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/*
* Copyright (c) 2003, 2015, Oracle and/or its affiliates. All rights reserved.
* 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.
*/
/*
* @test
* @bug 4530538
* @summary Basic unit test of RuntimeMXBean.getUptime()
* @author Alexei Guibadoulline
*/
import java.lang.management.*;
public class UpTime {
static final long DELAY = 5; // Seconds
static final long TIMEOUT = 30; // Minutes
static final long MULTIPLIER = 1000; // millisecond ticks
private static final RuntimeMXBean metrics
= ManagementFactory.getRuntimeMXBean();
public static void main(String argv[]) throws Exception {
long jvmStartTime = metrics.getStartTime();
// this will get an aproximate JVM uptime before starting this test
long jvmUptime = System.currentTimeMillis() - jvmStartTime;
long systemStartOuter = System_milliTime();
long metricsStart = metrics.getUptime();
long systemStartInner = System_milliTime();
// This JVM might have been running for some time if this test runs
// in samevm mode. The sanity check should apply to the test uptime.
long testUptime = metricsStart - jvmUptime;
// If uptime is more than 30 minutes then it looks like a bug in
// the method
if (testUptime > TIMEOUT * 60 * MULTIPLIER)
throw new RuntimeException("Uptime of the JVM is more than 30 "
+ "minutes ("
+ (metricsStart / 60 / MULTIPLIER)
+ " minutes).");
// Wait for DELAY seconds
Object o = new Object();
while (System_milliTime() < systemStartInner + DELAY * MULTIPLIER) {
synchronized (o) {
try {
o.wait(DELAY * 1000);
} catch (Exception e) {
e.printStackTrace();
throw e;
}
}
}
long systemEndInner = System_milliTime();
long metricsEnd = metrics.getUptime();
long systemEndOuter = System_milliTime();
long systemDifferenceInner = systemEndInner - systemStartInner;
long systemDifferenceOuter = systemEndOuter - systemStartOuter;
long metricsDifference = metricsEnd - metricsStart;
// Check the flow of time in RuntimeMXBean.getUptime(). See the
// picture below.
// The measured times can be off by 1 due to conversions from
// nanoseconds to milliseconds, using different channels to read the
// HR timer and rounding error. Bigger difference will make the test
// fail.
if (metricsDifference - systemDifferenceInner < -1)
throw new RuntimeException("Flow of the time in "
+ "RuntimeMXBean.getUptime() ("
+ metricsDifference + ") is slower than "
+ " in system (" + systemDifferenceInner
+ ")");
if (metricsDifference - systemDifferenceOuter > 1)
throw new RuntimeException("Flow of the time in "
+ "RuntimeMXBean.getUptime() ("
+ metricsDifference + ") is faster than "
+ "in system (" + systemDifferenceOuter
+ ")");
System.out.println("Test passed.");
}
private static long System_milliTime() {
return System.nanoTime() / 1000000; // nanoseconds / milliseconds;
}
}
/*
A picture to describe the second testcase that checks the flow of time in
RuntimeMXBean.getUptime()
start
o1 u1 i1 Sleep for DELAY minutes i2 u2 o2
|-------|---|---|--------------------------------|---|---|---------------> time
The following inequality (checked by the test) must always be true:
o2-o1 >= u2-u1 >= i2-i1
In the test:
i1 - systemStartInner
i2 - systemEndInner
o1 - systemStartOuter
o2 - systemEndOuter
u1 - metricsStart
u2 - metricsEnd
*/
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