1 /*
2 * Copyright (c) 2001, 2017, 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.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_RUNTIME_PERFMEMORY_HPP
26 #define SHARE_VM_RUNTIME_PERFMEMORY_HPP
27
28 #include "utilities/exceptions.hpp"
29
30 /*
31 * PerfData Version Constants
32 * - Major Version - change whenever the structure of PerfDataEntry changes
33 * - Minor Version - change whenever the data within the PerfDataEntry
34 * structure changes. for example, new unit or variability
35 * values are added or new PerfData subtypes are added.
36 */
37 #define PERFDATA_MAJOR_VERSION 2
38 #define PERFDATA_MINOR_VERSION 0
39
40 /* Byte order of the PerfData memory region. The byte order is exposed in
41 * the PerfData memory region as the data in the memory region may have
42 * been generated by a little endian JVM implementation. Tracking the byte
43 * order in the PerfData memory region allows Java applications to adapt
44 * to the native byte order for monitoring purposes. This indicator is
45 * also useful when a snapshot of the PerfData memory region is shipped
46 * to a machine with a native byte order different from that of the
47 * originating machine.
48 */
49 #define PERFDATA_BIG_ENDIAN 0
50 #define PERFDATA_LITTLE_ENDIAN 1
51
52 /*
53 * The PerfDataPrologue structure is known by the PerfDataBuffer Java class
54 * libraries that read the PerfData memory region. The size and the position
55 * of the fields must be changed along with their counterparts in the
56 * PerfDataBuffer Java class. The first four bytes of this structure
57 * should never change, or compatibility problems between the monitoring
58 * applications and HotSpot VMs will result. The reserved fields are
59 * available for future enhancements.
60 */
61 typedef struct {
62 jint magic; // magic number - 0xcafec0c0
63 jbyte byte_order; // byte order of the buffer
64 jbyte major_version; // major and minor version numbers
65 jbyte minor_version;
66 jbyte accessible; // ready to access
67 jint used; // number of PerfData memory bytes used
68 jint overflow; // number of bytes of overflow
69 jlong mod_time_stamp; // time stamp of last structural modification
70 jint entry_offset; // offset of the first PerfDataEntry
71 jint num_entries; // number of allocated PerfData entries
72 } PerfDataPrologue;
73
74 /* The PerfDataEntry structure defines the fixed portion of an entry
75 * in the PerfData memory region. The PerfDataBuffer Java libraries
76 * are aware of this structure and need to be changed when this
77 * structure changes.
78 */
79 typedef struct {
80
81 jint entry_length; // entry length in bytes
82 jint name_offset; // offset of the data item name
83 jint vector_length; // length of the vector. If 0, then scalar
84 jbyte data_type; // type of the data item -
85 // 'B','Z','J','I','S','C','D','F','V','L','['
86 jbyte flags; // flags indicating misc attributes
87 jbyte data_units; // unit of measure for the data type
88 jbyte data_variability; // variability classification of data type
89 jint data_offset; // offset of the data item
90
91 /*
92 body of PerfData memory entry is variable length
93
94 jbyte[name_length] data_name; // name of the data item
95 jbyte[pad_length] data_pad; // alignment of data item
96 j<data_type>[data_length] data_item; // array of appropriate types.
97 // data_length is > 1 only when the
98 // data_type is T_ARRAY.
99 */
100 } PerfDataEntry;
101
102 // Prefix of performance data file.
103 extern const char PERFDATA_NAME[];
104
105 // UINT_CHARS contains the number of characters holding a process id
106 // (i.e. pid). pid is defined as unsigned "int" so the maximum possible pid value
107 // would be 2^32 - 1 (4294967295) which can be represented as a 10 characters
108 // string.
109 static const size_t UINT_CHARS = 10;
110
111 /* the PerfMemory class manages creation, destruction,
112 * and allocation of the PerfData region.
113 */
114 class PerfMemory : AllStatic {
115 friend class VMStructs;
116 friend class PerfMemoryTest;
117 private:
118 static char* _start;
119 static char* _end;
120 static char* _top;
121 static size_t _capacity;
122 static PerfDataPrologue* _prologue;
123 static int _initialized;
124 static bool _destroyed;
125
126 static void create_memory_region(size_t sizep);
127 static void delete_memory_region();
128
129 public:
130 enum PerfMemoryMode {
131 PERF_MODE_RO = 0,
132 PERF_MODE_RW = 1
133 };
134
135 static char* alloc(size_t size);
136 static char* start() { return _start; }
137 static char* end() { return _end; }
138 static size_t used() { return (size_t) (_top - _start); }
139 static size_t capacity() { return _capacity; }
140 static bool is_initialized();
141 static bool is_destroyed() { return _destroyed; }
142 static bool is_usable() { return is_initialized() && !is_destroyed(); }
143 static bool contains(char* addr) {
144 return ((_start != NULL) && (addr >= _start) && (addr < _end));
145 }
146 static void mark_updated();
147
148 // methods for attaching to and detaching from the PerfData
149 // memory segment of another JVM process on the same system.
150 static void attach(const char* user, int vmid, PerfMemoryMode mode,
151 char** addrp, size_t* size, TRAPS);
152 static void detach(char* addr, size_t bytes, TRAPS);
153
154 static void initialize();
155 static void destroy();
156 static void set_accessible(bool value) {
157 if (UsePerfData) {
158 _prologue->accessible = value;
159 }
160 }
161
162 // returns the complete file path of hsperfdata.
163 // the caller is expected to free the allocated memory.
164 static char* get_perfdata_file_path();
165 };
166
167 void perfMemory_init();
168 void perfMemory_exit();
169
170 #endif // SHARE_VM_RUNTIME_PERFMEMORY_HPP