/*
 * @(#)GarbageCollectorMXBean.java	1.9 04/04/20
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.lang.management;

/**
 * The management interface for the garbage collection of
 * the Java virtual machine.  Garbage collection is the process 
 * that the Java virtual machine uses to find and reclaim unreachable 
 * objects to free up memory space.  A garbage collector is one type of
 * {@link MemoryManagerMXBean memory manager}.
 *
 * <p> A Java virtual machine may have one or more instances of 
 * the implementation class of this interface.  
 * An instance implementing this interface is
 * an <a href="ManagementFactory.html#MXBean">MXBean</a>
 * that can be obtained by calling
 * the {@link ManagementFactory#getGarbageCollectorMXBeans} method or
 * from the {@link ManagementFactory#getPlatformMBeanServer
 * platform <tt>MBeanServer</tt>} method.
 *
 * <p>The <tt>ObjectName</tt> for uniquely identifying the MXBean for
 * a garbage collector within an MBeanServer is:
 * <blockquote>
 *   {@link ManagementFactory#GARBAGE_COLLECTOR_MXBEAN_DOMAIN_TYPE
 *    <tt>java.lang:type=GarbageCollector</tt>}<tt>,name=</tt><i>collector's name</i>
 * </blockquote>
 *
 * A platform usually includes additional platform-dependent information 
 * specific to a garbage collection algorithm for monitoring.
 *
 * @see MemoryMXBean
 *
 * @see <a href="../../../javax/management/package-summary.html">
 *      JMX Specification.</a>
 * @see <a href="package-summary.html#examples">
 *      Ways to Access MXBeans</a>
 *
 * @author  Mandy Chung
 * @version 1.9, 04/20/04 
 * @since   1.5
 */
public interface GarbageCollectorMXBean extends MemoryManagerMXBean {
    /**
     * Returns the total number of collections that have occurred.
     * This method returns <tt>-1</tt> if the collection count is undefined for 
     * this collector.
     *
     * @return the total number of collections that have occurred.
     */
    public long getCollectionCount();
    
    /**
     * Returns the approximate accumulated collection elapsed time 
     * in milliseconds.  This method returns <tt>-1</tt> if the collection 
     * elapsed time is undefined for this collector.
     * <p>
     * The Java virtual machine implementation may use a high resolution
     * timer to measure the elapsed time.  This method may return the
     * same value even if the collection count has been incremented
     * if the collection elapsed time is very short.
     *
     * @return the approximate accumulated collection elapsed time 
     * in milliseconds.
     */
    public long getCollectionTime();
    
    
}