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;
  
  import net.jpountz.lz4.LZ4Compressor;
  import net.jpountz.lz4.LZ4Factory;
  import net.jpountz.lz4.LZ4SafeDecompressor;
  import org.openjdk.jmh.annotations.*;
  import org.xerial.snappy.Snappy;
  
  import java.io.IOException;
  import java.util.concurrent.ThreadLocalRandom;
  import java.util.concurrent.TimeUnit;
  
  @BenchmarkMode(Mode.Throughput)
  @OutputTimeUnit(TimeUnit.MILLISECONDS)
  @Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
  @Measurement(iterations = 5, time = 2, timeUnit = TimeUnit.SECONDS)
  @Fork(value = 1, jvmArgsAppend = "-Xmx512M")
  @Threads(1)
  @State(Scope.Benchmark)
  public class SampleBench
  {
      @Param({"65536"})
      private int pageSize;
  
      @Param({"1024"})
      private int uniquePages;
  
      @Param({"0.1"})
      private double randomRatio;
  
      @Param({"4..16"})
      private String randomRunLength;
  
      @Param({"4..128"})
      private String duplicateLookback;
  
      private byte[][] lz4Bytes;
      private byte[][] snappyBytes;
      private byte[][] rawBytes;
  
      private LZ4SafeDecompressor lz4Decompressor = LZ4Factory.fastestInstance().safeDecompressor();
  
      private LZ4Compressor lz4Compressor = LZ4Factory.fastestInstance().fastCompressor();
  
      @State(Scope.Thread)
      public static class ThreadState
      {
          byte[] bytes;
      }
  
      @Setup
      public void setup() throws IOException
      {
          ThreadLocalRandom random = ThreadLocalRandom.current();
          int[] randomRunLength = range(this.randomRunLength);
          int[] duplicateLookback = range(this.duplicateLookback);
          rawBytes = new byte[uniquePages][pageSize];
          lz4Bytes = new byte[uniquePages][];
          snappyBytes = new byte[uniquePages][];
          byte[][] runs = new byte[duplicateLookback[1] - duplicateLookback[0]][];
          for (int i = 0 ; i < rawBytes.length ; i++)
          {
              byte[] trg = rawBytes[0];
              int runCount = 0;
              int byteCount = 0;
              while (byteCount < trg.length)
              {
                  byte[] nextRun;
                  if (runCount == 0 || random.nextDouble() < this.randomRatio)
                  {
                      nextRun = new byte[random.nextInt(randomRunLength[0], randomRunLength[1])];
                      random.nextBytes(nextRun );
                      runs[runCount % runs.length] = nextRun;
                      runCount++;
                  }
                  else
                  {
                      int index = runCount < duplicateLookback[1]
                              ? random.nextInt(runCount)
                              : (runCount - random.nextInt(duplicateLookback[0], duplicateLookback[1]));
                      nextRun = runs[index % runs.length];
                  }
                  System.arraycopy(nextRun, 0, trg, byteCount, Math.min(nextRun.length, trg.length - byteCount));
                  byteCount += nextRun.length;
              }
              lz4Bytes[i] = lz4Compressor.compress(trg);
              snappyBytes[i] = Snappy.compress(trg);
          }
      }
  
      static int[] range(String spec)
      {
          String[] split = spec.split("\\.\\.");
          return new int[] { Integer.parseInt(split[0]), Integer.parseInt(split[1]) };
      }
  
      @Benchmark
      public void lz4(ThreadState state)
      {
          if (state.bytes == null)
              state.bytes = new byte[this.pageSize];
          byte[] in = lz4Bytes[ThreadLocalRandom.current().nextInt(lz4Bytes.length)];
          lz4Decompressor.decompress(in, state.bytes);
      }
  
      @Benchmark
      public void snappy(ThreadState state) throws IOException
      {
          byte[] in = snappyBytes[ThreadLocalRandom.current().nextInt(snappyBytes.length)];
          state.bytes = Snappy.uncompress(in);
      }
  }
  