LoopHelpers.java revision 3984:31619dfa6a4a 
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/publicdomain/zero/1.0/
32 */
33
34/**
35 * Misc utilities in JSR166 performance tests
36 */
37
38import java.util.concurrent.*;
39import java.util.concurrent.atomic.*;
40
41class LoopHelpers {
42
43    // Some mindless computation to do between synchronizations...
44
45    /**
46     * generates 32 bit pseudo-random numbers.
47     * Adapted from http://www.snippets.org
48     */
49    public static int compute1(int x) {
50        int lo = 16807 * (x & 0xFFFF);
51        int hi = 16807 * (x >>> 16);
52        lo += (hi & 0x7FFF) << 16;
53        if ((lo & 0x80000000) != 0) {
54            lo &= 0x7fffffff;
55            ++lo;
56        }
57        lo += hi >>> 15;
58        if (lo == 0 || (lo & 0x80000000) != 0) {
59            lo &= 0x7fffffff;
60            ++lo;
61        }
62        return lo;
63    }
64
65    /**
66     *  Computes a linear congruential random number a random number
67     *  of times.
68     */
69    public static int compute2(int x) {
70        int loops = (x >>> 4) & 7;
71        while (loops-- > 0) {
72            x = (x * 2147483647) % 16807;
73        }
74        return x;
75    }
76
77    /**
78     * An actually useful random number generator, but unsynchronized.
79     * Basically same as java.util.Random.
80     */
81    public static class SimpleRandom {
82        private static final long multiplier = 0x5DEECE66DL;
83        private static final long addend = 0xBL;
84        private static final long mask = (1L << 48) - 1;
85        static final AtomicLong seq = new AtomicLong(1);
86        private long seed = System.nanoTime() + seq.getAndIncrement();
87
88        public void setSeed(long s) {
89            seed = s;
90        }
91
92        public int next() {
93            long nextseed = (seed * multiplier + addend) & mask;
94            seed = nextseed;
95            return ((int)(nextseed >>> 17)) & 0x7FFFFFFF;
96        }
97    }
98
99    public static class BarrierTimer implements Runnable {
100        public volatile long startTime;
101        public volatile long endTime;
102        public void run() {
103            long t = System.nanoTime();
104            if (startTime == 0)
105                startTime = t;
106            else
107                endTime = t;
108        }
109        public void clear() {
110            startTime = 0;
111            endTime = 0;
112        }
113        public long getTime() {
114            return endTime - startTime;
115        }
116    }
117
118    public static String rightJustify(long n) {
119        // There's probably a better way to do this...
120        String field = "         ";
121        String num = Long.toString(n);
122        if (num.length() >= field.length())
123            return num;
124        StringBuffer b = new StringBuffer(field);
125        b.replace(b.length()-num.length(), b.length(), num);
126        return b.toString();
127    }
128
129}
130