001    /* GarbageCollectorMXBean.java - Interface for a garbage collector 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 garbage collectors
042     * of the virtual machine.  Garbage collectors are responsible
043     * for removing unreferenced objects from memory.  A garbage
044     * collector is a type of memory manager, so this interface
045     * is combined with that of generic memory managers.  An instance
046     * of this bean for each garbage collector is obtained by calling
047     * {@link ManagementFactory#getGarbageCollectorMXBeans()}.
048     *
049     * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
050     * @since 1.5
051     */
052    public interface GarbageCollectorMXBean
053      extends MemoryManagerMXBean
054    {
055    
056      /**
057       * Returns the number of collections the garbage collector
058       * represented by this bean has made.  -1 is returned if the
059       * collection count is undefined.
060       *
061       * @return the number of collections made, or -1 if this is
062       *         undefined.
063       */
064      long getCollectionCount();
065    
066      /**
067       * Returns the accumulated number of milliseconds this garbage
068       * collector has spent freeing the memory used by unreferenced
069       * objects.  -1 is returned if the collection time is undefined.
070       * Note that the accumulated time may not change, even when the
071       * collection count increases, if the time taken is sufficiently
072       * short; this depends on the resolution of the timer used.
073       * 
074       * @return the accumulated number of milliseconds spent collecting,
075       *         or -1 if this is undefined.
076       */
077      long getCollectionTime();
078    
079    }