/**
* 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.mahout.common;
import com.google.common.base.Charsets;
import org.uncommons.maths.random.MersenneTwisterRNG;
import org.uncommons.maths.random.RepeatableRNG;
import org.uncommons.maths.random.SeedException;
import org.uncommons.maths.random.SeedGenerator;
import java.util.Random;
public final class RandomWrapper extends Random {
private static final byte[] STANDARD_SEED = "Mahout=Hadoop+ML".getBytes(Charsets.US_ASCII);
private static final SeedGenerator SEED_GENERATOR = new FastRandomSeedGenerator();
private static boolean testSeed;
private Random random;
private final Long fixedSeed;
RandomWrapper() {
this.fixedSeed = null;
random = buildRandom();
}
RandomWrapper(long fixedSeed) {
this.fixedSeed = fixedSeed;
random = buildRandom();
}
static void useTestSeed() {
testSeed = true;
}
private Random buildRandom() {
if (fixedSeed == null) {
if (testSeed) {
return new MersenneTwisterRNG(STANDARD_SEED);
} else {
// Force use of standard generator, and disallow use of those based on /dev/random since
// it causes hangs on Ubuntu
try {
return new MersenneTwisterRNG(SEED_GENERATOR);
} catch (SeedException se) {
// Can't happen
throw new IllegalStateException(se);
}
}
} else {
return new MersenneTwisterRNG(RandomUtils.longSeedtoBytes(fixedSeed));
}
}
public Random getRandom() {
return random;
}
void reset() {
random = buildRandom();
}
public long getSeed() {
return RandomUtils.seedBytesToLong(((RepeatableRNG) random).getSeed());
}
@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:
random = new MersenneTwisterRNG(RandomUtils.longSeedtoBytes(seed));
}
@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();
}
}