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3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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.
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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   *
17   * You should have received a copy of the GNU General Public License version
18   * 2 along with this work; if not, write to the Free Software Foundation,
19   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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25  
26  package 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 <tt>MBeanServer</tt>} method.
39   *
40   * <p>The <tt>ObjectName</tt> for uniquely identifying the MXBean for
41   * the operating system within an MBeanServer is:
42   * <blockquote>
43   *    {@link ManagementFactory#OPERATING_SYSTEM_MXBEAN_NAME
44   *      <tt>java.lang:type=OperatingSystem</tt>}
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   */
63  public interface OperatingSystemMXBean extends PlatformManagedObject {
64      /**
65       * Returns the operating system name.
66       * This method is equivalent to <tt>System.getProperty("os.name")</tt>.
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 <tt>System.getProperty("os.arch")</tt>.
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 <tt>System.getProperty("os.version")</tt>.
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 }