2362N/A * Copyright (c) 2003, 2004, Oracle and/or its affiliates. All rights reserved. 0N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 0N/A * This code is free software; you can redistribute it and/or modify it 0N/A * under the terms of the GNU General Public License version 2 only, as 2362N/A * published by the Free Software Foundation. Oracle designates this 0N/A * particular file as subject to the "Classpath" exception as provided 2362N/A * by Oracle in the LICENSE file that accompanied this code. 0N/A * This code is distributed in the hope that it will be useful, but WITHOUT 0N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 0N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 0N/A * version 2 for more details (a copy is included in the LICENSE file that 0N/A * accompanied this code). 0N/A * You should have received a copy of the GNU General Public License version 0N/A * 2 along with this work; if not, write to the Free Software Foundation, 0N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 2362N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 2362N/A * or visit www.oracle.com if you need additional information or have any 0N/A * A <tt>MemoryUsage</tt> object represents a snapshot of memory usage. 0N/A * Instances of the <tt>MemoryUsage</tt> class are usually constructed 0N/A * by methods that are used to obtain memory usage 0N/A * information about individual memory pool of the Java virtual machine or 0N/A * the heap or non-heap memory of the Java virtual machine as a whole. 0N/A * <p> A <tt>MemoryUsage</tt> object contains four values: 0N/A * <td valign=top> <tt>init</tt> </td> 0N/A * <td valign=top> represents the initial amount of memory (in bytes) that 0N/A * the Java virtual machine requests from the operating system 0N/A * for memory management during startup. The Java virtual machine 0N/A * may request additional memory from the operating system and 0N/A * may also release memory to the system over time. 0N/A * The value of <tt>init</tt> may be undefined. 0N/A * <td valign=top> <tt>used</tt> </td> 0N/A * <td valign=top> represents the amount of memory currently used (in bytes). 0N/A * <td valign=top> <tt>committed</tt> </td> 0N/A * <td valign=top> represents the amount of memory (in bytes) that is 0N/A * guaranteed to be available for use by the Java virtual machine. 0N/A * The amount of committed memory may change over time (increase 0N/A * or decrease). The Java virtual machine may release memory to 0N/A * the system and <tt>committed</tt> could be less than <tt>init</tt>. 0N/A * <tt>committed</tt> will always be greater than 0N/A * or equal to <tt>used</tt>. 0N/A * <td valign=top> <tt>max</tt> </td> 0N/A * <td valign=top> represents the maximum amount of memory (in bytes) 0N/A * that can be used for memory management. Its value may be undefined. 0N/A * The maximum amount of memory may change over time if defined. 0N/A * The amount of used and committed memory will always be less than 0N/A * or equal to <tt>max</tt> if <tt>max</tt> is defined. 0N/A * A memory allocation may fail if it attempts to increase the 0N/A * used memory such that <tt>used > committed</tt> even 0N/A * if <tt>used <= max</tt> would still be true (for example, 0N/A * when the system is low on virtual memory). 0N/A * Below is a picture showing an example of a memory pool: 0N/A * +----------------------------------------------+ 0N/A * +//////////////// | + 0N/A * +//////////////// | + 0N/A * +----------------------------------------------+ 0N/A * |---------------------------| 0N/A * |----------------------------------------------| 0N/A * <h4>MXBean Mapping</h4> 0N/A * <tt>MemoryUsage</tt> is mapped to a {@link CompositeData CompositeData} 0N/A * with attributes as specified in the {@link #from from} method. 0N/A * @author Mandy Chung 0N/A * Constructs a <tt>MemoryUsage</tt> object. 0N/A * @param init the initial amount of memory in bytes that 0N/A * the Java virtual machine allocates; 0N/A * or <tt>-1</tt> if undefined. 0N/A * @param used the amount of used memory in bytes. 0N/A * @param committed the amount of committed memory in bytes. 0N/A * @param max the maximum amount of memory in bytes that 0N/A * can be used; or <tt>-1</tt> if undefined. 0N/A * @throws IllegalArgumentException if 0N/A * <li> the value of <tt>init</tt> or <tt>max</tt> is negative 0N/A * but not <tt>-1</tt>; or</li> 0N/A * <li> the value of <tt>used</tt> or <tt>committed</tt> is negative; 0N/A * <li> <tt>used</tt> is greater than the value of <tt>committed</tt>; 0N/A * <li> <tt>committed</tt> is greater than the value of <tt>max</tt> 0N/A * <tt>max</tt> if defined.</li> 0N/A init +
" is negative but not -1.");
0N/A max +
" is negative but not -1.");
0N/A * Constructs a <tt>MemoryUsage</tt> object from a 0N/A * {@link CompositeData CompositeData}. 0N/A // validate the input composite data 0N/A * Returns the amount of memory in bytes that the Java virtual machine 0N/A * initially requests from the operating system for memory management. 0N/A * This method returns <tt>-1</tt> if the initial memory size is undefined. 0N/A * @return the initial size of memory in bytes; 0N/A * <tt>-1</tt> if undefined. 0N/A * Returns the amount of used memory in bytes. 0N/A * @return the amount of used memory in bytes. 0N/A * Returns the amount of memory in bytes that is committed for 0N/A * the Java virtual machine to use. This amount of memory is 0N/A * guaranteed for the Java virtual machine to use. 0N/A * @return the amount of committed memory in bytes. 0N/A * Returns the maximum amount of memory in bytes that can be 0N/A * used for memory management. This method returns <tt>-1</tt> 0N/A * if the maximum memory size is undefined. 0N/A * <p> This amount of memory is not guaranteed to be available 0N/A * for memory management if it is greater than the amount of 0N/A * committed memory. The Java virtual machine may fail to allocate 0N/A * memory even if the amount of used memory does not exceed this 0N/A * @return the maximum amount of memory in bytes; 0N/A * <tt>-1</tt> if undefined. 0N/A * Returns a descriptive representation of this memory usage. 0N/A * Returns a <tt>MemoryUsage</tt> object represented by the 0N/A * given <tt>CompositeData</tt>. The given <tt>CompositeData</tt> 0N/A * must contain the following attributes: 0N/A * <th align=left>Attribute Name</th> 0N/A * <th align=left>Type</th> 0N/A * <td><tt>java.lang.Long</tt></td> 0N/A * <td><tt>java.lang.Long</tt></td> 0N/A * <td>committed</td> 0N/A * <td><tt>java.lang.Long</tt></td> 0N/A * <td><tt>java.lang.Long</tt></td> 0N/A * @param cd <tt>CompositeData</tt> representing a <tt>MemoryUsage</tt> 0N/A * @throws IllegalArgumentException if <tt>cd</tt> does not 0N/A * represent a <tt>MemoryUsage</tt> with the attributes described 0N/A * @return a <tt>MemoryUsage</tt> object represented by <tt>cd</tt> 0N/A * if <tt>cd</tt> is not <tt>null</tt>; 0N/A * <tt>null</tt> otherwise.