/*

 * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.

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

 *

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 * 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,

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 *

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package sun.jvmstat.perfdata.monitor.protocol.rmi;

import sun.jvmstat.monitor.*;

import sun.jvmstat.monitor.remote.*;

import sun.jvmstat.perfdata.monitor.*;

import java.io.*;

import java.rmi.RemoteException;

import java.nio.ByteBuffer;

/**

 * The concrete PerfDataBuffer implementation for the <em>rmi:</em>

 * protocol for the HotSpot PerfData monitoring implementation.

 * <p>

 * This class is responsible for acquiring the instrumentation buffer

 * data for a remote target HotSpot Java Virtual Machine.

 *

 * @author Brian Doherty

 * @since 1.5

 */

public class PerfDataBuffer extends AbstractPerfDataBuffer {

    private RemoteVm rvm;

    /**

     * Create a PerfDataBuffer instance for accessing the specified

     * instrumentation buffer.

     *

     * @param rvm the proxy to the remote MonitredVm object

     * @param lvmid the local Java Virtual Machine Identifier of the

     *              remote target.

     *

     * @throws MonitorException

     */

    public PerfDataBuffer(RemoteVm rvm, int lvmid) throws MonitorException {

        this.rvm = rvm;

        try {

            ByteBuffer buffer = ByteBuffer.allocate(rvm.getCapacity());

            sample(buffer);

            createPerfDataBuffer(buffer, lvmid);

        } catch (RemoteException e) {

            throw new MonitorException("Could not read data for remote JVM "

                                       + lvmid, e);

        }

    }

    /**

     * Get a copy of the remote instrumentation buffer.

     *<p>

     * The data in the remote instrumentation buffer is copied into

     * the local byte buffer.

     *

     * @param buffer the buffer to receive the copy of the remote

     *               instrumentation buffer.

     * @throws RemoteException Thrown on any communications errors with

     *                         the remote system.

     */

    public void sample(ByteBuffer buffer) throws RemoteException {

        assert buffer != null;

        assert rvm != null;

        synchronized(buffer) {

            buffer.clear();

            buffer.put(rvm.getBytes());

        }

    }

}