1 | /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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2 | /* ***** BEGIN LICENSE BLOCK *****
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3 | * Version: MPL 1.1/GPL 2.0/LGPL 2.1
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4 | *
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5 | * The contents of this file are subject to the Mozilla Public License Version
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6 | * 1.1 (the "License"); you may not use this file except in compliance with
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7 | * the License. You may obtain a copy of the License at
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8 | * http://www.mozilla.org/MPL/
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9 | *
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10 | * Software distributed under the License is distributed on an "AS IS" basis,
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11 | * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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12 | * for the specific language governing rights and limitations under the
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13 | * License.
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14 | *
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15 | * The Original Code is mozilla.org code.
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16 | *
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17 | * The Initial Developer of the Original Code is
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18 | * Netscape Communications Corporation.
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19 | * Portions created by the Initial Developer are Copyright (C) 1998
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20 | * the Initial Developer. All Rights Reserved.
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21 | *
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22 | * Contributor(s):
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23 | *
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24 | * Alternatively, the contents of this file may be used under the terms of
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25 | * either of the GNU General Public License Version 2 or later (the "GPL"),
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26 | * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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27 | * in which case the provisions of the GPL or the LGPL are applicable instead
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28 | * of those above. If you wish to allow use of your version of this file only
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29 | * under the terms of either the GPL or the LGPL, and not to allow others to
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30 | * use your version of this file under the terms of the MPL, indicate your
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31 | * decision by deleting the provisions above and replace them with the notice
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32 | * and other provisions required by the GPL or the LGPL. If you do not delete
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33 | * the provisions above, a recipient may use your version of this file under
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34 | * the terms of any one of the MPL, the GPL or the LGPL.
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35 | *
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36 | * ***** END LICENSE BLOCK ***** */
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37 |
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38 | #include "nsAutoLock.h"
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39 |
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40 | #ifdef DEBUG
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41 |
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42 | #include "plhash.h"
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43 | #include "prprf.h"
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44 | #include "prlock.h"
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45 | #include "prthread.h"
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46 | #include "nsDebug.h"
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47 | #include "nsVoidArray.h"
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48 |
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49 | #ifdef NS_TRACE_MALLOC_XXX
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50 | # include <stdio.h>
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51 | # include "nsTraceMalloc.h"
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52 | #endif
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53 |
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54 | static PRUintn LockStackTPI = (PRUintn)-1;
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55 | static PLHashTable* OrderTable = 0;
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56 | static PRLock* OrderTableLock = 0;
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57 |
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58 | static const char* const LockTypeNames[] = {"Lock", "Monitor", "CMonitor"};
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59 |
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60 | struct nsNamedVector : public nsVoidArray {
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61 | const char* mName;
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62 |
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63 | #ifdef NS_TRACE_MALLOC_XXX
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64 | // Callsites for the inner locks/monitors stored in our base nsVoidArray.
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65 | // This array parallels our base nsVoidArray.
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66 | nsVoidArray mInnerSites;
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67 | #endif
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68 |
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69 | nsNamedVector(const char* name = 0, PRUint32 initialSize = 0)
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70 | : nsVoidArray(initialSize),
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71 | mName(name)
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72 | {
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73 | }
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74 | };
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75 |
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76 | static void * PR_CALLBACK
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77 | _hash_alloc_table(void *pool, PRSize size)
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78 | {
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79 | return operator new(size);
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80 | }
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81 |
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82 | static void PR_CALLBACK
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83 | _hash_free_table(void *pool, void *item)
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84 | {
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85 | operator delete(item);
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86 | }
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87 |
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88 | static PLHashEntry * PR_CALLBACK
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89 | _hash_alloc_entry(void *pool, const void *key)
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90 | {
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91 | return new PLHashEntry;
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92 | }
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93 |
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94 | /*
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95 | * Because monitors and locks may be associated with an nsAutoLockBase,
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96 | * without having had their associated nsNamedVector created explicitly in
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97 | * nsAutoMonitor::NewMonitor/DeleteMonitor, we need to provide a freeEntry
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98 | * PLHashTable hook, to avoid leaking nsNamedVectors which are replaced by
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99 | * nsAutoMonitor::NewMonitor.
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100 | *
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101 | * There is still a problem with the OrderTable containing orphaned
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102 | * nsNamedVector entries, for manually created locks wrapped by nsAutoLocks.
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103 | * (there should be no manually created monitors wrapped by nsAutoMonitors:
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104 | * you should use nsAutoMonitor::NewMonitor and nsAutoMonitor::DestroyMonitor
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105 | * instead of PR_NewMonitor and PR_DestroyMonitor). These lock vectors don't
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106 | * strictly leak, as they are killed on shutdown, but there are unnecessary
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107 | * named vectors in the hash table that outlive their associated locks.
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108 | *
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109 | * XXX so we should have nsLock, nsMonitor, etc. and strongly type their
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110 | * XXX nsAutoXXX counterparts to take only the non-auto types as inputs
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111 | */
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112 | static void PR_CALLBACK
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113 | _hash_free_entry(void *pool, PLHashEntry *entry, PRUintn flag)
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114 | {
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115 | nsNamedVector* vec = (nsNamedVector*) entry->value;
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116 | if (vec) {
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117 | entry->value = 0;
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118 | delete vec;
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119 | }
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120 | if (flag == HT_FREE_ENTRY)
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121 | delete entry;
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122 | }
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123 |
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124 | static const PLHashAllocOps _hash_alloc_ops = {
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125 | _hash_alloc_table, _hash_free_table,
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126 | _hash_alloc_entry, _hash_free_entry
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127 | };
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128 |
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129 | PR_STATIC_CALLBACK(PRIntn)
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130 | _purge_one(PLHashEntry* he, PRIntn cnt, void* arg)
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131 | {
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132 | nsNamedVector* vec = (nsNamedVector*) he->value;
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133 |
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134 | if (he->key == arg)
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135 | return HT_ENUMERATE_REMOVE;
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136 | vec->RemoveElement(arg);
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137 | return HT_ENUMERATE_NEXT;
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138 | }
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139 |
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140 | PR_STATIC_CALLBACK(void)
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141 | OnMonitorRecycle(void* addr)
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142 | {
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143 | PR_Lock(OrderTableLock);
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144 | PL_HashTableEnumerateEntries(OrderTable, _purge_one, addr);
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145 | PR_Unlock(OrderTableLock);
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146 | }
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147 |
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148 | PR_STATIC_CALLBACK(PLHashNumber)
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149 | _hash_pointer(const void* key)
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150 | {
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151 | return PLHashNumber(NS_PTR_TO_INT32(key)) >> 2;
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152 | }
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153 |
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154 | // Must be single-threaded here, early in primordial thread.
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155 | static void InitAutoLockStatics()
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156 | {
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157 | (void) PR_NewThreadPrivateIndex(&LockStackTPI, 0);
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158 | OrderTable = PL_NewHashTable(64, _hash_pointer,
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159 | PL_CompareValues, PL_CompareValues,
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160 | &_hash_alloc_ops, 0);
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161 | if (OrderTable && !(OrderTableLock = PR_NewLock())) {
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162 | PL_HashTableDestroy(OrderTable);
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163 | OrderTable = 0;
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164 | }
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165 | PR_CSetOnMonitorRecycle(OnMonitorRecycle);
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166 | }
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167 |
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168 | void _FreeAutoLockStatics()
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169 | {
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170 | PLHashTable* table = OrderTable;
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171 | if (!table) return;
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172 |
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173 | // Called at shutdown, so we don't need to lock.
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174 | PR_CSetOnMonitorRecycle(0);
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175 | PR_DestroyLock(OrderTableLock);
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176 | OrderTableLock = 0;
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177 | PL_HashTableDestroy(table);
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178 | OrderTable = 0;
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179 | }
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180 |
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181 | static nsNamedVector* GetVector(PLHashTable* table, const void* key)
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182 | {
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183 | PLHashNumber hash = _hash_pointer(key);
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184 | PLHashEntry** hep = PL_HashTableRawLookup(table, hash, key);
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185 | PLHashEntry* he = *hep;
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186 | if (he)
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187 | return (nsNamedVector*) he->value;
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188 | nsNamedVector* vec = new nsNamedVector();
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189 | if (vec)
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190 | PL_HashTableRawAdd(table, hep, hash, key, vec);
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191 | return vec;
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192 | }
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193 |
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194 | // We maintain an acyclic graph in OrderTable, so recursion can't diverge.
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195 | static PRBool Reachable(PLHashTable* table, const void* goal, const void* start)
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196 | {
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197 | PR_ASSERT(goal);
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198 | PR_ASSERT(start);
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199 | nsNamedVector* vec = GetVector(table, start);
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200 | for (PRUint32 i = 0, n = vec->Count(); i < n; i++) {
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201 | void* addr = vec->ElementAt(i);
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202 | if (addr == goal || Reachable(table, goal, addr))
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203 | return PR_TRUE;
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204 | }
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205 | return PR_FALSE;
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206 | }
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207 |
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208 | static PRBool WellOrdered(const void* addr1, const void* addr2,
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209 | const void *callsite2, PRUint32* index2p,
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210 | nsNamedVector** vec1p, nsNamedVector** vec2p)
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211 | {
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212 | PRBool rv = PR_TRUE;
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213 | PLHashTable* table = OrderTable;
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214 | if (!table) return rv;
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215 | PR_Lock(OrderTableLock);
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216 |
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217 | // Check whether we've already asserted (addr1 < addr2).
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218 | nsNamedVector* vec1 = GetVector(table, addr1);
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219 | if (vec1) {
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220 | PRUint32 i, n;
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221 |
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222 | for (i = 0, n = vec1->Count(); i < n; i++)
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223 | if (vec1->ElementAt(i) == addr2)
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224 | break;
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225 |
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226 | if (i == n) {
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227 | // Now check for (addr2 < addr1) and return false if so.
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228 | nsNamedVector* vec2 = GetVector(table, addr2);
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229 | if (vec2) {
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230 | for (i = 0, n = vec2->Count(); i < n; i++) {
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231 | void* addri = vec2->ElementAt(i);
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232 | PR_ASSERT(addri);
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233 | if (addri == addr1 || Reachable(table, addr1, addri)) {
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234 | *index2p = i;
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235 | *vec1p = vec1;
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236 | *vec2p = vec2;
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237 | rv = PR_FALSE;
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238 | break;
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239 | }
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240 | }
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241 |
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242 | if (rv) {
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243 | // Assert (addr1 < addr2) into the order table.
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244 | // XXX fix plvector/nsVector to use const void*
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245 | vec1->AppendElement((void*) addr2);
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246 | #ifdef NS_TRACE_MALLOC_XXX
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247 | vec1->mInnerSites.AppendElement((void*) callsite2);
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248 | #endif
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249 | }
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250 | }
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251 | }
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252 | }
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253 |
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254 | PR_Unlock(OrderTableLock);
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255 | return rv;
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256 | }
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257 |
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258 | nsAutoLockBase::nsAutoLockBase(void* addr, nsAutoLockType type)
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259 | {
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260 | if (LockStackTPI == PRUintn(-1))
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261 | InitAutoLockStatics();
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262 |
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263 | nsAutoLockBase* stackTop =
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264 | (nsAutoLockBase*) PR_GetThreadPrivate(LockStackTPI);
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265 | if (stackTop) {
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266 | if (stackTop->mAddr == addr) {
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267 | // Ignore reentry: it's legal for monitors, and NSPR will assert
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268 | // if you reenter a PRLock.
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269 | } else if (!addr) {
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270 | // Ignore null addresses: the caller promises not to use the
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271 | // lock at all, and NSPR will assert if you enter it.
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272 | } else {
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273 | const void* node =
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274 | #ifdef NS_TRACE_MALLOC_XXX
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275 | NS_GetStackTrace(1)
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276 | #else
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277 | nsnull
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278 | #endif
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279 | ;
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280 | nsNamedVector* vec1;
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281 | nsNamedVector* vec2;
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282 | PRUint32 i2;
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283 |
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284 | if (!WellOrdered(stackTop->mAddr, addr, node, &i2, &vec1, &vec2)) {
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285 | char buf[128];
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286 | PR_snprintf(buf, sizeof buf,
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287 | "Potential deadlock between %s%s@%p and %s%s@%p",
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288 | vec1->mName ? vec1->mName : "",
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289 | LockTypeNames[stackTop->mType],
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290 | stackTop->mAddr,
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291 | vec2->mName ? vec2->mName : "",
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292 | LockTypeNames[type],
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293 | addr);
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294 | #ifdef NS_TRACE_MALLOC_XXX
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295 | fprintf(stderr, "\n*** %s\n\nCurrent stack:\n", buf);
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296 | NS_DumpStackTrace(node, stderr);
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297 |
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298 | fputs("\nPrevious stack:\n", stderr);
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299 | NS_DumpStackTrace(vec2->mInnerSites.ElementAt(i2), stderr);
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300 | putc('\n', stderr);
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301 | #endif
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302 | NS_ERROR(buf);
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303 | }
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304 | }
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305 | }
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306 |
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307 | mAddr = addr;
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308 | mDown = stackTop;
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309 | mType = type;
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310 | if (mAddr)
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311 | (void) PR_SetThreadPrivate(LockStackTPI, this);
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312 | }
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313 |
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314 | nsAutoLockBase::~nsAutoLockBase()
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315 | {
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316 | if (mAddr)
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317 | (void) PR_SetThreadPrivate(LockStackTPI, mDown);
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318 | }
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319 |
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320 | void nsAutoLockBase::Show()
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321 | {
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322 | if (!mAddr)
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323 | return;
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324 | nsAutoLockBase* curr = (nsAutoLockBase*) PR_GetThreadPrivate(LockStackTPI);
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325 | nsAutoLockBase* prev = nsnull;
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326 | while (curr != mDown) {
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327 | prev = curr;
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328 | curr = prev->mDown;
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329 | }
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330 | if (!prev)
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331 | PR_SetThreadPrivate(LockStackTPI, this);
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332 | else
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333 | prev->mDown = this;
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334 | }
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335 |
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336 | void nsAutoLockBase::Hide()
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337 | {
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338 | if (!mAddr)
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339 | return;
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340 | nsAutoLockBase* curr = (nsAutoLockBase*) PR_GetThreadPrivate(LockStackTPI);
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341 | nsAutoLockBase* prev = nsnull;
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342 | while (curr != this) {
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343 | prev = curr;
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344 | curr = prev->mDown;
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345 | }
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346 | if (!prev)
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347 | PR_SetThreadPrivate(LockStackTPI, mDown);
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348 | else
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349 | prev->mDown = mDown;
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350 | }
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351 |
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352 | #endif /* DEBUG */
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353 |
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354 | PRMonitor* nsAutoMonitor::NewMonitor(const char* name)
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355 | {
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356 | PRMonitor* mon = PR_NewMonitor();
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357 | #ifdef DEBUG
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358 | if (mon && OrderTable) {
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359 | nsNamedVector* value = new nsNamedVector(name);
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360 | if (value) {
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361 | PR_Lock(OrderTableLock);
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362 | PL_HashTableAdd(OrderTable, mon, value);
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363 | PR_Unlock(OrderTableLock);
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364 | }
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365 | }
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366 | #endif
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367 | return mon;
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368 | }
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369 |
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370 | void nsAutoMonitor::DestroyMonitor(PRMonitor* mon)
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371 | {
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372 | #ifdef DEBUG
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373 | if (OrderTable)
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374 | OnMonitorRecycle(mon);
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375 | #endif
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376 | PR_DestroyMonitor(mon);
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377 | }
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378 |
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379 | void nsAutoMonitor::Enter()
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380 | {
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381 | #ifdef DEBUG
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382 | if (!mAddr) {
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383 | NS_ERROR("It is not legal to enter a null monitor");
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384 | return;
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385 | }
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386 | nsAutoLockBase* stackTop =
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387 | (nsAutoLockBase*) PR_GetThreadPrivate(LockStackTPI);
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388 | NS_ASSERTION(stackTop == mDown, "non-LIFO nsAutoMonitor::Enter");
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389 | mDown = stackTop;
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390 | (void) PR_SetThreadPrivate(LockStackTPI, this);
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391 | #endif
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392 | PR_EnterMonitor(mMonitor);
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393 | mLockCount += 1;
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394 | }
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395 |
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396 | void nsAutoMonitor::Exit()
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397 | {
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398 | #ifdef DEBUG
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399 | if (!mAddr) {
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400 | NS_ERROR("It is not legal to exit a null monitor");
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401 | return;
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402 | }
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403 | (void) PR_SetThreadPrivate(LockStackTPI, mDown);
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404 | #endif
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405 | PRStatus status = PR_ExitMonitor(mMonitor);
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406 | NS_ASSERTION(status == PR_SUCCESS, "PR_ExitMonitor failed");
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407 | mLockCount -= 1;
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408 | }
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409 |
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410 | // XXX we don't worry about cached monitors being destroyed behind our back.
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411 | // XXX current NSPR (mozilla/nsprpub/pr/src/threads/prcmon.c) never destroys
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412 | // XXX a cached monitor! potential resource pig in conjunction with necko...
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413 |
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414 | void nsAutoCMonitor::Enter()
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415 | {
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416 | #ifdef DEBUG
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417 | nsAutoLockBase* stackTop =
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418 | (nsAutoLockBase*) PR_GetThreadPrivate(LockStackTPI);
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419 | NS_ASSERTION(stackTop == mDown, "non-LIFO nsAutoCMonitor::Enter");
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420 | mDown = stackTop;
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421 | (void) PR_SetThreadPrivate(LockStackTPI, this);
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422 | #endif
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423 | PR_CEnterMonitor(mLockObject);
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424 | mLockCount += 1;
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425 | }
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426 |
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427 | void nsAutoCMonitor::Exit()
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428 | {
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429 | #ifdef DEBUG
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430 | (void) PR_SetThreadPrivate(LockStackTPI, mDown);
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431 | #endif
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432 | PRStatus status = PR_CExitMonitor(mLockObject);
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433 | NS_ASSERTION(status == PR_SUCCESS, "PR_CExitMonitor failed");
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434 | mLockCount -= 1;
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435 | }
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