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
#	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.Test;
10	import junit.framework.TestSuite;
11
12	public class SystemTest extends JSR166TestCase {
13	public static void main(String[] args) {
14	junit.textui.TestRunner.run(suite());
15	}
16
17	public static Test suite() {
18	return new TestSuite(SystemTest.class);
19	}
20
21	/**
22	* Worst case rounding for millisecs; set for 60 cycle millis clock.
23	* This value might need to be changed on JVMs with coarser
24	* System.currentTimeMillis clocks.
25	*/
26	static final long MILLIS_ROUND = 17;
27
28	/**
29	* Nanos between readings of millis is no longer than millis (plus
30	* possible rounding).
31	* This shows only that nano timing not (much) worse than milli.
32	*/
33	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	}
47
48	/**
49	* Millis between readings of nanos is less than nanos, adjusting
50	* for rounding.
51	* This shows only that nano timing not (much) worse than milli.
52	*/
53	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
64	assertTrue(nanos >= 0);
65	long nanosAsMillis = nanos / 1000000;
66	assertTrue(millis <= nanosAsMillis + MILLIS_ROUND);
67	}
68
69	}