MyBenchmark.java

/*
 * Copyright (c) 2014, Oracle America, Inc.
 * All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
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 *    this list of conditions and the following disclaimer.
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 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
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 *  * Neither the name of Oracle nor the names of its contributors may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 */

package org.sample;

import java.nio.ByteBuffer;
import org.openjdk.jmh.annotations.Benchmark;

public class MyBenchmark {
    private static class FileDesc {
      private final ByteBuffer bb;
      int bbPos;

      FileDesc(ByteBuffer bb) {
        bbPos = bb.getShort(bb.position()) + bb.position();
        this.bb = bb;
      }

      public int getVal() {
        return bb.getInt(bbPos);
      }
    }

    private static class FileDesc2 {
      private final byte[] bb;
      int bbPos;

      FileDesc2(byte[] bb) {
        bbPos = getShort(bb, 0);
        this.bb = bb;
      }

      public int getVal() {
        return getInt(bb, bbPos);
      }
      public static short getShort(final byte[] b, final int offset) {
        return (short) ((b[offset + 1] & 0xFF) | (b[offset] << 8));
      }
      public static int getInt(final byte[] b, final int offset) {
        return (b[offset + 0] & 0xFF) << 24 |
            (b[offset + 1] & 0xFF) << 16 |
            (b[offset + 2] & 0xFF) << 8 |
            (b[offset + 3] & 0xFF) << 0;
      }
    }

    static final byte[] foo = new byte[]{0, 4,3,4,5,6,7,8,9};

    @Benchmark
    public int testMethod() {
      return new FileDesc(ByteBuffer.wrap(foo)).getVal();
    }

    @Benchmark
    public int testWithBytes() {
      return new FileDesc2(foo).getVal();
    }

}