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Java example source code file (SynchronizedRandomGeneratorTest.java)

This example Java source code file (SynchronizedRandomGeneratorTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraylist, callable, double, executionexception, executorservice, interruptedexception, list, mersennetwister, randomgenerator, synchronizedrandomgenerator, synchronizedrandomgeneratortest, test, threading, threads, throwable, util

The SynchronizedRandomGeneratorTest.java Java example source code

/*
 * 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.math3.random;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

import org.junit.Assert;
import org.junit.Test;

public class SynchronizedRandomGeneratorTest {
    private final int numberOfThreads = 5;
    private final int numberOfGenerators = 5;
    private final int numberOfSamples = 100000;

    @Test
    public void testAdapter() {
        final int seed = 12345;
        final RandomGenerator orig = new MersenneTwister(seed);
        final RandomGenerator wrap
            = new SynchronizedRandomGenerator(new MersenneTwister(seed));

        final int bSize = 67;
        final byte[] bOrig = new byte[bSize];
        final byte[] bWrap = new byte[bSize];

        for (int i = 0; i < 100; i++) {
            orig.nextBytes(bOrig);
            wrap.nextBytes(bWrap);
            for (int k = 0; k < bSize; k++) {
                Assert.assertEquals(bOrig[k], bWrap[k]);
            }

            Assert.assertEquals(orig.nextInt(), wrap.nextInt());

            final int range = (i + 1) * 89;
            Assert.assertEquals(orig.nextInt(range), wrap.nextInt(range));

            Assert.assertEquals(orig.nextLong(), wrap.nextLong());
            Assert.assertEquals(orig.nextBoolean(), wrap.nextBoolean());
            Assert.assertEquals(orig.nextFloat(), wrap.nextFloat(), 0);
            Assert.assertEquals(orig.nextDouble(), wrap.nextDouble(), 0);
            Assert.assertEquals(orig.nextGaussian(), wrap.nextGaussian(), 0);

        }
    }

    @Test
    public void testMath899Sync() throws Throwable {
        try {
            // Running the test several times in order to decrease the
            // probability that a non-thread-safe code did not trigger
            // a concurrency problem.
            for (int i = 0; i < 10; i++) {
                doTestMath899(true, numberOfThreads, numberOfGenerators, numberOfSamples);
            }
        } catch (InterruptedException e) {
            Assert.fail(e.getMessage());
        } catch (ExecutionException e) {
            throw e.getCause();
        }
    }

    /**
     * @param sync Whether to use a synchronizing wrapper.
     */
    private double[] doTestMath899(final boolean sync,
                                   final int numThreads,
                                   final int numGenerators,
                                   final int numSamples)
        throws InterruptedException,
               ExecutionException {
        final RandomGenerator rng = new MersenneTwister();
        final RandomGenerator wrapper = sync ? new SynchronizedRandomGenerator(rng) : rng;

        final List<Callable tasks = new ArrayList>();
        for (int i = 0; i < numGenerators; i++) {
            tasks.add(new Callable<Double>() {
                    public Double call() {
                        Double lastValue = 0d;
                        for (int j = 0; j < numSamples; j++) {
                            lastValue = wrapper.nextGaussian();
                        }
                        return lastValue;
                    }
                });
        }

        final ExecutorService exec = Executors.newFixedThreadPool(numThreads);
        final List<Future results = exec.invokeAll(tasks);

        final double[] values = new double[numGenerators];
        for (int i = 0; i < numGenerators; i++) {
            values[i] = results.get(i).get();
        }
        return values;
    }
}

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