1 /*
   2  * Copyright (c) 2014 Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package org.openjdk.bench.java.lang.invoke;
  26 
  27 import org.openjdk.jmh.annotations.Benchmark;
  28 import org.openjdk.jmh.annotations.BenchmarkMode;
  29 import org.openjdk.jmh.annotations.Mode;
  30 import org.openjdk.jmh.annotations.OutputTimeUnit;
  31 import org.openjdk.jmh.annotations.Scope;
  32 import org.openjdk.jmh.annotations.Setup;
  33 import org.openjdk.jmh.annotations.State;
  34 
  35 import java.lang.invoke.MethodHandle;
  36 import java.lang.invoke.MethodHandles;
  37 import java.util.concurrent.TimeUnit;
  38 
  39 /**
  40  * Benchmark assesses the performance of MethodHandles.arrayElementSetter
  41  *
  42  * @author Aleksey Shipilev (aleksey.shipilev@oracle.com)
  43  */
  44 @BenchmarkMode(Mode.AverageTime)
  45 @OutputTimeUnit(TimeUnit.NANOSECONDS)
  46 @State(Scope.Thread)
  47 public class MethodHandlesArrayElementSetter {
  48 
  49     /**
  50      * Implementation notes:
  51      *   - creating simple array, and accessing the middle element
  52      *   - might have done iteration over array, but that will measure pipelining effects instead
  53      *   - volatile modifier on array breaks the DCE, which would otherwise eliminate the array store
  54      *   - the array is not shared to prevent true sharing
  55      *   - the array is large enough to prevent false sharing
  56      */
  57 
  58     private static final int SIZE = 1024;
  59     private static final int POS = SIZE/2;
  60 
  61     private static MethodHandle mh;
  62     private volatile int[] array;
  63 
  64     @Setup
  65     public void setup() throws Throwable {
  66         array = new int[SIZE];
  67         for (int i = 0; i < SIZE; i++) {
  68             array[i] = i;
  69         }
  70         mh = MethodHandles.arrayElementSetter(int[].class);
  71     }
  72 
  73     @Benchmark
  74     public MethodHandle testCreate() {
  75         return MethodHandles.arrayElementSetter(int[].class);
  76     }
  77 
  78     @Benchmark
  79     public void baselineRaw() {
  80         access(array, POS, 1);
  81     }
  82 
  83     @Benchmark
  84     public void testSetter() throws Throwable {
  85         mh.invoke(array, POS, 1);
  86     }
  87 
  88     public void access(int[] array, int pos, int v) {
  89         array[pos] = v;
  90     }
  91 
  92 }