/*

 * 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 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 java.util.concurrent.CyclicBarrier;

import java.util.concurrent.Executors;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.atomic.DoubleAdder;

import junit.framework.Test;

import junit.framework.TestSuite;

public class DoubleAdderTest extends JSR166TestCase {

    public static void main(String[] args) {

        main(suite(), args);

    }

    public static Test suite() {

        return new TestSuite(DoubleAdderTest.class);

    }

    /**

     * default constructed initializes to zero

     */

    public void testConstructor() {

        DoubleAdder ai = new DoubleAdder();

        assertEquals(0.0, ai.sum());

    }

    /**

     * add adds given value to current, and sum returns current value

     */

    public void testAddAndSum() {

        DoubleAdder ai = new DoubleAdder();

        ai.add(2.0);

        assertEquals(2.0, ai.sum());

        ai.add(-4.0);

        assertEquals(-2.0, ai.sum());

    }

    /**

     * reset() causes subsequent sum() to return zero

     */

    public void testReset() {

        DoubleAdder ai = new DoubleAdder();

        ai.add(2.0);

        assertEquals(2.0, ai.sum());

        ai.reset();

        assertEquals(0.0, ai.sum());

    }

    /**

     * sumThenReset() returns sum; subsequent sum() returns zero

     */

    public void testSumThenReset() {

        DoubleAdder ai = new DoubleAdder();

        ai.add(2.0);

        assertEquals(2.0, ai.sum());

        assertEquals(2.0, ai.sumThenReset());

        assertEquals(0.0, ai.sum());

    }

    /**

     * a deserialized serialized adder holds same value

     */

    public void testSerialization() throws Exception {

        DoubleAdder x = new DoubleAdder();

        DoubleAdder y = serialClone(x);

        assertNotSame(x, y);

        x.add(-22.0);

        DoubleAdder z = serialClone(x);

        assertEquals(-22.0, x.sum());

        assertEquals(0.0, y.sum());

        assertEquals(-22.0, z.sum());

    }

    /**

     * toString returns current value.

     */

    public void testToString() {

        DoubleAdder ai = new DoubleAdder();

        assertEquals(Double.toString(0.0), ai.toString());

        ai.add(1.0);

        assertEquals(Double.toString(1.0), ai.toString());

    }

    /**

     * intValue returns current value.

     */

    public void testIntValue() {

        DoubleAdder ai = new DoubleAdder();

        assertEquals(0, ai.intValue());

        ai.add(1.0);

        assertEquals(1, ai.intValue());

    }

    /**

     * longValue returns current value.

     */

    public void testLongValue() {

        DoubleAdder ai = new DoubleAdder();

        assertEquals(0, ai.longValue());

        ai.add(1.0);

        assertEquals(1, ai.longValue());

    }

    /**

     * floatValue returns current value.

     */

    public void testFloatValue() {

        DoubleAdder ai = new DoubleAdder();

        assertEquals(0.0f, ai.floatValue());

        ai.add(1.0);

        assertEquals(1.0f, ai.floatValue());

    }

    /**

     * doubleValue returns current value.

     */

    public void testDoubleValue() {

        DoubleAdder ai = new DoubleAdder();

        assertEquals(0.0, ai.doubleValue());

        ai.add(1.0);

        assertEquals(1.0, ai.doubleValue());

    }

    /**

     * adds by multiple threads produce correct sum

     */

    public void testAddAndSumMT() throws Throwable {

        final int incs = 1000000;

        final int nthreads = 4;

        final ExecutorService pool = Executors.newCachedThreadPool();

        DoubleAdder a = new DoubleAdder();

        CyclicBarrier barrier = new CyclicBarrier(nthreads + 1);

        for (int i = 0; i < nthreads; ++i)

            pool.execute(new AdderTask(a, barrier, incs));

        barrier.await();

        barrier.await();

        double total = (long)nthreads * incs;

        double sum = a.sum();

        assertEquals(sum, total);

        pool.shutdown();

    }

    static final class AdderTask implements Runnable {

        final DoubleAdder adder;

        final CyclicBarrier barrier;

        final int incs;

        volatile double result;

        AdderTask(DoubleAdder adder, CyclicBarrier barrier, int incs) {

            this.adder = adder;

            this.barrier = barrier;

            this.incs = incs;

        }

        public void run() {

            try {

                barrier.await();

                DoubleAdder a = adder;

                for (int i = 0; i < incs; ++i)

                    a.add(1.0);

                result = a.sum();

                barrier.await();

            } catch (Throwable t) { throw new Error(t); }

        }

    }

}