/*
* Copyright (c) 2001, 2008, 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.
*
*/
/*
* 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();