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 /*

  * Copyright (c) 2001, 2010, 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.

  *

  * 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.

  *

  */

 #ifndef SHARE_VM_RUNTIME_PERFMEMORY_HPP

 #define SHARE_VM_RUNTIME_PERFMEMORY_HPP

 #include "utilities/exceptions.hpp"

 /*

  * PerfData Version Constants

  *   - Major Version - change whenever the structure of PerfDataEntry changes

  *   - Minor Version - change whenever the data within the PerfDataEntry

  *                     structure changes. for example, new unit or variability

  *                     values are added or new PerfData subtypes are added.

  */

 #define PERFDATA_MAJOR_VERSION 2

 #define PERFDATA_MINOR_VERSION 0

 /* Byte order of the PerfData memory region. The byte order is exposed in

  * the PerfData memory region as the data in the memory region may have

  * been generated by a little endian JVM implementation. Tracking the byte

  * order in the PerfData memory region allows Java applications to adapt

  * to the native byte order for monitoring purposes. This indicator is

  * also useful when a snapshot of the PerfData memory region is shipped

  * to a machine with a native byte order different from that of the

  * originating machine.

  */

 #define PERFDATA_BIG_ENDIAN     0

 #define PERFDATA_LITTLE_ENDIAN  1

 /*

  * The PerfDataPrologue structure is known by the PerfDataBuffer Java class

  * libraries that read the PerfData memory region. The size and the position

  * of the fields must be changed along with their counterparts in the

  * PerfDataBuffer Java class. The first four bytes of this structure

  * should never change, or compatibility problems between the monitoring

  * applications and Hotspot VMs will result. The reserved fields are

  * available for future enhancements.

  */

 typedef struct {

   jint   magic;              // magic number - 0xcafec0c0

   jbyte  byte_order;         // byte order of the buffer

   jbyte  major_version;      // major and minor version numbers

   jbyte  minor_version;

   jbyte  accessible;         // ready to access

   jint   used;               // number of PerfData memory bytes used

   jint   overflow;           // number of bytes of overflow

   jlong  mod_time_stamp;     // time stamp of last structural modification

   jint   entry_offset;       // offset of the first PerfDataEntry

   jint   num_entries;        // number of allocated PerfData entries

 } PerfDataPrologue;

 /* The PerfDataEntry structure defines the fixed portion of an entry

  * in the PerfData memory region. The PerfDataBuffer Java libraries

  * are aware of this structure and need to be changed when this

  * structure changes.

  */

 typedef struct {

   jint entry_length;      // entry length in bytes

   jint name_offset;       // offset of the data item name

   jint vector_length;     // length of the vector. If 0, then scalar

   jbyte data_type;        // type of the data item -

                           // 'B','Z','J','I','S','C','D','F','V','L','['

   jbyte flags;            // flags indicating misc attributes

   jbyte data_units;       // unit of measure for the data type

   jbyte data_variability; // variability classification of data type

   jint  data_offset;      // offset of the data item

 /*

   body of PerfData memory entry is variable length

   jbyte[name_length] data_name;        // name of the data item

   jbyte[pad_length] data_pad;          // alignment of data item

   j<data_type>[data_length] data_item; // array of appropriate types.

                                        // data_length is > 1 only when the

                                        // data_type is T_ARRAY.

 */

 } PerfDataEntry;

 // Prefix of performance data file.

 extern const char PERFDATA_NAME[];

 // UINT_CHARS contains the number of characters holding a process id

 // (i.e. pid). pid is defined as unsigned "int" so the maximum possible pid value

 // would be 2^32 - 1 (4294967295) which can be represented as a 10 characters

 // string.

 static const size_t UINT_CHARS = 10;

 /* the PerfMemory class manages creation, destruction,

  * and allocation of the PerfData region.

  */

 class PerfMemory : AllStatic {

     friend class VMStructs;

   private:

     static char*  _start;

     static char*  _end;

     static char*  _top;

     static size_t _capacity;

     static PerfDataPrologue*  _prologue;

     static jint   _initialized;

     static void create_memory_region(size_t sizep);

     static void delete_memory_region();

   public:

     enum PerfMemoryMode {

       PERF_MODE_RO = 0,

       PERF_MODE_RW = 1

     };

     static char* alloc(size_t size);

     static char* start() { return _start; }

     static char* end() { return _end; }

     static size_t used() { return (size_t) (_top - _start); }

     static size_t capacity() { return _capacity; }

     static bool is_initialized() { return _initialized != 0; }

     static bool contains(char* addr) {

       return ((_start != NULL) && (addr >= _start) && (addr < _end));

     }

     static void mark_updated();

     // methods for attaching to and detaching from the PerfData

     // memory segment of another JVM process on the same system.

     static void attach(const char* user, int vmid, PerfMemoryMode mode,

                        char** addrp, size_t* size, TRAPS);

     static void detach(char* addr, size_t bytes, TRAPS);

     static void initialize();

     static void destroy();

     static void set_accessible(bool value) {

       if (UsePerfData) {

         _prologue->accessible = value;

       }

     }

     // filename of backing store or NULL if none.

     static char* backing_store_filename();

     // returns the complete file path of hsperfdata.

     // the caller is expected to free the allocated memory.

     static char* get_perfdata_file_path();

 };

 void perfMemory_init();

 void perfMemory_exit();

 #endif // SHARE_VM_RUNTIME_PERFMEMORY_HPP