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 }