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1 /* |
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2 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 * |
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23 */ |
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24 |
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25 #ifndef SHARE_VM_RUNTIME_OBJECTMONITOR_HPP |
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26 #define SHARE_VM_RUNTIME_OBJECTMONITOR_HPP |
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27 |
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28 #include "runtime/os.hpp" |
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29 #include "runtime/park.hpp" |
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30 #include "runtime/perfData.hpp" |
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31 |
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32 // ObjectWaiter serves as a "proxy" or surrogate thread. |
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33 // TODO-FIXME: Eliminate ObjectWaiter and use the thread-specific |
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34 // ParkEvent instead. Beware, however, that the JVMTI code |
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35 // knows about ObjectWaiters, so we'll have to reconcile that code. |
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36 // See next_waiter(), first_waiter(), etc. |
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37 |
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38 class ObjectWaiter : public StackObj { |
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39 public: |
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40 enum TStates { TS_UNDEF, TS_READY, TS_RUN, TS_WAIT, TS_ENTER, TS_CXQ } ; |
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41 enum Sorted { PREPEND, APPEND, SORTED } ; |
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42 ObjectWaiter * volatile _next; |
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43 ObjectWaiter * volatile _prev; |
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44 Thread* _thread; |
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45 jlong _notifier_tid; |
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46 ParkEvent * _event; |
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47 volatile int _notified ; |
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48 volatile TStates TState ; |
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49 Sorted _Sorted ; // List placement disposition |
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50 bool _active ; // Contention monitoring is enabled |
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51 public: |
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52 ObjectWaiter(Thread* thread); |
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53 |
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54 void wait_reenter_begin(ObjectMonitor *mon); |
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55 void wait_reenter_end(ObjectMonitor *mon); |
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56 }; |
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57 |
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58 // forward declaration to avoid include tracing.hpp |
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59 class EventJavaMonitorWait; |
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60 |
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61 // WARNING: |
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62 // This is a very sensitive and fragile class. DO NOT make any |
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63 // change unless you are fully aware of the underlying semantics. |
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64 |
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65 // This class can not inherit from any other class, because I have |
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66 // to let the displaced header be the very first word. Otherwise I |
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67 // have to let markOop include this file, which would export the |
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68 // monitor data structure to everywhere. |
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69 // |
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70 // The ObjectMonitor class is used to implement JavaMonitors which have |
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71 // transformed from the lightweight structure of the thread stack to a |
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72 // heavy weight lock due to contention |
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73 |
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74 // It is also used as RawMonitor by the JVMTI |
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75 |
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76 |
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77 class ObjectMonitor { |
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78 public: |
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79 enum { |
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80 OM_OK, // no error |
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81 OM_SYSTEM_ERROR, // operating system error |
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82 OM_ILLEGAL_MONITOR_STATE, // IllegalMonitorStateException |
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83 OM_INTERRUPTED, // Thread.interrupt() |
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84 OM_TIMED_OUT // Object.wait() timed out |
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85 }; |
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86 |
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87 public: |
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88 // TODO-FIXME: the "offset" routines should return a type of off_t instead of int ... |
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89 // ByteSize would also be an appropriate type. |
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90 static int header_offset_in_bytes() { return offset_of(ObjectMonitor, _header); } |
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91 static int object_offset_in_bytes() { return offset_of(ObjectMonitor, _object); } |
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92 static int owner_offset_in_bytes() { return offset_of(ObjectMonitor, _owner); } |
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93 static int count_offset_in_bytes() { return offset_of(ObjectMonitor, _count); } |
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94 static int recursions_offset_in_bytes() { return offset_of(ObjectMonitor, _recursions); } |
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95 static int cxq_offset_in_bytes() { return offset_of(ObjectMonitor, _cxq) ; } |
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96 static int succ_offset_in_bytes() { return offset_of(ObjectMonitor, _succ) ; } |
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97 static int EntryList_offset_in_bytes() { return offset_of(ObjectMonitor, _EntryList); } |
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98 static int FreeNext_offset_in_bytes() { return offset_of(ObjectMonitor, FreeNext); } |
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99 static int WaitSet_offset_in_bytes() { return offset_of(ObjectMonitor, _WaitSet) ; } |
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100 static int Responsible_offset_in_bytes() { return offset_of(ObjectMonitor, _Responsible);} |
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101 static int Spinner_offset_in_bytes() { return offset_of(ObjectMonitor, _Spinner); } |
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102 |
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103 public: |
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104 // Eventaully we'll make provisions for multiple callbacks, but |
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105 // now one will suffice. |
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106 static int (*SpinCallbackFunction)(intptr_t, int) ; |
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107 static intptr_t SpinCallbackArgument ; |
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108 |
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109 |
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110 public: |
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111 markOop header() const; |
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112 void set_header(markOop hdr); |
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113 |
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114 intptr_t is_busy() const { |
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115 // TODO-FIXME: merge _count and _waiters. |
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116 // TODO-FIXME: assert _owner == null implies _recursions = 0 |
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117 // TODO-FIXME: assert _WaitSet != null implies _count > 0 |
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118 return _count|_waiters|intptr_t(_owner)|intptr_t(_cxq)|intptr_t(_EntryList ) ; |
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119 } |
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120 |
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121 intptr_t is_entered(Thread* current) const; |
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122 |
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123 void* owner() const; |
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124 void set_owner(void* owner); |
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125 |
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126 intptr_t waiters() const; |
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127 |
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128 intptr_t count() const; |
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129 void set_count(intptr_t count); |
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130 intptr_t contentions() const ; |
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131 intptr_t recursions() const { return _recursions; } |
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132 |
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133 // JVM/DI GetMonitorInfo() needs this |
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134 ObjectWaiter* first_waiter() { return _WaitSet; } |
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135 ObjectWaiter* next_waiter(ObjectWaiter* o) { return o->_next; } |
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136 Thread* thread_of_waiter(ObjectWaiter* o) { return o->_thread; } |
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137 |
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138 // initialize the monitor, exception the semaphore, all other fields |
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139 // are simple integers or pointers |
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140 ObjectMonitor() { |
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141 _header = NULL; |
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142 _count = 0; |
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143 _waiters = 0, |
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144 _recursions = 0; |
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145 _object = NULL; |
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146 _owner = NULL; |
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147 _WaitSet = NULL; |
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148 _WaitSetLock = 0 ; |
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149 _Responsible = NULL ; |
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150 _succ = NULL ; |
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151 _cxq = NULL ; |
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152 FreeNext = NULL ; |
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153 _EntryList = NULL ; |
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154 _SpinFreq = 0 ; |
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155 _SpinClock = 0 ; |
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156 OwnerIsThread = 0 ; |
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157 _previous_owner_tid = 0; |
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158 } |
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159 |
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160 ~ObjectMonitor() { |
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161 // TODO: Add asserts ... |
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162 // _cxq == 0 _succ == NULL _owner == NULL _waiters == 0 |
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163 // _count == 0 _EntryList == NULL etc |
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164 } |
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165 |
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166 private: |
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167 void Recycle () { |
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168 // TODO: add stronger asserts ... |
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169 // _cxq == 0 _succ == NULL _owner == NULL _waiters == 0 |
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170 // _count == 0 EntryList == NULL |
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171 // _recursions == 0 _WaitSet == NULL |
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172 // TODO: assert (is_busy()|_recursions) == 0 |
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173 _succ = NULL ; |
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174 _EntryList = NULL ; |
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175 _cxq = NULL ; |
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176 _WaitSet = NULL ; |
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177 _recursions = 0 ; |
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178 _SpinFreq = 0 ; |
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179 _SpinClock = 0 ; |
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180 OwnerIsThread = 0 ; |
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181 } |
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182 |
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183 public: |
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184 |
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185 void* object() const; |
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186 void* object_addr(); |
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187 void set_object(void* obj); |
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188 |
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189 bool check(TRAPS); // true if the thread owns the monitor. |
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190 void check_slow(TRAPS); |
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191 void clear(); |
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192 #ifndef PRODUCT |
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193 void verify(); |
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194 void print(); |
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195 #endif |
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196 |
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197 bool try_enter (TRAPS) ; |
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198 void enter(TRAPS); |
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199 void exit(bool not_suspended, TRAPS); |
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200 void wait(jlong millis, bool interruptable, TRAPS); |
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201 void notify(TRAPS); |
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202 void notifyAll(TRAPS); |
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203 |
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204 // Use the following at your own risk |
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205 intptr_t complete_exit(TRAPS); |
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206 void reenter(intptr_t recursions, TRAPS); |
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207 |
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208 private: |
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209 void AddWaiter (ObjectWaiter * waiter) ; |
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210 static void DeferredInitialize(); |
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211 |
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212 ObjectWaiter * DequeueWaiter () ; |
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213 void DequeueSpecificWaiter (ObjectWaiter * waiter) ; |
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214 void EnterI (TRAPS) ; |
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215 void ReenterI (Thread * Self, ObjectWaiter * SelfNode) ; |
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216 void UnlinkAfterAcquire (Thread * Self, ObjectWaiter * SelfNode) ; |
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217 int TryLock (Thread * Self) ; |
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218 int NotRunnable (Thread * Self, Thread * Owner) ; |
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219 int TrySpin_Fixed (Thread * Self) ; |
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220 int TrySpin_VaryFrequency (Thread * Self) ; |
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221 int TrySpin_VaryDuration (Thread * Self) ; |
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222 void ctAsserts () ; |
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223 void ExitEpilog (Thread * Self, ObjectWaiter * Wakee) ; |
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224 bool ExitSuspendEquivalent (JavaThread * Self) ; |
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225 void post_monitor_wait_event(EventJavaMonitorWait * event, |
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226 jlong notifier_tid, |
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227 jlong timeout, |
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228 bool timedout); |
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229 |
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230 private: |
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231 friend class ObjectSynchronizer; |
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232 friend class ObjectWaiter; |
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233 friend class VMStructs; |
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234 |
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235 // WARNING: this must be the very first word of ObjectMonitor |
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236 // This means this class can't use any virtual member functions. |
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237 // TODO-FIXME: assert that offsetof(_header) is 0 or get rid of the |
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238 // implicit 0 offset in emitted code. |
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239 |
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240 volatile markOop _header; // displaced object header word - mark |
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241 void* volatile _object; // backward object pointer - strong root |
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242 |
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243 double SharingPad [1] ; // temp to reduce false sharing |
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244 |
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245 // All the following fields must be machine word aligned |
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246 // The VM assumes write ordering wrt these fields, which can be |
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247 // read from other threads. |
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248 |
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249 protected: // protected for jvmtiRawMonitor |
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250 void * volatile _owner; // pointer to owning thread OR BasicLock |
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251 volatile jlong _previous_owner_tid; // thread id of the previous owner of the monitor |
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252 volatile intptr_t _recursions; // recursion count, 0 for first entry |
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253 private: |
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254 int OwnerIsThread ; // _owner is (Thread *) vs SP/BasicLock |
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255 ObjectWaiter * volatile _cxq ; // LL of recently-arrived threads blocked on entry. |
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256 // The list is actually composed of WaitNodes, acting |
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257 // as proxies for Threads. |
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258 protected: |
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259 ObjectWaiter * volatile _EntryList ; // Threads blocked on entry or reentry. |
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260 private: |
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261 Thread * volatile _succ ; // Heir presumptive thread - used for futile wakeup throttling |
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262 Thread * volatile _Responsible ; |
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263 int _PromptDrain ; // rqst to drain cxq into EntryList ASAP |
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264 |
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265 volatile int _Spinner ; // for exit->spinner handoff optimization |
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266 volatile int _SpinFreq ; // Spin 1-out-of-N attempts: success rate |
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267 volatile int _SpinClock ; |
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268 volatile int _SpinDuration ; |
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269 volatile intptr_t _SpinState ; // MCS/CLH list of spinners |
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270 |
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271 // TODO-FIXME: _count, _waiters and _recursions should be of |
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272 // type int, or int32_t but not intptr_t. There's no reason |
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273 // to use 64-bit fields for these variables on a 64-bit JVM. |
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274 |
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275 volatile intptr_t _count; // reference count to prevent reclaimation/deflation |
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276 // at stop-the-world time. See deflate_idle_monitors(). |
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277 // _count is approximately |_WaitSet| + |_EntryList| |
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278 protected: |
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279 volatile intptr_t _waiters; // number of waiting threads |
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280 private: |
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281 protected: |
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282 ObjectWaiter * volatile _WaitSet; // LL of threads wait()ing on the monitor |
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283 private: |
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284 volatile int _WaitSetLock; // protects Wait Queue - simple spinlock |
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285 |
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286 public: |
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287 int _QMix ; // Mixed prepend queue discipline |
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288 ObjectMonitor * FreeNext ; // Free list linkage |
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289 intptr_t StatA, StatsB ; |
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290 |
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291 public: |
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292 static void Initialize () ; |
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293 static PerfCounter * _sync_ContendedLockAttempts ; |
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294 static PerfCounter * _sync_FutileWakeups ; |
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295 static PerfCounter * _sync_Parks ; |
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296 static PerfCounter * _sync_EmptyNotifications ; |
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297 static PerfCounter * _sync_Notifications ; |
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298 static PerfCounter * _sync_SlowEnter ; |
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299 static PerfCounter * _sync_SlowExit ; |
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300 static PerfCounter * _sync_SlowNotify ; |
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301 static PerfCounter * _sync_SlowNotifyAll ; |
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302 static PerfCounter * _sync_FailedSpins ; |
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303 static PerfCounter * _sync_SuccessfulSpins ; |
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304 static PerfCounter * _sync_PrivateA ; |
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305 static PerfCounter * _sync_PrivateB ; |
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306 static PerfCounter * _sync_MonInCirculation ; |
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307 static PerfCounter * _sync_MonScavenged ; |
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308 static PerfCounter * _sync_Inflations ; |
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309 static PerfCounter * _sync_Deflations ; |
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310 static PerfLongVariable * _sync_MonExtant ; |
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311 |
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312 public: |
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313 static int Knob_Verbose; |
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314 static int Knob_SpinLimit; |
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315 void* operator new (size_t size) throw() { |
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316 return AllocateHeap(size, mtInternal); |
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317 } |
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318 void* operator new[] (size_t size) throw() { |
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319 return operator new (size); |
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320 } |
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321 void operator delete(void* p) { |
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322 FreeHeap(p, mtInternal); |
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323 } |
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324 void operator delete[] (void *p) { |
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325 operator delete(p); |
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326 } |
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327 }; |
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328 |
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329 #undef TEVENT |
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330 #define TEVENT(nom) {if (SyncVerbose) FEVENT(nom); } |
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331 |
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332 #define FEVENT(nom) { static volatile int ctr = 0 ; int v = ++ctr ; if ((v & (v-1)) == 0) { ::printf (#nom " : %d \n", v); ::fflush(stdout); }} |
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333 |
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334 #undef TEVENT |
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335 #define TEVENT(nom) {;} |
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336 |
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337 |
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338 #endif // SHARE_VM_RUNTIME_OBJECTMONITOR_HPP |