermits());
404 >        assertEquals(10, s.drainPermits());
405 >        assertEquals(0, s.availablePermits());
406 >        assertEquals(0, s.drainPermits());
407      }
408  
409      /**
410 <     * getQueueLength reports number of waiting threads
410 >     * release(-N) throws IllegalArgumentException
411       */
412 <    public void testGetQueueLength() {
413 <        final Semaphore lock = new Semaphore(1, false);
414 <        Thread t1 = new Thread(new InterruptedLockRunnable(lock));
415 <        Thread t2 = new Thread(new InterruptibleLockRunnable(lock));
412 >    public void testReleaseIAE()      { testReleaseIAE(false); }
413 >    public void testReleaseIAE_fair() { testReleaseIAE(true); }
414 >    public void testReleaseIAE(boolean fair) {
415 >        Semaphore s = new Semaphore(10, fair);
416          try {
417 <            assertEquals(0, lock.getQueueLength());
418 <            lock.acquireUninterruptibly();
419 <            t1.start();
420 <            Thread.sleep(SHORT_DELAY_MS);
304 <            assertEquals(1, lock.getQueueLength());
305 <            t2.start();
306 <            Thread.sleep(SHORT_DELAY_MS);
307 <            assertEquals(2, lock.getQueueLength());
308 <            t1.interrupt();
309 <            Thread.sleep(SHORT_DELAY_MS);
310 <            assertEquals(1, lock.getQueueLength());
311 <            lock.release();
312 <            Thread.sleep(SHORT_DELAY_MS);
313 <            assertEquals(0, lock.getQueueLength());
314 <            t1.join();
315 <            t2.join();
316 <        } catch(Exception e){
317 <            unexpectedException();
318 <        }
319 <    }
417 >            s.release(-1);
418 >            shouldThrow();
419 >        } catch (IllegalArgumentException success) {}
420 >    }
421  
422      /**
423 <     * getQueuedThreads includes waiting threads
423 >     * reducePermits(-N) throws IllegalArgumentException
424       */
425 <    public void testGetQueuedThreads() {
426 <        final PublicSemaphore lock = new PublicSemaphore(1, false);
427 <        Thread t1 = new Thread(new InterruptedLockRunnable(lock));
428 <        Thread t2 = new Thread(new InterruptibleLockRunnable(lock));
425 >    public void testReducePermitsIAE()      { testReducePermitsIAE(false); }
426 >    public void testReducePermitsIAE_fair() { testReducePermitsIAE(true); }
427 >    public void testReducePermitsIAE(boolean fair) {
428 >        PublicSemaphore s = new PublicSemaphore(10, fair);
429          try {
430 <            assertTrue(lock.getQueuedThreads().isEmpty());
431 <            lock.acquireUninterruptibly();
432 <            assertTrue(lock.getQueuedThreads().isEmpty());
433 <            t1.start();
333 <            Thread.sleep(SHORT_DELAY_MS);
334 <            assertTrue(lock.getQueuedThreads().contains(t1));
335 <            t2.start();
336 <            Thread.sleep(SHORT_DELAY_MS);
337 <            assertTrue(lock.getQueuedThreads().contains(t1));
338 <            assertTrue(lock.getQueuedThreads().contains(t2));
339 <            t1.interrupt();
340 <            Thread.sleep(SHORT_DELAY_MS);
341 <            assertFalse(lock.getQueuedThreads().contains(t1));
342 <            assertTrue(lock.getQueuedThreads().contains(t2));
343 <            lock.release();
344 <            Thread.sleep(SHORT_DELAY_MS);
345 <            assertTrue(lock.getQueuedThreads().isEmpty());
346 <            t1.join();
347 <            t2.join();
348 <        } catch(Exception e){
349 <            unexpectedException();
350 <        }
351 <    }
352 <
430 >            s.reducePermits(-1);
431 >            shouldThrow();
432 >        } catch (IllegalArgumentException success) {}
433 >    }
434  
435      /**
436       * reducePermits reduces number of permits
437       */
438 <    public void testReducePermits() {
439 <        PublicSemaphore s = new PublicSemaphore(10, false);
438 >    public void testReducePermits()      { testReducePermits(false); }
439 >    public void testReducePermits_fair() { testReducePermits(true); }
440 >    public void testReducePermits(boolean fair) {
441 >        PublicSemaphore s = new PublicSemaphore(10, fair);
442 >        assertEquals(10, s.availablePermits());
443 >        s.reducePermits(0);
444          assertEquals(10, s.availablePermits());
445          s.reducePermits(1);
446          assertEquals(9, s.availablePermits());
447          s.reducePermits(10);
448          assertEquals(-1, s.availablePermits());
449 +        s.reducePermits(10);
450 +        assertEquals(-11, s.availablePermits());
451 +        s.reducePermits(0);
452 +        assertEquals(-11, s.availablePermits());
453      }
454  
455      /**
456 <     * a deserialized serialized semaphore has same number of permits
457 <     */
369 <    public void testSerialization() {
370 <        Semaphore l = new Semaphore(3, false);
371 <        try {
372 <            l.acquire();
373 <            l.release();
374 <            ByteArrayOutputStream bout = new ByteArrayOutputStream(10000);
375 <            ObjectOutputStream out = new ObjectOutputStream(new BufferedOutputStream(bout));
376 <            out.writeObject(l);
377 <            out.close();
378 <
379 <            ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());
380 <            ObjectInputStream in = new ObjectInputStream(new BufferedInputStream(bin));
381 <            Semaphore r = (Semaphore) in.readObject();
382 <            assertEquals(3, r.availablePermits());
383 <            assertFalse(r.isFair());
384 <            r.acquire();
385 <            r.release();
386 <        } catch(Exception e){
387 <            unexpectedException();
388 <        }
389 <    }
390 <
391 <
392 <    /**
393 <     * Zero, negative, and positive initial values are allowed in constructor
394 <     */
395 <    public void testConstructor_fair() {
396 <        Semaphore s0 = new Semaphore(0, true);
397 <        assertEquals(0, s0.availablePermits());
398 <        assertTrue(s0.isFair());
399 <        Semaphore s1 = new Semaphore(-1, true);
400 <        assertEquals(-1, s1.availablePermits());
401 <        Semaphore s2 = new Semaphore(-1, true);
402 <        assertEquals(-1, s2.availablePermits());
403 <    }
404 <
405 <    /**
406 <     * tryAcquire succeeds when sufficent permits, else fails
407 <     */
408 <    public void testTryAcquireInSameThread_fair() {
409 <        Semaphore s = new Semaphore(2, true);
410 <        assertEquals(2, s.availablePermits());
411 <        assertTrue(s.tryAcquire());
412 <        assertTrue(s.tryAcquire());
413 <        assertEquals(0, s.availablePermits());
414 <        assertFalse(s.tryAcquire());
415 <    }
416 <
417 <    /**
418 <     * tryAcquire(n) succeeds when sufficent permits, else fails
419 <     */
420 <    public void testTryAcquireNInSameThread_fair() {
421 <        Semaphore s = new Semaphore(2, true);
422 <        assertEquals(2, s.availablePermits());
423 <        assertTrue(s.tryAcquire(2));
424 <        assertEquals(0, s.availablePermits());
425 <        assertFalse(s.tryAcquire());
426 <    }
427 <
428 <    /**
429 <     * Acquire and release of semaphore succeed if initially available
456 >     * a reserialized semaphore has same number of permits and
457 >     * fairness, but no queued threads
458       */
459 <    public void testAcquireReleaseInSameThread_fair() {
460 <        Semaphore s = new Semaphore(1, true);
459 >    public void testSerialization()      { testSerialization(false); }
460 >    public void testSerialization_fair() { testSerialization(true); }
461 >    public void testSerialization(boolean fair) {
462          try {
463 +            Semaphore s = new Semaphore(3, fair);
464              s.acquire();
435            s.release();
436            s.acquire();
437            s.release();
438            s.acquire();
439            s.release();
440            s.acquire();
441            s.release();
465              s.acquire();
466              s.release();
444            assertEquals(1, s.availablePermits());
445        } catch( InterruptedException e){
446            unexpectedException();
447        }
448    }
449
450    /**
451     * Acquire(n) and release(n) of semaphore succeed if initially available
452     */
453    public void testAcquireReleaseNInSameThread_fair() {
454        Semaphore s = new Semaphore(1, true);
455        try {
456            s.release(1);
457            s.acquire(1);
458            s.release(2);
459            s.acquire(2);
460            s.release(3);
461            s.acquire(3);
462            s.release(4);
463            s.acquire(4);
464            s.release(5);
465            s.acquire(5);
466            assertEquals(1, s.availablePermits());
467        } catch( InterruptedException e){
468            unexpectedException();
469        }
470    }
467  
468 <    /**
469 <     * Acquire(n) and release(n) of semaphore succeed if initially available
470 <     */
471 <    public void testAcquireUninterruptiblyReleaseNInSameThread_fair() {
472 <        Semaphore s = new Semaphore(1, true);
473 <        try {
474 <            s.release(1);
475 <            s.acquireUninterruptibly(1);
476 <            s.release(2);
477 <            s.acquireUninterruptibly(2);
478 <            s.release(3);
479 <            s.acquireUninterruptibly(3);
480 <            s.release(4);
481 <            s.acquireUninterruptibly(4);
482 <            s.release(5);
483 <            s.acquireUninterruptibly(5);
484 <            assertEquals(1, s.availablePermits());
485 <        } finally {
468 >            Semaphore clone = serialClone(s);
469 >            assertEquals(fair, s.isFair());
470 >            assertEquals(fair, clone.isFair());
471 >            assertEquals(2, s.availablePermits());
472 >            assertEquals(2, clone.availablePermits());
473 >            clone.acquire();
474 >            clone.acquire();
475 >            clone.release();
476 >            assertEquals(2, s.availablePermits());
477 >            assertEquals(1, clone.availablePermits());
478 >            assertFalse(s.hasQueuedThreads());
479 >            assertFalse(clone.hasQueuedThreads());
480 >        } catch (InterruptedException e) { threadUnexpectedException(e); }
481 >
482 >        {
483 >            PublicSemaphore s = new PublicSemaphore(0, fair);
484 >            Thread t = newStartedThread(new InterruptibleLockRunnable(s));
485 >            // waitForQueuedThreads(s); // suffers from "flicker", so ...
486 >            waitForQueuedThread(s, t);  // ... we use this instead
487 >            PublicSemaphore clone = serialClone(s);
488 >            assertEquals(fair, s.isFair());
489 >            assertEquals(fair, clone.isFair());
490 >            assertEquals(0, s.availablePermits());
491 >            assertEquals(0, clone.availablePermits());
492 >            assertTrue(s.hasQueuedThreads());
493 >            assertFalse(clone.hasQueuedThreads());
494 >            s.release();
495 >            awaitTermination(t);
496 >            assertFalse(s.hasQueuedThreads());
497 >            assertFalse(clone.hasQueuedThreads());
498          }
499      }
500  
501      /**
502 <     * release(n) in one thread enables timed acquire(n) in another thread
503 <     */
504 <    public void testTimedAcquireReleaseNInSameThread_fair() {
505 <        Semaphore s = new Semaphore(1, true);
506 <        try {
507 <            s.release(1);
508 <            assertTrue(s.tryAcquire(1, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
509 <            s.release(2);
510 <            assertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
511 <            s.release(3);
512 <            assertTrue(s.tryAcquire(3, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
513 <            s.release(4);
514 <            assertTrue(s.tryAcquire(4, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
515 <            s.release(5);
508 <            assertTrue(s.tryAcquire(5, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
509 <            assertEquals(1, s.availablePermits());
510 <        } catch( InterruptedException e){
511 <            unexpectedException();
512 <        }
502 >     * tryAcquire(n) succeeds when sufficient permits, else fails
503 >     */
504 >    public void testTryAcquireNInSameThread()      { testTryAcquireNInSameThread(false); }
505 >    public void testTryAcquireNInSameThread_fair() { testTryAcquireNInSameThread(true); }
506 >    public void testTryAcquireNInSameThread(boolean fair) {
507 >        Semaphore s = new Semaphore(2, fair);
508 >        assertEquals(2, s.availablePermits());
509 >        assertFalse(s.tryAcquire(3));
510 >        assertEquals(2, s.availablePermits());
511 >        assertTrue(s.tryAcquire(2));
512 >        assertEquals(0, s.availablePermits());
513 >        assertFalse(s.tryAcquire(1));
514 >        assertFalse(s.tryAcquire(2));
515 >        assertEquals(0, s.availablePermits());
516      }
517  
518      /**
519 <     * release in one thread enables timed acquire in another thread
519 >     * acquire succeeds if permits available
520       */
521 <    public void testTimedAcquireReleaseInSameThread_fair() {
522 <        Semaphore s = new Semaphore(1, true);
523 <        try {
524 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
525 <            s.release();
526 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
527 <            s.release();
528 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
529 <            s.release();
530 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
531 <            s.release();
532 <            assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
533 <            s.release();
521 >    public void testReleaseAcquireSameThread_acquire()       { testReleaseAcquireSameThread(false, AcquireMethod.acquire); }
522 >    public void testReleaseAcquireSameThread_acquire_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.acquire); }
523 >    public void testReleaseAcquireSameThread_acquireN()      { testReleaseAcquireSameThread(false, AcquireMethod.acquireN); }
524 >    public void testReleaseAcquireSameThread_acquireN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.acquireN); }
525 >    public void testReleaseAcquireSameThread_acquireUninterruptibly()       { testReleaseAcquireSameThread(false, AcquireMethod.acquireUninterruptibly); }
526 >    public void testReleaseAcquireSameThread_acquireUninterruptibly_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.acquireUninterruptibly); }
527 >    public void testReleaseAcquireSameThread_acquireUninterruptiblyN()      { testReleaseAcquireSameThread(false, AcquireMethod.acquireUninterruptibly); }
528 >    public void testReleaseAcquireSameThread_acquireUninterruptiblyN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.acquireUninterruptibly); }
529 >    public void testReleaseAcquireSameThread_tryAcquire()       { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquire); }
530 >    public void testReleaseAcquireSameThread_tryAcquire_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquire); }
531 >    public void testReleaseAcquireSameThread_tryAcquireN()      { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireN); }
532 >    public void testReleaseAcquireSameThread_tryAcquireN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireN); }
533 >    public void testReleaseAcquireSameThread_tryAcquireTimed()       { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireTimed); }
534 >    public void testReleaseAcquireSameThread_tryAcquireTimed_fair()  { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireTimed); }
535 >    public void testReleaseAcquireSameThread_tryAcquireTimedN()      { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireTimedN); }
536 >    public void testReleaseAcquireSameThread_tryAcquireTimedN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireTimedN); }
537 >    public void testReleaseAcquireSameThread(boolean fair,
538 >                                             final AcquireMethod acquirer) {
539 >        Semaphore s = new Semaphore(1, fair);
540 >        for (int i = 1; i < 6; i++) {
541 >            s.release(i);
542 >            assertEquals(1 + i, s.availablePermits());
543 >            try {
544 >                acquirer.acquire(s, i);
545 >            } catch (InterruptedException e) { threadUnexpectedException(e); }
546              assertEquals(1, s.availablePermits());
532        } catch( InterruptedException e){
533            unexpectedException();
547          }
548      }
549  
550      /**
551 <     * A release in one thread enables an acquire in another thread
551 >     * release in one thread enables acquire in another thread
552       */
553 <    public void testAcquireReleaseInDifferentThreads_fair() {
554 <        final Semaphore s = new Semaphore(0, true);
555 <        Thread t = new Thread(new Runnable() {
556 <                public void run() {
557 <                    try {
558 <                        s.acquire();
559 <                        s.acquire();
560 <                        s.acquire();
561 <                        s.acquire();
562 <                    } catch(InterruptedException ie){
563 <                        threadUnexpectedException();
564 <                    }
565 <                }
566 <            });
567 <        try {
568 <            t.start();
569 <            Thread.sleep(SHORT_DELAY_MS);
570 <            s.release();
571 <            s.release();
572 <            s.release();
573 <            s.release();
574 <            s.release();
575 <            s.release();
576 <            t.join();
577 <            assertEquals(2, s.availablePermits());
578 <        } catch( InterruptedException e){
579 <            unexpectedException();
553 >    public void testReleaseAcquireDifferentThreads_acquire()       { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquire); }
554 >    public void testReleaseAcquireDifferentThreads_acquire_fair()  { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquire); }
555 >    public void testReleaseAcquireDifferentThreads_acquireN()      { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireN); }
556 >    public void testReleaseAcquireDifferentThreads_acquireN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireN); }
557 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptibly()       { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireUninterruptibly); }
558 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptibly_fair()  { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireUninterruptibly); }
559 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptiblyN()      { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireUninterruptibly); }
560 >    public void testReleaseAcquireDifferentThreads_acquireUninterruptiblyN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireUninterruptibly); }
561 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimed()       { testReleaseAcquireDifferentThreads(false, AcquireMethod.tryAcquireTimed); }
562 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimed_fair()  { testReleaseAcquireDifferentThreads(true, AcquireMethod.tryAcquireTimed); }
563 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimedN()      { testReleaseAcquireDifferentThreads(false, AcquireMethod.tryAcquireTimedN); }
564 >    public void testReleaseAcquireDifferentThreads_tryAcquireTimedN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.tryAcquireTimedN); }
565 >    public void testReleaseAcquireDifferentThreads(boolean fair,
566 >                                                   final AcquireMethod acquirer) {
567 >        final Semaphore s = new Semaphore(0, fair);
568 >        final int rounds = 4;
569 >        long startTime = System.nanoTime();
570 >        Thread t = newStartedThread(new CheckedRunnable() {
571 >            public void realRun() throws InterruptedException {
572 >                for (int i = 0; i < rounds; i++) {
573 >                    assertFalse(s.hasQueuedThreads());
574 >                    if (i % 2 == 0)
575 >                        acquirer.acquire(s);
576 >                    else
577 >                        acquirer.acquire(s, 3);
578 >                }}});
579 >
580 >        for (int i = 0; i < rounds; i++) {
581 >            while (! (s.availablePermits() == 0 && s.hasQueuedThreads()))
582 >                Thread.yield();
583 >            assertTrue(t.isAlive());
584 >            if (i % 2 == 0)
585 >                s.release();
586 >            else
587 >                s.release(3);
588          }
589 +        awaitTermination(t);
590 +        assertEquals(0, s.availablePermits());
591 +        assertTrue(millisElapsedSince(startTime) < LONG_DELAY_MS);
592      }
593  
594      /**
595 <     * release(n) in one thread enables acquire(n) in another thread
595 >     * fair locks are strictly FIFO
596       */
597 <    public void testAcquireReleaseNInDifferentThreads_fair() {
598 <        final Semaphore s = new Semaphore(0, true);
599 <        Thread t = new Thread(new Runnable() {
600 <                public void run() {
601 <                    try {
602 <                        s.acquire(2);
603 <                        s.acquire(2);
604 <                        s.release(4);
605 <                    } catch(InterruptedException ie){
606 <                        threadUnexpectedException();
607 <                    }
608 <                }
609 <            });
610 <        try {
611 <            t.start();
612 <            Thread.sleep(SHORT_DELAY_MS);
613 <            s.release(6);
614 <            s.acquire(2);
615 <            s.acquire(2);
616 <            s.release(2);
617 <            t.join();
618 <        } catch( InterruptedException e){
619 <            unexpectedException();
620 <        }
621 <    }
622 <
623 <
624 <
625 <    /**
626 <     * release in one thread enables timed acquire in another thread
627 <     */
628 <    public void testTimedAcquireReleaseInDifferentThreads_fair() {
629 <        final Semaphore s = new Semaphore(1, true);
630 <        Thread t = new Thread(new Runnable() {
631 <                public void run() {
608 <                    try {
609 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
610 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
611 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
612 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
613 <                        threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
614 <
615 <                    } catch(InterruptedException ie){
616 <                        threadUnexpectedException();
617 <                    }
618 <                }
619 <            });
620 <        t.start();
621 <        try {
622 <            s.release();
623 <            s.release();
624 <            s.release();
625 <            s.release();
626 <            s.release();
627 <            t.join();
628 <        } catch( InterruptedException e){
629 <            unexpectedException();
630 <        }
631 <    }
632 <
633 <    /**
634 <     * release(n) in one thread enables timed acquire(n) in another thread
635 <     */
636 <    public void testTimedAcquireReleaseNInDifferentThreads_fair() {
637 <        final Semaphore s = new Semaphore(2, true);
638 <        Thread t = new Thread(new Runnable() {
639 <                public void run() {
640 <                    try {
641 <                        threadAssertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
642 <                        s.release(2);
643 <                        threadAssertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
644 <                        s.release(2);
645 <                    } catch(InterruptedException ie){
646 <                        threadUnexpectedException();
647 <                    }
648 <                }
649 <            });
650 <        t.start();
651 <        try {
652 <            assertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
653 <            s.release(2);
654 <            assertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
655 <            s.release(2);
656 <            t.join();
657 <        } catch( InterruptedException e){
658 <            unexpectedException();
659 <        }
660 <    }
661 <
662 <    /**
663 <     * A waiting acquire blocks interruptibly
664 <     */
665 <    public void testAcquire_InterruptedException_fair() {
666 <        final Semaphore s = new Semaphore(0, true);
667 <        Thread t = new Thread(new Runnable() {
668 <                public void run() {
669 <                    try {
670 <                        s.acquire();
671 <                        threadShouldThrow();
672 <                    } catch(InterruptedException success){}
673 <                }
674 <            });
675 <        t.start();
676 <        try {
677 <            Thread.sleep(SHORT_DELAY_MS);
678 <            t.interrupt();
679 <            t.join();
680 <        } catch(InterruptedException e){
681 <            unexpectedException();
682 <        }
683 <    }
684 <
685 <    /**
686 <     * A waiting acquire(n) blocks interruptibly
687 <     */
688 <    public void testAcquireN_InterruptedException_fair() {
689 <        final Semaphore s = new Semaphore(2, true);
690 <        Thread t = new Thread(new Runnable() {
691 <                public void run() {
692 <                    try {
693 <                        s.acquire(3);
694 <                        threadShouldThrow();
695 <                    } catch(InterruptedException success){}
696 <                }
697 <            });
698 <        t.start();
699 <        try {
700 <            Thread.sleep(SHORT_DELAY_MS);
701 <            t.interrupt();
702 <            t.join();
703 <        } catch(InterruptedException e){
704 <            unexpectedException();
705 <        }
706 <    }
707 <    
708 <    /**
709 <     *  A waiting tryAcquire blocks interruptibly
710 <     */
711 <    public void testTryAcquire_InterruptedException_fair() {
712 <        final Semaphore s = new Semaphore(0, true);
713 <        Thread t = new Thread(new Runnable() {
714 <                public void run() {
715 <                    try {
716 <                        s.tryAcquire(MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS);
717 <                        threadShouldThrow();
718 <                    } catch(InterruptedException success){
719 <                    }
720 <                }
721 <            });
722 <        t.start();
723 <        try {
724 <            Thread.sleep(SHORT_DELAY_MS);
725 <            t.interrupt();
726 <            t.join();
727 <        } catch(InterruptedException e){
728 <            unexpectedException();
729 <        }
730 <    }
731 <
732 <    /**
733 <     *  A waiting tryAcquire(n) blocks interruptibly
734 <     */
735 <    public void testTryAcquireN_InterruptedException_fair() {
736 <        final Semaphore s = new Semaphore(1, true);
737 <        Thread t = new Thread(new Runnable() {
738 <                public void run() {
739 <                    try {
740 <                        s.tryAcquire(4, MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS);
741 <                        threadShouldThrow();
742 <                    } catch(InterruptedException success){
743 <                    }
744 <                }
745 <            });
746 <        t.start();
747 <        try {
748 <            Thread.sleep(SHORT_DELAY_MS);
749 <            t.interrupt();
750 <            t.join();
751 <        } catch(InterruptedException e){
752 <            unexpectedException();
753 <        }
597 >    public void testFairLocksFifo() {
598 >        final PublicSemaphore s = new PublicSemaphore(1, true);
599 >        final CountDownLatch pleaseRelease = new CountDownLatch(1);
600 >        Thread t1 = newStartedThread(new CheckedRunnable() {
601 >            public void realRun() throws InterruptedException {
602 >                // Will block; permits are available, but not three
603 >                s.acquire(3);
604 >            }});
605 >
606 >        waitForQueuedThread(s, t1);
607 >
608 >        Thread t2 = newStartedThread(new CheckedRunnable() {
609 >            public void realRun() throws InterruptedException {
610 >                // Will fail, even though 1 permit is available
611 >                assertFalse(s.tryAcquire(0L, MILLISECONDS));
612 >                assertFalse(s.tryAcquire(1, 0L, MILLISECONDS));
613 >
614 >                // untimed tryAcquire will barge and succeed
615 >                assertTrue(s.tryAcquire());
616 >                s.release(2);
617 >                assertTrue(s.tryAcquire(2));
618 >                s.release();
619 >
620 >                pleaseRelease.countDown();
621 >                // Will queue up behind t1, even though 1 permit is available
622 >                s.acquire();
623 >            }});
624 >
625 >        await(pleaseRelease);
626 >        waitForQueuedThread(s, t2);
627 >        s.release(2);
628 >        awaitTermination(t1);
629 >        assertTrue(t2.isAlive());
630 >        s.release();
631 >        awaitTermination(t2);
632      }
633  
634      /**
635 <     * getQueueLength reports number of waiting threads
636 <     */
637 <    public void testGetQueueLength_fair() {
638 <        final Semaphore lock = new Semaphore(1, true);
639 <        Thread t1 = new Thread(new InterruptedLockRunnable(lock));
640 <        Thread t2 = new Thread(new InterruptibleLockRunnable(lock));
641 <        try {
642 <            assertEquals(0, lock.getQueueLength());
643 <            lock.acquireUninterruptibly();
644 <            t1.start();
645 <            Thread.sleep(SHORT_DELAY_MS);
646 <            assertEquals(1, lock.getQueueLength());
647 <            t2.start();
770 <            Thread.sleep(SHORT_DELAY_MS);
771 <            assertEquals(2, lock.getQueueLength());
772 <            t1.interrupt();
773 <            Thread.sleep(SHORT_DELAY_MS);
774 <            assertEquals(1, lock.getQueueLength());
775 <            lock.release();
776 <            Thread.sleep(SHORT_DELAY_MS);
777 <            assertEquals(0, lock.getQueueLength());
778 <            t1.join();
779 <            t2.join();
780 <        } catch(Exception e){
781 <            unexpectedException();
782 <        }
783 <    }
784 <
785 <
786 <    /**
787 <     * a deserialized serialized semaphore has same number of permits
788 <     */
789 <    public void testSerialization_fair() {
790 <        Semaphore l = new Semaphore(3, true);
791 <
792 <        try {
793 <            l.acquire();
794 <            l.release();
795 <            ByteArrayOutputStream bout = new ByteArrayOutputStream(10000);
796 <            ObjectOutputStream out = new ObjectOutputStream(new BufferedOutputStream(bout));
797 <            out.writeObject(l);
798 <            out.close();
799 <
800 <            ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());
801 <            ObjectInputStream in = new ObjectInputStream(new BufferedInputStream(bin));
802 <            Semaphore r = (Semaphore) in.readObject();
803 <            assertEquals(3, r.availablePermits());
804 <            assertTrue(r.isFair());
805 <            r.acquire();
806 <            r.release();
807 <        } catch(Exception e){
808 <            unexpectedException();
809 <        }
635 >     * toString indicates current number of permits
636 >     */
637 >    public void testToString()      { testToString(false); }
638 >    public void testToString_fair() { testToString(true); }
639 >    public void testToString(boolean fair) {
640 >        PublicSemaphore s = new PublicSemaphore(0, fair);
641 >        assertTrue(s.toString().contains("Permits = 0"));
642 >        s.release();
643 >        assertTrue(s.toString().contains("Permits = 1"));
644 >        s.release(2);
645 >        assertTrue(s.toString().contains("Permits = 3"));
646 >        s.reducePermits(5);
647 >        assertTrue(s.toString().contains("Permits = -2"));
648      }
649  
812
650   }

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