src/loops/LoopHelpers.java

/**
 * Misc utilities in JSR166 performance tests
 */

import java.util.concurrent.*;
import java.util.concurrent.atomic.*;

class LoopHelpers {

    static final SimpleRandom staticRNG = new SimpleRandom();

    // Some mindless computation to do between synchronizations...

    /**
     * generates 32 bit pseudo-random numbers.
     * Adapted from http://www.snippets.org
     */
    public static int compute1(int x) {
        int lo = 16807 * (x & 0xFFFF);
        int hi = 16807 * (x >>> 16);
        lo += (hi & 0x7FFF) << 16;
        if ((lo & 0x80000000) != 0) {
            lo &= 0x7fffffff;
            ++lo;
        }
        lo += hi >>> 15;
        if (lo == 0 || (lo & 0x80000000) != 0) {
            lo &= 0x7fffffff;
            ++lo;
        }
        return lo;
    }

    /**
     *  Computes a linear congruential random number a random number
     *  of times.
     */
    public static int compute2(int x) {
        int loops = (x >>> 4) & 7;
        while (loops-- > 0) {
            x = (x * 2147483647) % 16807;
        }
        return x;
    }

    /**
     * Yet another random number generator
     */
    public static int compute3(int x) {
        int t = (x % 127773) * 16807 - (x / 127773) * 2836;
        return (t > 0)? t : t + 0x7fffffff;
    }

    /**
     * Yet another random number generator
     */
    public static int compute4(int x) {
        return x * 134775813 + 1;
    }

    /**
     * An actually useful random number generator, but unsynchronized.
     * Basically same as java.util.Random.
     */
    public static class SimpleRandom {
        private final static long multiplier = 0x5DEECE66DL;
        private final static long addend = 0xBL;
        private final static long mask = (1L << 48) - 1;
        static final AtomicLong seq = new AtomicLong(1);
        private long seed = System.nanoTime() + seq.getAndIncrement();

        public void setSeed(long s) {
            seed = s;
        }

        public int next() {
            long nextseed = (seed * multiplier + addend) & mask;
            seed = nextseed;
            return ((int)(nextseed >>> 17)) & 0x7FFFFFFF;
        }
    }

    public static class BarrierTimer implements Runnable {
        public volatile long startTime;
        public volatile long endTime;
        public void run() {
            long t = System.nanoTime();
            if (startTime == 0)
                startTime = t;
            else
                endTime = t;
        }
        public void clear() {
            startTime = 0;
            endTime = 0;
        }
        public long getTime() {
            return endTime - startTime;
        }
    }

    public static String rightJustify(long n) {
        // There's probably a better way to do this...
        String field = "         ";
        String num = Long.toString(n);
        if (num.length() >= field.length())
            return num;
        StringBuffer b = new StringBuffer(field);
        b.replace(b.length()-num.length(), b.length(), num);
        return b.toString();
    }

}
Revision:	1.2
Committed:	Thu Dec 30 15:15:43 2004 UTC (19 years, 6 months ago) by peierls
Branch:	MAIN
Changes since 1.1:	+15 -5 lines
Log Message:	Quick and dirty TimeUnit performance check
#	User	Rev	Content
1	jsr166	1.1	/**
2			* Misc utilities in JSR166 performance tests
3			*/
4
5			import java.util.concurrent.*;
6			import java.util.concurrent.atomic.*;
7
8			class LoopHelpers {
9
10			static final SimpleRandom staticRNG = new SimpleRandom();
11
12			// Some mindless computation to do between synchronizations...
13
14			/**
15	peierls	1.2	* generates 32 bit pseudo-random numbers.
16	jsr166	1.1	* Adapted from http://www.snippets.org
17			*/
18	peierls	1.2	public static int compute1(int x) {
19	jsr166	1.1	int lo = 16807 * (x & 0xFFFF);
20			int hi = 16807 * (x >>> 16);
21			lo += (hi & 0x7FFF) << 16;
22			if ((lo & 0x80000000) != 0) {
23			lo &= 0x7fffffff;
24			++lo;
25			}
26			lo += hi >>> 15;
27			if (lo == 0 \|\| (lo & 0x80000000) != 0) {
28			lo &= 0x7fffffff;
29			++lo;
30			}
31			return lo;
32			}
33
34			/**
35			* Computes a linear congruential random number a random number
36			* of times.
37			*/
38	peierls	1.2	public static int compute2(int x) {
39	jsr166	1.1	int loops = (x >>> 4) & 7;
40			while (loops-- > 0) {
41			x = (x * 2147483647) % 16807;
42			}
43			return x;
44			}
45
46	peierls	1.2	/**
47			* Yet another random number generator
48			*/
49			public static int compute3(int x) {
50	jsr166	1.1	int t = (x % 127773) * 16807 - (x / 127773) * 2836;
51			return (t > 0)? t : t + 0x7fffffff;
52			}
53
54			/**
55	peierls	1.2	* Yet another random number generator
56			*/
57			public static int compute4(int x) {
58			return x * 134775813 + 1;
59			}
60
61			/**
62	jsr166	1.1	* An actually useful random number generator, but unsynchronized.
63			* Basically same as java.util.Random.
64			*/
65			public static class SimpleRandom {
66			private final static long multiplier = 0x5DEECE66DL;
67			private final static long addend = 0xBL;
68			private final static long mask = (1L << 48) - 1;
69			static final AtomicLong seq = new AtomicLong(1);
70			private long seed = System.nanoTime() + seq.getAndIncrement();
71
72			public void setSeed(long s) {
73			seed = s;
74			}
75
76			public int next() {
77			long nextseed = (seed * multiplier + addend) & mask;
78			seed = nextseed;
79			return ((int)(nextseed >>> 17)) & 0x7FFFFFFF;
80			}
81			}
82
83			public static class BarrierTimer implements Runnable {
84			public volatile long startTime;
85			public volatile long endTime;
86			public void run() {
87			long t = System.nanoTime();
88			if (startTime == 0)
89			startTime = t;
90			else
91			endTime = t;
92			}
93			public void clear() {
94			startTime = 0;
95			endTime = 0;
96			}
97			public long getTime() {
98			return endTime - startTime;
99			}
100			}
101
102			public static String rightJustify(long n) {
103			// There's probably a better way to do this...
104			String field = " ";
105			String num = Long.toString(n);
106			if (num.length() >= field.length())
107			return num;
108			StringBuffer b = new StringBuffer(field);
109			b.replace(b.length()-num.length(), b.length(), num);
110			return b.toString();
111			}
112	peierls	1.2
113	jsr166	1.1	}