1 /*

     2  * Copyright 2007-2008 Sun Microsystems, Inc.  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.  Sun designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    22  * CA 95054 USA or visit www.sun.com if you need additional information or

    23  * have any questions.

    24  */

    25 

    26 package java.nio;

    27 

    28 import java.lang.management.PlatformManagedObject;

    29 

    30 /**

    31  * The management interface for a buffer pool.

    32  *

    33  * <p> A class implementing this interface is an <a href=

    34  * "java.lang.management.ManagementFactory.html#MXBean">MXBean</a>. A Java

    35  * virtual machine has one or more implementations of this interface. The {@link

    36  * java.lang.management.ManagementFactory#getPlatformMXBeans getPlatformMXBeans}

    37  * method can be used to obtain the list of {@code BufferPoolMXBean} objects

    38  * representing the management interfaces for pools of buffers as follows:

    39  * <pre>

    40  *     List<BufferPoolMXBean> pools = ManagementFactory.getPlatformMXBeans(BufferPoolMXBean.class);

    41  * </pre>

    42  *

    43  * <p> The management interfaces are also registered with the platform {@link

    44  * javax.management.MBeanServer MBeanServer}. The {@link

    45  * javax.management.ObjectName ObjectName} that uniquely identifies the

    46  * management interface within the {@code MBeanServer} takes the form:

    47  * <blockquote>

    48  *    <tt>java.nio:type=BufferPool</tt><tt>,name=</tt><i>pool name</i>

    49  * </blockquote>

    50  * where <em>pool name</em> is the {@link #getName name} of the buffer pool.

    51  *

    52  * @since   1.7

    53  */

    54 

    55 public interface BufferPoolMXBean extends PlatformManagedObject {

    56 

    57     /**

    58      * Returns the name representing this buffer pool.

    59      *

    60      * @return  The name of this buffer pool.

    61      */

    62     String getName();

    63 

    64     /**

    65      * Returns an estimate of the number of buffers in the pool.

    66      *

    67      * @return  An estimate of the number of buffers in this pool

    68      */

    69     long getCount();

    70 

    71     /**

    72      * Returns an estimate of the total capacity of the buffers in this pool.

    73      * A buffer's capacity is the number of elements it contains and the value

    74      * returned by this method is an estimate of the total capacity of buffers

    75      * in the pool in bytes.

    76      *

    77      * @return  An estimate of the total capacity of the buffers in this pool

    78      *          in bytes

    79      */

    80     long getTotalCapacity();

    81 

    82     /**

    83      * Returns an estimate of the memory that the Java virtual machine is using

    84      * for this buffer pool. The value returned by this method may differ

    85      * from the estimate of the total {@link #getTotalCapacity capacity} of

    86      * the buffers in this pool. This difference is explained by alignment,

    87      * memory allocator, and other implementation specific reasons.

    88      *

    89      * @return  An estimate of the memory that the Java virtual machine is using

    90      *          for this buffer pool in bytes, or {@code -1L} if an estimate of

    91      *          the memory usage is not available

    92      */

    93     long getMemoryUsed();

    94 }