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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,
   * 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;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.UUID;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.cassandra.utils.btree.BTreeSearchIterator;
  import org.apache.cassandra.utils.btree.BTree;
  import org.apache.cassandra.utils.btree.BTree.Dir;
  import org.apache.cassandra.utils.btree.FullBTreeSearchIterator;
  import org.apache.cassandra.utils.btree.LeafBTreeSearchIterator;
  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.SampleTime)
  @OutputTimeUnit(TimeUnit.NANOSECONDS)
  @Warmup(iterations = 1, time = 1, timeUnit = TimeUnit.SECONDS)
  @Measurement(iterations = 2, time = 4, timeUnit = TimeUnit.SECONDS)
  @Fork(value = 2)
  @Threads(1)
  @State(Scope.Benchmark)
  public class BTreeSearchIteratorBench
  {
      private final int btreeSize = 32;
  
      @Param({"TREE", "LEAF"})
      private String iteratorType;
  
      @Param({ "0",  "1",  "2",  "3", "16", "17", "18", "19",
              "24", "25", "26", "30", "31" })
      private int targetIdx;
  
      private final int cellSize = 1000;
  
      @Param({"ASC", "DESC"})
      private String dirParam;
  
      private Dir dir;
      private Object[] btree;
      private ArrayList<String> data;
      private ArrayList<String> nonExistData;
  
      private static ArrayList<String> seq(int count, int minCellSize)
      {
          ArrayList<String> ret = new ArrayList<>();
          for (int i = 0 ; i < count ; i++)
          {
              StringBuilder sb = new StringBuilder();
              while (sb.length() < minCellSize)
              {
                  String uuid = UUID.randomUUID().toString();
                  sb.append(uuid);
              }
              ret.add(sb.toString());
          }
          Collections.sort(ret);
          return ret;
      }
  
      private static final Comparator<String> CMP = new Comparator<String>()
      {
          public int compare(String s1, String s2)
          {
              return s1.compareTo(s2);
          }
      };
  
      @Setup(Level.Trial)
      public void setup() throws Throwable
      {
          data = seq(btreeSize, cellSize);
          nonExistData = new ArrayList<>();
          btree = BTree.build(data, UpdateFunction.noOp());
          for (String d : data)
          {
              nonExistData.add(d.substring(0, d.length() - 1) + "!");
          }
          dir = Dir.valueOf(dirParam);
  
      }
  
      @Benchmark
      public void searchFound()
      {
          BTreeSearchIterator<String, String> iter = getIterator();
          String val = iter.next(data.get(targetIdx));
          assert(val != null);
      }
  
      private BTreeSearchIterator<String,String> getIterator()
      {
          switch (iteratorType)
          {
              case "LEAF":
                  return new LeafBTreeSearchIterator<>(btree, CMP, dir);
              case "TREE":
                  return new FullBTreeSearchIterator<>(btree, CMP, dir);
              default:
                  throw new IllegalArgumentException("unknown btree iterator type: " + iteratorType);
          }
      }
  
      @Benchmark
      public void searchNotFound()
      {
          BTreeSearchIterator<String, String> iter = getIterator();
          String val = iter.next(nonExistData.get(targetIdx));
          assert(val == null);
      }
  }
  