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;

    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.OperationsPerInvocation;

    31 import org.openjdk.jmh.annotations.OutputTimeUnit;

    32 import org.openjdk.jmh.annotations.Scope;

    33 import org.openjdk.jmh.annotations.Setup;

    34 import org.openjdk.jmh.annotations.State;

    35 

    36 import java.util.concurrent.TimeUnit;

    37 

    38 /**

    39  * Benchmark measuring System.arraycopy in different ways.

    40  */

    41 @BenchmarkMode(Mode.AverageTime)

    42 @OutputTimeUnit(TimeUnit.NANOSECONDS)

    43 @State(Scope.Thread)

    44 public class ArrayCopy {

    45 

    46     private static final byte[] TEST_BYTES = "HTTP/1.0".getBytes();

    47     private static final char[] TEST_CHARS = new char[46];

    48     private static final Object[] TEST_OBJECTS = new Object[200];  // Uses a minimum of 160 internal positions for internal copying

    49 

    50     // a length which the compiler cannot prove is a constant

    51     public static int nonConstCharLength = TEST_CHARS.length;

    52     public static int nonConstByteLength = TEST_BYTES.length;

    53     public static int nonConstObjectLength = TEST_OBJECTS.length;

    54 

    55     // Use this array to copy objects in.

    56     public char[] dummyCharArray = new char[TEST_CHARS.length];

    57     public byte[] dummyByteArray = new byte[TEST_BYTES.length];

    58     public Object[] dummyObjectArray = new Object[TEST_OBJECTS.length];

    59 

    60     @Setup

    61     public void setup() {

    62         for (int i = 0; i < TEST_OBJECTS.length; i++) {

    63             TEST_OBJECTS[i] = new Object();

    64             dummyObjectArray[i] = new Object();

    65         }

    66     }

    67 

    68     /**

    69      * This test case do the same work as testArrayCopy. We should make sure

    70      * testArrayCopy is equally fast or better. Compare the two and you measure

    71      * the system call versus explicit copy for-loop.

    72      */

    73     @Benchmark

    74     public void copyLoop() {

    75         for (int j = 0; j < dummyByteArray.length; j++) {

    76             dummyByteArray[j] = TEST_BYTES[j];

    77         }

    78     }

    79 

    80     /**

    81      * Test that we can optimize away the code since it should not have any side

    82      * effects

    83      */

    84     @Benchmark

    85     public void copyLoopLocalArray() {

    86         byte[] localDummyByteArray = new byte[TEST_BYTES.length];

    87         for (int j = 0; j < localDummyByteArray.length; j++) {

    88             localDummyByteArray[j] = TEST_BYTES[j];

    89         }

    90     }

    91 

    92     /**

    93      * This test case do the same work as testArrayCopy. We should make sure

    94      * testArrayCopy is equally fast or better. Compare the two and you measure

    95      * the system call versus explicit copy for-loop.

    96      * <p/>

    97      * Uses non-provable constant length.

    98      */

    99     @Benchmark

   100     public void copyLoopNonConst() {

   101         for (int i = 0; i < nonConstByteLength; i++) {

   102             dummyByteArray[i] = TEST_BYTES[i];

   103         }

   104     }

   105 

   106     /**

   107      * This test case do the same work as testCopyLoop. We should make sure

   108      * testArrayCopy is equally fast or better. Compare the two and you measure

   109      * the system call versus explicit copy for-loop.

   110      */

   111     @Benchmark

   112     public void arrayCopy() {

   113         System.arraycopy(TEST_BYTES, 0, dummyByteArray, 0, dummyByteArray.length);

   114     }

   115 

   116     /**

   117      * Test that we can optimize away the code since it should not have any side

   118      * effects

   119      */

   120     @Benchmark

   121     public void arrayCopyLocalArray() {

   122         byte[] localDummyByteArray = new byte[TEST_BYTES.length];

   123         System.arraycopy(TEST_BYTES, 0, localDummyByteArray, 0, localDummyByteArray.length);

   124     }

   125 

   126     /**

   127      * This test case do the same work as testCopyLoop. We should make sure

   128      * testArrayCopy is equally fast or better. Compare the two and you measure

   129      * the system call versus explicit copy for-loop.

   130      * <p/>

   131      * Uses non-provable constant length.

   132      */

   133     @Benchmark

   134     public void arrayCopyNonConst() {

   135         System.arraycopy(TEST_BYTES, 0, dummyByteArray, 0, nonConstByteLength);

   136     }

   137 

   138     @Benchmark

   139     public void arrayCopyChar() {

   140         System.arraycopy(TEST_CHARS, 0, dummyCharArray, 0, dummyCharArray.length);

   141     }

   142 

   143     @Benchmark

   144     public void arrayCopyCharNonConst() {

   145         System.arraycopy(TEST_CHARS, 0, dummyCharArray, 0, nonConstCharLength);

   146     }

   147 

   148     @Benchmark

   149     public void arrayCopyObject() {

   150         System.arraycopy(TEST_OBJECTS, 0, dummyObjectArray, 0, dummyObjectArray.length);

   151     }

   152 

   153     @Benchmark

   154     public void arrayCopyObjectNonConst() {

   155         System.arraycopy(TEST_OBJECTS, 0, dummyObjectArray, 0, nonConstObjectLength);

   156     }

   157 

   158     /**

   159      * This test copies inside a object array, that is same source array as dest

   160      * array. Copies backwards in the array.

   161      */

   162     @Benchmark

   163     @OperationsPerInvocation(40)

   164     public void arrayCopyObjectSameArraysBackward() {

   165         for (int i = 0; i < 40; i++) {

   166             System.arraycopy(dummyObjectArray, i, dummyObjectArray, i + 40, 80);

   167         }

   168     }

   169 

   170     /**

   171      * This test copies inside a object array, that is same source array as dest

   172      * array. Copies forward in the array. There is a special version for this

   173      * in JRockit.

   174      */

   175     @Benchmark

   176     @OperationsPerInvocation(40)

   177     public void arrayCopyObjectSameArraysForward() {

   178         for (int i = 0; i < 40; i++) {

   179             System.arraycopy(dummyObjectArray, i + 40, dummyObjectArray, i, 80);

   180         }

   181     }

   182 }