/*

 * 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

/*

 * 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 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 java.util.concurrent.atomic.AtomicReference;

import junit.framework.Test;

import junit.framework.TestSuite;

public class AtomicReferenceTest extends JSR166TestCase {

    public static void main(String[] args) {

        main(suite(), args);

    }

    public static Test suite() {

        return new TestSuite(AtomicReferenceTest.class);

    }

    /**

     * constructor initializes to given value

     */

    public void testConstructor() {

        AtomicReference ai = new AtomicReference(one);

        assertSame(one, ai.get());

    }

    /**

     * default constructed initializes to null

     */

    public void testConstructor2() {

        AtomicReference ai = new AtomicReference();

        assertNull(ai.get());

    }

    /**

     * get returns the last value set

     */

    public void testGetSet() {

        AtomicReference ai = new AtomicReference(one);

        assertSame(one, ai.get());

        ai.set(two);

        assertSame(two, ai.get());

        ai.set(m3);

        assertSame(m3, ai.get());

    }

    /**

     * get returns the last value lazySet in same thread

     */

    public void testGetLazySet() {

        AtomicReference ai = new AtomicReference(one);

        assertSame(one, ai.get());

        ai.lazySet(two);

        assertSame(two, ai.get());

        ai.lazySet(m3);

        assertSame(m3, ai.get());

    }

    /**

     * compareAndSet succeeds in changing value if equal to expected else fails

     */

    public void testCompareAndSet() {

        AtomicReference ai = new AtomicReference(one);

        assertTrue(ai.compareAndSet(one, two));

        assertTrue(ai.compareAndSet(two, m4));

        assertSame(m4, ai.get());

        assertFalse(ai.compareAndSet(m5, seven));

        assertSame(m4, ai.get());

        assertTrue(ai.compareAndSet(m4, seven));

        assertSame(seven, ai.get());

    }

    /**

     * compareAndSet in one thread enables another waiting for value

     * to succeed

     */

    public void testCompareAndSetInMultipleThreads() throws Exception {

        final AtomicReference ai = new AtomicReference(one);

        Thread t = new Thread(new CheckedRunnable() {

            public void realRun() {

                while (!ai.compareAndSet(two, three))

                    Thread.yield();

            }});

        t.start();

        assertTrue(ai.compareAndSet(one, two));

        t.join(LONG_DELAY_MS);

        assertFalse(t.isAlive());

        assertSame(three, ai.get());

    }

    /**

     * repeated weakCompareAndSet succeeds in changing value when equal

     * to expected

     */

    public void testWeakCompareAndSet() {

        AtomicReference ai = new AtomicReference(one);

        do {} while (!ai.weakCompareAndSet(one, two));

        do {} while (!ai.weakCompareAndSet(two, m4));

        assertSame(m4, ai.get());

        do {} while (!ai.weakCompareAndSet(m4, seven));

        assertSame(seven, ai.get());

    }

    /**

     * getAndSet returns previous value and sets to given value

     */

    public void testGetAndSet() {

        AtomicReference ai = new AtomicReference(one);

        assertSame(one, ai.getAndSet(zero));

        assertSame(zero, ai.getAndSet(m10));

        assertSame(m10, ai.getAndSet(one));

    }

    /**

     * a deserialized serialized atomic holds same value

     */

    public void testSerialization() throws Exception {

        AtomicReference x = new AtomicReference();

        AtomicReference y = serialClone(x);

        assertNotSame(x, y);

        x.set(one);

        AtomicReference z = serialClone(x);

        assertNotSame(y, z);

        assertEquals(one, x.get());

        assertEquals(null, y.get());

        assertEquals(one, z.get());

    }

    /**

     * toString returns current value.

     */

    public void testToString() {

        AtomicReference<Integer> ai = new AtomicReference<>(one);

        assertEquals(one.toString(), ai.toString());

        ai.set(two);

        assertEquals(two.toString(), ai.toString());

    }

}