/*

 * 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/

 * Other contributors include Andrew Wright, Jeffrey Hayes,

 * Pat Fisher, Mike Judd.

 */

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

import java.util.concurrent.CountDownLatch;

import java.util.concurrent.atomic.AtomicBoolean;

import java.util.concurrent.locks.LockSupport;

import junit.framework.Test;

import junit.framework.TestSuite;

public class LockSupportTest extends JSR166TestCase {

    public static void main(String[] args) {

        main(suite(), args);

    }

    public static Test suite() {

        return new TestSuite(LockSupportTest.class);

    }

    static {

        // Reduce the risk of rare disastrous classloading in first call to

        // LockSupport.park: https://bugs.openjdk.java.net/browse/JDK-8074773

        Class<?> ensureLoaded = LockSupport.class;

    }

    /**

     * Returns the blocker object used by tests in this file.

     * Any old object will do; we'll return a convenient one.

     */

    static Object theBlocker() {

        return LockSupportTest.class;

    }

    enum ParkMethod {

        park() {

            void park() {

                LockSupport.park();

            }

            Thread.State parkedState() { return Thread.State.WAITING; }

        },

        parkUntil() {

            void park(long millis) {

                LockSupport.parkUntil(deadline(millis));

            }

        },

        parkNanos() {

            void park(long millis) {

                LockSupport.parkNanos(MILLISECONDS.toNanos(millis));

            }

        },

        parkBlocker() {

            void park() {

                LockSupport.park(theBlocker());

            }

            Thread.State parkedState() { return Thread.State.WAITING; }

        },

        parkUntilBlocker() {

            void park(long millis) {

                LockSupport.parkUntil(theBlocker(), deadline(millis));

            }

        },

        parkNanosBlocker() {

            void park(long millis) {

                LockSupport.parkNanos(theBlocker(),

                                      MILLISECONDS.toNanos(millis));

            }

        };

        void park() { park(2 * LONG_DELAY_MS); }

        void park(long millis) {

            throw new UnsupportedOperationException();

        }

        Thread.State parkedState() { return Thread.State.TIMED_WAITING; }

        /** Returns a deadline to use with parkUntil. */

        long deadline(long millis) {

            // beware of rounding

            return System.currentTimeMillis() + millis + 1;

        }

    }

    /**

     * park is released by subsequent unpark

     */

    public void testParkBeforeUnpark_park() {

        testParkBeforeUnpark(ParkMethod.park);

    }

    public void testParkBeforeUnpark_parkNanos() {

        testParkBeforeUnpark(ParkMethod.parkNanos);

    }

    public void testParkBeforeUnpark_parkUntil() {

        testParkBeforeUnpark(ParkMethod.parkUntil);

    }

    public void testParkBeforeUnpark_parkBlocker() {

        testParkBeforeUnpark(ParkMethod.parkBlocker);

    }

    public void testParkBeforeUnpark_parkNanosBlocker() {

        testParkBeforeUnpark(ParkMethod.parkNanosBlocker);

    }

    public void testParkBeforeUnpark_parkUntilBlocker() {

        testParkBeforeUnpark(ParkMethod.parkUntilBlocker);

    }

    public void testParkBeforeUnpark(final ParkMethod parkMethod) {

        final CountDownLatch pleaseUnpark = new CountDownLatch(1);

        Thread t = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                pleaseUnpark.countDown();

                parkMethod.park();

            }});

        await(pleaseUnpark);

        LockSupport.unpark(t);

        awaitTermination(t);

    }

    /**

     * park is released by preceding unpark

     */

    public void testParkAfterUnpark_park() {

        testParkAfterUnpark(ParkMethod.park);

    }

    public void testParkAfterUnpark_parkNanos() {

        testParkAfterUnpark(ParkMethod.parkNanos);

    }

    public void testParkAfterUnpark_parkUntil() {

        testParkAfterUnpark(ParkMethod.parkUntil);

    }

    public void testParkAfterUnpark_parkBlocker() {

        testParkAfterUnpark(ParkMethod.parkBlocker);

    }

    public void testParkAfterUnpark_parkNanosBlocker() {

        testParkAfterUnpark(ParkMethod.parkNanosBlocker);

    }

    public void testParkAfterUnpark_parkUntilBlocker() {

        testParkAfterUnpark(ParkMethod.parkUntilBlocker);

    }

    public void testParkAfterUnpark(final ParkMethod parkMethod) {

        final CountDownLatch pleaseUnpark = new CountDownLatch(1);

        final AtomicBoolean pleasePark = new AtomicBoolean(false);

        Thread t = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                pleaseUnpark.countDown();

                while (!pleasePark.get())

                    Thread.yield();

                parkMethod.park();

            }});

        await(pleaseUnpark);

        LockSupport.unpark(t);

        pleasePark.set(true);

        awaitTermination(t);

    }

    /**

     * park is released by subsequent interrupt

     */

    public void testParkBeforeInterrupt_park() {

        testParkBeforeInterrupt(ParkMethod.park);

    }

    public void testParkBeforeInterrupt_parkNanos() {

        testParkBeforeInterrupt(ParkMethod.parkNanos);

    }

    public void testParkBeforeInterrupt_parkUntil() {

        testParkBeforeInterrupt(ParkMethod.parkUntil);

    }

    public void testParkBeforeInterrupt_parkBlocker() {

        testParkBeforeInterrupt(ParkMethod.parkBlocker);

    }

    public void testParkBeforeInterrupt_parkNanosBlocker() {

        testParkBeforeInterrupt(ParkMethod.parkNanosBlocker);

    }

    public void testParkBeforeInterrupt_parkUntilBlocker() {

        testParkBeforeInterrupt(ParkMethod.parkUntilBlocker);

    }

    public void testParkBeforeInterrupt(final ParkMethod parkMethod) {

        final CountDownLatch pleaseInterrupt = new CountDownLatch(1);

        Thread t = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                pleaseInterrupt.countDown();

                for (int tries = MAX_SPURIOUS_WAKEUPS; tries-->0; ) {

                    parkMethod.park();

                    if (Thread.interrupted())

                        return;

                }

                fail("too many consecutive spurious wakeups?");

            }});

        await(pleaseInterrupt);

        assertThreadBlocks(t, parkMethod.parkedState());

        t.interrupt();

        awaitTermination(t);

    }

    /**

     * park is released by preceding interrupt

     */

    public void testParkAfterInterrupt_park() {

        testParkAfterInterrupt(ParkMethod.park);

    }

    public void testParkAfterInterrupt_parkNanos() {

        testParkAfterInterrupt(ParkMethod.parkNanos);

    }

    public void testParkAfterInterrupt_parkUntil() {

        testParkAfterInterrupt(ParkMethod.parkUntil);

    }

    public void testParkAfterInterrupt_parkBlocker() {

        testParkAfterInterrupt(ParkMethod.parkBlocker);

    }

    public void testParkAfterInterrupt_parkNanosBlocker() {

        testParkAfterInterrupt(ParkMethod.parkNanosBlocker);

    }

    public void testParkAfterInterrupt_parkUntilBlocker() {

        testParkAfterInterrupt(ParkMethod.parkUntilBlocker);

    }

    public void testParkAfterInterrupt(final ParkMethod parkMethod) {

        final CountDownLatch pleaseInterrupt = new CountDownLatch(1);

        Thread t = newStartedThread(new CheckedRunnable() {

            public void realRun() throws Exception {

                pleaseInterrupt.countDown();

                while (!Thread.currentThread().isInterrupted())

                    Thread.yield();

                parkMethod.park();

                assertTrue(Thread.interrupted());

            }});

        await(pleaseInterrupt);

        t.interrupt();

        awaitTermination(t);

    }

    /**

     * timed park times out if not unparked

     */

    public void testParkTimesOut_parkNanos() {

        testParkTimesOut(ParkMethod.parkNanos);

    }

    public void testParkTimesOut_parkUntil() {

        testParkTimesOut(ParkMethod.parkUntil);

    }

    public void testParkTimesOut_parkNanosBlocker() {

        testParkTimesOut(ParkMethod.parkNanosBlocker);

    }

    public void testParkTimesOut_parkUntilBlocker() {

        testParkTimesOut(ParkMethod.parkUntilBlocker);

    }

    public void testParkTimesOut(final ParkMethod parkMethod) {

        Thread t = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                for (int tries = MAX_SPURIOUS_WAKEUPS; tries-->0; ) {

                    long startTime = System.nanoTime();

                    parkMethod.park(timeoutMillis());

                    if (millisElapsedSince(startTime) >= timeoutMillis())

                        return;

                }

                fail("too many consecutive spurious wakeups?");

            }});

        awaitTermination(t);

    }

    /**

     * getBlocker(null) throws NullPointerException

     */

    public void testGetBlockerNull() {

        try {

            LockSupport.getBlocker(null);

            shouldThrow();

        } catch (NullPointerException success) {}

    }

    /**

     * getBlocker returns the blocker object passed to park

     */

    public void testGetBlocker_parkBlocker() {

        testGetBlocker(ParkMethod.parkBlocker);

    }

    public void testGetBlocker_parkNanosBlocker() {

        testGetBlocker(ParkMethod.parkNanosBlocker);

    }

    public void testGetBlocker_parkUntilBlocker() {

        testGetBlocker(ParkMethod.parkUntilBlocker);

    }

    public void testGetBlocker(final ParkMethod parkMethod) {

        final CountDownLatch started = new CountDownLatch(1);

        Thread t = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                Thread t = Thread.currentThread();

                started.countDown();

                for (int tries = MAX_SPURIOUS_WAKEUPS; tries-->0; ) {

                    assertNull(LockSupport.getBlocker(t));

                    parkMethod.park();

                    assertNull(LockSupport.getBlocker(t));

                    if (Thread.interrupted())

                        return;

                }

                fail("too many consecutive spurious wakeups?");

            }});

        long startTime = System.nanoTime();

        await(started);

        for (;;) {

            Object x = LockSupport.getBlocker(t);

            if (x == theBlocker()) { // success

                t.interrupt();

                awaitTermination(t);

                assertNull(LockSupport.getBlocker(t));

                return;

            } else {

                assertNull(x);  // ok

                if (millisElapsedSince(startTime) > LONG_DELAY_MS)

                    fail("timed out");

                if (t.getState() == Thread.State.TERMINATED)

                    break;

                Thread.yield();

            }

        }

    }

    /**

     * timed park(0) returns immediately.

     *

     * Requires hotspot fix for:

     * 6763959 java.util.concurrent.locks.LockSupport.parkUntil(0) blocks forever

     * which is in jdk7-b118 and 6u25.

     */

    public void testPark0_parkNanos() {

        testPark0(ParkMethod.parkNanos);

    }

    public void testPark0_parkUntil() {

        testPark0(ParkMethod.parkUntil);

    }

    public void testPark0_parkNanosBlocker() {

        testPark0(ParkMethod.parkNanosBlocker);

    }

    public void testPark0_parkUntilBlocker() {

        testPark0(ParkMethod.parkUntilBlocker);

    }

    public void testPark0(final ParkMethod parkMethod) {

        Thread t = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                parkMethod.park(0L);

            }});

        awaitTermination(t);

    }

    /**

     * timed park(Long.MIN_VALUE) returns immediately.

     */

    public void testParkNeg_parkNanos() {

        testParkNeg(ParkMethod.parkNanos);

    }

    public void testParkNeg_parkUntil() {

        testParkNeg(ParkMethod.parkUntil);

    }

    public void testParkNeg_parkNanosBlocker() {

        testParkNeg(ParkMethod.parkNanosBlocker);

    }

    public void testParkNeg_parkUntilBlocker() {

        testParkNeg(ParkMethod.parkUntilBlocker);

    }

    public void testParkNeg(final ParkMethod parkMethod) {

        Thread t = newStartedThread(new CheckedRunnable() {

            public void realRun() {

                parkMethod.park(Long.MIN_VALUE);

            }});

        awaitTermination(t);

    }

}