1/*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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24 */
25
26package java.lang.management;
27
28/**
29 * The management interface for the operating system on which
30 * the Java virtual machine is running.
31 *
32 * <p> A Java virtual machine has a single instance of the implementation
33 * class of this interface.  This instance implementing this interface is
34 * an <a href="ManagementFactory.html#MXBean">MXBean</a>
35 * that can be obtained by calling
36 * the {@link ManagementFactory#getOperatingSystemMXBean} method or
37 * from the {@link ManagementFactory#getPlatformMBeanServer
38 * platform MBeanServer} method.
39 *
40 * <p>The {@code ObjectName} for uniquely identifying the MXBean for
41 * the operating system within an MBeanServer is:
42 * <blockquote>
43 *    {@link ManagementFactory#OPERATING_SYSTEM_MXBEAN_NAME
44 *      java.lang:type=OperatingSystem}
45 * </blockquote>
46 *
47 * It can be obtained by calling the
48 * {@link PlatformManagedObject#getObjectName} method.
49 *
50 * <p> This interface defines several convenient methods for accessing
51 * system properties about the operating system on which the Java
52 * virtual machine is running.
53 *
54 * @see ManagementFactory#getPlatformMXBeans(Class)
55 * @see <a href="../../../javax/management/package-summary.html">
56 *      JMX Specification.</a>
57 * @see <a href="package-summary.html#examples">
58 *      Ways to Access MXBeans</a>
59 *
60 * @author  Mandy Chung
61 * @since   1.5
62 */
63public interface OperatingSystemMXBean extends PlatformManagedObject {
64    /**
65     * Returns the operating system name.
66     * This method is equivalent to {@code System.getProperty("os.name")}.
67     *
68     * @return the operating system name.
69     *
70     * @throws  java.lang.SecurityException
71     *     if a security manager exists and its
72     *     <code>checkPropertiesAccess</code> method doesn't allow access
73     *     to this system property.
74     * @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
75     * @see java.lang.System#getProperty
76     */
77    public String getName();
78
79    /**
80     * Returns the operating system architecture.
81     * This method is equivalent to {@code System.getProperty("os.arch")}.
82     *
83     * @return the operating system architecture.
84     *
85     * @throws  java.lang.SecurityException
86     *     if a security manager exists and its
87     *     <code>checkPropertiesAccess</code> method doesn't allow access
88     *     to this system property.
89     * @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
90     * @see java.lang.System#getProperty
91     */
92    public String getArch();
93
94    /**
95     * Returns the operating system version.
96     * This method is equivalent to {@code System.getProperty("os.version")}.
97     *
98     * @return the operating system version.
99     *
100     * @throws  java.lang.SecurityException
101     *     if a security manager exists and its
102     *     <code>checkPropertiesAccess</code> method doesn't allow access
103     *     to this system property.
104     * @see java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
105     * @see java.lang.System#getProperty
106     */
107    public String getVersion();
108
109    /**
110     * Returns the number of processors available to the Java virtual machine.
111     * This method is equivalent to the {@link Runtime#availableProcessors()}
112     * method.
113     * <p> This value may change during a particular invocation of
114     * the virtual machine.
115     *
116     * @return  the number of processors available to the virtual
117     *          machine; never smaller than one.
118     */
119    public int getAvailableProcessors();
120
121    /**
122     * Returns the system load average for the last minute.
123     * The system load average is the sum of the number of runnable entities
124     * queued to the {@linkplain #getAvailableProcessors available processors}
125     * and the number of runnable entities running on the available processors
126     * averaged over a period of time.
127     * The way in which the load average is calculated is operating system
128     * specific but is typically a damped time-dependent average.
129     * <p>
130     * If the load average is not available, a negative value is returned.
131     * <p>
132     * This method is designed to provide a hint about the system load
133     * and may be queried frequently.
134     * The load average may be unavailable on some platform where it is
135     * expensive to implement this method.
136     *
137     * @return the system load average; or a negative value if not available.
138     *
139     * @since 1.6
140     */
141    public double getSystemLoadAverage();
142}
143