1 | // -*- Mode: CFA -*- |
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2 | // |
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3 | // Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo |
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4 | // |
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5 | // The contents of this file are covered under the licence agreement in the |
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6 | // file "LICENCE" distributed with Cforall. |
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7 | // |
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8 | // monitor_desc.c -- |
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9 | // |
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10 | // Author : Thierry Delisle |
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11 | // Created On : Thd Feb 23 12:27:26 2017 |
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12 | // Last Modified By : Thierry Delisle |
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13 | // Last Modified On : -- |
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14 | // Update Count : 0 |
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15 | // |
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16 | |
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17 | #include "monitor" |
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18 | |
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19 | #include "kernel_private.h" |
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20 | #include "libhdr.h" |
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21 | |
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22 | void set_owner( monitor_desc * this, thread_desc * owner ) { |
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23 | //Pass the monitor appropriately |
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24 | this->owner = owner; |
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25 | |
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26 | //We are passing the monitor to someone else, which means recursion level is not 0 |
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27 | this->recursion = owner ? 1 : 0; |
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28 | } |
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29 | |
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30 | extern "C" { |
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31 | void __enter_monitor_desc(monitor_desc * this, monitor_desc * leader) { |
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32 | lock( &this->lock ); |
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33 | thread_desc * thrd = this_thread(); |
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34 | |
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35 | //Update the stack owner |
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36 | this->stack_owner = leader; |
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37 | |
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38 | if( !this->owner ) { |
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39 | //No one has the monitor, just take it |
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40 | this->owner = thrd; |
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41 | this->recursion = 1; |
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42 | } |
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43 | else if( this->owner == thrd) { |
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44 | //We already have the monitor, just not how many times we took it |
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45 | assert( this->recursion > 0 ); |
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46 | this->recursion += 1; |
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47 | } |
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48 | else { |
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49 | //Some one else has the monitor, wait in line for it |
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50 | append( &this->entry_queue, thrd ); |
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51 | ScheduleInternal( &this->lock ); |
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52 | |
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53 | //ScheduleInternal will unlock spinlock, no need to unlock ourselves |
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54 | return; |
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55 | } |
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56 | |
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57 | unlock( &this->lock ); |
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58 | return; |
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59 | } |
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60 | |
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61 | // leave pseudo code : |
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62 | // decrement level |
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63 | // leve == 0 ? |
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64 | // no : done |
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65 | // yes : |
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66 | // signal stack empty ? |
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67 | // has leader : |
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68 | // bulk acquiring means we don't own the signal stack |
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69 | // ignore it but don't release the monitor |
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70 | // yes : |
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71 | // next in entry queue is new owner |
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72 | // no : |
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73 | // top of the signal stack is the owner |
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74 | // context switch to him right away |
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75 | // |
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76 | void __leave_monitor_desc(monitor_desc * this, monitor_desc * leader) { |
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77 | lock( &this->lock ); |
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78 | |
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79 | thread_desc * thrd = this_thread(); |
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80 | assert( thrd == this->owner || this->stack_owner ); |
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81 | |
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82 | //Leaving a recursion level, decrement the counter |
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83 | this->recursion -= 1; |
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84 | |
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85 | //If we haven't left the last level of recursion |
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86 | //it means we don't need to do anything |
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87 | if( this->recursion != 0) { |
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88 | this->stack_owner = leader; |
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89 | unlock( &this->lock ); |
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90 | return; |
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91 | } |
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92 | |
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93 | //If we don't own the signal stack then just leave it to the owner |
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94 | if( this->stack_owner ) { |
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95 | this->stack_owner = leader; |
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96 | unlock( &this->lock ); |
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97 | return; |
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98 | } |
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99 | |
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100 | //We are the stack owner and have left the last recursion level. |
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101 | //We are in charge of passing the monitor |
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102 | thread_desc * new_owner = 0; |
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103 | |
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104 | //Check the signaller stack |
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105 | new_owner = pop( &this->signal_stack ); |
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106 | if( new_owner ) { |
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107 | //The signaller stack is not empty, |
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108 | //transfer control immediately |
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109 | set_owner( this, new_owner ); |
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110 | this->stack_owner = leader; |
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111 | ScheduleInternal( &this->lock, new_owner ); |
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112 | return; |
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113 | } |
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114 | |
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115 | // No signaller thread |
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116 | // Get the next thread in the entry_queue |
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117 | new_owner = pop_head( &this->entry_queue ); |
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118 | set_owner( this, new_owner ); |
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119 | |
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120 | //Update the stack owner |
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121 | this->stack_owner = leader; |
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122 | |
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123 | //We can now let other threads in safely |
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124 | unlock( &this->lock ); |
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125 | |
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126 | //We need to wake-up the thread |
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127 | ScheduleThread( new_owner ); |
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128 | } |
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129 | } |
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130 | |
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131 | static inline void enter(monitor_desc ** monitors, int count) { |
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132 | __enter_monitor_desc( monitors[0], NULL ); |
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133 | for(int i = 1; i < count; i++) { |
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134 | __enter_monitor_desc( monitors[i], monitors[0] ); |
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135 | } |
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136 | } |
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137 | |
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138 | static inline void leave(monitor_desc ** monitors, int count) { |
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139 | __leave_monitor_desc( monitors[0], NULL ); |
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140 | for(int i = count - 1; i >= 0; i--) { |
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141 | __leave_monitor_desc( monitors[i], monitors[0] ); |
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142 | } |
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143 | } |
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144 | |
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145 | void ?{}( monitor_guard_t * this, monitor_desc ** m, int count ) { |
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146 | this->m = m; |
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147 | this->count = count; |
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148 | qsort(this->m, count); |
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149 | enter( this->m, this->count ); |
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150 | |
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151 | this->prev_mntrs = this_thread()->current_monitors; |
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152 | this->prev_count = this_thread()->current_monitor_count; |
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153 | |
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154 | this_thread()->current_monitors = m; |
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155 | this_thread()->current_monitor_count = count; |
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156 | } |
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157 | |
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158 | void ^?{}( monitor_guard_t * this ) { |
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159 | leave( this->m, this->count ); |
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160 | |
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161 | this_thread()->current_monitors = this->prev_mntrs; |
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162 | this_thread()->current_monitor_count = this->prev_count; |
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163 | } |
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164 | |
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165 | //----------------------------------------------------------------------------- |
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166 | // Internal scheduling |
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167 | void wait( condition * this ) { |
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168 | // LIB_DEBUG_FPRINTF("Waiting\n"); |
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169 | thread_desc * this_thrd = this_thread(); |
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170 | |
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171 | if( !this->monitors ) { |
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172 | this->monitors = this_thrd->current_monitors; |
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173 | this->monitor_count = this_thrd->current_monitor_count; |
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174 | } |
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175 | |
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176 | unsigned short count = this->monitor_count; |
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177 | |
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178 | //Check that everything is as expected |
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179 | assert( this->monitors != NULL ); |
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180 | assert( this->monitor_count != 0 ); |
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181 | |
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182 | unsigned int recursions[ count ]; //Save the current recursion levels to restore them later |
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183 | spinlock * locks [ count ]; //We need to pass-in an array of locks to ScheduleInternal |
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184 | |
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185 | // LIB_DEBUG_FPRINTF("Getting ready to wait\n"); |
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186 | |
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187 | //Loop on all the monitors and release the owner |
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188 | for( unsigned int i = 0; i < count; i++ ) { |
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189 | monitor_desc * cur = this->monitors[i]; |
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190 | |
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191 | assert( cur ); |
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192 | |
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193 | // LIB_DEBUG_FPRINTF("cur %p lock %p\n", cur, &cur->lock); |
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194 | |
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195 | //Store the locks for later |
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196 | locks[i] = &cur->lock; |
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197 | |
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198 | //Protect the monitors |
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199 | lock( locks[i] ); |
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200 | { |
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201 | //Save the recursion levels |
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202 | recursions[i] = cur->recursion; |
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203 | |
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204 | //Release the owner |
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205 | cur->recursion = 0; |
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206 | cur->owner = NULL; |
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207 | } |
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208 | //Release the monitor |
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209 | unlock( locks[i] ); |
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210 | } |
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211 | |
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212 | // LIB_DEBUG_FPRINTF("Waiting now\n"); |
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213 | |
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214 | //Everything is ready to go to sleep |
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215 | ScheduleInternal( locks, count ); |
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216 | |
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217 | |
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218 | //WE WOKE UP |
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219 | |
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220 | |
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221 | //We are back, restore the owners and recursions |
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222 | for( unsigned int i = 0; i < count; i++ ) { |
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223 | monitor_desc * cur = this->monitors[i]; |
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224 | |
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225 | //Protect the monitors |
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226 | lock( locks[i] ); |
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227 | { |
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228 | //Release the owner |
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229 | cur->owner = this_thrd; |
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230 | cur->recursion = recursions[i]; |
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231 | } |
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232 | //Release the monitor |
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233 | unlock( locks[i] ); |
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234 | } |
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235 | } |
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236 | |
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237 | static void __signal_internal( condition * this ) { |
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238 | if( !this->blocked.head ) return; |
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239 | |
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240 | //Check that everything is as expected |
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241 | assert( this->monitors ); |
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242 | assert( this->monitor_count != 0 ); |
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243 | |
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244 | LIB_DEBUG_DO( |
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245 | if ( this->monitors != this_thread()->current_monitors ) { |
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246 | abortf( "Signal on condition %p made outside of the correct monitor(s)", this ); |
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247 | } // if |
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248 | ); |
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249 | |
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250 | monitor_desc * owner = this->monitors[0]; |
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251 | lock( &owner->lock ); |
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252 | { |
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253 | thread_desc * unblock = pop_head( &this->blocked ); |
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254 | push( &owner->signal_stack, unblock ); |
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255 | } |
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256 | unlock( &owner->lock ); |
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257 | } |
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258 | |
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259 | void signal( condition * this ) { |
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260 | __signal_internal( this ); |
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261 | } |
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