/*

 * Copyright (c) 2007, 2008, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

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

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package java.nio;

import java.lang.management.PlatformManagedObject;

/**

 * The management interface for a buffer pool.

 *

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

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

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

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

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

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

 * <pre>

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

 * </pre>

 *

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

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

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

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

 * <blockquote>

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

 * </blockquote>

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

 *

 * @since   1.7

 */

public interface BufferPoolMXBean extends PlatformManagedObject {

    /**

     * Returns the name representing this buffer pool.

     *

     * @return  The name of this buffer pool.

     */

    String getName();

    /**

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

     *

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

     */

    long getCount();

    /**

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

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

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

     * in the pool in bytes.

     *

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

     *          in bytes

     */

    long getTotalCapacity();

    /**

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

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

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

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

     * memory allocator, and other implementation specific reasons.

     *

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

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

     *          the memory usage is not available

     */

    long getMemoryUsed();

}