1/*
2 * Copyright (c) 2003, 2008, Oracle and/or its affiliates. All rights reserved.
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
6 * under the terms of the GNU General Public License version 2 only, as
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 *
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.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package java.lang.management;
27
28/**
29 * The management interface for the garbage collection of
30 * the Java virtual machine.  Garbage collection is the process
31 * that the Java virtual machine uses to find and reclaim unreachable
32 * objects to free up memory space.  A garbage collector is one type of
33 * {@link MemoryManagerMXBean memory manager}.
34 *
35 * <p> A Java virtual machine may have one or more instances of
36 * the implementation class of this interface.
37 * An instance implementing this interface is
38 * an <a href="ManagementFactory.html#MXBean">MXBean</a>
39 * that can be obtained by calling
40 * the {@link ManagementFactory#getGarbageCollectorMXBeans} method or
41 * from the {@link ManagementFactory#getPlatformMBeanServer
42 * platform MBeanServer} method.
43 *
44 * <p>The {@code ObjectName} for uniquely identifying the MXBean for
45 * a garbage collector within an MBeanServer is:
46 * <blockquote>
47 *   {@link ManagementFactory#GARBAGE_COLLECTOR_MXBEAN_DOMAIN_TYPE
48 *    java.lang:type=GarbageCollector}{@code ,name=}<i>collector's name</i>
49 * </blockquote>
50 *
51 * It can be obtained by calling the
52 * {@link PlatformManagedObject#getObjectName} method.
53 *
54 * A platform usually includes additional platform-dependent information
55 * specific to a garbage collection algorithm for monitoring.
56 *
57 * @see ManagementFactory#getPlatformMXBeans(Class)
58 * @see MemoryMXBean
59 *
60 * @see <a href="../../../javax/management/package-summary.html">
61 *      JMX Specification.</a>
62 * @see <a href="package-summary.html#examples">
63 *      Ways to Access MXBeans</a>
64 *
65 * @author  Mandy Chung
66 * @since   1.5
67 */
68public interface GarbageCollectorMXBean extends MemoryManagerMXBean {
69    /**
70     * Returns the total number of collections that have occurred.
71     * This method returns {@code -1} if the collection count is undefined for
72     * this collector.
73     *
74     * @return the total number of collections that have occurred.
75     */
76    public long getCollectionCount();
77
78    /**
79     * Returns the approximate accumulated collection elapsed time
80     * in milliseconds.  This method returns {@code -1} if the collection
81     * elapsed time is undefined for this collector.
82     * <p>
83     * The Java virtual machine implementation may use a high resolution
84     * timer to measure the elapsed time.  This method may return the
85     * same value even if the collection count has been incremented
86     * if the collection elapsed time is very short.
87     *
88     * @return the approximate accumulated collection elapsed time
89     * in milliseconds.
90     */
91    public long getCollectionTime();
92
93
94}
95