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   /*
    * Copyright 2018 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 io.netty.microbench.util.AbstractMicrobenchmark;
  import org.openjdk.jmh.annotations.Benchmark;
  import org.openjdk.jmh.annotations.Measurement;
  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 java.nio.charset.Charset;
  import java.util.Arrays;
  import java.util.concurrent.TimeUnit;
  
  @Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
  @Measurement(iterations = 10, time = 1, timeUnit = TimeUnit.SECONDS)
  public class AbstractByteBufGetCharSequenceBenchmark extends AbstractMicrobenchmark {
  
      public enum ByteBufType {
          DIRECT {
              @Override
              ByteBuf newBuffer(byte[] bytes, int length) {
                  ByteBuf buffer = Unpooled.directBuffer(length);
                  buffer.writeBytes(bytes, 0, length);
                  return buffer;
              }
          },
          HEAP_OFFSET {
              @Override
              ByteBuf newBuffer(byte[] bytes, int length) {
                  return Unpooled.wrappedBuffer(bytes, 1, length);
              }
          },
          HEAP {
              @Override
              ByteBuf newBuffer(byte[] bytes, int length) {
                  return Unpooled.wrappedBuffer(bytes, 0, length);
              }
          },
          COMPOSITE {
              @Override
              ByteBuf newBuffer(byte[] bytes, int length) {
                  CompositeByteBuf buffer = Unpooled.compositeBuffer();
                  int offset = 0;
                  // 8 buffers per composite.
                  int capacity = length / 8;
  
                  while (length > 0) {
                      buffer.addComponent(true, Unpooled.wrappedBuffer(bytes, offset, Math.min(length, capacity)));
                      length -= capacity;
                      offset += capacity;
                  }
                  return buffer;
              }
          };
          abstract ByteBuf newBuffer(byte[] bytes, int length);
      }
  
      @Param({ "8", "64", "1024", "10240", "1073741824" })
      public int size;
  
      @Param({ "US-ASCII", "ISO_8859_1" })
      public String charsetName;
  
      @Param
      public ByteBufType bufferType;
  
      private ByteBuf buffer;
      private Charset charset;
  
      @Override
      protected String[] jvmArgs() {
          // Ensure we minimize the GC overhead by sizing the heap big enough.
          return new String[] { "-XX:MaxDirectMemorySize=2g", "-Xmx8g", "-Xms8g", "-Xmn6g" };
      }
  
      @Setup
      public void setup() {
          byte[] bytes = new byte[size + 2];
          Arrays.fill(bytes, (byte) 'a');
  
          // Use an offset to not allow any optimizations because we use the exact passed in byte[] for heap buffers.
          buffer = bufferType.newBuffer(bytes, size);
          charset = Charset.forName(charsetName);
     }
 
     @TearDown
     public void teardown() {
         buffer.release();
     }
 
     @Benchmark
     public int getCharSequence() {
         return traverse(buffer.getCharSequence(buffer.readerIndex(), size, charset));
     }
 
     @Benchmark
     public int getCharSequenceOld() {
         return traverse(buffer.toString(buffer.readerIndex(), size, charset));
     }
 
     private static int traverse(CharSequence cs) {
         int i = 0, len = cs.length();
         while (i < len && cs.charAt(i++) != 0) {
             // ensure result is "used"
         }
         return i;
     }
 }