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   /*
   * Copyright 2019 The Netty Project
   *
   * The Netty Project 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:
   *
   *   https://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 io.netty.buffer;
  
  import java.nio.ByteBuffer;
  import java.util.concurrent.TimeUnit;
  
  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.Setup;
  import org.openjdk.jmh.annotations.TearDown;
  import org.openjdk.jmh.annotations.Warmup;
  
  import io.netty.microbench.util.AbstractMicrobenchmark;
  import io.netty.util.internal.PlatformDependent;
  
  @Warmup(iterations = 5, time = 1500, timeUnit = TimeUnit.MILLISECONDS)
  @Measurement(iterations = 10, time = 1500, timeUnit = TimeUnit.MILLISECONDS)
  @Fork(3)
  @BenchmarkMode(Mode.AverageTime)
  @OutputTimeUnit(TimeUnit.NANOSECONDS)
  public class ByteBufAccessBenchmark extends AbstractMicrobenchmark {
  
      static final class NioFacade extends WrappedByteBuf {
          private final ByteBuffer byteBuffer;
          NioFacade(ByteBuffer byteBuffer) {
              super(Unpooled.EMPTY_BUFFER);
              this.byteBuffer = byteBuffer;
          }
          @Override
          public ByteBuf setLong(int index, long value) {
              byteBuffer.putLong(index, value);
              return this;
          }
          @Override
          public long getLong(int index) {
              return byteBuffer.getLong(index);
          }
          @Override
          public byte readByte() {
              return byteBuffer.get();
          }
          @Override
          public ByteBuf touch() {
              // hack since WrappedByteBuf.readerIndex(int) is final
              byteBuffer.position(0);
              return this;
          }
          @Override
          public boolean release() {
              PlatformDependent.freeDirectBuffer(byteBuffer);
              return true;
          }
      }
  
      public enum ByteBufType {
          UNSAFE {
              @Override
              ByteBuf newBuffer() {
                  return new UnpooledUnsafeDirectByteBuf(
                          UnpooledByteBufAllocator.DEFAULT, 64, 64).setIndex(0, 64);
              }
          },
          UNSAFE_SLICE {
              @Override
              ByteBuf newBuffer() {
                  return UNSAFE.newBuffer().slice(16, 48);
              }
          },
          HEAP {
              @Override
              ByteBuf newBuffer() {
                  return new UnpooledUnsafeHeapByteBuf(
                          UnpooledByteBufAllocator.DEFAULT, 64, 64).setIndex(0,  64);
              }
          },
          COMPOSITE {
              @Override
              ByteBuf newBuffer() {
                  return Unpooled.wrappedBuffer(UNSAFE.newBuffer(), HEAP.newBuffer());
              }
         },
         NIO {
             @Override
             ByteBuf newBuffer() {
                 return new NioFacade(ByteBuffer.allocateDirect(64));
             }
         };
         abstract ByteBuf newBuffer();
     }
 
     @Param
     public ByteBufType bufferType;
 
     @Param({ "true", "false" })
     public String checkAccessible;
 
     @Param({ "true", "false" })
     public String checkBounds;
 
     @Param({ "8" })
     public int batchSize; // applies only to readBatch benchmark
 
     @Setup
     public void setup() {
         System.setProperty("io.netty.buffer.checkAccessible", checkAccessible);
         System.setProperty("io.netty.buffer.checkBounds", checkBounds);
         buffer = bufferType.newBuffer();
     }
 
     private ByteBuf buffer;
 
     @TearDown
     public void tearDown() {
         buffer.release();
         System.clearProperty("io.netty.buffer.checkAccessible");
         System.clearProperty("io.netty.buffer.checkBounds");
     }
 
     @Benchmark
     public long setGetLong() {
         return buffer.setLong(0, 1).getLong(0);
     }
 
     @Benchmark
     public ByteBuf setLong() {
         return buffer.setLong(0, 1);
     }
 
     @Benchmark
     public int readBatch() {
         buffer.readerIndex(0).touch();
         int result = 0;
         // WARNING!
         // Please do not replace this sum loop with a BlackHole::consume loop:
         // BlackHole::consume could prevent the JVM to perform certain optimizations
         // forcing ByteBuf::readByte to be executed in order.
         // The purpose of the benchmark is to mimic accesses on ByteBuf
         // as in a real (single-threaded) case ie without (compiler) memory barriers that would
         // disable certain optimizations or would make bounds checks (if enabled)
         // to happen on each access.
         for (int i = 0, size = batchSize; i < size; i++) {
             result += buffer.readByte();
         }
         return result;
     }
 }