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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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* Other contributors include Andrew Wright, Jeffrey Hayes, |
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* Pat Fisher, Mike Judd. |
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*/ |
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|
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import junit.framework.Test; |
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import junit.framework.TestSuite; |
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|
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public class SystemTest extends JSR166TestCase { |
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public static void main(String[] args) { |
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main(suite(), args); |
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} |
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|
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public static Test suite() { |
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return new TestSuite(SystemTest.class); |
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} |
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|
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/** |
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* Worst case rounding for millisecs; set for 60 cycle millis clock. |
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* This value might need to be changed on JVMs with coarser |
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* System.currentTimeMillis clocks. |
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*/ |
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static final long MILLIS_ROUND = 17; |
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|
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/** |
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* Nanos between readings of millis is no longer than millis (plus |
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* possible rounding), and vice versa. |
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* This shows only that nano timing not (much) worse than milli. |
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*/ |
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public void testNanoTime() throws InterruptedException { |
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long m0 = System.currentTimeMillis(); |
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long n0 = System.nanoTime(); |
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Thread.sleep(1); |
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long m1 = System.currentTimeMillis(); |
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long n1 = System.nanoTime(); |
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Thread.sleep(50); // avoid possibly scaled SHORT_DELAY_MS |
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long m2 = System.currentTimeMillis(); |
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long n2 = System.nanoTime(); |
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Thread.sleep(1); |
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long m3 = System.currentTimeMillis(); |
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long n3 = System.nanoTime(); |
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assertTrue((n2 - n1) / 1_000_000 <= m3 - m0 + MILLIS_ROUND); |
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assertTrue(m2 - m1 <= (n3 - n0) / 1_000_000 + MILLIS_ROUND); |
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} |
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} |
