001    /* OperatingSystemMXBean.java - Interface for an operating system bean
002       Copyright (C) 2006 Free Software Foundation
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    package java.lang.management;
039    
040    /**
041     * Provides access to information about the underlying operating
042     * system.  An instance of this bean is obtained by calling
043     * {@link ManagementFactory#getOperatingSystemMXBean()}.
044     *
045     * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
046     * @since 1.5
047     */
048    public interface OperatingSystemMXBean
049    {
050    
051      /**
052       * Returns the name of the underlying system architecture.  This
053       * is equivalent to obtaining the <code>os.arch</code> property
054       * via {@link System#getProperty(String)}.
055       *
056       * @return the name of the underlying system architecture on which
057       *         the VM is running.
058       * @throws SecurityException if a security manager exists which
059       *                           prevents access to the name property.
060       * @see java.lang.System#getProperty(String)
061       * @see java.lang.SecurityManager#checkPropertyAccess(String)
062       */
063      String getArch();
064    
065      /**
066       * Returns the number of processors currently available to the
067       * virtual machine.  This number is subject to change during
068       * execution of the virtual machine, and will always be >= 1.
069       * The call is equivalent to {@link Runtime#availableProcessors()}.
070       *
071       * @return the number of processors available to the VM.
072       */
073      int getAvailableProcessors();
074    
075      /**
076       * Returns the name of the underlying operating system.  This
077       * is equivalent to obtaining the <code>os.name</code> property
078       * via {@link System#getProperty(String)}.
079       *
080       * @return the name of the operating system on which the VM
081       *         is running.
082       * @throws SecurityException if a security manager exists which
083       *                           prevents access to the name property.
084       * @see java.lang.System#getProperty(String)
085       * @see java.lang.SecurityManager#checkPropertyAccess(String)
086       */
087      String getName();
088    
089      /**
090       * Returns the system load average for the last minute, or -1
091       * if this is unavailable.  The availability and calculation
092       * of the load average is system-dependent, but is usually 
093       * a damped time-dependent average obtained by monitoring the
094       * number of queued and running processes.  It is expected
095       * that this method will be called frequently to monitor the
096       * average over time, so it may not be implemented on systems
097       * where such a call is expensive.
098       *
099       * @return the system load average for the last minute, or -1
100       *         if this is unavailable.
101       * @since 1.6
102       */
103      double getSystemLoadAverage();
104    
105      /**
106       * Returns the version of the underlying operating system.  This
107       * is equivalent to obtaining the <code>os.version</code> property
108       * via {@link System#getProperty(String)}.
109       *
110       * @return the version of the operating system on which the VM
111       *         is running.
112       * @throws SecurityException if a security manager exists which
113       *                           prevents access to the name property.
114       * @see java.lang.System#getProperty(String)
115       * @see java.lang.SecurityManager#checkPropertyAccess(String)
116       */
117      String getVersion();
118    
119    }