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.Test;
import junit.framework.TestSuite;

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:	1.12
Committed:	Wed Dec 31 19:05:43 2014 UTC (9 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.11:	+2 -1 lines
Log Message:	no wildcard imports
#	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	jsr166	1.11	* http://creativecommons.org/publicdomain/zero/1.0/
5	jsr166	1.7	* Other contributors include Andrew Wright, Jeffrey Hayes,
6			* Pat Fisher, Mike Judd.
7	dl	1.1	*/
8
9	jsr166	1.12	import junit.framework.Test;
10			import junit.framework.TestSuite;
11	dl	1.1
12	dl	1.2	public class SystemTest extends JSR166TestCase {
13	dl	1.1	public static void main(String[] args) {
14	jsr166	1.7	junit.textui.TestRunner.run(suite());
15	dl	1.1	}
16	jsr166	1.7
17	dl	1.1	public static Test suite() {
18	tim	1.4	return new TestSuite(SystemTest.class);
19	dl	1.1	}
20
21	jsr166	1.7	/**
22	dl	1.6	* Worst case rounding for millisecs; set for 60 cycle millis clock.
23	jsr166	1.9	* This value might need to be changed on JVMs with coarser
24	jsr166	1.10	* System.currentTimeMillis clocks.
25	dl	1.6	*/
26			static final long MILLIS_ROUND = 17;
27
28	dl	1.2	/**
29	tim	1.4	* Nanos between readings of millis is no longer than millis (plus
30	dl	1.6	* possible rounding).
31	dl	1.2	* This shows only that nano timing not (much) worse than milli.
32			*/
33	jsr166	1.9	public void testNanoTime1() throws InterruptedException {
34			long m1 = System.currentTimeMillis();
35			Thread.sleep(1);
36			long n1 = System.nanoTime();
37			Thread.sleep(SHORT_DELAY_MS);
38			long n2 = System.nanoTime();
39			Thread.sleep(1);
40			long m2 = System.currentTimeMillis();
41			long millis = m2 - m1;
42			long nanos = n2 - n1;
43			assertTrue(nanos >= 0);
44			long nanosAsMillis = nanos / 1000000;
45			assertTrue(nanosAsMillis <= millis + MILLIS_ROUND);
46	dl	1.1	}
47
48	dl	1.2	/**
49	dl	1.6	* Millis between readings of nanos is less than nanos, adjusting
50			* for rounding.
51	dl	1.2	* This shows only that nano timing not (much) worse than milli.
52			*/
53	jsr166	1.9	public void testNanoTime2() throws InterruptedException {
54			long n1 = System.nanoTime();
55			Thread.sleep(1);
56			long m1 = System.currentTimeMillis();
57			Thread.sleep(SHORT_DELAY_MS);
58			long m2 = System.currentTimeMillis();
59			Thread.sleep(1);
60			long n2 = System.nanoTime();
61			long millis = m2 - m1;
62			long nanos = n2 - n1;
63	jsr166	1.7
64	jsr166	1.9	assertTrue(nanos >= 0);
65			long nanosAsMillis = nanos / 1000000;
66			assertTrue(millis <= nanosAsMillis + MILLIS_ROUND);
67	dl	1.1	}
68
69			}