1 /*

     2  * Copyright (c) 2004, Oracle and/or its affiliates. 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.  Oracle designates this

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

     9  * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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

    23  * questions.

    24  */

    25 

    26 package sun.jvmstat.perfdata.monitor.v1_0;

    27 

    28 import sun.jvmstat.monitor.*;

    29 import sun.jvmstat.perfdata.monitor.*;

    30 import java.nio.*;

    31 

    32 /**

    33  * Class representing the 1.0 version of the HotSpot PerfData instrumentation

    34  * buffer header.

    35  * <p>

    36  * The PerfDataBufferPrologue2_0 class supports parsing of the version

    37  * specific portions of the PerfDataPrologue C structure:

    38  * <pre>

    39  * typedef struct {

    40  *   ...                      // handled by superclass

    41  *   jint used;               // number of PerfData memory bytes used

    42  *   jint overflow;           // number of bytes of overflow

    43  *   jlong mod_time_stamp;    // time stamp of the last structural modification

    44  * } PerfDataPrologue

    45  * </pre>

    46  *

    47  * @author Brian Doherty

    48  * @since 1.5

    49  */

    50 public class PerfDataBufferPrologue extends AbstractPerfDataBufferPrologue {

    51 

    52     private static final int SUPPORTED_MAJOR_VERSION = 1;

    53     private static final int SUPPORTED_MINOR_VERSION = 0;

    54 

    55     /*

    56      * the following constants must match the field offsets and sizes

    57      * in the PerfDataPrologue structure in perfMemory.hpp

    58      */

    59     final static int PERFDATA_PROLOG_USED_OFFSET=8;

    60     final static int PERFDATA_PROLOG_USED_SIZE=4;              // sizeof(int)

    61     final static int PERFDATA_PROLOG_OVERFLOW_OFFSET=12;

    62     final static int PERFDATA_PROLOG_OVERFLOW_SIZE=4;          // sizeof(int)

    63     final static int PERFDATA_PROLOG_MODTIMESTAMP_OFFSET=16;

    64     final static int PERFDATA_PROLOG_MODTIMESTAMP_SIZE=8;      // sizeof(long)

    65     final static int PERFDATA_PROLOG_SIZE=24;  // sizeof(struct PerfDataProlog)

    66 

    67     // counter names for prologue psuedo counters

    68     final static String PERFDATA_BUFFER_SIZE_NAME  = "sun.perfdata.size";

    69     final static String PERFDATA_BUFFER_USED_NAME  = "sun.perfdata.used";

    70     final static String PERFDATA_OVERFLOW_NAME     = "sun.perfdata.overflow";

    71     final static String PERFDATA_MODTIMESTAMP_NAME = "sun.perfdata.timestamp";

    72 

    73     /**

    74      * Create an instance of PerfDataBufferPrologue from the given

    75      * ByteBuffer object.

    76      *

    77      * @param byteBuffer the buffer containing the binary header data

    78      */

    79     public PerfDataBufferPrologue(ByteBuffer byteBuffer)

    80            throws MonitorException  {

    81         super(byteBuffer);

    82         assert ((getMajorVersion() == 1) && (getMinorVersion() == 0));

    83     }

    84 

    85     /**

    86      * {@inheritDoc}

    87      */

    88     public boolean supportsAccessible() {

    89         return false;

    90     }

    91 

    92     /**

    93      * {@inheritDoc}

    94      */

    95     public boolean isAccessible() {

    96         return true;

    97     }

    98 

    99     /**

   100      * Get the utilization of the instrumentation memory buffer.

   101      *

   102      * @return int - the utilization of the buffer

   103      */

   104     public int getUsed() {

   105         byteBuffer.position(PERFDATA_PROLOG_USED_OFFSET);

   106         return byteBuffer.getInt();

   107     }

   108 

   109     /**

   110      * Get the size of the instrumentation memory buffer.

   111      *

   112      * @return int - the size of the buffer

   113      */

   114     public int getBufferSize() {

   115         return byteBuffer.capacity();

   116     }

   117 

   118     /**

   119      * Get the buffer overflow amount. This value is non-zero if the

   120      * HotSpot JVM has overflowed the instrumentation memory buffer.

   121      * The target JVM can be restarted with -XX:PerfDataMemSize=X to

   122      * create a larger memory buffer.

   123      *

   124      * @return int - the size of the buffer

   125      */

   126     public int getOverflow() {

   127         byteBuffer.position(PERFDATA_PROLOG_OVERFLOW_OFFSET);

   128         return byteBuffer.getInt();

   129     }

   130 

   131     /**

   132      * Get the time of last modification for the instrumentation

   133      * memory buffer. This method returns the time, as ticks since the

   134      * start of the target JVM, of the last structural modification to

   135      * the instrumentation buffer. Structural modifications correspond to

   136      * the addition or deletion of instrumentation objects. Updates to

   137      * counter values are not structural modifications.

   138      */

   139     public long getModificationTimeStamp() {

   140         byteBuffer.position(PERFDATA_PROLOG_MODTIMESTAMP_OFFSET);

   141         return byteBuffer.getLong();

   142     }

   143 

   144     /**

   145      * {@inheritDoc}

   146      */

   147     public int getSize() {

   148         return PERFDATA_PROLOG_SIZE;  // sizeof(struct PerfDataProlog)

   149     }

   150 

   151     /**

   152      * Return an IntBuffer that accesses the used value. This is used

   153      * to create a Monitor object for this value.

   154      *

   155      * @return IntBuffer - a ByteBuffer that accesses the used value

   156      *                     in the instrumentation buffer header.

   157      * @see #getUsed()

   158      */

   159     public IntBuffer usedBuffer() {

   160         byteBuffer.position(PERFDATA_PROLOG_USED_OFFSET);

   161         IntBuffer ib = byteBuffer.asIntBuffer();

   162         ib.limit(1);

   163         return ib;

   164     }

   165 

   166     /**

   167      * Return an IntBuffer that accesses the size value. This is used

   168      * to create a Monitor object for this value.

   169      *

   170      * @return IntBuffer - a ByteBuffer that accesses the size value

   171      *                     in the instrumentation buffer header.

   172      * @see #getBufferSize()

   173      */

   174     public IntBuffer sizeBuffer() {

   175         IntBuffer ib = IntBuffer.allocate(1);

   176         ib.put(byteBuffer.capacity());

   177         return ib;

   178     }

   179 

   180     /**

   181      * Return an IntBuffer that accesses the overflow value. This is used

   182      * to create a Monitor object for this value.

   183      *

   184      * @return IntBuffer - a ByteBuffer that accesses the overflow value

   185      *                     in the instrumentation buffer header.

   186      * @see #getOverflow()

   187      */

   188     public IntBuffer overflowBuffer() {

   189         byteBuffer.position(PERFDATA_PROLOG_OVERFLOW_OFFSET);

   190         IntBuffer ib = byteBuffer.asIntBuffer();

   191         ib.limit(1);

   192         return ib;

   193     }

   194 

   195     /**

   196      * Return an LongBuffer that accesses the modification timestamp value.

   197      * This is used* to create a Monitor object for this value.

   198      *

   199      * @return LongBuffer - a ByteBuffer that accesses the modification time

   200      *                      stamp value in the instrumentation buffer header.

   201      * @see #getModificationTimeStamp()

   202      */

   203     public LongBuffer modificationTimeStampBuffer() {

   204         byteBuffer.position(PERFDATA_PROLOG_MODTIMESTAMP_OFFSET);

   205         LongBuffer lb = byteBuffer.asLongBuffer();

   206         lb.limit(1);

   207         return lb;

   208     }

   209 }