src/loops/TimeUnitLoops.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 */

import java.util.concurrent.*;
import java.util.Random;

public class TimeUnitLoops {

    static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();

    /**
     * False value allows aggressive inlining of cvt() calls from
     * test(). True value prevents any inlining, requiring virtual
     * method dispatch.
     */
    static final boolean PREVENT_INLINING = true;

    // The following all are used by inlining prevention clause:
    static int index = 0;
    static final int NUNITS = 100;
    static final TimeUnit[] units = new TimeUnit[NUNITS];
    static {
        TimeUnit[] v = TimeUnit.values();
        for (int i = 0; i < NUNITS; ++i)
            units[i] = v[rng.next() % v.length];
    }

    public static void main(String[] args) throws Exception {
        long start = System.currentTimeMillis();
        long s = 0;
        for (int i = 0; i < 100; ++i) {
            s += test();
            if (s == start) System.out.println(" ");
        }
        long end = System.currentTimeMillis();
        System.out.println("Time: " + (end - start) + " ms");
    }

    static long test() {
        long sum = 0;
        int x = rng.next();
        for (int i = 0; i < 1000000; ++i) {
            long l = (long)x + (long)x;
            sum += cvt(l, TimeUnit.SECONDS);
            sum += TimeUnit.MILLISECONDS.toMicros(l+2);
            sum += cvt(l+17, TimeUnit.NANOSECONDS);
            sum += cvt(l+42, TimeUnit.MILLISECONDS);
            x = LoopHelpers.compute4(x);
        }
        return sum + x;
    }

    static long cvt(long d, TimeUnit u) {
        if (PREVENT_INLINING) {
            u = units[index];
            index = (index+1) % NUNITS;
        }

        return u.toNanos(d);
    }
}
Revision:	1.2
Committed:	Sat Feb 16 21:37:44 2013 UTC (11 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.1:	+6 -0 lines
Log Message:	add missing public domain notices
#	User	Rev	Content
1	jsr166	1.2	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3			* Expert Group and released to the public domain, as explained at
4			* http://creativecommons.org/publicdomain/zero/1.0/
5			*/
6
7	peierls	1.1	import java.util.concurrent.*;
8			import java.util.Random;
9
10			public class TimeUnitLoops {
11
12			static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
13
14			/**
15			* False value allows aggressive inlining of cvt() calls from
16			* test(). True value prevents any inlining, requiring virtual
17			* method dispatch.
18			*/
19			static final boolean PREVENT_INLINING = true;
20
21			// The following all are used by inlining prevention clause:
22			static int index = 0;
23			static final int NUNITS = 100;
24			static final TimeUnit[] units = new TimeUnit[NUNITS];
25			static {
26			TimeUnit[] v = TimeUnit.values();
27			for (int i = 0; i < NUNITS; ++i)
28			units[i] = v[rng.next() % v.length];
29			}
30
31			public static void main(String[] args) throws Exception {
32			long start = System.currentTimeMillis();
33			long s = 0;
34			for (int i = 0; i < 100; ++i) {
35			s += test();
36			if (s == start) System.out.println(" ");
37			}
38			long end = System.currentTimeMillis();
39			System.out.println("Time: " + (end - start) + " ms");
40			}
41
42			static long test() {
43			long sum = 0;
44			int x = rng.next();
45			for (int i = 0; i < 1000000; ++i) {
46			long l = (long)x + (long)x;
47			sum += cvt(l, TimeUnit.SECONDS);
48			sum += TimeUnit.MILLISECONDS.toMicros(l+2);
49			sum += cvt(l+17, TimeUnit.NANOSECONDS);
50			sum += cvt(l+42, TimeUnit.MILLISECONDS);
51			x = LoopHelpers.compute4(x);
52			}
53			return sum + x;
54			}
55
56			static long cvt(long d, TimeUnit u) {
57			if (PREVENT_INLINING) {
58			u = units[index];
59			index = (index+1) % NUNITS;
60			}
61
62			return u.toNanos(d);
63			}
64			}