commons-rng-examples/examples-jmh/src/main/java/org/apache/commons/rng/examples/jmh/sampling/distribution/NextGaussianPerformance.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.rng.examples.jmh.sampling.distribution;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.Warmup;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import java.util.concurrent.TimeUnit;
import java.util.Random;

/**
 * Benchmark for {@link Random#nextGaussian()} in order to compare
 * the speed of generation of normally-distributed random numbers.
 */
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@State(Scope.Benchmark)
@Fork(value = 1, jvmArgs = {"-server", "-Xms128M", "-Xmx128M"})
public class NextGaussianPerformance {
    /** JDK's generator. */
    private final Random random = new Random();

    /**
     * The value.
     *
     * <p>This must NOT be final!</p>
     */
    private double value;

    /**
     * Baseline for the JMH timing overhead for production of an {@code double} value.
     *
     * @return the {@code double} value
     */
    @Benchmark
    public double baseline() {
        return value;
    }

    /**
     * Run JDK random gaussian sampler.
     *
     * @return the double
     */
    @Benchmark
    public double runJDKRandomGaussianSampler() {
        return random.nextGaussian();
    }
}