/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

/*

 * This file is available under and governed by the GNU General Public

 * License version 2 only, as published by the Free Software Foundation.

 * However, the following notice accompanied the original version of this

 * file:

 *

 * 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) {

        main(suite(), args);

    }

    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);

    }

}