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.test.microbench.btree;
  
  import java.util.Random;
  
  /**
   * A utility class to visit 2^n integers, around a median value, in an order that rapidly covers a wide range of values
   */
  public class IntVisitor
  {
      int invocations;
      int shift;
      int mask;
      int base;
  
      public IntVisitor()
      {
      }
  
      public IntVisitor(int median)
      {
          setup(median);
      }
  
      public void setup(int median)
      {
          int variance = Integer.highestOneBit(median);
          mask = variance - 1;
          base = median - variance/2;
          shift = 32 - Integer.bitCount(mask);
      }
  
      public int i()
      {
          return invocations;
      }
  
      public int cur()
      {
          return size(invocations);
      }
  
      public int next()
      {
          return size(invocations = invocations == Integer.MAX_VALUE ? 0 : invocations + 1);
      }
  
      public int min()
      {
          return base;
      };
  
      public int size()
      {
          return mask + 1;
      };
  
      public int size(int invocations)
      {
          // we reverse the integer to more evenly distribute the visitation of sizes
          return base + (Integer.reverse(invocations & mask) >>> shift);
      }
  
      public void randomise(Random random)
      {
          invocations = random.nextInt(Integer.MAX_VALUE);
      }
  }