content: /*
  * 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.cassandra.stress.generate;
  
  import java.util.Random;
  
  import org.apache.commons.math3.random.RandomGenerator;
  
  // based on http://en.wikipedia.org/wiki/Xorshift, but periodically we reseed with our stronger random generator
  // note it is also non-atomically updated, so expects to be used by a single thread
  public class FasterRandom implements RandomGenerator
  {
      final Random random = new Random();
  
      private long seed;
      private int reseed;
  
      public void setSeed(int seed)
      {
          setSeed((long) seed);
      }
  
      public void setSeed(int[] ints)
      {
          if (ints.length > 1)
              setSeed (((long) ints[0] << 32) | ints[1]);
          else
              setSeed(ints[0]);
      }
  
      public void setSeed(long seed)
      {
          this.seed = seed;
          rollover();
      }
  
      private void rollover()
      {
          this.reseed = 0;
          random.setSeed(seed);
          seed = random.nextLong();
      }
  
      public void nextBytes(byte[] bytes)
      {
          int i = 0;
          while (i < bytes.length)
          {
              long next = nextLong();
              while (i < bytes.length)
              {
                  bytes[i++] = (byte) (next & 0xFF);
                  next >>>= 8;
              }
          }
      }
  
      public int nextInt()
      {
          return (int) nextLong();
      }
  
      public int nextInt(int i)
      {
          return Math.abs((int) nextLong() % i);
      }
  
      public long nextLong()
      {
          if (++this.reseed == 32)
              rollover();
  
          long seed = this.seed;
          seed ^= seed >> 12;
          seed ^= seed << 25;
          seed ^= seed >> 27;
          this.seed = seed;
          return seed * 2685821657736338717L;
      }
  
      public boolean nextBoolean()
      {
          return ((int) nextLong() & 1) == 1;
      }
  
      public float nextFloat()
      {
          return Float.intBitsToFloat((int) nextLong());
      }
  
      public double nextDouble()
      {
          return Double.longBitsToDouble(nextLong());
      }
  
      public double nextGaussian()
      {
          return random.nextGaussian();
      }
  }
  