/*

 * Copyright (c) 2004, 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 sun.jvmstat.perfdata.monitor.protocol.file;

import sun.jvmstat.monitor.*;

import sun.jvmstat.perfdata.monitor.*;

import java.io.*;

import java.net.URI;

import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

/**

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

 * protocol for the HotSpot PerfData monitoring implemetation.

 * <p>

 * This class is responsible for acquiring access to the instrumentation

 * buffer stored in a file referenced by a file URI.

 *

 * @author Brian Doherty

 * @since 1.5

 */

public class PerfDataBuffer extends AbstractPerfDataBuffer {

    /**

     * Create a PerfDataBuffer instance for accessing the specified

     * instrumentation buffer.

     *

     * @param vmid the <em>file:</em> URI to the instrumentation buffer file

     *

     * @throws MonitorException

     */

    public PerfDataBuffer(VmIdentifier vmid) throws MonitorException {

        File f = new File(vmid.getURI());

        String mode = vmid.getMode();

        try {

            FileChannel fc = new RandomAccessFile(f, mode).getChannel();

            ByteBuffer bb = null;

            if (mode.compareTo("r") == 0) {

                bb = fc.map(FileChannel.MapMode.READ_ONLY, 0L, (int)fc.size());

            } else if (mode.compareTo("rw") == 0) {

                bb = fc.map(FileChannel.MapMode.READ_WRITE, 0L, (int)fc.size());

            } else {

                throw new IllegalArgumentException("Invalid mode: " + mode);

            }

            fc.close();               // doesn't need to remain open

            createPerfDataBuffer(bb, 0);

        } catch (FileNotFoundException e) {

            throw new MonitorException("Could not find " + vmid.toString());

        } catch (IOException e) {

            throw new MonitorException("Could not read " + vmid.toString());

        }

    }

}