/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program 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 for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on Oct 26, 2006
*/
package com.bigdata.util;
import java.util.Date;
import junit.framework.TestCase;
/**
* Test suite for {@link MillisecondTimestampFactory}.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*/
public class TestMillisecondTimestampFactory extends TestCase {
public TestMillisecondTimestampFactory() {
}
public TestMillisecondTimestampFactory(String arg0) {
super(arg0);
}
/**
* This test simply displays some timestamps where I observed time going
* backward on a Fedora core 6 host using Sun JDK <code>1.6.0_03</code>.
* The first timestamp was the previous value assigned by the factory as
* reported by {@link System#currentTimeMillis()}. The second timestamp was
* the next distinct value reported by {@link System#currentTimeMillis()}.
* As you can see, the 2nd timestamp was actually earlier than the first
* timestamp. This event lead to a refactor of the
* {@link MillisecondTimestampFactory} to introduce a failback
* "auto-increment" mode for handling precisely such bizarre events.
*
* <pre>
* lastTimestamp = Tue Apr 22 21:12:16 EDT 2008
* millisTime = Tue Apr 22 21:12:14 EDT 2008
* </pre>
*
* The actual long integer values reported were:
*
* <pre>
* lastTimestamp = 1208913136715
* millisTime = 1208913134964
* </pre>
*/
public void test_showTime() {
System.err.println("lastTimestamp = " + new Date(1208913136715L));
System.err.println("millisTime = " + new Date(1208913134964L));
}
/**
* Test determines whether or not millisecond timestamps are always distinct
* from the last generated timestamp (as assigned by
* {@link System#currentTimeMillis()}.
* <p>
* Note: This test is NOT designed to pass/fail but simply to test determine
* a characteristic of the platform on which it is executing.
*/
public void test_nextTimestamp1() {
final int limit = 3000;
long lastTimestamp = System.currentTimeMillis();
long timestamp;
long minDiff = Long.MAX_VALUE;
for( int i=0; i<limit; i++ ) {
timestamp = System.currentTimeMillis();
if( timestamp == lastTimestamp ) {
System.err
.println("This platform can generate identical timestamps with millisecond resolution");
return;
}
long diff = timestamp - lastTimestamp;
if( diff < 0 ) diff = -diff;
if( diff < minDiff ) minDiff = diff;
lastTimestamp = timestamp;
}
System.err.println("Millisecond times appear to be distinct on this platorm.");
System.err.println("The minimum difference in milliseconds is "
+ minDiff + " over " + limit + " trials");
}
/**
* Test verifies that timestamps are always distinct from the last generated
* timestamp as generated by
* {@link MillisecondTimestampFactory#nextMillis()}.
*/
public void test_nextTimestamp2() {
final int limit = 1000;
long lastTimestamp = System.currentTimeMillis() - 1;
final long begin = lastTimestamp;
long timestamp;
long minDiff = Long.MAX_VALUE;
for( int i=0; i<limit; i++ ) {
timestamp = MillisecondTimestampFactory.nextMillis();
if( timestamp == lastTimestamp ) fail("Same timestamp?");
if( timestamp < lastTimestamp ) fail("Time goes backwards?");
long diff = timestamp - lastTimestamp;
if( diff < 0 ) diff = -diff;
if( diff < minDiff ) minDiff = diff;
lastTimestamp = timestamp;
}
long elapsed = lastTimestamp - begin;
System.err.println("Minimum time difference is " + minDiff
+ " milliseconds over " + limit + " trials and "+elapsed+" milliseconds");
}
}