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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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Thread.State parkedState() { return Thread.State.TIMED_WAITING; } |
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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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Thread.State parkedState() { return Thread.State.TIMED_WAITING; } |
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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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Thread.State parkedState() { return Thread.State.WAITING; } |
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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 java.util.concurrent.CyclicBarrier pleaseInterrupt |
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= new java.util.concurrent.CyclicBarrier(2); |
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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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assertFalse(Thread.interrupted()); |
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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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assertFalse(Thread.interrupted()); |
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|
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// Interrupt during acquire |
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await(pleaseInterrupt); |
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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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assertFalse(Thread.interrupted()); |
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|
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// Interrupt during acquire(N) |
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await(pleaseInterrupt); |
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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) {} |
267 |
assertFalse(Thread.interrupted()); |
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}}); |
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|
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for (int n = 2; n-->0; ) { |
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await(pleaseInterrupt); |
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assertThreadBlocks(t, acquirer.parkedState()); |
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t.interrupt(); |
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} |
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|
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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); |
297 |
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); |
305 |
assertTrue(Thread.interrupted()); |
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}}); |
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|
308 |
await(pleaseInterrupt); |
309 |
waitForQueuedThread(s, t1); |
310 |
waitForQueuedThread(s, t2); |
311 |
t2.interrupt(); |
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|
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assertThreadBlocks(t1, Thread.State.WAITING); |
314 |
assertThreadBlocks(t2, Thread.State.WAITING); |
315 |
|
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s.release(2); |
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|
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awaitTermination(t1); |
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awaitTermination(t2); |
320 |
} |
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|
322 |
/** |
323 |
* hasQueuedThreads reports whether there are waiting threads |
324 |
*/ |
325 |
public void testHasQueuedThreads() { testHasQueuedThreads(false); } |
326 |
public void testHasQueuedThreads_fair() { testHasQueuedThreads(true); } |
327 |
public void testHasQueuedThreads(boolean fair) { |
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final PublicSemaphore lock = new PublicSemaphore(1, fair); |
329 |
assertFalse(lock.hasQueuedThreads()); |
330 |
lock.acquireUninterruptibly(); |
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Thread t1 = newStartedThread(new InterruptedLockRunnable(lock)); |
332 |
waitForQueuedThread(lock, t1); |
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assertTrue(lock.hasQueuedThreads()); |
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Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock)); |
335 |
waitForQueuedThread(lock, t2); |
336 |
assertTrue(lock.hasQueuedThreads()); |
337 |
t1.interrupt(); |
338 |
awaitTermination(t1); |
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assertTrue(lock.hasQueuedThreads()); |
340 |
lock.release(); |
341 |
awaitTermination(t2); |
342 |
assertFalse(lock.hasQueuedThreads()); |
343 |
} |
344 |
|
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/** |
346 |
* getQueueLength reports number of waiting threads |
347 |
*/ |
348 |
public void testGetQueueLength() { testGetQueueLength(false); } |
349 |
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); |
352 |
assertEquals(0, lock.getQueueLength()); |
353 |
lock.acquireUninterruptibly(); |
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Thread t1 = newStartedThread(new InterruptedLockRunnable(lock)); |
355 |
waitForQueuedThread(lock, t1); |
356 |
assertEquals(1, lock.getQueueLength()); |
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Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock)); |
358 |
waitForQueuedThread(lock, t2); |
359 |
assertEquals(2, lock.getQueueLength()); |
360 |
t1.interrupt(); |
361 |
awaitTermination(t1); |
362 |
assertEquals(1, lock.getQueueLength()); |
363 |
lock.release(); |
364 |
awaitTermination(t2); |
365 |
assertEquals(0, lock.getQueueLength()); |
366 |
} |
367 |
|
368 |
/** |
369 |
* getQueuedThreads includes waiting threads |
370 |
*/ |
371 |
public void testGetQueuedThreads() { testGetQueuedThreads(false); } |
372 |
public void testGetQueuedThreads_fair() { testGetQueuedThreads(true); } |
373 |
public void testGetQueuedThreads(boolean fair) { |
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final PublicSemaphore lock = new PublicSemaphore(1, fair); |
375 |
assertTrue(lock.getQueuedThreads().isEmpty()); |
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lock.acquireUninterruptibly(); |
377 |
assertTrue(lock.getQueuedThreads().isEmpty()); |
378 |
Thread t1 = newStartedThread(new InterruptedLockRunnable(lock)); |
379 |
waitForQueuedThread(lock, t1); |
380 |
assertTrue(lock.getQueuedThreads().contains(t1)); |
381 |
Thread t2 = newStartedThread(new InterruptibleLockRunnable(lock)); |
382 |
waitForQueuedThread(lock, t2); |
383 |
assertTrue(lock.getQueuedThreads().contains(t1)); |
384 |
assertTrue(lock.getQueuedThreads().contains(t2)); |
385 |
t1.interrupt(); |
386 |
awaitTermination(t1); |
387 |
assertFalse(lock.getQueuedThreads().contains(t1)); |
388 |
assertTrue(lock.getQueuedThreads().contains(t2)); |
389 |
lock.release(); |
390 |
awaitTermination(t2); |
391 |
assertTrue(lock.getQueuedThreads().isEmpty()); |
392 |
} |
393 |
|
394 |
/** |
395 |
* drainPermits reports and removes given number of permits |
396 |
*/ |
397 |
public void testDrainPermits() { testDrainPermits(false); } |
398 |
public void testDrainPermits_fair() { testDrainPermits(true); } |
399 |
public void testDrainPermits(boolean fair) { |
400 |
Semaphore s = new Semaphore(0, fair); |
401 |
assertEquals(0, s.availablePermits()); |
402 |
assertEquals(0, s.drainPermits()); |
403 |
s.release(10); |
404 |
assertEquals(10, s.availablePermits()); |
405 |
assertEquals(10, s.drainPermits()); |
406 |
assertEquals(0, s.availablePermits()); |
407 |
assertEquals(0, s.drainPermits()); |
408 |
} |
409 |
|
410 |
/** |
411 |
* release(-N) throws IllegalArgumentException |
412 |
*/ |
413 |
public void testReleaseIAE() { testReleaseIAE(false); } |
414 |
public void testReleaseIAE_fair() { testReleaseIAE(true); } |
415 |
public void testReleaseIAE(boolean fair) { |
416 |
Semaphore s = new Semaphore(10, fair); |
417 |
try { |
418 |
s.release(-1); |
419 |
shouldThrow(); |
420 |
} catch (IllegalArgumentException success) {} |
421 |
} |
422 |
|
423 |
/** |
424 |
* reducePermits(-N) throws IllegalArgumentException |
425 |
*/ |
426 |
public void testReducePermitsIAE() { testReducePermitsIAE(false); } |
427 |
public void testReducePermitsIAE_fair() { testReducePermitsIAE(true); } |
428 |
public void testReducePermitsIAE(boolean fair) { |
429 |
PublicSemaphore s = new PublicSemaphore(10, fair); |
430 |
try { |
431 |
s.reducePermits(-1); |
432 |
shouldThrow(); |
433 |
} catch (IllegalArgumentException success) {} |
434 |
} |
435 |
|
436 |
/** |
437 |
* reducePermits reduces number of permits |
438 |
*/ |
439 |
public void testReducePermits() { testReducePermits(false); } |
440 |
public void testReducePermits_fair() { testReducePermits(true); } |
441 |
public void testReducePermits(boolean fair) { |
442 |
PublicSemaphore s = new PublicSemaphore(10, fair); |
443 |
assertEquals(10, s.availablePermits()); |
444 |
s.reducePermits(0); |
445 |
assertEquals(10, s.availablePermits()); |
446 |
s.reducePermits(1); |
447 |
assertEquals(9, s.availablePermits()); |
448 |
s.reducePermits(10); |
449 |
assertEquals(-1, s.availablePermits()); |
450 |
s.reducePermits(10); |
451 |
assertEquals(-11, s.availablePermits()); |
452 |
s.reducePermits(0); |
453 |
assertEquals(-11, s.availablePermits()); |
454 |
} |
455 |
|
456 |
/** |
457 |
* a reserialized semaphore has same number of permits and |
458 |
* fairness, but no queued threads |
459 |
*/ |
460 |
public void testSerialization() { testSerialization(false); } |
461 |
public void testSerialization_fair() { testSerialization(true); } |
462 |
public void testSerialization(boolean fair) { |
463 |
try { |
464 |
Semaphore s = new Semaphore(3, fair); |
465 |
s.acquire(); |
466 |
s.acquire(); |
467 |
s.release(); |
468 |
|
469 |
Semaphore clone = serialClone(s); |
470 |
assertEquals(fair, s.isFair()); |
471 |
assertEquals(fair, clone.isFair()); |
472 |
assertEquals(2, s.availablePermits()); |
473 |
assertEquals(2, clone.availablePermits()); |
474 |
clone.acquire(); |
475 |
clone.acquire(); |
476 |
clone.release(); |
477 |
assertEquals(2, s.availablePermits()); |
478 |
assertEquals(1, clone.availablePermits()); |
479 |
assertFalse(s.hasQueuedThreads()); |
480 |
assertFalse(clone.hasQueuedThreads()); |
481 |
} catch (InterruptedException e) { threadUnexpectedException(e); } |
482 |
|
483 |
{ |
484 |
PublicSemaphore s = new PublicSemaphore(0, fair); |
485 |
Thread t = newStartedThread(new InterruptibleLockRunnable(s)); |
486 |
// waitForQueuedThreads(s); // suffers from "flicker", so ... |
487 |
waitForQueuedThread(s, t); // ... we use this instead |
488 |
PublicSemaphore clone = serialClone(s); |
489 |
assertEquals(fair, s.isFair()); |
490 |
assertEquals(fair, clone.isFair()); |
491 |
assertEquals(0, s.availablePermits()); |
492 |
assertEquals(0, clone.availablePermits()); |
493 |
assertTrue(s.hasQueuedThreads()); |
494 |
assertFalse(clone.hasQueuedThreads()); |
495 |
s.release(); |
496 |
awaitTermination(t); |
497 |
assertFalse(s.hasQueuedThreads()); |
498 |
assertFalse(clone.hasQueuedThreads()); |
499 |
} |
500 |
} |
501 |
|
502 |
/** |
503 |
* tryAcquire(n) succeeds when sufficient permits, else fails |
504 |
*/ |
505 |
public void testTryAcquireNInSameThread() { testTryAcquireNInSameThread(false); } |
506 |
public void testTryAcquireNInSameThread_fair() { testTryAcquireNInSameThread(true); } |
507 |
public void testTryAcquireNInSameThread(boolean fair) { |
508 |
Semaphore s = new Semaphore(2, fair); |
509 |
assertEquals(2, s.availablePermits()); |
510 |
assertFalse(s.tryAcquire(3)); |
511 |
assertEquals(2, s.availablePermits()); |
512 |
assertTrue(s.tryAcquire(2)); |
513 |
assertEquals(0, s.availablePermits()); |
514 |
assertFalse(s.tryAcquire(1)); |
515 |
assertFalse(s.tryAcquire(2)); |
516 |
assertEquals(0, s.availablePermits()); |
517 |
} |
518 |
|
519 |
/** |
520 |
* acquire succeeds if permits available |
521 |
*/ |
522 |
public void testReleaseAcquireSameThread_acquire() { testReleaseAcquireSameThread(false, AcquireMethod.acquire); } |
523 |
public void testReleaseAcquireSameThread_acquire_fair() { testReleaseAcquireSameThread(true, AcquireMethod.acquire); } |
524 |
public void testReleaseAcquireSameThread_acquireN() { testReleaseAcquireSameThread(false, AcquireMethod.acquireN); } |
525 |
public void testReleaseAcquireSameThread_acquireN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.acquireN); } |
526 |
public void testReleaseAcquireSameThread_acquireUninterruptibly() { testReleaseAcquireSameThread(false, AcquireMethod.acquireUninterruptibly); } |
527 |
public void testReleaseAcquireSameThread_acquireUninterruptibly_fair() { testReleaseAcquireSameThread(true, AcquireMethod.acquireUninterruptibly); } |
528 |
public void testReleaseAcquireSameThread_acquireUninterruptiblyN() { testReleaseAcquireSameThread(false, AcquireMethod.acquireUninterruptibly); } |
529 |
public void testReleaseAcquireSameThread_acquireUninterruptiblyN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.acquireUninterruptibly); } |
530 |
public void testReleaseAcquireSameThread_tryAcquire() { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquire); } |
531 |
public void testReleaseAcquireSameThread_tryAcquire_fair() { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquire); } |
532 |
public void testReleaseAcquireSameThread_tryAcquireN() { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireN); } |
533 |
public void testReleaseAcquireSameThread_tryAcquireN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireN); } |
534 |
public void testReleaseAcquireSameThread_tryAcquireTimed() { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireTimed); } |
535 |
public void testReleaseAcquireSameThread_tryAcquireTimed_fair() { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireTimed); } |
536 |
public void testReleaseAcquireSameThread_tryAcquireTimedN() { testReleaseAcquireSameThread(false, AcquireMethod.tryAcquireTimedN); } |
537 |
public void testReleaseAcquireSameThread_tryAcquireTimedN_fair() { testReleaseAcquireSameThread(true, AcquireMethod.tryAcquireTimedN); } |
538 |
public void testReleaseAcquireSameThread(boolean fair, |
539 |
final AcquireMethod acquirer) { |
540 |
Semaphore s = new Semaphore(1, fair); |
541 |
for (int i = 1; i < 6; i++) { |
542 |
s.release(i); |
543 |
assertEquals(1 + i, s.availablePermits()); |
544 |
try { |
545 |
acquirer.acquire(s, i); |
546 |
} catch (InterruptedException e) { threadUnexpectedException(e); } |
547 |
assertEquals(1, s.availablePermits()); |
548 |
} |
549 |
} |
550 |
|
551 |
/** |
552 |
* release in one thread enables acquire in another thread |
553 |
*/ |
554 |
public void testReleaseAcquireDifferentThreads_acquire() { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquire); } |
555 |
public void testReleaseAcquireDifferentThreads_acquire_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquire); } |
556 |
public void testReleaseAcquireDifferentThreads_acquireN() { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireN); } |
557 |
public void testReleaseAcquireDifferentThreads_acquireN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireN); } |
558 |
public void testReleaseAcquireDifferentThreads_acquireUninterruptibly() { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireUninterruptibly); } |
559 |
public void testReleaseAcquireDifferentThreads_acquireUninterruptibly_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireUninterruptibly); } |
560 |
public void testReleaseAcquireDifferentThreads_acquireUninterruptiblyN() { testReleaseAcquireDifferentThreads(false, AcquireMethod.acquireUninterruptibly); } |
561 |
public void testReleaseAcquireDifferentThreads_acquireUninterruptiblyN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.acquireUninterruptibly); } |
562 |
public void testReleaseAcquireDifferentThreads_tryAcquireTimed() { testReleaseAcquireDifferentThreads(false, AcquireMethod.tryAcquireTimed); } |
563 |
public void testReleaseAcquireDifferentThreads_tryAcquireTimed_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.tryAcquireTimed); } |
564 |
public void testReleaseAcquireDifferentThreads_tryAcquireTimedN() { testReleaseAcquireDifferentThreads(false, AcquireMethod.tryAcquireTimedN); } |
565 |
public void testReleaseAcquireDifferentThreads_tryAcquireTimedN_fair() { testReleaseAcquireDifferentThreads(true, AcquireMethod.tryAcquireTimedN); } |
566 |
public void testReleaseAcquireDifferentThreads(boolean fair, |
567 |
final AcquireMethod acquirer) { |
568 |
final Semaphore s = new Semaphore(0, fair); |
569 |
final int rounds = 4; |
570 |
long startTime = System.nanoTime(); |
571 |
Thread t = newStartedThread(new CheckedRunnable() { |
572 |
public void realRun() throws InterruptedException { |
573 |
for (int i = 0; i < rounds; i++) { |
574 |
assertFalse(s.hasQueuedThreads()); |
575 |
if (i % 2 == 0) |
576 |
acquirer.acquire(s); |
577 |
else |
578 |
acquirer.acquire(s, 3); |
579 |
}}}); |
580 |
|
581 |
for (int i = 0; i < rounds; i++) { |
582 |
while (! (s.availablePermits() == 0 && s.hasQueuedThreads())) |
583 |
Thread.yield(); |
584 |
assertTrue(t.isAlive()); |
585 |
if (i % 2 == 0) |
586 |
s.release(); |
587 |
else |
588 |
s.release(3); |
589 |
} |
590 |
awaitTermination(t); |
591 |
assertEquals(0, s.availablePermits()); |
592 |
assertTrue(millisElapsedSince(startTime) < LONG_DELAY_MS); |
593 |
} |
594 |
|
595 |
/** |
596 |
* fair locks are strictly FIFO |
597 |
*/ |
598 |
public void testFairLocksFifo() { |
599 |
final PublicSemaphore s = new PublicSemaphore(1, true); |
600 |
final CountDownLatch pleaseRelease = new CountDownLatch(1); |
601 |
Thread t1 = newStartedThread(new CheckedRunnable() { |
602 |
public void realRun() throws InterruptedException { |
603 |
// Will block; permits are available, but not three |
604 |
s.acquire(3); |
605 |
}}); |
606 |
|
607 |
waitForQueuedThread(s, t1); |
608 |
|
609 |
Thread t2 = newStartedThread(new CheckedRunnable() { |
610 |
public void realRun() throws InterruptedException { |
611 |
// Will fail, even though 1 permit is available |
612 |
assertFalse(s.tryAcquire(0L, MILLISECONDS)); |
613 |
assertFalse(s.tryAcquire(1, 0L, MILLISECONDS)); |
614 |
|
615 |
// untimed tryAcquire will barge and succeed |
616 |
assertTrue(s.tryAcquire()); |
617 |
s.release(2); |
618 |
assertTrue(s.tryAcquire(2)); |
619 |
s.release(); |
620 |
|
621 |
pleaseRelease.countDown(); |
622 |
// Will queue up behind t1, even though 1 permit is available |
623 |
s.acquire(); |
624 |
}}); |
625 |
|
626 |
await(pleaseRelease); |
627 |
waitForQueuedThread(s, t2); |
628 |
s.release(2); |
629 |
awaitTermination(t1); |
630 |
assertTrue(t2.isAlive()); |
631 |
s.release(); |
632 |
awaitTermination(t2); |
633 |
} |
634 |
|
635 |
/** |
636 |
* toString indicates current number of permits |
637 |
*/ |
638 |
public void testToString() { testToString(false); } |
639 |
public void testToString_fair() { testToString(true); } |
640 |
public void testToString(boolean fair) { |
641 |
PublicSemaphore s = new PublicSemaphore(0, fair); |
642 |
assertTrue(s.toString().contains("Permits = 0")); |
643 |
s.release(); |
644 |
assertTrue(s.toString().contains("Permits = 1")); |
645 |
s.release(2); |
646 |
assertTrue(s.toString().contains("Permits = 3")); |
647 |
s.reducePermits(5); |
648 |
assertTrue(s.toString().contains("Permits = -2")); |
649 |
} |
650 |
|
651 |
} |