/*

 * Copyright (c) 2014, 2019, Oracle and/or its affiliates. All rights reserved.

 * 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

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 */

package org.openjdk.bench.vm.lang;

import org.openjdk.jmh.annotations.Benchmark;

import org.openjdk.jmh.annotations.BenchmarkMode;

import org.openjdk.jmh.annotations.Mode;

import org.openjdk.jmh.annotations.OutputTimeUnit;

import org.openjdk.jmh.annotations.Param;

import org.openjdk.jmh.annotations.Scope;

import org.openjdk.jmh.annotations.Setup;

import org.openjdk.jmh.annotations.State;

import org.openjdk.jmh.annotations.Threads;

import java.util.concurrent.TimeUnit;

/**

 * Benchmark class for simple lock unlock tests. Nothing big should ever go into this class.

 */

@BenchmarkMode(Mode.AverageTime)

@OutputTimeUnit(TimeUnit.NANOSECONDS)

@State(Scope.Benchmark)

public class LockUnlock {

    @Param("100")

    private int innerCount;

    public Object lockObject1;

    public Object lockObject2;

    public int factorial;

    public int dummyInt1;

    public int dummyInt2;

    @Setup

    public void setup() {

        lockObject1 = new Object();

        lockObject2 = new Object();

        dummyInt1 = 47;

        dummyInt2 = 11; // anything

    }

    /** Perform a synchronized on a local object within a loop. */

    @Benchmark

    public void testSimpleLockUnlock() {

        Object localObject = lockObject1;

        for (int i = 0; i < innerCount; i++) {

            synchronized (localObject) {

                dummyInt1++;

                dummyInt2++;

            }

        }

    }

    /** Perform a recursive synchronized on a local object within a loop. */

    @Benchmark

    public void testRecursiveLockUnlock() {

        Object localObject = lockObject1;

        for (int i = 0; i < innerCount; i++) {

            synchronized (localObject) {

                synchronized (localObject) {

                    dummyInt1++;

                    dummyInt2++;

                }

            }

        }

    }

    /** Perform two synchronized after each other on the same local object. */

    @Benchmark

    public void testSerialLockUnlock() {

        Object localObject = lockObject1;

        for (int i = 0; i < innerCount; i++) {

            synchronized (localObject) {

                dummyInt1++;

            }

            synchronized (localObject) {

                dummyInt2++;

            }

        }

    }

    /**

     * Performs recursive synchronizations on the same local object.

     * <p/>

     * Result is 3628800

     */

    @Benchmark

    public void testRecursiveSynchronization() {

        factorial = fact(10);

    }

    private synchronized int fact(int n) {

        if (n == 0) {

            return 1;

        } else {

            return fact(n - 1) * n;

        }

    }

    /**

     * With two threads lockObject1 will be contended so should be

     * inflated.

     */

    @Threads(2)

    @Benchmark

    public void testContendedLock() {

        synchronized (lockObject1) {

            dummyInt1++;

        }

    }

}