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160
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1
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2 /*
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3 * Copyright (C) Igor Sysoev
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660
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4 * Copyright (C) Nginx, Inc.
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160
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5 */
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6
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7
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8 #include <ngx_config.h>
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9 #include <ngx_core.h>
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10
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11
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12 #if (NGX_HAVE_ATOMIC_OPS)
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13
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14
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650
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15 static void ngx_shmtx_wakeup(ngx_shmtx_t *mtx);
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16
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17
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160
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18 ngx_int_t
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650
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19 ngx_shmtx_create(ngx_shmtx_t *mtx, ngx_shmtx_sh_t *addr, u_char *name)
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160
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20 {
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650
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21 mtx->lock = &addr->lock;
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160
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22
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624
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23 if (mtx->spin == (ngx_uint_t) -1) {
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24 return NGX_OK;
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25 }
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26
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27 mtx->spin = 2048;
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28
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29 #if (NGX_HAVE_POSIX_SEM)
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30
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650
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31 mtx->wait = &addr->wait;
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32
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624
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33 if (sem_init(&mtx->sem, 1, 0) == -1) {
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34 ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno,
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35 "sem_init() failed");
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36 } else {
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37 mtx->semaphore = 1;
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38 }
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39
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40 #endif
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41
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160
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42 return NGX_OK;
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43 }
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44
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624
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45
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46 void
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680
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47 ngx_shmtx_destroy(ngx_shmtx_t *mtx)
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624
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48 {
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49 #if (NGX_HAVE_POSIX_SEM)
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50
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51 if (mtx->semaphore) {
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52 if (sem_destroy(&mtx->sem) == -1) {
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53 ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno,
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54 "sem_destroy() failed");
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55 }
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56 }
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57
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58 #endif
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59 }
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60
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61
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62 ngx_uint_t
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63 ngx_shmtx_trylock(ngx_shmtx_t *mtx)
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64 {
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650
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65 return (*mtx->lock == 0 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid));
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624
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66 }
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67
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68
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69 void
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70 ngx_shmtx_lock(ngx_shmtx_t *mtx)
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71 {
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72 ngx_uint_t i, n;
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73
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74 ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx lock");
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75
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76 for ( ;; ) {
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77
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650
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78 if (*mtx->lock == 0 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid)) {
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624
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79 return;
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80 }
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81
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82 if (ngx_ncpu > 1) {
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83
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84 for (n = 1; n < mtx->spin; n <<= 1) {
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85
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86 for (i = 0; i < n; i++) {
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87 ngx_cpu_pause();
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88 }
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89
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650
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90 if (*mtx->lock == 0
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91 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid))
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624
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92 {
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93 return;
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94 }
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95 }
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96 }
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97
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98 #if (NGX_HAVE_POSIX_SEM)
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99
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100 if (mtx->semaphore) {
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650
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101 (void) ngx_atomic_fetch_add(mtx->wait, 1);
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624
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102
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650
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103 if (*mtx->lock == 0 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid)) {
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104 return;
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105 }
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106
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107 ngx_log_debug1(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
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108 "shmtx wait %uA", *mtx->wait);
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624
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109
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650
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110 while (sem_wait(&mtx->sem) == -1) {
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111 ngx_err_t err;
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624
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112
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650
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113 err = ngx_errno;
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624
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114
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650
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115 if (err != NGX_EINTR) {
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116 ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, err,
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117 "sem_wait() failed while waiting on shmtx");
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118 break;
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624
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119 }
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120
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121 ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
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122 "shmtx awoke");
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123 }
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124
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125 continue;
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126 }
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127
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128 #endif
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129
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130 ngx_sched_yield();
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131 }
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132 }
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133
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134
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135 void
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136 ngx_shmtx_unlock(ngx_shmtx_t *mtx)
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137 {
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138 if (mtx->spin != (ngx_uint_t) -1) {
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139 ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx unlock");
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140 }
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141
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650
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142 if (ngx_atomic_cmp_set(mtx->lock, ngx_pid, 0)) {
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143 ngx_shmtx_wakeup(mtx);
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144 }
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145 }
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146
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147
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148 ngx_uint_t
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149 ngx_shmtx_force_unlock(ngx_shmtx_t *mtx, ngx_pid_t pid)
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150 {
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151 ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
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152 "shmtx forced unlock");
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153
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154 if (ngx_atomic_cmp_set(mtx->lock, pid, 0)) {
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155 ngx_shmtx_wakeup(mtx);
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156 return 1;
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157 }
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158
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159 return 0;
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160 }
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161
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162
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163 static void
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164 ngx_shmtx_wakeup(ngx_shmtx_t *mtx)
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165 {
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166 #if (NGX_HAVE_POSIX_SEM)
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167 ngx_atomic_uint_t wait;
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168
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169 if (!mtx->semaphore) {
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170 return;
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171 }
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172
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624
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173 for ( ;; ) {
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174
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650
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175 wait = *mtx->wait;
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624
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176
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650
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177 if (wait == 0) {
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178 return;
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179 }
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180
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181 if (ngx_atomic_cmp_set(mtx->wait, wait, wait - 1)) {
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624
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182 break;
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183 }
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184 }
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185
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186 ngx_log_debug1(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
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650
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187 "shmtx wake %uA", wait);
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624
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188
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189 if (sem_post(&mtx->sem) == -1) {
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190 ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno,
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191 "sem_post() failed while wake shmtx");
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192 }
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193
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194 #endif
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195 }
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196
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197
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160
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198 #else
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199
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200
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201 ngx_int_t
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650
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202 ngx_shmtx_create(ngx_shmtx_t *mtx, ngx_shmtx_sh_t *addr, u_char *name)
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160
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203 {
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204 if (mtx->name) {
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205
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206 if (ngx_strcmp(name, mtx->name) == 0) {
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207 mtx->name = name;
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208 return NGX_OK;
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209 }
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210
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680
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211 ngx_shmtx_destroy(mtx);
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160
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212 }
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213
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284
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214 mtx->fd = ngx_open_file(name, NGX_FILE_RDWR, NGX_FILE_CREATE_OR_OPEN,
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215 NGX_FILE_DEFAULT_ACCESS);
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160
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216
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217 if (mtx->fd == NGX_INVALID_FILE) {
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258
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218 ngx_log_error(NGX_LOG_EMERG, ngx_cycle->log, ngx_errno,
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160
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219 ngx_open_file_n " \"%s\" failed", name);
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220 return NGX_ERROR;
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221 }
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222
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223 if (ngx_delete_file(name) == NGX_FILE_ERROR) {
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258
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224 ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno,
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160
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225 ngx_delete_file_n " \"%s\" failed", name);
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226 }
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227
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228 mtx->name = name;
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229
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230 return NGX_OK;
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231 }
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232
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233
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234 void
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680
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235 ngx_shmtx_destroy(ngx_shmtx_t *mtx)
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160
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236 {
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237 if (ngx_close_file(mtx->fd) == NGX_FILE_ERROR) {
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258
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238 ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno,
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160
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239 ngx_close_file_n " \"%s\" failed", mtx->name);
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240 }
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241 }
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242
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243
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624
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244 ngx_uint_t
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245 ngx_shmtx_trylock(ngx_shmtx_t *mtx)
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246 {
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247 ngx_err_t err;
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248
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249 err = ngx_trylock_fd(mtx->fd);
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250
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251 if (err == 0) {
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252 return 1;
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253 }
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254
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255 if (err == NGX_EAGAIN) {
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256 return 0;
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257 }
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258
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259 #if __osf__ /* Tru64 UNIX */
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260
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261 if (err == NGX_EACCESS) {
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262 return 0;
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263 }
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264
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160
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265 #endif
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624
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266
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267 ngx_log_abort(err, ngx_trylock_fd_n " %s failed", mtx->name);
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268
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269 return 0;
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270 }
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271
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272
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273 void
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274 ngx_shmtx_lock(ngx_shmtx_t *mtx)
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275 {
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276 ngx_err_t err;
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277
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278 err = ngx_lock_fd(mtx->fd);
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279
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280 if (err == 0) {
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281 return;
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282 }
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283
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284 ngx_log_abort(err, ngx_lock_fd_n " %s failed", mtx->name);
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285 }
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286
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287
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288 void
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289 ngx_shmtx_unlock(ngx_shmtx_t *mtx)
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290 {
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291 ngx_err_t err;
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292
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293 err = ngx_unlock_fd(mtx->fd);
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294
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295 if (err == 0) {
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296 return;
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297 }
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298
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299 ngx_log_abort(err, ngx_unlock_fd_n " %s failed", mtx->name);
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300 }
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301
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650
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302
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303 ngx_uint_t
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304 ngx_shmtx_force_unlock(ngx_shmtx_t *mtx, ngx_pid_t pid)
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305 {
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306 return 0;
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307 }
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308
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624
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309 #endif
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