/*

 * Copyright (c) 2003, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.management.counter.perf;

import sun.management.counter.*;

import java.nio.*;

import java.io.UnsupportedEncodingException;

class PerfDataEntry {

    private class EntryFieldOffset {

        private final static int SIZEOF_BYTE = 1;

        private final static int SIZEOF_INT  = 4;

        private final static int SIZEOF_LONG = 8;

        private final static int ENTRY_LENGTH_SIZE    = SIZEOF_INT;

        private final static int NAME_OFFSET_SIZE     = SIZEOF_INT;

        private final static int VECTOR_LENGTH_SIZE   = SIZEOF_INT;

        private final static int DATA_TYPE_SIZE       = SIZEOF_BYTE;

        private final static int FLAGS_SIZE           = SIZEOF_BYTE;

        private final static int DATA_UNIT_SIZE       = SIZEOF_BYTE;

        private final static int DATA_VAR_SIZE        = SIZEOF_BYTE;

        private final static int DATA_OFFSET_SIZE     = SIZEOF_INT;

        final static int ENTRY_LENGTH  = 0;

        final static int NAME_OFFSET   = ENTRY_LENGTH + ENTRY_LENGTH_SIZE;

        final static int VECTOR_LENGTH = NAME_OFFSET + NAME_OFFSET_SIZE;;

        final static int DATA_TYPE     = VECTOR_LENGTH + VECTOR_LENGTH_SIZE;

        final static int FLAGS         = DATA_TYPE + DATA_TYPE_SIZE;

        final static int DATA_UNIT     = FLAGS + FLAGS_SIZE;

        final static int DATA_VAR      = DATA_UNIT + DATA_UNIT_SIZE;

        final static int DATA_OFFSET   = DATA_VAR + DATA_VAR_SIZE;

    }

    private String       name;

    private int          entryStart;

    private int          entryLength;

    private int          vectorLength;

    private PerfDataType dataType;

    private int          flags;

    private Units        unit;

    private Variability  variability;

    private int          dataOffset;

    private int          dataSize;

    private ByteBuffer   data;

    PerfDataEntry(ByteBuffer b) {

        entryStart = b.position();

        entryLength = b.getInt();

        // check for valid entry length

        if (entryLength <= 0 || entryLength > b.limit()) {

            throw new InstrumentationException("Invalid entry length: " +

                                               " entryLength = " + entryLength);

        }

        // check if last entry occurs before the eof.

        if ((entryStart + entryLength) > b.limit()) {

            throw new InstrumentationException("Entry extends beyond end of buffer: " +

                                               " entryStart = " + entryStart +

                                               " entryLength = " + entryLength +

                                               " buffer limit = " + b.limit());

        }

        b.position(entryStart + EntryFieldOffset.NAME_OFFSET);

        int nameOffset = b.getInt();

        if ((entryStart + nameOffset) > b.limit()) {

            throw new InstrumentationException("Invalid name offset: " +

                                               " entryStart = " + entryStart +

                                               " nameOffset = " + nameOffset +

                                               " buffer limit = " + b.limit());

        }

        b.position(entryStart + EntryFieldOffset.VECTOR_LENGTH);

        vectorLength = b.getInt();

        b.position(entryStart + EntryFieldOffset.DATA_TYPE);

        dataType = PerfDataType.toPerfDataType(b.get());

        b.position(entryStart + EntryFieldOffset.FLAGS);

        flags = b.get();

        b.position(entryStart + EntryFieldOffset.DATA_UNIT);

        unit = Units.toUnits(b.get());

        b.position(entryStart + EntryFieldOffset.DATA_VAR);

        variability = Variability.toVariability(b.get());

        b.position(entryStart + EntryFieldOffset.DATA_OFFSET);

        dataOffset = b.getInt();

        // read in the perfData item name, casting bytes to chars. skip the

        // null terminator

        b.position(entryStart + nameOffset);

        // calculate the length of the name

        int nameLength = 0;

        byte c;

        for (; (c = b.get()) != (byte)0; nameLength++);

        byte[] symbolBytes = new byte[nameLength];

        b.position(entryStart + nameOffset);

        for (int i = 0; i < nameLength; i++) {

            symbolBytes[i] = b.get();

        }

        // convert name into a String

        try {

            name = new String(symbolBytes, "UTF-8");

        }

        catch (UnsupportedEncodingException e) {

            // should not reach here

            // "UTF-8" is always a known encoding

        }

        if (variability == Variability.INVALID) {

            throw new InstrumentationException("Invalid variability attribute:" +

                                               " name = " + name);

        }

        if (unit == Units.INVALID) {

            throw new InstrumentationException("Invalid units attribute: " +

                                               " name = " + name);

        }

        if (vectorLength > 0) {

            dataSize = vectorLength * dataType.size();

        } else {

            dataSize = dataType.size();

        }

        // check if data beyond the eof.

        if ((entryStart + dataOffset + dataSize) > b.limit()) {

            throw new InstrumentationException("Data extends beyond end of buffer: " +

                                               " entryStart = " + entryStart +

                                               " dataOffset = " + dataOffset+

                                               " dataSize = " + dataSize +

                                               " buffer limit = " + b.limit());

        }

        // Construct a ByteBuffer for the data

        b.position(entryStart + dataOffset);

        data = b.slice();

        data.order(b.order());

        data.limit(dataSize);

    }

    public int size() {

        return entryLength;

    }

    public String name() {

        return name;

    }

    public PerfDataType type() {

        return dataType;

    }

    public Units units() {

        return unit;

    }

    public int flags() {

        return flags;

    }

    /**

     * Returns the number of elements in the data.

     */

    public int vectorLength() {

        return vectorLength;

    }

    public Variability variability() {

        return variability;

    }

    public ByteBuffer byteData() {

        data.position(0);

        assert data.remaining() == vectorLength();

        return data.duplicate();

    }

    public LongBuffer longData() {

        LongBuffer lb = data.asLongBuffer();

        return lb;

    }

}