org.recommender101.recommender.extensions.mahout.impl.random.RandomWrapper.java Source code

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Here is the source code for org.recommender101.recommender.extensions.mahout.impl.random.RandomWrapper.java

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package org.recommender101.recommender.extensions.mahout.impl.random;

/**
 * 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.
 */

import org.apache.commons.math3.random.MersenneTwister;
import org.apache.commons.math3.random.RandomGenerator;

import java.util.Random;

/**
 * Copied from the current version (0.9) of mahout to avoid a bug 
 * that blocked everything (only on linux systems) until /dev/random 
 * had some new entropy to offer.
 * @author Jugovac
 *
 */
@SuppressWarnings("serial")
public final class RandomWrapper extends Random {

    private static final long STANDARD_SEED = 0xCAFEDEADBEEFBABEL;

    private final RandomGenerator random;
    private static final Object syncer = new Object();

    RandomWrapper() {
        synchronized (syncer) {
            random = new MersenneTwister();
            random.setSeed(System.nanoTime() + System.identityHashCode(random));
        }

    }

    RandomWrapper(long seed) {
        random = new MersenneTwister(seed);
    }

    @Override
    public void setSeed(long seed) {
        // Since this will be called by the java.util.Random() constructor before we construct
        // the delegate... and because we don't actually care about the result of this for our
        // purpose:
        if (random != null) {
            random.setSeed(seed);
        }
    }

    void resetToTestSeed() {
        setSeed(STANDARD_SEED);
    }

    public RandomGenerator getRandomGenerator() {
        return random;
    }

    @Override
    protected int next(int bits) {
        // Ugh, can't delegate this method -- it's protected
        // Callers can't use it and other methods are delegated, so shouldn't matter
        throw new UnsupportedOperationException();
    }

    @Override
    public void nextBytes(byte[] bytes) {
        random.nextBytes(bytes);
    }

    @Override
    public int nextInt() {
        return random.nextInt();
    }

    @Override
    public int nextInt(int n) {
        return random.nextInt(n);
    }

    @Override
    public long nextLong() {
        return random.nextLong();
    }

    @Override
    public boolean nextBoolean() {
        return random.nextBoolean();
    }

    @Override
    public float nextFloat() {
        return random.nextFloat();
    }

    @Override
    public double nextDouble() {
        return random.nextDouble();
    }

    @Override
    public double nextGaussian() {
        return random.nextGaussian();
    }

}