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   * Licensed to the Apache Software Foundation (ASF) under one
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   * 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
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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.concurrent.ThreadLocalRandom;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.cassandra.metrics.DecayingEstimatedHistogramReservoir;
  import org.apache.cassandra.utils.MonotonicClock;
  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;
  import org.openjdk.jmh.runner.Runner;
  import org.openjdk.jmh.runner.RunnerException;
  import org.openjdk.jmh.runner.options.Options;
  import org.openjdk.jmh.runner.options.OptionsBuilder;
  
  import static org.apache.cassandra.metrics.DecayingEstimatedHistogramReservoir.DEFAULT_BUCKET_COUNT;
  import static org.apache.cassandra.metrics.DecayingEstimatedHistogramReservoir.DEFAULT_STRIPE_COUNT;
  import static org.apache.cassandra.metrics.DecayingEstimatedHistogramReservoir.DEFAULT_ZERO_CONSIDERATION;
  
  @BenchmarkMode(Mode.Throughput)
  @OutputTimeUnit(TimeUnit.MILLISECONDS)
  @Warmup(iterations = 2, time = 1, timeUnit = TimeUnit.SECONDS)
  @Measurement(iterations = 4, time = 2, timeUnit = TimeUnit.SECONDS)
  @Threads(4)
  @Fork(value = 3)
  @State(Scope.Benchmark)
  public class DecayingEstimatedHistogramBench
  {
      @Param({ "100000", "500000", "1000000" })
      private long landmarkResetIntervalNs;
  
      DecayingEstimatedHistogramReservoir reservoir;
  
      @Setup
      public void setup()
      {
          reservoir = new DecayingEstimatedHistogramReservoir(DEFAULT_ZERO_CONSIDERATION,
                                                              DEFAULT_BUCKET_COUNT,
                                                              DEFAULT_STRIPE_COUNT,
                                                              MonotonicClock.Global.approxTime,
                                                              landmarkResetIntervalNs);
      }
  
      @State(Scope.Thread)
      public static class HistogramUpdateState
      {
          int update;
  
          @Setup(Level.Invocation)
          public void setup() throws Throwable
          {
              update = ThreadLocalRandom.current().nextInt(10, 1000);
          }
      }
  
      @Benchmark
      public void update(HistogramUpdateState state)
      {
          reservoir.update(state.update);
      }
  
      public static void main(String[] args) throws RunnerException
      {
          Options options = new OptionsBuilder()
                                .include(DecayingEstimatedHistogramBench.class.getSimpleName())
                                .build();
          new Runner(options).run();
      }
  }
  