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| package org.jboss.cache.lock; |
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| import junit.framework.Test; |
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| import junit.framework.TestCase; |
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| import junit.framework.TestSuite; |
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| |
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| import java.util.concurrent.TimeUnit; |
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| import java.util.concurrent.locks.ReentrantReadWriteLock; |
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| public class ReentrantWriterPreference2Readers1WriterLockTest extends TestCase |
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| { |
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| ReentrantReadWriteLock lock; |
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| ReentrantReadWriteLock.ReadLock rl; |
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| ReentrantReadWriteLock.WriteLock wl; |
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| Exception thread_ex = null; |
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| |
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| protected void setUp() throws Exception
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| { |
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| super.setUp();
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| lock = new ReentrantReadWriteLock();
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| rl = lock.readLock();
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| wl = lock.writeLock();
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| thread_ex = null;
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| } |
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| |
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| protected void tearDown() throws Exception
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| { |
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| super.tearDown();
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| lock = null;
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| if (thread_ex != null)
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| throw thread_ex;
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| } |
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| private void log(String msg)
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| { |
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| System.out.println(System.currentTimeMillis() + " " + Thread.currentThread() +
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| " [" + Thread.currentThread().getName() + "]: " + msg); |
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| } |
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| public void testSimpleUpgradeFromReadLockToWriteLock()
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| { |
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| int readers, writers;
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| try
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| { |
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| rl.lock();
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| readers = lock.getReadLockCount();
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| assertEquals(1, readers);
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| boolean wl_acquired = wl.tryLock(500, TimeUnit.MILLISECONDS);
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| if (!wl_acquired)
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| { |
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| fail("write lock could not be acquired");
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| return;
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| } |
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| readers = lock.getReadLockCount();
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| assertEquals(1, readers);
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| writers = lock.getWriteHoldCount();
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| assertEquals(1, writers);
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| } |
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| catch (InterruptedException e) |
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| { |
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| |
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| } |
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| finally |
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| { |
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| rl.unlock();
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| if (lock.getWriteHoldCount() > 0)
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| wl.unlock();
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| } |
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| } |
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| public void test2ReadersAnd1Writer() throws InterruptedException
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| { |
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| int readers, writers;
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| Upgrader upgrader = new Upgrader("Upgrader");
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| Reader reader = new Reader("Reader");
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| reader.start();
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| sleepThread(500);
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| readers = lock.getReadLockCount();
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| assertEquals(1, readers);
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| upgrader.start();
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| sleepThread(500);
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| readers = lock.getReadLockCount();
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| assertEquals(2, readers);
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| synchronized (upgrader)
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| { |
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| upgrader.notify();
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| } |
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| sleepThread(500);
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| readers = lock.getReadLockCount();
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| assertEquals(2, readers);
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| writers = lock.getWriteHoldCount();
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| assertEquals(0, writers);
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| synchronized (reader)
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| { |
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| reader.notify();
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| } |
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| reader.join();
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| readers = lock.getReadLockCount();
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| assertEquals(1, readers);
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| writers = lock.getWriteHoldCount();
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| assertEquals(1, writers);
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| synchronized (upgrader)
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| { |
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| upgrader.notify();
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| } |
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| sleepThread(500);
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| readers = lock.getReadLockCount();
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| assertEquals(0, readers);
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| writers = lock.getWriteHoldCount();
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| assertEquals(0, writers);
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| upgrader.join(3000);
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| assertTrue("Known failure. See JBCACHE-461; This is due to a potential bug in ReentrantWriterPreferenceReadWriteLock !",
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| upgrader.wasUpgradeSuccessful()); |
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| } |
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| private class Reader extends Thread |
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| { |
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| public Reader(String name)
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| { |
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| super(name);
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| } |
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| public void run()
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| { |
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| try
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| { |
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| log("acquiring RL");
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| rl.lock();
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| log("acquired RL");
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| synchronized (this)
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| { |
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| this.wait();
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| } |
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| } |
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| catch (InterruptedException e) |
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| { |
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| } |
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| finally |
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| { |
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| log("releasing RL");
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| rl.unlock();
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| log("released RL");
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| } |
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| } |
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| } |
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| private class Upgrader extends Thread |
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| { |
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| boolean upgradeSuccessful = false; |
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| public Upgrader(String name)
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| { |
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| super(name);
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| } |
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| public boolean wasUpgradeSuccessful()
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| { |
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| return upgradeSuccessful;
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| } |
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| public void run()
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| { |
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| try
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| { |
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| log("acquiring RL");
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| rl.lock();
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| log("acquired RL");
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| synchronized (this)
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| { |
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| this.wait();
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| } |
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| log("attempting to acquire WL");
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| wl.lock();
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| upgradeSuccessful = true;
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| log("acquired WL");
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| synchronized (this)
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| { |
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| this.wait();
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| } |
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| log("releasing WL");
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| rl.unlock();
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| log("released WL");
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| } |
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| catch (InterruptedException e) |
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| { |
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| ; |
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| } |
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| finally |
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| { |
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| wl.unlock();
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| rl.unlock();
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| } |
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| } |
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| } |
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| static void sleepThread(long timeout)
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| { |
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| try
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| { |
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| Thread.sleep(timeout);
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| } |
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| catch (InterruptedException e) |
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| { |
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| } |
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| } |
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| public static Test suite()
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| { |
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| return new TestSuite(ReentrantWriterPreference2Readers1WriterLockTest.class);
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| } |
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| public static void main(String[] args)
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| { |
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| junit.textui.TestRunner.run(ReentrantWriterPreference2Readers1WriterLockTest.suite());
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| } |
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| } |