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/*
 * Copyright (c) 2005, 2013, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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.jmh.samples;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.Group;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.infra.Control;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.RunnerException;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;

import java.util.concurrent.atomic.AtomicBoolean;

@State(Scope.Group)
public class JMHSample_18_Control {

    /*
     * Sometimes you need the tap into the harness mind to get the info
     * on the transition change. For this, we have the experimental state object,
     * Control, which is updated by JMH as we go.
     */

    /*
     * In this example, we want to estimate the ping-pong speed for the simple
     * AtomicBoolean. Unfortunately, doing that in naive manner will livelock
     * one of the threads, because the executions of ping/pong are not paired
     * perfectly. We need the escape hatch to terminate the loop if threads
     * are about to leave the measurement.
     */

    public final AtomicBoolean flag = new AtomicBoolean();

    @Benchmark
    @Group("pingpong")
    public void ping(Control cnt) {
        while (!cnt.stopMeasurement && !flag.compareAndSet(false, true)) {
            // this body is intentionally left blank
        }
    }

    @Benchmark
    @Group("pingpong")
    public void pong(Control cnt) {
        while (!cnt.stopMeasurement && !flag.compareAndSet(true, false)) {
            // this body is intentionally left blank
        }
    }

    /*
     * ============================== HOW TO RUN THIS TEST: ====================================
     *
     * You can run this test:
     *
     * a) Via the command line:
     *    $ mvn clean install
     *    $ java -jar target/benchmarks.jar ".*JMHSample_18.*" -wi 1 -i 5 -t 2 -f 1
     *    (we requested 1 warmup iterations, 5 iterations, 2 threads, and single fork)
     *
     * b) Via the Java API:
     *    (see the JMH homepage for possible caveats when running from IDE:
     *      http://openjdk.java.net/projects/code-tools/jmh/)
     */

    public static void main(String[] args) throws RunnerException {
        Options opt = new OptionsBuilder()
                .include(".*" + JMHSample_18_Control.class.getSimpleName() + ".*")
                .warmupIterations(1)
                .measurementIterations(5)
                .threads(2)
                .forks(1)
                .build();

        new Runner(opt).run();
    }

}