test/tck/SystemTest.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/
 * Other contributors include Andrew Wright, Jeffrey Hayes,
 * Pat Fisher, Mike Judd.
 */

import junit.framework.*;

public class SystemTest extends JSR166TestCase {
    public static void main(String[] args) {
        junit.textui.TestRunner.run(suite());
    }

    public static Test suite() {
        return new TestSuite(SystemTest.class);
    }

    /**
     * Worst case rounding for millisecs; set for 60 cycle millis clock.
     * This value might need to be changed on JVMs with coarser
     * System.currentTimeMillis clocks.
     */
    static final long MILLIS_ROUND = 17;

    /**
     * Nanos between readings of millis is no longer than millis (plus
     * possible rounding).
     * This shows only that nano timing not (much) worse than milli.
     */
    public void testNanoTime1() throws InterruptedException {
        long m1 = System.currentTimeMillis();
        Thread.sleep(1);
        long n1 = System.nanoTime();
        Thread.sleep(SHORT_DELAY_MS);
        long n2 = System.nanoTime();
        Thread.sleep(1);
        long m2 = System.currentTimeMillis();
        long millis = m2 - m1;
        long nanos = n2 - n1;
        assertTrue(nanos >= 0);
        long nanosAsMillis = nanos / 1000000;
        assertTrue(nanosAsMillis <= millis + MILLIS_ROUND);
    }

    /**
     * Millis between readings of nanos is less than nanos, adjusting
     * for rounding.
     * This shows only that nano timing not (much) worse than milli.
     */
    public void testNanoTime2() throws InterruptedException {
        long n1 = System.nanoTime();
        Thread.sleep(1);
        long m1 = System.currentTimeMillis();
        Thread.sleep(SHORT_DELAY_MS);
        long m2 = System.currentTimeMillis();
        Thread.sleep(1);
        long n2 = System.nanoTime();
        long millis = m2 - m1;
        long nanos = n2 - n1;

        assertTrue(nanos >= 0);
        long nanosAsMillis = nanos / 1000000;
        assertTrue(millis <= nanosAsMillis + MILLIS_ROUND);
    }

}
Revision:	1.11
Committed:	Tue Mar 15 19:47:07 2011 UTC (13 years, 1 month ago) by jsr166
Branch:	MAIN
CVS Tags:	release-1_7_0
Changes since 1.10:	+1 -1 lines
Log Message:	Update Creative Commons license URL in legal notices
#	Content
1	/*
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	* Other contributors include Andrew Wright, Jeffrey Hayes,
6	* Pat Fisher, Mike Judd.
7	*/
8
9	import junit.framework.*;
10
11	public class SystemTest extends JSR166TestCase {
12	public static void main(String[] args) {
13	junit.textui.TestRunner.run(suite());
14	}
15
16	public static Test suite() {
17	return new TestSuite(SystemTest.class);
18	}
19
20	/**
21	* Worst case rounding for millisecs; set for 60 cycle millis clock.
22	* This value might need to be changed on JVMs with coarser
23	* System.currentTimeMillis clocks.
24	*/
25	static final long MILLIS_ROUND = 17;
26
27	/**
28	* Nanos between readings of millis is no longer than millis (plus
29	* possible rounding).
30	* This shows only that nano timing not (much) worse than milli.
31	*/
32	public void testNanoTime1() throws InterruptedException {
33	long m1 = System.currentTimeMillis();
34	Thread.sleep(1);
35	long n1 = System.nanoTime();
36	Thread.sleep(SHORT_DELAY_MS);
37	long n2 = System.nanoTime();
38	Thread.sleep(1);
39	long m2 = System.currentTimeMillis();
40	long millis = m2 - m1;
41	long nanos = n2 - n1;
42	assertTrue(nanos >= 0);
43	long nanosAsMillis = nanos / 1000000;
44	assertTrue(nanosAsMillis <= millis + MILLIS_ROUND);
45	}
46
47	/**
48	* Millis between readings of nanos is less than nanos, adjusting
49	* for rounding.
50	* This shows only that nano timing not (much) worse than milli.
51	*/
52	public void testNanoTime2() throws InterruptedException {
53	long n1 = System.nanoTime();
54	Thread.sleep(1);
55	long m1 = System.currentTimeMillis();
56	Thread.sleep(SHORT_DELAY_MS);
57	long m2 = System.currentTimeMillis();
58	Thread.sleep(1);
59	long n2 = System.nanoTime();
60	long millis = m2 - m1;
61	long nanos = n2 - n1;
62
63	assertTrue(nanos >= 0);
64	long nanosAsMillis = nanos / 1000000;
65	assertTrue(millis <= nanosAsMillis + MILLIS_ROUND);
66	}
67
68	}