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/licenses/publicdomain
 * 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:	1.10
Committed:	Sat Oct 9 19:30:35 2010 UTC (13 years, 6 months ago) by jsr166
Branch:	MAIN
Changes since 1.9:	+1 -1 lines
Log Message:	whitespace
#	User	Rev	Content
1	dl	1.1	/*
2	dl	1.5	* 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/licenses/publicdomain
5	jsr166	1.7	* Other contributors include Andrew Wright, Jeffrey Hayes,
6			* Pat Fisher, Mike Judd.
7	dl	1.1	*/
8
9			import junit.framework.*;
10
11	dl	1.2	public class SystemTest extends JSR166TestCase {
12	dl	1.1	public static void main(String[] args) {
13	jsr166	1.7	junit.textui.TestRunner.run(suite());
14	dl	1.1	}
15	jsr166	1.7
16	dl	1.1	public static Test suite() {
17	tim	1.4	return new TestSuite(SystemTest.class);
18	dl	1.1	}
19
20	jsr166	1.7	/**
21	dl	1.6	* Worst case rounding for millisecs; set for 60 cycle millis clock.
22	jsr166	1.9	* This value might need to be changed on JVMs with coarser
23	jsr166	1.10	* System.currentTimeMillis clocks.
24	dl	1.6	*/
25			static final long MILLIS_ROUND = 17;
26
27	dl	1.2	/**
28	tim	1.4	* Nanos between readings of millis is no longer than millis (plus
29	dl	1.6	* possible rounding).
30	dl	1.2	* This shows only that nano timing not (much) worse than milli.
31			*/
32	jsr166	1.9	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	dl	1.1	}
46
47	dl	1.2	/**
48	dl	1.6	* Millis between readings of nanos is less than nanos, adjusting
49			* for rounding.
50	dl	1.2	* This shows only that nano timing not (much) worse than milli.
51			*/
52	jsr166	1.9	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	jsr166	1.7
63	jsr166	1.9	assertTrue(nanos >= 0);
64			long nanosAsMillis = nanos / 1000000;
65			assertTrue(millis <= nanosAsMillis + MILLIS_ROUND);
66	dl	1.1	}
67
68			}