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   * 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,
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   * See the License for the specific language governing permissions and
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  package org.apache.cassandra.test.microbench;
  
  import java.util.ArrayList;
  import java.util.Comparator;
  import java.util.List;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.cassandra.utils.btree.BTree;
  import org.apache.cassandra.utils.btree.UpdateFunction;
  import org.openjdk.jmh.annotations.Benchmark;
  import org.openjdk.jmh.annotations.BenchmarkMode;
  import org.openjdk.jmh.annotations.Fork;
  import org.openjdk.jmh.annotations.Level;
  import org.openjdk.jmh.annotations.Measurement;
  import org.openjdk.jmh.annotations.Mode;
  import org.openjdk.jmh.annotations.OutputTimeUnit;
  import org.openjdk.jmh.annotations.Param;
  import org.openjdk.jmh.annotations.Scope;
  import org.openjdk.jmh.annotations.Setup;
  import org.openjdk.jmh.annotations.State;
  import org.openjdk.jmh.annotations.Threads;
  import org.openjdk.jmh.annotations.Warmup;
  
  @BenchmarkMode(Mode.Throughput)
  @OutputTimeUnit(TimeUnit.MILLISECONDS)
  @Warmup(iterations = 4, time = 1, timeUnit = TimeUnit.SECONDS)
  @Measurement(iterations = 8, time = 2, timeUnit = TimeUnit.SECONDS)
  @Fork(value = 2)
  @Threads(4)
  @State(Scope.Benchmark)
  public class BTreeBuildBench
  {
      private List<Integer> data;
  
      @Param({"1", "2", "5", "10", "20", "40", "100", "1000", "10000", "100000"})
      int dataSize;
  
      private static final Comparator<Integer> CMP = new Comparator<Integer>()
      {
          public int compare(Integer o1, Integer o2)
          {
              return Integer.compare(o1, o2);
          }
      };
  
      @Setup(Level.Trial)
      public void setup()
      {
          data = new ArrayList<>(dataSize);
          for (int i = 0 ; i < dataSize; i++)
              data.add(i);
      }
  
      private int buildTree(List<Integer> data)
      {
          Object[] btree = BTree.build(data, UpdateFunction.noOp());
          // access the btree to avoid java optimized out this code
          return BTree.size(btree);
      }
  
      private int treeBuilderAddAll(List<Integer> data)
      {
          BTree.Builder<Integer> builder = BTree.builder(Comparator.naturalOrder());
          Object[] btree = builder.addAll(data).build();
          return BTree.size(btree);
      }
  
      @Benchmark
      public int treeBuilderRecycleAdd()
      {
          BTree.Builder<Integer> builder = BTree.builder(Comparator.naturalOrder());
          builder.auto(false);
          for (Integer v : data)
              builder.add(v);
          Object[] btree = builder.build();
          return BTree.size(btree);
      }
  
      @Benchmark
      public int buildTreeTest()
      {
          return buildTree(data);
      }
  }
  