1 /*
2 * Copyright (c) 2003, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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22 */
23
24 /*
25 * @test
26 * @bug 4530538
27 * @summary Basic unit test of RuntimeMXBean.getUptime()
28 * @author Alexei Guibadoulline
29 */
30
31 import java.lang.management.*;
32
33 public class UpTime {
34 static final long DELAY = 5; // Seconds
35 static final long TIMEOUT = 30; // Minutes
36 static final long MULTIPLIER = 1000; // millisecond ticks
37
38 private static final RuntimeMXBean metrics
39 = ManagementFactory.getRuntimeMXBean();
40
41 public static void main(String argv[]) throws Exception {
42 long jvmStartTime = metrics.getStartTime();
43 // this will get an aproximate JVM uptime before starting this test
44 long jvmUptime = System.currentTimeMillis() - jvmStartTime;
45 long systemStartOuter = System_milliTime();
46 long metricsStart = metrics.getUptime();
47 long systemStartInner = System_milliTime();
48
49 // This JVM might have been running for some time if this test runs
50 // in samevm mode. The sanity check should apply to the test uptime.
51 long testUptime = metricsStart - jvmUptime;
52
53 // If uptime is more than 30 minutes then it looks like a bug in
54 // the method
55 if (testUptime > TIMEOUT * 60 * MULTIPLIER)
56 throw new RuntimeException("Uptime of the JVM is more than 30 "
57 + "minutes ("
58 + (metricsStart / 60 / MULTIPLIER)
59 + " minutes).");
60
61 // Wait for DELAY seconds
62 Object o = new Object();
63 while (System_milliTime() < systemStartInner + DELAY * MULTIPLIER) {
64 synchronized (o) {
65 try {
66 o.wait(DELAY * 1000);
67 } catch (Exception e) {
68 e.printStackTrace();
69 throw e;
70 }
71 }
72 }
73
74 long systemEndInner = System_milliTime();
75 long metricsEnd = metrics.getUptime();
76 long systemEndOuter = System_milliTime();
77
78 long systemDifferenceInner = systemEndInner - systemStartInner;
79 long systemDifferenceOuter = systemEndOuter - systemStartOuter;
80 long metricsDifference = metricsEnd - metricsStart;
81
82 // Check the flow of time in RuntimeMXBean.getUptime(). See the
83 // picture below.
84 // The measured times can be off by 1 due to conversions from
85 // nanoseconds to milliseconds, using different channels to read the
86 // HR timer and rounding error. Bigger difference will make the test
87 // fail.
88 if (metricsDifference - systemDifferenceInner < -1)
89 throw new RuntimeException("Flow of the time in "
90 + "RuntimeMXBean.getUptime() ("
91 + metricsDifference + ") is slower than "
92 + " in system (" + systemDifferenceInner
93 + ")");
94 if (metricsDifference - systemDifferenceOuter > 1)
95 throw new RuntimeException("Flow of the time in "
96 + "RuntimeMXBean.getUptime() ("
97 + metricsDifference + ") is faster than "
98 + "in system (" + systemDifferenceOuter
99 + ")");
100
101 System.out.println("Test passed.");
102 }
103
104 private static long System_milliTime() {
105 return System.nanoTime() / 1000000; // nanoseconds / milliseconds;
106 }
107 }
108
109 /*
110
111 A picture to describe the second testcase that checks the flow of time in
112 RuntimeMXBean.getUptime()
113
114
115 start
116 o1 u1 i1 Sleep for DELAY minutes i2 u2 o2
117 |-------|---|---|--------------------------------|---|---|---------------> time
118
119
120 The following inequality (checked by the test) must always be true:
121
122 o2-o1 >= u2-u1 >= i2-i1
123
124 In the test:
125
126 i1 - systemStartInner
127 i2 - systemEndInner
128 o1 - systemStartOuter
129 o2 - systemEndOuter
130 u1 - metricsStart
131 u2 - metricsEnd
132
133 */