1 /*
2 * Copyright (c) 2001, 2008, 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 /*
26 * PerfData Version Constants
27 * - Major Version - change whenever the structure of PerfDataEntry changes
28 * - Minor Version - change whenever the data within the PerfDataEntry
29 * structure changes. for example, new unit or variability
30 * values are added or new PerfData subtypes are added.
31 */
32 #define PERFDATA_MAJOR_VERSION 2
33 #define PERFDATA_MINOR_VERSION 0
34
35 /* Byte order of the PerfData memory region. The byte order is exposed in
36 * the PerfData memory region as the data in the memory region may have
37 * been generated by a little endian JVM implementation. Tracking the byte
38 * order in the PerfData memory region allows Java applications to adapt
39 * to the native byte order for monitoring purposes. This indicator is
40 * also useful when a snapshot of the PerfData memory region is shipped
41 * to a machine with a native byte order different from that of the
42 * originating machine.
43 */
44 #define PERFDATA_BIG_ENDIAN 0
45 #define PERFDATA_LITTLE_ENDIAN 1
46
47 /*
48 * The PerfDataPrologue structure is known by the PerfDataBuffer Java class
49 * libraries that read the PerfData memory region. The size and the position
50 * of the fields must be changed along with their counterparts in the
51 * PerfDataBuffer Java class. The first four bytes of this structure
52 * should never change, or compatibility problems between the monitoring
53 * applications and Hotspot VMs will result. The reserved fields are
54 * available for future enhancements.
55 */
56 typedef struct {
57 jint magic; // magic number - 0xcafec0c0
58 jbyte byte_order; // byte order of the buffer
59 jbyte major_version; // major and minor version numbers
60 jbyte minor_version;
61 jbyte accessible; // ready to access
62 jint used; // number of PerfData memory bytes used
63 jint overflow; // number of bytes of overflow
64 jlong mod_time_stamp; // time stamp of last structural modification
65 jint entry_offset; // offset of the first PerfDataEntry
66 jint num_entries; // number of allocated PerfData entries
67 } PerfDataPrologue;
68
69 /* The PerfDataEntry structure defines the fixed portion of an entry
70 * in the PerfData memory region. The PerfDataBuffer Java libraries
71 * are aware of this structure and need to be changed when this
72 * structure changes.
73 */
74 typedef struct {
75
76 jint entry_length; // entry length in bytes
77 jint name_offset; // offset of the data item name
78 jint vector_length; // length of the vector. If 0, then scalar
79 jbyte data_type; // type of the data item -
80 // 'B','Z','J','I','S','C','D','F','V','L','['
81 jbyte flags; // flags indicating misc attributes
82 jbyte data_units; // unit of measure for the data type
83 jbyte data_variability; // variability classification of data type
84 jint data_offset; // offset of the data item
85
86 /*
87 body of PerfData memory entry is variable length
88
89 jbyte[name_length] data_name; // name of the data item
90 jbyte[pad_length] data_pad; // alignment of data item
91 j<data_type>[data_length] data_item; // array of appropriate types.
92 // data_length is > 1 only when the
93 // data_type is T_ARRAY.
94 */
95 } PerfDataEntry;
96
97 // Prefix of performance data file.
98 extern const char PERFDATA_NAME[];
99
100 // UINT_CHARS contains the number of characters holding a process id
101 // (i.e. pid). pid is defined as unsigned "int" so the maximum possible pid value
102 // would be 2^32 - 1 (4294967295) which can be represented as a 10 characters
103 // string.
104 static const size_t UINT_CHARS = 10;
105
106 /* the PerfMemory class manages creation, destruction,
107 * and allocation of the PerfData region.
108 */
109 class PerfMemory : AllStatic {
110 friend class VMStructs;
111 private:
112 static char* _start;
113 static char* _end;
114 static char* _top;
115 static size_t _capacity;
116 static PerfDataPrologue* _prologue;
117 static jint _initialized;
118
119 static void create_memory_region(size_t sizep);
120 static void delete_memory_region();
121
122 public:
123 enum PerfMemoryMode {
124 PERF_MODE_RO = 0,
125 PERF_MODE_RW = 1
126 };
127
128 static char* alloc(size_t size);
129 static char* start() { return _start; }
130 static char* end() { return _end; }
131 static size_t used() { return (size_t) (_top - _start); }
132 static size_t capacity() { return _capacity; }
133 static bool is_initialized() { return _initialized != 0; }
134 static bool contains(char* addr) {
135 return ((_start != NULL) && (addr >= _start) && (addr < _end));
136 }
137 static void mark_updated();
138
139 // methods for attaching to and detaching from the PerfData
140 // memory segment of another JVM process on the same system.
141 static void attach(const char* user, int vmid, PerfMemoryMode mode,
142 char** addrp, size_t* size, TRAPS);
143 static void detach(char* addr, size_t bytes, TRAPS);
144
145 static void initialize();
146 static void destroy();
147 static void set_accessible(bool value) {
148 if (UsePerfData) {
149 _prologue->accessible = value;
150 }
151 }
152
153 // filename of backing store or NULL if none.
154 static char* backing_store_filename();
155
156 // returns the complete file path of hsperfdata.
157 // the caller is expected to free the allocated memory.
158 static char* get_perfdata_file_path();
159 };
160
161 void perfMemory_init();
162 void perfMemory_exit();