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 26 package 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 <tt>MBeanServer</tt>} method. 43 * 44 * <p>The <tt>ObjectName</tt> 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 * <tt>java.lang:type=GarbageCollector</tt>}<tt>,name=</tt><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 */ 68 public interface GarbageCollectorMXBean extends MemoryManagerMXBean { 69 /** 70 * Returns the total number of collections that have occurred. 71 * This method returns <tt>-1</tt> if the collection count is undefined for 72 * this collector. 73 * 74 * @return the total number of collections that have occurred. 75 */ getCollectionCount()76 public long getCollectionCount(); 77 78 /** 79 * Returns the approximate accumulated collection elapsed time 80 * in milliseconds. This method returns <tt>-1</tt> 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 */ getCollectionTime()91 public long getCollectionTime(); 92 93 94 } 95