/*
* Written by Doug Lea with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
* http://creativecommons.org/licenses/publicdomain
* Other contributors include Andrew Wright, Jeffrey Hayes,
* Pat Fisher, Mike Judd.
*/
import junit.framework.*;
import java.util.*;
import java.util.concurrent.*;
import java.io.*;
public class SemaphoreTest extends JSR166TestCase {
public static void main(String[] args) {
junit.textui.TestRunner.run (suite());
}
public static Test suite() {
return new TestSuite(SemaphoreTest.class);
}
/**
* Subclass to expose protected methods
*/
static class PublicSemaphore extends Semaphore {
PublicSemaphore(int p, boolean f) { super(p, f); }
public Collection<Thread> getQueuedThreads() {
return super.getQueuedThreads();
}
public void reducePermits(int p) {
super.reducePermits(p);
}
}
/**
* A runnable calling acquire
*/
class InterruptibleLockRunnable implements Runnable {
final Semaphore lock;
InterruptibleLockRunnable(Semaphore l) { lock = l; }
public void run() {
try {
lock.acquire();
} catch(InterruptedException success){}
}
}
/**
* A runnable calling acquire that expects to be
* interrupted
*/
class InterruptedLockRunnable implements Runnable {
final Semaphore lock;
InterruptedLockRunnable(Semaphore l) { lock = l; }
public void run() {
try {
lock.acquire();
threadShouldThrow();
} catch(InterruptedException success){}
}
}
/**
* Zero, negative, and positive initial values are allowed in constructor
*/
public void testConstructor() {
Semaphore s0 = new Semaphore(0, false);
assertEquals(0, s0.availablePermits());
assertFalse(s0.isFair());
Semaphore s1 = new Semaphore(-1, false);
assertEquals(-1, s1.availablePermits());
assertFalse(s1.isFair());
Semaphore s2 = new Semaphore(-1, false);
assertEquals(-1, s2.availablePermits());
assertFalse(s2.isFair());
}
/**
* Constructor without fairness argument behaves as nonfair
*/
public void testConstructor2() {
Semaphore s0 = new Semaphore(0);
assertEquals(0, s0.availablePermits());
assertFalse(s0.isFair());
Semaphore s1 = new Semaphore(-1);
assertEquals(-1, s1.availablePermits());
assertFalse(s1.isFair());
Semaphore s2 = new Semaphore(-1);
assertEquals(-1, s2.availablePermits());
assertFalse(s2.isFair());
}
/**
* tryAcquire succeeds when sufficient permits, else fails
*/
public void testTryAcquireInSameThread() {
Semaphore s = new Semaphore(2, false);
assertEquals(2, s.availablePermits());
assertTrue(s.tryAcquire());
assertTrue(s.tryAcquire());
assertEquals(0, s.availablePermits());
assertFalse(s.tryAcquire());
}
/**
* Acquire and release of semaphore succeed if initially available
*/
public void testAcquireReleaseInSameThread() {
Semaphore s = new Semaphore(1, false);
try {
s.acquire();
s.release();
s.acquire();
s.release();
s.acquire();
s.release();
s.acquire();
s.release();
s.acquire();
s.release();
assertEquals(1, s.availablePermits());
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* Uninterruptible acquire and release of semaphore succeed if
* initially available
*/
public void testAcquireUninterruptiblyReleaseInSameThread() {
Semaphore s = new Semaphore(1, false);
try {
s.acquireUninterruptibly();
s.release();
s.acquireUninterruptibly();
s.release();
s.acquireUninterruptibly();
s.release();
s.acquireUninterruptibly();
s.release();
s.acquireUninterruptibly();
s.release();
assertEquals(1, s.availablePermits());
} finally {
}
}
/**
* Timed Acquire and release of semaphore succeed if
* initially available
*/
public void testTimedAcquireReleaseInSameThread() {
Semaphore s = new Semaphore(1, false);
try {
assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release();
assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release();
assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release();
assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release();
assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release();
assertEquals(1, s.availablePermits());
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* A release in one thread enables an acquire in another thread
*/
public void testAcquireReleaseInDifferentThreads() {
final Semaphore s = new Semaphore(0, false);
Thread t = new Thread(new Runnable() {
public void run() {
try {
s.acquire();
s.release();
s.release();
s.acquire();
} catch(InterruptedException ie){
threadUnexpectedException();
}
}
});
try {
t.start();
Thread.sleep(SHORT_DELAY_MS);
s.release();
s.release();
s.acquire();
s.acquire();
s.release();
t.join();
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* A release in one thread enables an uninterruptible acquire in another thread
*/
public void testUninterruptibleAcquireReleaseInDifferentThreads() {
final Semaphore s = new Semaphore(0, false);
Thread t = new Thread(new Runnable() {
public void run() {
s.acquireUninterruptibly();
s.release();
s.release();
s.acquireUninterruptibly();
}
});
try {
t.start();
Thread.sleep(SHORT_DELAY_MS);
s.release();
s.release();
s.acquireUninterruptibly();
s.acquireUninterruptibly();
s.release();
t.join();
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* A release in one thread enables a timed acquire in another thread
*/
public void testTimedAcquireReleaseInDifferentThreads() {
final Semaphore s = new Semaphore(1, false);
Thread t = new Thread(new Runnable() {
public void run() {
try {
s.release();
threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release();
threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
} catch(InterruptedException ie){
threadUnexpectedException();
}
}
});
try {
t.start();
assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release();
assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release();
s.release();
t.join();
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* A waiting acquire blocks interruptibly
*/
public void testAcquire_InterruptedException() {
final Semaphore s = new Semaphore(0, false);
Thread t = new Thread(new Runnable() {
public void run() {
try {
s.acquire();
threadShouldThrow();
} catch(InterruptedException success){}
}
});
t.start();
try {
Thread.sleep(SHORT_DELAY_MS);
t.interrupt();
t.join();
} catch(InterruptedException e){
unexpectedException();
}
}
/**
* A waiting timed acquire blocks interruptibly
*/
public void testTryAcquire_InterruptedException() {
final Semaphore s = new Semaphore(0, false);
Thread t = new Thread(new Runnable() {
public void run() {
try {
s.tryAcquire(MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS);
threadShouldThrow();
} catch(InterruptedException success){
}
}
});
t.start();
try {
Thread.sleep(SHORT_DELAY_MS);
t.interrupt();
t.join();
} catch(InterruptedException e){
unexpectedException();
}
}
/**
* hasQueuedThreads reports whether there are waiting threads
*/
public void testHasQueuedThreads() {
final Semaphore lock = new Semaphore(1, false);
Thread t1 = new Thread(new InterruptedLockRunnable(lock));
Thread t2 = new Thread(new InterruptibleLockRunnable(lock));
try {
assertFalse(lock.hasQueuedThreads());
lock.acquireUninterruptibly();
t1.start();
Thread.sleep(SHORT_DELAY_MS);
assertTrue(lock.hasQueuedThreads());
t2.start();
Thread.sleep(SHORT_DELAY_MS);
assertTrue(lock.hasQueuedThreads());
t1.interrupt();
Thread.sleep(SHORT_DELAY_MS);
assertTrue(lock.hasQueuedThreads());
lock.release();
Thread.sleep(SHORT_DELAY_MS);
assertFalse(lock.hasQueuedThreads());
t1.join();
t2.join();
} catch(Exception e){
unexpectedException();
}
}
/**
* getQueueLength reports number of waiting threads
*/
public void testGetQueueLength() {
final Semaphore lock = new Semaphore(1, false);
Thread t1 = new Thread(new InterruptedLockRunnable(lock));
Thread t2 = new Thread(new InterruptibleLockRunnable(lock));
try {
assertEquals(0, lock.getQueueLength());
lock.acquireUninterruptibly();
t1.start();
Thread.sleep(SHORT_DELAY_MS);
assertEquals(1, lock.getQueueLength());
t2.start();
Thread.sleep(SHORT_DELAY_MS);
assertEquals(2, lock.getQueueLength());
t1.interrupt();
Thread.sleep(SHORT_DELAY_MS);
assertEquals(1, lock.getQueueLength());
lock.release();
Thread.sleep(SHORT_DELAY_MS);
assertEquals(0, lock.getQueueLength());
t1.join();
t2.join();
} catch(Exception e){
unexpectedException();
}
}
/**
* getQueuedThreads includes waiting threads
*/
public void testGetQueuedThreads() {
final PublicSemaphore lock = new PublicSemaphore(1, false);
Thread t1 = new Thread(new InterruptedLockRunnable(lock));
Thread t2 = new Thread(new InterruptibleLockRunnable(lock));
try {
assertTrue(lock.getQueuedThreads().isEmpty());
lock.acquireUninterruptibly();
assertTrue(lock.getQueuedThreads().isEmpty());
t1.start();
Thread.sleep(SHORT_DELAY_MS);
assertTrue(lock.getQueuedThreads().contains(t1));
t2.start();
Thread.sleep(SHORT_DELAY_MS);
assertTrue(lock.getQueuedThreads().contains(t1));
assertTrue(lock.getQueuedThreads().contains(t2));
t1.interrupt();
Thread.sleep(SHORT_DELAY_MS);
assertFalse(lock.getQueuedThreads().contains(t1));
assertTrue(lock.getQueuedThreads().contains(t2));
lock.release();
Thread.sleep(SHORT_DELAY_MS);
assertTrue(lock.getQueuedThreads().isEmpty());
t1.join();
t2.join();
} catch(Exception e){
unexpectedException();
}
}
/**
* drainPermits reports and removes given number of permits
*/
public void testDrainPermits() {
Semaphore s = new Semaphore(0, false);
assertEquals(0, s.availablePermits());
assertEquals(0, s.drainPermits());
s.release(10);
assertEquals(10, s.availablePermits());
assertEquals(10, s.drainPermits());
assertEquals(0, s.availablePermits());
assertEquals(0, s.drainPermits());
}
/**
* reducePermits reduces number of permits
*/
public void testReducePermits() {
PublicSemaphore s = new PublicSemaphore(10, false);
assertEquals(10, s.availablePermits());
s.reducePermits(1);
assertEquals(9, s.availablePermits());
s.reducePermits(10);
assertEquals(-1, s.availablePermits());
}
/**
* a deserialized serialized semaphore has same number of permits
*
TODO(tball): enable when serialization is supported.
public void testSerialization() {
Semaphore l = new Semaphore(3, false);
try {
l.acquire();
l.release();
ByteArrayOutputStream bout = new ByteArrayOutputStream(10000);
ObjectOutputStream out = new ObjectOutputStream(new BufferedOutputStream(bout));
out.writeObject(l);
out.close();
ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());
ObjectInputStream in = new ObjectInputStream(new BufferedInputStream(bin));
Semaphore r = (Semaphore) in.readObject();
assertEquals(3, r.availablePermits());
assertFalse(r.isFair());
r.acquire();
r.release();
} catch(Exception e){
unexpectedException();
}
}*/
/**
* Zero, negative, and positive initial values are allowed in constructor
*/
public void testConstructor_fair() {
Semaphore s0 = new Semaphore(0, true);
assertEquals(0, s0.availablePermits());
assertTrue(s0.isFair());
Semaphore s1 = new Semaphore(-1, true);
assertEquals(-1, s1.availablePermits());
Semaphore s2 = new Semaphore(-1, true);
assertEquals(-1, s2.availablePermits());
}
/**
* tryAcquire succeeds when sufficient permits, else fails
*/
public void testTryAcquireInSameThread_fair() {
Semaphore s = new Semaphore(2, true);
assertEquals(2, s.availablePermits());
assertTrue(s.tryAcquire());
assertTrue(s.tryAcquire());
assertEquals(0, s.availablePermits());
assertFalse(s.tryAcquire());
}
/**
* tryAcquire(n) succeeds when sufficient permits, else fails
*/
public void testTryAcquireNInSameThread_fair() {
Semaphore s = new Semaphore(2, true);
assertEquals(2, s.availablePermits());
assertTrue(s.tryAcquire(2));
assertEquals(0, s.availablePermits());
assertFalse(s.tryAcquire());
}
/**
* Acquire and release of semaphore succeed if initially available
*/
public void testAcquireReleaseInSameThread_fair() {
Semaphore s = new Semaphore(1, true);
try {
s.acquire();
s.release();
s.acquire();
s.release();
s.acquire();
s.release();
s.acquire();
s.release();
s.acquire();
s.release();
assertEquals(1, s.availablePermits());
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* Acquire(n) and release(n) of semaphore succeed if initially available
*/
public void testAcquireReleaseNInSameThread_fair() {
Semaphore s = new Semaphore(1, true);
try {
s.release(1);
s.acquire(1);
s.release(2);
s.acquire(2);
s.release(3);
s.acquire(3);
s.release(4);
s.acquire(4);
s.release(5);
s.acquire(5);
assertEquals(1, s.availablePermits());
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* Acquire(n) and release(n) of semaphore succeed if initially available
*/
public void testAcquireUninterruptiblyReleaseNInSameThread_fair() {
Semaphore s = new Semaphore(1, true);
try {
s.release(1);
s.acquireUninterruptibly(1);
s.release(2);
s.acquireUninterruptibly(2);
s.release(3);
s.acquireUninterruptibly(3);
s.release(4);
s.acquireUninterruptibly(4);
s.release(5);
s.acquireUninterruptibly(5);
assertEquals(1, s.availablePermits());
} finally {
}
}
/**
* release(n) in one thread enables timed acquire(n) in another thread
*/
public void testTimedAcquireReleaseNInSameThread_fair() {
Semaphore s = new Semaphore(1, true);
try {
s.release(1);
assertTrue(s.tryAcquire(1, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release(2);
assertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release(3);
assertTrue(s.tryAcquire(3, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release(4);
assertTrue(s.tryAcquire(4, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release(5);
assertTrue(s.tryAcquire(5, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
assertEquals(1, s.availablePermits());
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* release in one thread enables timed acquire in another thread
*/
public void testTimedAcquireReleaseInSameThread_fair() {
Semaphore s = new Semaphore(1, true);
try {
assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release();
assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release();
assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release();
assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release();
assertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release();
assertEquals(1, s.availablePermits());
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* A release in one thread enables an acquire in another thread
*/
public void testAcquireReleaseInDifferentThreads_fair() {
final Semaphore s = new Semaphore(0, true);
Thread t = new Thread(new Runnable() {
public void run() {
try {
s.acquire();
s.acquire();
s.acquire();
s.acquire();
} catch(InterruptedException ie){
threadUnexpectedException();
}
}
});
try {
t.start();
Thread.sleep(SHORT_DELAY_MS);
s.release();
s.release();
s.release();
s.release();
s.release();
s.release();
t.join();
assertEquals(2, s.availablePermits());
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* release(n) in one thread enables acquire(n) in another thread
*/
public void testAcquireReleaseNInDifferentThreads_fair() {
final Semaphore s = new Semaphore(0, true);
Thread t = new Thread(new Runnable() {
public void run() {
try {
s.acquire();
s.release(2);
s.acquire();
} catch(InterruptedException ie){
threadUnexpectedException();
}
}
});
try {
t.start();
Thread.sleep(SHORT_DELAY_MS);
s.release(2);
s.acquire(2);
s.release(1);
t.join();
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* release(n) in one thread enables acquire(n) in another thread
*/
public void testAcquireReleaseNInDifferentThreads_fair2() {
final Semaphore s = new Semaphore(0, true);
Thread t = new Thread(new Runnable() {
public void run() {
try {
s.acquire(2);
s.acquire(2);
s.release(4);
} catch(InterruptedException ie){
threadUnexpectedException();
}
}
});
try {
t.start();
Thread.sleep(SHORT_DELAY_MS);
s.release(6);
s.acquire(2);
s.acquire(2);
s.release(2);
t.join();
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* release in one thread enables timed acquire in another thread
*/
public void testTimedAcquireReleaseInDifferentThreads_fair() {
final Semaphore s = new Semaphore(1, true);
Thread t = new Thread(new Runnable() {
public void run() {
try {
threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
threadAssertTrue(s.tryAcquire(SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
} catch(InterruptedException ie){
threadUnexpectedException();
}
}
});
t.start();
try {
s.release();
s.release();
s.release();
s.release();
s.release();
t.join();
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* release(n) in one thread enables timed acquire(n) in another thread
*/
public void testTimedAcquireReleaseNInDifferentThreads_fair() {
final Semaphore s = new Semaphore(2, true);
Thread t = new Thread(new Runnable() {
public void run() {
try {
threadAssertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release(2);
threadAssertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release(2);
} catch(InterruptedException ie){
threadUnexpectedException();
}
}
});
t.start();
try {
assertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release(2);
assertTrue(s.tryAcquire(2, SHORT_DELAY_MS, TimeUnit.MILLISECONDS));
s.release(2);
t.join();
} catch( InterruptedException e){
unexpectedException();
}
}
/**
* A waiting acquire blocks interruptibly
*/
public void testAcquire_InterruptedException_fair() {
final Semaphore s = new Semaphore(0, true);
Thread t = new Thread(new Runnable() {
public void run() {
try {
s.acquire();
threadShouldThrow();
} catch(InterruptedException success){}
}
});
t.start();
try {
Thread.sleep(SHORT_DELAY_MS);
t.interrupt();
t.join();
} catch(InterruptedException e){
unexpectedException();
}
}
/**
* A waiting acquire(n) blocks interruptibly
*/
public void testAcquireN_InterruptedException_fair() {
final Semaphore s = new Semaphore(2, true);
Thread t = new Thread(new Runnable() {
public void run() {
try {
s.acquire(3);
threadShouldThrow();
} catch(InterruptedException success){}
}
});
t.start();
try {
Thread.sleep(SHORT_DELAY_MS);
t.interrupt();
t.join();
} catch(InterruptedException e){
unexpectedException();
}
}
/**
* A waiting tryAcquire blocks interruptibly
*/
public void testTryAcquire_InterruptedException_fair() {
final Semaphore s = new Semaphore(0, true);
Thread t = new Thread(new Runnable() {
public void run() {
try {
s.tryAcquire(MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS);
threadShouldThrow();
} catch(InterruptedException success){
}
}
});
t.start();
try {
Thread.sleep(SHORT_DELAY_MS);
t.interrupt();
t.join();
} catch(InterruptedException e){
unexpectedException();
}
}
/**
* A waiting tryAcquire(n) blocks interruptibly
*/
public void testTryAcquireN_InterruptedException_fair() {
final Semaphore s = new Semaphore(1, true);
Thread t = new Thread(new Runnable() {
public void run() {
try {
s.tryAcquire(4, MEDIUM_DELAY_MS, TimeUnit.MILLISECONDS);
threadShouldThrow();
} catch(InterruptedException success){
}
}
});
t.start();
try {
Thread.sleep(SHORT_DELAY_MS);
t.interrupt();
t.join();
} catch(InterruptedException e){
unexpectedException();
}
}
/**
* getQueueLength reports number of waiting threads
*/
public void testGetQueueLength_fair() {
final Semaphore lock = new Semaphore(1, true);
Thread t1 = new Thread(new InterruptedLockRunnable(lock));
Thread t2 = new Thread(new InterruptibleLockRunnable(lock));
try {
assertEquals(0, lock.getQueueLength());
lock.acquireUninterruptibly();
t1.start();
Thread.sleep(SHORT_DELAY_MS);
assertEquals(1, lock.getQueueLength());
t2.start();
Thread.sleep(SHORT_DELAY_MS);
assertEquals(2, lock.getQueueLength());
t1.interrupt();
Thread.sleep(SHORT_DELAY_MS);
assertEquals(1, lock.getQueueLength());
lock.release();
Thread.sleep(SHORT_DELAY_MS);
assertEquals(0, lock.getQueueLength());
t1.join();
t2.join();
} catch(Exception e){
unexpectedException();
}
}
/**
* a deserialized serialized semaphore has same number of permits
*
TODO(tball): enable when serialization is supported.
public void testSerialization_fair() {
Semaphore l = new Semaphore(3, true);
try {
l.acquire();
l.release();
ByteArrayOutputStream bout = new ByteArrayOutputStream(10000);
ObjectOutputStream out = new ObjectOutputStream(new BufferedOutputStream(bout));
out.writeObject(l);
out.close();
ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());
ObjectInputStream in = new ObjectInputStream(new BufferedInputStream(bin));
Semaphore r = (Semaphore) in.readObject();
assertEquals(3, r.availablePermits());
assertTrue(r.isFair());
r.acquire();
r.release();
} catch(Exception e){
unexpectedException();
}
}
*/
/**
* toString indicates current number of permits
*/
public void testToString() {
Semaphore s = new Semaphore(0);
String us = s.toString();
assertTrue(us.indexOf("Permits = 0") >= 0);
s.release();
String s1 = s.toString();
assertTrue(s1.indexOf("Permits = 1") >= 0);
s.release();
String s2 = s.toString();
assertTrue(s2.indexOf("Permits = 2") >= 0);
}
}