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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.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.util.Random;
  import java.util.concurrent.TimeUnit;
  
  import com.google.common.hash.Hasher;
  import com.google.common.hash.Hashing;
  
  import org.openjdk.jmh.annotations.Benchmark;
  import org.openjdk.jmh.annotations.BenchmarkMode;
  import org.openjdk.jmh.annotations.Fork;
  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.AverageTime)
  @OutputTimeUnit(TimeUnit.NANOSECONDS)
  @Warmup(iterations = 3, time = 1, timeUnit = TimeUnit.SECONDS)
  @Measurement(iterations = 5, time = 2, timeUnit = TimeUnit.SECONDS)
  @Fork(value = 1, jvmArgsAppend = { "-Xmx512M", "-Djmh.executor=CUSTOM", "-Djmh.executor.class=org.apache.cassandra.test.microbench.FastThreadExecutor"})
  @Threads(4) // make sure this matches the number of _physical_cores_
  @State(Scope.Benchmark)
  public class HashingBench
  {
      private static final Random random = new Random(12345678);
  
      private static final MessageDigest messageDigest;
      static
      {
          try
          {
              messageDigest = MessageDigest.getInstance("MD5");
          }
          catch (NoSuchAlgorithmException nsae)
          {
              throw new RuntimeException("MD5 digest algorithm is not available", nsae);
          }
      }
  
  
      // intentionally not on power-of-2 values
      @Param({ "31", "131", "517", "2041" })
      private int bufferSize;
  
      private byte[] array;
  
      @Setup
      public void setup() throws NoSuchAlgorithmException
      {
          array = new byte[bufferSize];
          random.nextBytes(array);
      }
  
      @Benchmark
      public byte[] benchMessageDigestMD5()
      {
          try
          {
              MessageDigest clone = (MessageDigest) messageDigest.clone();
              clone.update(array);
              return clone.digest();
          }
          catch (CloneNotSupportedException e)
          {
              throw new RuntimeException(e);
          }
      }
  
      @Benchmark
      public byte[] benchHasherMD5()
      {
          Hasher md5Hasher = Hashing.md5().newHasher();
          md5Hasher.putBytes(array);
          return md5Hasher.hash().asBytes();
      }
  
      @Benchmark
      public byte[] benchHasherMurmur3_128()
      {
          Hasher murmur3_128Hasher = Hashing.murmur3_128().newHasher();
          murmur3_128Hasher.putBytes(array);
          return murmur3_128Hasher.hash().asBytes();
      }
  }
  