1 /*
   2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  */
  22 
  23 /*
  24  * This file is available under and governed by the GNU General Public
  25  * License version 2 only, as published by the Free Software Foundation.
  26  * However, the following notice accompanied the original version of this
  27  * file:
  28  *
  29  * Written by Doug Lea with assistance from members of JCP JSR-166
  30  * Expert Group and released to the public domain, as explained at
  31  * http://creativecommons.org/licenses/publicdomain
  32  */
  33 /**
  34  * Misc utilities in JSR166 performance tests
  35  */
  36 
  37 import java.util.concurrent.*;
  38 import java.util.concurrent.atomic.*;
  39 
  40 class LoopHelpers {
  41 
  42     // Some mindless computation to do between synchronizations...
  43 
  44     /**
  45      * generates 32 bit pseudo-random numbers.
  46      * Adapted from http://www.snippets.org
  47      */
  48     public static int compute1(int x) {
  49         int lo = 16807 * (x & 0xFFFF);
  50         int hi = 16807 * (x >>> 16);
  51         lo += (hi & 0x7FFF) << 16;
  52         if ((lo & 0x80000000) != 0) {
  53             lo &= 0x7fffffff;
  54             ++lo;
  55         }
  56         lo += hi >>> 15;
  57         if (lo == 0 || (lo & 0x80000000) != 0) {
  58             lo &= 0x7fffffff;
  59             ++lo;
  60         }
  61         return lo;
  62     }
  63 
  64     /**
  65      *  Computes a linear congruential random number a random number
  66      *  of times.
  67      */
  68     public static int compute2(int x) {
  69         int loops = (x >>> 4) & 7;
  70         while (loops-- > 0) {
  71             x = (x * 2147483647) % 16807;
  72         }
  73         return x;
  74     }
  75 
  76     /**
  77      * An actually useful random number generator, but unsynchronized.
  78      * Basically same as java.util.Random.
  79      */
  80     public static class SimpleRandom {
  81         private final static long multiplier = 0x5DEECE66DL;
  82         private final static long addend = 0xBL;
  83         private final static long mask = (1L << 48) - 1;
  84         static final AtomicLong seq = new AtomicLong(1);
  85         private long seed = System.nanoTime() + seq.getAndIncrement();
  86 
  87         public void setSeed(long s) {
  88             seed = s;
  89         }
  90 
  91         public int next() {
  92             long nextseed = (seed * multiplier + addend) & mask;
  93             seed = nextseed;
  94             return ((int)(nextseed >>> 17)) & 0x7FFFFFFF;
  95         }
  96     }
  97 
  98     public static class BarrierTimer implements Runnable {
  99         public volatile long startTime;
 100         public volatile long endTime;
 101         public void run() {
 102             long t = System.nanoTime();
 103             if (startTime == 0)
 104                 startTime = t;
 105             else
 106                 endTime = t;
 107         }
 108         public void clear() {
 109             startTime = 0;
 110             endTime = 0;
 111         }
 112         public long getTime() {
 113             return endTime - startTime;
 114         }
 115     }
 116 
 117     public static String rightJustify(long n) {
 118         // There's probably a better way to do this...
 119         String field = "         ";
 120         String num = Long.toString(n);
 121         if (num.length() >= field.length())
 122             return num;
 123         StringBuffer b = new StringBuffer(field);
 124         b.replace(b.length()-num.length(), b.length(), num);
 125         return b.toString();
 126     }
 127 
 128 }