/* * Copyright (c) 2001, 2017, 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_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; friend class PerfMemoryTest; private: static char* _start; static char* _end; static char* _top; static size_t _capacity; static PerfDataPrologue* _prologue; static int _initialized; static bool _destroyed; 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(); static bool is_destroyed() { return _destroyed; } static bool is_usable() { return is_initialized() && !is_destroyed(); } 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; } } // 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