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1 /*
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2 * Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 /*
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26 * PerfData Version Constants
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27 * - Major Version - change whenever the structure of PerfDataEntry changes
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28 * - Minor Version - change whenever the data within the PerfDataEntry
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29 * structure changes. for example, new unit or variability
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30 * values are added or new PerfData subtypes are added.
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31 */
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32 #define PERFDATA_MAJOR_VERSION 2
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33 #define PERFDATA_MINOR_VERSION 0
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34
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35 /* Byte order of the PerfData memory region. The byte order is exposed in
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36 * the PerfData memory region as the data in the memory region may have
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37 * been generated by a little endian JVM implementation. Tracking the byte
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38 * order in the PerfData memory region allows Java applications to adapt
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39 * to the native byte order for monitoring purposes. This indicator is
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40 * also useful when a snapshot of the PerfData memory region is shipped
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41 * to a machine with a native byte order different from that of the
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42 * originating machine.
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43 */
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44 #define PERFDATA_BIG_ENDIAN 0
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45 #define PERFDATA_LITTLE_ENDIAN 1
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46
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47 /*
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48 * The PerfDataPrologue structure is known by the PerfDataBuffer Java class
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49 * libraries that read the PerfData memory region. The size and the position
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50 * of the fields must be changed along with their counterparts in the
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51 * PerfDataBuffer Java class. The first four bytes of this structure
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52 * should never change, or compatibility problems between the monitoring
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53 * applications and Hotspot VMs will result. The reserved fields are
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54 * available for future enhancements.
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55 */
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56 typedef struct {
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57 jint magic; // magic number - 0xcafec0c0
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58 jbyte byte_order; // byte order of the buffer
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59 jbyte major_version; // major and minor version numbers
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60 jbyte minor_version;
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61 jbyte accessible; // ready to access
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62 jint used; // number of PerfData memory bytes used
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63 jint overflow; // number of bytes of overflow
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64 jlong mod_time_stamp; // time stamp of last structural modification
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65 jint entry_offset; // offset of the first PerfDataEntry
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66 jint num_entries; // number of allocated PerfData entries
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67 } PerfDataPrologue;
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68
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69 /* The PerfDataEntry structure defines the fixed portion of an entry
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70 * in the PerfData memory region. The PerfDataBuffer Java libraries
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71 * are aware of this structure and need to be changed when this
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72 * structure changes.
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73 */
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74 typedef struct {
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75
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76 jint entry_length; // entry length in bytes
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77 jint name_offset; // offset of the data item name
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78 jint vector_length; // length of the vector. If 0, then scalar
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79 jbyte data_type; // type of the data item -
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80 // 'B','Z','J','I','S','C','D','F','V','L','['
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81 jbyte flags; // flags indicating misc attributes
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82 jbyte data_units; // unit of measure for the data type
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83 jbyte data_variability; // variability classification of data type
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84 jint data_offset; // offset of the data item
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85
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86 /*
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87 body of PerfData memory entry is variable length
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88
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89 jbyte[name_length] data_name; // name of the data item
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90 jbyte[pad_length] data_pad; // alignment of data item
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91 j<data_type>[data_length] data_item; // array of appropriate types.
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92 // data_length is > 1 only when the
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93 // data_type is T_ARRAY.
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94 */
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95 } PerfDataEntry;
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96
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97 // Prefix of performance data file.
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98 static const char PERFDATA_NAME[] = "hsperfdata";
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99
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100 // UINT_CHARS contains the number of characters holding a process id
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101 // (i.e. pid). pid is defined as unsigned "int" so the maximum possible pid value
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102 // would be 2^32 - 1 (4294967295) which can be represented as a 10 characters
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103 // string.
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104 static const size_t UINT_CHARS = 10;
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105
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106 // Add 1 for the '_' character between PERFDATA_NAME and pid. The '\0' terminating
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107 // character will be included in the sizeof(PERFDATA_NAME) operation.
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108 static const size_t PERFDATA_FILENAME_LEN = sizeof(PERFDATA_NAME) +
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109 UINT_CHARS + 1;
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110
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111 /* the PerfMemory class manages creation, destruction,
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112 * and allocation of the PerfData region.
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113 */
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114 class PerfMemory : AllStatic {
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115 friend class VMStructs;
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116 private:
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117 static char* _start;
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118 static char* _end;
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119 static char* _top;
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120 static size_t _capacity;
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121 static PerfDataPrologue* _prologue;
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122 static jint _initialized;
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123
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124 static void create_memory_region(size_t sizep);
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125 static void delete_memory_region();
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126
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127 public:
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128 enum PerfMemoryMode {
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129 PERF_MODE_RO = 0,
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130 PERF_MODE_RW = 1
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131 };
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132
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133 static char* alloc(size_t size);
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134 static char* start() { return _start; }
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135 static char* end() { return _end; }
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136 static size_t used() { return (size_t) (_top - _start); }
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137 static size_t capacity() { return _capacity; }
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138 static bool is_initialized() { return _initialized != 0; }
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139 static bool contains(char* addr) {
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140 return ((_start != NULL) && (addr >= _start) && (addr < _end));
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141 }
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142 static void mark_updated();
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143
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144 // methods for attaching to and detaching from the PerfData
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145 // memory segment of another JVM process on the same system.
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146 static void attach(const char* user, int vmid, PerfMemoryMode mode,
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147 char** addrp, size_t* size, TRAPS);
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148 static void detach(char* addr, size_t bytes, TRAPS);
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149
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150 static void initialize();
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151 static void destroy();
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152 static void set_accessible(bool value) {
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153 if (UsePerfData) {
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154 _prologue->accessible = value;
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155 }
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156 }
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157
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158 // filename of backing store or NULL if none.
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159 static char* backing_store_filename();
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160
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161 // returns the complete file path of hsperfdata.
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162 // the caller is expected to free the allocated memory.
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163 static char* get_perfdata_file_path();
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164 };
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165
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166 void perfMemory_init();
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167 void perfMemory_exit();
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