/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

/*

 * This file is available under and governed by the GNU General Public

 * License version 2 only, as published by the Free Software Foundation.

 * However, the following notice accompanied the original version of this

 * file:

 *

 * Written by Doug Lea and Martin Buchholz

 * with assistance from members of JCP JSR-166 Expert Group and

 * released to the public domain, as explained at

 * http://creativecommons.org/publicdomain/zero/1.0/

 */

import static java.util.concurrent.TimeUnit.MILLISECONDS;

import java.util.concurrent.CountDownLatch;

import java.util.concurrent.locks.Lock;

import java.util.concurrent.locks.StampedLock;

import junit.framework.Test;

import junit.framework.TestSuite;

public class StampedLockTest extends JSR166TestCase {

    public static void main(String[] args) {

        main(suite(), args);

    }

    public static Test suite() {

        return new TestSuite(StampedLockTest.class);

    }

    /**

     * A runnable calling writeLockInterruptibly

     */

    class InterruptibleLockRunnable extends CheckedRunnable {

        final StampedLock lock;

        InterruptibleLockRunnable(StampedLock l) { lock = l; }

        public void realRun() throws InterruptedException {

            lock.writeLockInterruptibly();

        }

    }

    /**

     * A runnable calling writeLockInterruptibly that expects to be

     * interrupted

     */

    class InterruptedLockRunnable extends CheckedInterruptedRunnable {

        final StampedLock lock;

        InterruptedLockRunnable(StampedLock l) { lock = l; }

        public void realRun() throws InterruptedException {

            lock.writeLockInterruptibly();

        }

    }

    /**

     * Releases write lock, checking isWriteLocked before and after

     */

    void releaseWriteLock(StampedLock lock, long s) {

        assertTrue(lock.isWriteLocked());

        lock.unlockWrite(s);

        assertFalse(lock.isWriteLocked());

    }

    /**

     * Constructed StampedLock is in unlocked state

     */

    public void testConstructor() {

        StampedLock lock;

        lock = new StampedLock();

        assertFalse(lock.isWriteLocked());

        assertFalse(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 0);

    }

    /**

     * write-locking and read-locking an unlocked lock succeed

     */

    public void testLock() {

        StampedLock lock = new StampedLock();

        assertFalse(lock.isWriteLocked());

        assertFalse(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 0);

        long s = lock.writeLock();

        assertTrue(lock.isWriteLocked());

        assertFalse(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 0);

        lock.unlockWrite(s);

        assertFalse(lock.isWriteLocked());

        assertFalse(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 0);

        long rs = lock.readLock();

        assertFalse(lock.isWriteLocked());

        assertTrue(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 1);

        lock.unlockRead(rs);

        assertFalse(lock.isWriteLocked());

        assertFalse(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 0);

    }

    /**

     * unlock releases either a read or write lock

     */

    public void testUnlock() {

        StampedLock lock = new StampedLock();

        assertFalse(lock.isWriteLocked());

        assertFalse(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 0);

        long s = lock.writeLock();

        assertTrue(lock.isWriteLocked());

        assertFalse(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 0);

        lock.unlock(s);

        assertFalse(lock.isWriteLocked());

        assertFalse(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 0);

        long rs = lock.readLock();

        assertFalse(lock.isWriteLocked());

        assertTrue(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 1);

        lock.unlock(rs);

        assertFalse(lock.isWriteLocked());

        assertFalse(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 0);

    }

    /**

     * tryUnlockRead/Write succeeds if locked in associated mode else

     * returns false

     */

    public void testTryUnlock() {

        StampedLock lock = new StampedLock();

        assertFalse(lock.isWriteLocked());

        assertFalse(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 0);

        long s = lock.writeLock();

        assertTrue(lock.isWriteLocked());

        assertFalse(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 0);

        assertFalse(lock.tryUnlockRead());

        assertTrue(lock.tryUnlockWrite());

        assertFalse(lock.tryUnlockWrite());

        assertFalse(lock.tryUnlockRead());

        assertFalse(lock.isWriteLocked());

        assertFalse(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 0);

        long rs = lock.readLock();

        assertFalse(lock.isWriteLocked());

        assertTrue(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 1);

        assertFalse(lock.tryUnlockWrite());

        assertTrue(lock.tryUnlockRead());

        assertFalse(lock.tryUnlockRead());

        assertFalse(lock.tryUnlockWrite());

        assertFalse(lock.isWriteLocked());

        assertFalse(lock.isReadLocked());

        assertEquals(lock.getReadLockCount(), 0);

    }

    /**

     * write-unlocking an unlocked lock throws IllegalMonitorStateException

     */

    public void testWriteUnlock_IMSE() {

        StampedLock lock = new StampedLock();

        try {

            lock.unlockWrite(0L);

            shouldThrow();

        } catch (IllegalMonitorStateException success) {}

    }

    /**

     * write-unlocking an unlocked lock throws IllegalMonitorStateException

     */

    public void testWriteUnlock_IMSE2() {

        StampedLock lock = new StampedLock();

        long s = lock.writeLock();

        lock.unlockWrite(s);

        try {

            lock.unlockWrite(s);

            shouldThrow();

        } catch (IllegalMonitorStateException success) {}

    }

    /**

     * write-unlocking after readlock throws IllegalMonitorStateException

     */

    public void testWriteUnlock_IMSE3() {

        StampedLock lock = new StampedLock();

        long s = lock.readLock();

        try {

            lock.unlockWrite(s);

            shouldThrow();

        } catch (IllegalMonitorStateException success) {}

    }

    /**

     * read-unlocking an unlocked lock throws IllegalMonitorStateException

     */

    public void testReadUnlock_IMSE() {

        StampedLock lock = new StampedLock();

        long s = lock.readLock();

        lock.unlockRead(s);

        try {

            lock.unlockRead(s);

            shouldThrow();

        } catch (IllegalMonitorStateException success) {}

    }

    /**

     * read-unlocking an unlocked lock throws IllegalMonitorStateException

     */

    public void testReadUnlock_IMSE2() {

        StampedLock lock = new StampedLock();

        try {

            lock.unlockRead(0L);

            shouldThrow();

        } catch (IllegalMonitorStateException success) {}

    }

    /**

     * read-unlocking after writeLock throws IllegalMonitorStateException

     */

    public void testReadUnlock_IMSE3() {

        StampedLock lock = new StampedLock();

        long s = lock.writeLock();

        try {

            lock.unlockRead(s);

            shouldThrow();

        } catch (IllegalMonitorStateException success) {}

    }

    /**

     * validate(0) fails

     */

    public void testValidate0() {

        StampedLock lock = new StampedLock();

        assertFalse(lock.validate(0L));

    }

    /**

     * A stamp obtained from a successful lock operation validates

     */

    public void testValidate() throws InterruptedException {

        StampedLock lock = new StampedLock();

        long s = lock.writeLock();

        assertTrue(lock.validate(s));

        lock.unlockWrite(s);

        s = lock.readLock();

        assertTrue(lock.validate(s));

        lock.unlockRead(s);

        assertTrue((s = lock.tryWriteLock()) != 0L);

        assertTrue(lock.validate(s));

        lock.unlockWrite(s);

        assertTrue((s = lock.tryReadLock()) != 0L);

        assertTrue(lock.validate(s));

        lock.unlockRead(s);

        assertTrue((s = lock.tryWriteLock(100L, MILLISECONDS)) != 0L);

        assertTrue(lock.validate(s));

        lock.unlockWrite(s);

        assertTrue((s = lock.tryReadLock(100L, MILLISECONDS)) != 0L);

        assertTrue(lock.validate(s));

        lock.unlockRead(s);

        assertTrue((s = lock.tryOptimisticRead()) != 0L);

    }

    /**

     * A stamp obtained from an unsuccessful lock operation does not validate

     */

    public void testValidate2() throws InterruptedException {

        StampedLock lock = new StampedLock();

        long s;

        assertTrue((s = lock.writeLock()) != 0L);

        assertTrue(lock.validate(s));

        assertFalse(lock.validate(lock.tryWriteLock()));

        assertFalse(lock.validate(lock.tryWriteLock(10L, MILLISECONDS)));

        assertFalse(lock.validate(lock.tryReadLock()));

        assertFalse(lock.validate(lock.tryReadLock(10L, MILLISECONDS)));

        assertFalse(lock.validate(lock.tryOptimisticRead()));

        lock.unlockWrite(s);

    }

    /**

     * writeLockInterruptibly is interruptible

     */

    public void testWriteLockInterruptibly_Interruptible()

            throws InterruptedException {

        final CountDownLatch running = new CountDownLatch(1);

        final StampedLock lock = new StampedLock();

        long s = lock.writeLock();

        Thread t = newStartedThread(new CheckedInterruptedRunnable() {

            public void realRun() throws InterruptedException {

                running.countDown();

                lock.writeLockInterruptibly();

            }});

        running.await();

        waitForThreadToEnterWaitState(t, 100);

        t.interrupt();

        awaitTermination(t);

        releaseWriteLock(lock, s);

    }

    /**

     * timed tryWriteLock is interruptible

     */

    public void testWriteTryLock_Interruptible() throws InterruptedException {

        final CountDownLatch running = new CountDownLatch(1);

        final StampedLock lock = new StampedLock();

        long s = lock.writeLock();

        Thread t = newStartedThread(new CheckedInterruptedRunnable() {

            public void realRun() throws InterruptedException {

                running.countDown();

                lock.tryWriteLock(2 * LONG_DELAY_MS, MILLISECONDS);

            }});

        running.await();

        waitForThreadToEnterWaitState(t, 100);

        t.interrupt();

        awaitTermination(t);

        releaseWriteLock(lock, s);

    }

    /**

     * readLockInterruptibly is interruptible

     */

    public void testReadLockInterruptibly_Interruptible()

            throws InterruptedException {

        final CountDownLatch running = new CountDownLatch(1);

        final StampedLock lock = new StampedLock();

        long s = lock.writeLock();

        Thread t = newStartedThread(new CheckedInterruptedRunnable() {

            public void realRun() throws InterruptedException {

                running.countDown();

                lock.readLockInterruptibly();

            }});

        running.await();

        waitForThreadToEnterWaitState(t, 100);

        t.interrupt();

        awaitTermination(t);

        releaseWriteLock(lock, s);

    }

    /**

     * timed tryReadLock is interruptible

     */

    public void testReadTryLock_Interruptible() throws InterruptedException {

        final CountDownLatch running = new CountDownLatch(1);

        final StampedLock lock = new StampedLock();

        long s = lock.writeLock();

        Thread t = newStartedThread(new CheckedInterruptedRunnable() {

            public void realRun() throws InterruptedException {

                running.countDown();

                lock.tryReadLock(2 * LONG_DELAY_MS, MILLISECONDS);

            }});

        running.await();

        waitForThreadToEnterWaitState(t, 100);

        t.interrupt();

        awaitTermination(t);

        releaseWriteLock(lock, s);

    }

    /**

     * tryWriteLock on an unlocked lock succeeds

     */

    public void testWriteTryLock() {

        final StampedLock lock = new StampedLock();

        long s = lock.tryWriteLock();

        assertTrue(s != 0L);

        assertTrue(lock.isWriteLocked());

        long s2 = lock.tryWriteLock();

        assertEquals(s2, 0L);

        releaseWriteLock(lock, s);

    }

    /**

     * tryWriteLock fails if locked

     */

    public void testWriteTryLockWhenLocked() {

        final StampedLock lock = new StampedLock();

        long s = lock.writeLock();

        Thread t = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                long ws = lock.tryWriteLock();

                assertTrue(ws == 0L);

            }});

        awaitTermination(t);

        releaseWriteLock(lock, s);

    }

    /**

     * tryReadLock fails if write-locked

     */

    public void testReadTryLockWhenLocked() {

        final StampedLock lock = new StampedLock();

        long s = lock.writeLock();

        Thread t = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                long rs = lock.tryReadLock();

                assertEquals(rs, 0L);

            }});

        awaitTermination(t);

        releaseWriteLock(lock, s);

    }

    /**

     * Multiple threads can hold a read lock when not write-locked

     */

    public void testMultipleReadLocks() {

        final StampedLock lock = new StampedLock();

        final long s = lock.readLock();

        Thread t = newStartedThread(new CheckedRunnable() {

            public void realRun() throws InterruptedException {

                long s2 = lock.tryReadLock();

                assertTrue(s2 != 0L);

                lock.unlockRead(s2);

                long s3 = lock.tryReadLock(LONG_DELAY_MS, MILLISECONDS);

                assertTrue(s3 != 0L);

                lock.unlockRead(s3);

                long s4 = lock.readLock();

                lock.unlockRead(s4);

            }});

        awaitTermination(t);

        lock.unlockRead(s);

    }

    /**

     * A writelock succeeds only after a reading thread unlocks

     */

    public void testWriteAfterReadLock() throws InterruptedException {

        final CountDownLatch running = new CountDownLatch(1);

        final StampedLock lock = new StampedLock();

        long rs = lock.readLock();

        Thread t = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                running.countDown();

                long s = lock.writeLock();

                lock.unlockWrite(s);

            }});

        running.await();

        waitForThreadToEnterWaitState(t, 100);

        assertFalse(lock.isWriteLocked());

        lock.unlockRead(rs);

        awaitTermination(t);

        assertFalse(lock.isWriteLocked());

    }

    /**

     * A writelock succeeds only after reading threads unlock

     */

    public void testWriteAfterMultipleReadLocks() {

        final StampedLock lock = new StampedLock();

        long s = lock.readLock();

        Thread t1 = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                long rs = lock.readLock();

                lock.unlockRead(rs);

            }});

        awaitTermination(t1);

        Thread t2 = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                long ws = lock.writeLock();

                lock.unlockWrite(ws);

            }});

        assertFalse(lock.isWriteLocked());

        lock.unlockRead(s);

        awaitTermination(t2);

        assertFalse(lock.isWriteLocked());

    }

    /**

     * Readlocks succeed only after a writing thread unlocks

     */

    public void testReadAfterWriteLock() {

        final StampedLock lock = new StampedLock();

        final long s = lock.writeLock();

        Thread t1 = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                long rs = lock.readLock();

                lock.unlockRead(rs);

            }});

        Thread t2 = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                long rs = lock.readLock();

                lock.unlockRead(rs);

            }});

        releaseWriteLock(lock, s);

        awaitTermination(t1);

        awaitTermination(t2);

    }

    /**

     * tryReadLock succeeds if readlocked but not writelocked

     */

    public void testTryLockWhenReadLocked() {

        final StampedLock lock = new StampedLock();

        long s = lock.readLock();

        Thread t = newStartedThread(new CheckedRunnable() {

            public void realRun() {