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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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* Other contributors include Andrew Wright, Jeffrey Hayes, |
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* Pat Fisher, Mike Judd. |
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*/ |
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|
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import static java.util.concurrent.TimeUnit.MILLISECONDS; |
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|
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import java.util.Collection; |
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import java.util.concurrent.CountDownLatch; |
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import java.util.concurrent.Semaphore; |
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|
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import junit.framework.AssertionFailedError; |
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import junit.framework.Test; |
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import junit.framework.TestSuite; |
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|
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public class SemaphoreTest extends JSR166TestCase { |
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public static void main(String[] args) { |
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main(suite(), args); |
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} |
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public static Test suite() { |
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return new TestSuite(SemaphoreTest.class); |
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} |
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|
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/** |
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* Subclass to expose protected methods |
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*/ |
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static class PublicSemaphore extends Semaphore { |
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PublicSemaphore(int permits) { super(permits); } |
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PublicSemaphore(int permits, boolean fair) { super(permits, fair); } |
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public Collection<Thread> getQueuedThreads() { |
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return super.getQueuedThreads(); |
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} |
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public boolean hasQueuedThread(Thread t) { |
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return super.getQueuedThreads().contains(t); |
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} |
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public void reducePermits(int reduction) { |
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super.reducePermits(reduction); |
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} |
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} |
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|
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/** |
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* A runnable calling acquire |
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*/ |
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class InterruptibleLockRunnable extends CheckedRunnable { |
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final Semaphore lock; |
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InterruptibleLockRunnable(Semaphore s) { lock = s; } |
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public void realRun() { |
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try { |
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lock.acquire(); |
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} |
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catch (InterruptedException ignored) {} |
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} |
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} |
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|
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/** |
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* A runnable calling acquire that expects to be interrupted |
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*/ |
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class InterruptedLockRunnable extends CheckedInterruptedRunnable { |
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final Semaphore lock; |
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InterruptedLockRunnable(Semaphore s) { lock = s; } |
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public void realRun() throws InterruptedException { |
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lock.acquire(); |
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} |
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} |
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|
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/** |
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* Spin-waits until s.hasQueuedThread(t) becomes true. |
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*/ |
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void waitForQueuedThread(PublicSemaphore s, Thread t) { |
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long startTime = System.nanoTime(); |
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while (!s.hasQueuedThread(t)) { |
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if (millisElapsedSince(startTime) > LONG_DELAY_MS) |
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throw new AssertionFailedError("timed out"); |
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Thread.yield(); |
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} |
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assertTrue(s.hasQueuedThreads()); |
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assertTrue(t.isAlive()); |
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} |
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|
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/** |
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* Spin-waits until s.hasQueuedThreads() becomes true. |
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*/ |
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void waitForQueuedThreads(Semaphore s) { |
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long startTime = System.nanoTime(); |
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while (!s.hasQueuedThreads()) { |
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if (millisElapsedSince(startTime) > LONG_DELAY_MS) |
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throw new AssertionFailedError("timed out"); |
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Thread.yield(); |
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} |
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} |
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|
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enum AcquireMethod { |
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acquire() { |
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void acquire(Semaphore s) throws InterruptedException { |
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s.acquire(); |
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} |
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}, |
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acquireN() { |
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void acquire(Semaphore s, int permits) throws InterruptedException { |
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s.acquire(permits); |
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} |
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}, |
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acquireUninterruptibly() { |
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void acquire(Semaphore s) { |
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s.acquireUninterruptibly(); |
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} |
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}, |
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acquireUninterruptiblyN() { |
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void acquire(Semaphore s, int permits) { |
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s.acquireUninterruptibly(permits); |
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} |
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}, |
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tryAcquire() { |
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void acquire(Semaphore s) { |
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assertTrue(s.tryAcquire()); |
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} |
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}, |
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tryAcquireN() { |
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void acquire(Semaphore s, int permits) { |
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assertTrue(s.tryAcquire(permits)); |
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} |
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}, |
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tryAcquireTimed() { |
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void acquire(Semaphore s) throws InterruptedException { |
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assertTrue(s.tryAcquire(2 * LONG_DELAY_MS, MILLISECONDS)); |
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} |
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}, |
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tryAcquireTimedN { |
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void acquire(Semaphore s, int permits) throws InterruptedException { |
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assertTrue(s.tryAcquire(permits, 2 * LONG_DELAY_MS, MILLISECONDS)); |
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} |
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}; |
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|
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// Intentionally meta-circular |
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|
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/** Acquires 1 permit. */ |
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void acquire(Semaphore s) throws InterruptedException { |
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acquire(s, 1); |
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} |
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/** Acquires the given number of permits. */ |
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void acquire(Semaphore s, int permits) throws InterruptedException { |
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for (int i = 0; i < permits; i++) |
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acquire(s); |
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} |
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} |
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|
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/** |
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* Zero, negative, and positive initial values are allowed in constructor |
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*/ |
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public void testConstructor() { testConstructor(false); } |
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public void testConstructor_fair() { testConstructor(true); } |
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public void testConstructor(boolean fair) { |
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for (int permits : new int[] { -42, -1, 0, 1, 42 }) { |
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Semaphore s = new Semaphore(permits, fair); |
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assertEquals(permits, s.availablePermits()); |
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assertEquals(fair, s.isFair()); |
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} |
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} |
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|
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/** |
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* Constructor without fairness argument behaves as nonfair |
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*/ |
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public void testConstructorDefaultsToNonFair() { |
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for (int permits : new int[] { -42, -1, 0, 1, 42 }) { |
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Semaphore s = new Semaphore(permits); |
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assertEquals(permits, s.availablePermits()); |
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assertFalse(s.isFair()); |
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} |
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} |
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|
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/** |
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* tryAcquire succeeds when sufficient permits, else fails |
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*/ |
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public void testTryAcquireInSameThread() { testTryAcquireInSameThread(false); } |
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public void testTryAcquireInSameThread_fair() { testTryAcquireInSameThread(true); } |
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public void testTryAcquireInSameThread(boolean fair) { |
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Semaphore s = new Semaphore(2, fair); |
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assertEquals(2, s.availablePermits()); |
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assertTrue(s.tryAcquire()); |
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assertTrue(s.tryAcquire()); |
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assertEquals(0, s.availablePermits()); |
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assertFalse(s.tryAcquire()); |
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assertFalse(s.tryAcquire()); |
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assertEquals(0, s.availablePermits()); |
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} |
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|
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/** |
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* timed tryAcquire times out |
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*/ |
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public void testTryAcquire_timeout() { testTryAcquire_timeout(false); } |
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public void testTryAcquire_timeout_fair() { testTryAcquire_timeout(true); } |
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public void testTryAcquire_timeout(boolean fair) { |
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Semaphore s = new Semaphore(0, fair); |
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long startTime = System.nanoTime(); |
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try { assertFalse(s.tryAcquire(timeoutMillis(), MILLISECONDS)); } |
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catch (InterruptedException e) { threadUnexpectedException(e); } |
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assertTrue(millisElapsedSince(startTime) >= timeoutMillis()); |
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} |
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|
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/** |
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* timed tryAcquire(N) times out |
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*/ |
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public void testTryAcquireN_timeout() { testTryAcquireN_timeout(false); } |
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public void testTryAcquireN_timeout_fair() { testTryAcquireN_timeout(true); } |
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public void testTryAcquireN_timeout(boolean fair) { |
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Semaphore s = new Semaphore(2, fair); |
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long startTime = System.nanoTime(); |
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try { assertFalse(s.tryAcquire(3, timeoutMillis(), MILLISECONDS)); } |
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catch (InterruptedException e) { threadUnexpectedException(e); } |
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assertTrue(millisElapsedSince(startTime) >= timeoutMillis()); |
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} |
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|
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/** |
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* acquire(), acquire(N), timed tryAcquired, timed tryAcquire(N) |
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* are interruptible |
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*/ |
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public void testInterruptible_acquire() { testInterruptible(false, AcquireMethod.acquire); } |
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public void testInterruptible_acquire_fair() { testInterruptible(true, AcquireMethod.acquire); } |
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public void testInterruptible_acquireN() { testInterruptible(false, AcquireMethod.acquireN); } |
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public void testInterruptible_acquireN_fair() { testInterruptible(true, AcquireMethod.acquireN); } |
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public void testInterruptible_tryAcquireTimed() { testInterruptible(false, AcquireMethod.tryAcquireTimed); } |
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public void testInterruptible_tryAcquireTimed_fair() { testInterruptible(true, AcquireMethod.tryAcquireTimed); } |
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public void testInterruptible_tryAcquireTimedN() { testInterruptible(false, AcquireMethod.tryAcquireTimedN); } |
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public void testInterruptible_tryAcquireTimedN_fair() { testInterruptible(true, AcquireMethod.tryAcquireTimedN); } |
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public void testInterruptible(boolean fair, final AcquireMethod acquirer) { |
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final PublicSemaphore s = new PublicSemaphore(0, fair); |
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final Semaphore pleaseInterrupt = new Semaphore(0, fair); |
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Thread t = newStartedThread(new CheckedRunnable() { |
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public void realRun() { |
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// Interrupt before acquire |
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Thread.currentThread().interrupt(); |
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try { |
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acquirer.acquire(s); |
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shouldThrow(); |
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} catch (InterruptedException success) {} |
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|
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// Interrupt during acquire |
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try { |
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acquirer.acquire(s); |
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shouldThrow(); |
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} catch (InterruptedException success) {} |
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|
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// Interrupt before acquire(N) |
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Thread.currentThread().interrupt(); |
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try { |
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acquirer.acquire(s, 3); |
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shouldThrow(); |
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} catch (InterruptedException success) {} |
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|
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pleaseInterrupt.release(); |
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|
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// Interrupt during acquire(N) |
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try { |
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acquirer.acquire(s, 3); |
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shouldThrow(); |
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} catch (InterruptedException success) {} |
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}}); |
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|
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waitForQueuedThread(s, t); |
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t.interrupt(); |
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await(pleaseInterrupt); |
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waitForQueuedThread(s, t); |
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t.interrupt(); |
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awaitTermination(t); |
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} |
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|
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/** |
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* acquireUninterruptibly(), acquireUninterruptibly(N) are |
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* uninterruptible |
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*/ |
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public void testUninterruptible_acquireUninterruptibly() { testUninterruptible(false, AcquireMethod.acquireUninterruptibly); } |
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public void testUninterruptible_acquireUninterruptibly_fair() { testUninterruptible(true, AcquireMethod.acquireUninterruptibly); } |
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public void testUninterruptible_acquireUninterruptiblyN() { testUninterruptible(false, AcquireMethod.acquireUninterruptiblyN); } |
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public void testUninterruptible_acquireUninterruptiblyN_fair() { testUninterruptible(true, AcquireMethod.acquireUninterruptiblyN); } |
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public void testUninterruptible(boolean fair, final AcquireMethod acquirer) { |
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final PublicSemaphore s = new PublicSemaphore(0, fair); |
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final Semaphore pleaseInterrupt = new Semaphore(-1, fair); |
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|
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Thread t1 = newStartedThread(new CheckedRunnable() { |
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public void realRun() throws InterruptedException { |
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// Interrupt before acquire |
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pleaseInterrupt.release(); |
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Thread.currentThread().interrupt(); |
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acquirer.acquire(s); |
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assertTrue(Thread.interrupted()); |
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}}); |
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|
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Thread t2 = newStartedThread(new CheckedRunnable() { |
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public void realRun() throws InterruptedException { |
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// Interrupt during acquire |
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pleaseInterrupt.release(); |
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acquirer.acquire(s); |
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assertTrue(Thread.interrupted()); |
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}}); |
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|
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await(pleaseInterrupt); |
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waitForQueuedThread(s, t1); |
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waitForQueuedThread(s, t2); |
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t2.interrupt(); |
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|
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assertThreadBlocks(t1, Thread.State.WAITING); |
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assertThreadBlocks(t2, Thread.State.WAITING); |
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|
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s.release(2); |
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|
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awaitTermination(t1); |
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awaitTermination(t2); |
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} |
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|
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/** |
314 |
* hasQueuedThreads reports whether there are waiting threads |
315 |
*/ |
316 |
public void testHasQueuedThreads() { testHasQueuedThreads(false); } |
317 |
public void testHasQueuedThreads_fair() { testHasQueuedThreads(true); } |
318 |
public void testHasQueuedThreads(boolean fair) { |
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final PublicSemaphore lock = new PublicSemaphore(1, fair); |
320 |
assertFalse(lock.hasQueuedThreads()); |
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lock.acquireUninterruptibly(); |
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Thread t1 = newStartedThread(new InterruptedLockRunnable(lock)); |
323 |
waitForQueuedThread(lock, t1); |
324 |
assertTrue(lock.hasQueuedThreads()); |
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Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock)); |
326 |
waitForQueuedThread(lock, t2); |
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assertTrue(lock.hasQueuedThreads()); |
328 |
t1.interrupt(); |
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awaitTermination(t1); |
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assertTrue(lock.hasQueuedThreads()); |
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lock.release(); |
332 |
awaitTermination(t2); |
333 |
assertFalse(lock.hasQueuedThreads()); |
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} |
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|
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/** |
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* getQueueLength reports number of waiting threads |
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*/ |
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public void testGetQueueLength() { testGetQueueLength(false); } |
340 |
public void testGetQueueLength_fair() { testGetQueueLength(true); } |
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public void testGetQueueLength(boolean fair) { |
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final PublicSemaphore lock = new PublicSemaphore(1, fair); |
343 |
assertEquals(0, lock.getQueueLength()); |
344 |
lock.acquireUninterruptibly(); |
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Thread t1 = newStartedThread(new InterruptedLockRunnable(lock)); |
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waitForQueuedThread(lock, t1); |
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assertEquals(1, lock.getQueueLength()); |
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Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock)); |
349 |
waitForQueuedThread(lock, t2); |
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assertEquals(2, lock.getQueueLength()); |
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t1.interrupt(); |
352 |
awaitTermination(t1); |
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assertEquals(1, lock.getQueueLength()); |
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lock.release(); |
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awaitTermination(t2); |
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assertEquals(0, lock.getQueueLength()); |
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} |
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|
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/** |
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* getQueuedThreads includes waiting threads |
361 |
*/ |
362 |
public void testGetQueuedThreads() { testGetQueuedThreads(false); } |
363 |
public void testGetQueuedThreads_fair() { testGetQueuedThreads(true); } |
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public void testGetQueuedThreads(boolean fair) { |
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final PublicSemaphore lock = new PublicSemaphore(1, fair); |
366 |
assertTrue(lock.getQueuedThreads().isEmpty()); |
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lock.acquireUninterruptibly(); |
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assertTrue(lock.getQueuedThreads().isEmpty()); |
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Thread t1 = newStartedThread(new InterruptedLockRunnable(lock)); |
370 |
waitForQueuedThread(lock, t1); |
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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)); |
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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()); |
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} |
384 |
|
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/** |
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) { |
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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 |
* release(-N) throws IllegalArgumentException |
403 |
*/ |
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 |
s.release(-1); |
410 |
shouldThrow(); |
411 |
} catch (IllegalArgumentException success) {} |
412 |
} |
413 |
|
414 |
/** |
415 |
* reducePermits(-N) throws IllegalArgumentException |
416 |
*/ |
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 |
s.reducePermits(-1); |
423 |
shouldThrow(); |
424 |
} catch (IllegalArgumentException success) {} |
425 |
} |
426 |
|
427 |
/** |
428 |
* reducePermits reduces number of permits |
429 |
*/ |
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 reserialized semaphore has same number of permits and |
449 |
* fairness, but no queued threads |
450 |
*/ |
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(); |
457 |
s.acquire(); |
458 |
s.release(); |
459 |
|
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 |
* tryAcquire(n) succeeds when sufficient permits, else fails |
495 |
*/ |
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 |
* acquire succeeds if permits available |
512 |
*/ |
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()); |
539 |
} |
540 |
} |
541 |
|
542 |
/** |
543 |
* release in one thread enables acquire in another thread |
544 |
*/ |
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 |
* fair locks are strictly FIFO |
588 |
*/ |
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 |
* 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 |
|
642 |
} |