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1
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2 /*
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3 * Copyright (C) Igor Sysoev
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4 */
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5
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6
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7 #include <ngx_config.h>
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8 #include <ngx_core.h>
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9 #include <ngx_event.h>
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10
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11
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12 static int ngx_event_busy_lock_look_cachable(ngx_event_busy_lock_t *bl,
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13 ngx_event_busy_lock_ctx_t *ctx);
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14 static void ngx_event_busy_lock_handler(ngx_event_t *ev);
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15 static void ngx_event_busy_lock_posted_handler(ngx_event_t *ev);
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16
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17
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18 /*
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19 * NGX_OK: the busy lock is held
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20 * NGX_AGAIN: the all busy locks are held but we will wait the specified time
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21 * NGX_BUSY: ctx->timer == 0: there are many the busy locks
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22 * ctx->timer != 0: there are many the waiting locks
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23 * NGX_ERROR: an error occured while the mutex locking
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24 */
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25
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26 ngx_int_t ngx_event_busy_lock(ngx_event_busy_lock_t *bl,
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27 ngx_event_busy_lock_ctx_t *ctx)
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28 {
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29 ngx_int_t rc;
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30
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31 if (ngx_mutex_lock(bl->mutex) == NGX_ERROR) {
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32 return NGX_ERROR;
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33 }
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34
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35 ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ctx->event->log, 0,
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36 "event busy lock: b:%d mb:%d",
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37 bl->busy, bl->max_busy);
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38
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39 if (bl->busy < bl->max_busy) {
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40 bl->busy++;
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41 rc = NGX_OK;
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42
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43 } else if (ctx->timer && bl->waiting < bl->max_waiting) {
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44 bl->waiting++;
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45 ngx_add_timer(ctx->event, ctx->timer);
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46 ctx->event->event_handler = ngx_event_busy_lock_handler;
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47
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48 if (bl->events) {
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49 bl->last->next = ctx;
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50
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51 } else {
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52 bl->events = ctx;
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53 }
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54
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55 bl->last = ctx;
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56
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57 rc = NGX_AGAIN;
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58
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59 } else {
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60 rc = NGX_BUSY;
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61 }
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62
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63 ngx_mutex_unlock(bl->mutex);
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64
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65 return rc;
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66 }
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67
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68
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69 ngx_int_t ngx_event_busy_lock_cachable(ngx_event_busy_lock_t *bl,
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70 ngx_event_busy_lock_ctx_t *ctx)
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71 {
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72 ngx_int_t rc;
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73
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74 if (ngx_mutex_lock(bl->mutex) == NGX_ERROR) {
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75 return NGX_ERROR;
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76 }
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77
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78 rc = ngx_event_busy_lock_look_cachable(bl, ctx);
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79
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80 ngx_log_debug3(NGX_LOG_DEBUG_EVENT, ctx->event->log, 0,
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81 "event busy lock: %d w:%d mw:%d",
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82 rc, bl->waiting, bl->max_waiting);
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83
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84 /*
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85 * NGX_OK: no the same request, there is free slot and we locked it
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86 * NGX_BUSY: no the same request and there is no free slot
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87 * NGX_AGAIN: the same request is processing
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88 */
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89
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90 if (rc == NGX_AGAIN) {
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91
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92 if (ctx->timer && bl->waiting < bl->max_waiting) {
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93 bl->waiting++;
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94 ngx_add_timer(ctx->event, ctx->timer);
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95 ctx->event->event_handler = ngx_event_busy_lock_handler;
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96
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97 if (bl->events == NULL) {
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98 bl->events = ctx;
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99 } else {
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100 bl->last->next = ctx;
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101 }
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102 bl->last = ctx;
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103
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104 } else {
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105 rc = NGX_BUSY;
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106 }
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107 }
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108
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109 ngx_mutex_unlock(bl->mutex);
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110
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111 return rc;
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112 }
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113
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114
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115 ngx_int_t ngx_event_busy_unlock(ngx_event_busy_lock_t *bl,
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116 ngx_event_busy_lock_ctx_t *ctx)
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117 {
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118 ngx_event_t *ev;
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119 ngx_event_busy_lock_ctx_t *wakeup;
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120
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121 if (ngx_mutex_lock(bl->mutex) == NGX_ERROR) {
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122 return NGX_ERROR;
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123 }
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124
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125 if (bl->events) {
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126 wakeup = bl->events;
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127 bl->events = bl->events->next;
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128
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129 } else {
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130 wakeup = NULL;
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131 bl->busy--;
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132 }
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133
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134 /*
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135 * MP: all ctx's and their queue must be in shared memory,
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136 * each ctx has pid to wake up
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137 */
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138
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139 if (wakeup == NULL) {
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140 ngx_mutex_unlock(bl->mutex);
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141 return NGX_OK;
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142 }
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143
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144 if (ctx->md5) {
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145 for (wakeup = bl->events; wakeup; wakeup = wakeup->next) {
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146 if (wakeup->md5 == NULL || wakeup->slot != ctx->slot) {
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147 continue;
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148 }
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149
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150 wakeup->handler = ngx_event_busy_lock_posted_handler;
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151 wakeup->cache_updated = 1;
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152
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153 ev = wakeup->event;
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154
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155 if (ngx_mutex_lock(ngx_posted_events_mutex) == NGX_ERROR) {
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156 return NGX_ERROR;
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157 }
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158
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159 ngx_post_event(ev);
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160
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161 ngx_mutex_unlock(ngx_posted_events_mutex);
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162 }
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163
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164 ngx_mutex_unlock(bl->mutex);
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165
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166 } else {
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167 bl->waiting--;
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168
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169 ngx_mutex_unlock(bl->mutex);
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170
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171 wakeup->handler = ngx_event_busy_lock_posted_handler;
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172 wakeup->locked = 1;
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173
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174 ev = wakeup->event;
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175
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176 if (ev->timer_set) {
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177 ngx_del_timer(ev);
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178 }
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179
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180 if (ngx_mutex_lock(ngx_posted_events_mutex) == NGX_ERROR) {
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181 return NGX_ERROR;
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182 }
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183
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184 ngx_post_event(ev);
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185
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186 ngx_mutex_unlock(ngx_posted_events_mutex);
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187 }
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188
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189 return NGX_OK;
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190 }
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191
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192
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193 ngx_int_t ngx_event_busy_lock_cancel(ngx_event_busy_lock_t *bl,
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194 ngx_event_busy_lock_ctx_t *ctx)
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195 {
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196 ngx_event_busy_lock_ctx_t *c, *p;
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197
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198 if (ngx_mutex_lock(bl->mutex) == NGX_ERROR) {
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199 return NGX_ERROR;
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200 }
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201
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202 bl->waiting--;
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203
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204 if (ctx == bl->events) {
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205 bl->events = ctx->next;
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206
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207 } else {
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208 p = bl->events;
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209 for (c = bl->events->next; c; c = c->next) {
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210 if (c == ctx) {
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211 p->next = ctx->next;
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212 break;
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213 }
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214 p = c;
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215 }
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216 }
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217
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218 ngx_mutex_unlock(bl->mutex);
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219
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220 return NGX_OK;
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221 }
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222
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223
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224 static int ngx_event_busy_lock_look_cachable(ngx_event_busy_lock_t *bl,
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225 ngx_event_busy_lock_ctx_t *ctx)
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226 {
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227 ngx_int_t free;
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228 ngx_uint_t i, bit, cachable, mask;
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229
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230 bit = 0;
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231 cachable = 0;
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232 free = -1;
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233
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234 #if (NGX_SUPPRESS_WARN)
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235 mask = 0;
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236 #endif
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237
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238 for (i = 0; i < bl->max_busy; i++) {
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239
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240 if ((bit & 7) == 0) {
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241 mask = bl->md5_mask[i / 8];
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242 }
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243
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244 if (mask & 1) {
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245 if (ngx_memcmp(&bl->md5[i * 16], ctx->md5, 16) == 0) {
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246 ctx->waiting = 1;
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247 ctx->slot = i;
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248 return NGX_AGAIN;
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249 }
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250 cachable++;
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251
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252 } else if (free == -1) {
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253 free = i;
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254 }
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255
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256 if (cachable == bl->cachable) {
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257 if (free == -1 && cachable < bl->max_busy) {
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258 free = i + 1;
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259 }
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260
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261 break;
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262 }
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263
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264 mask >>= 1;
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265 bit++;
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266 }
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267
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268 if (free == -1) {
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269 return NGX_BUSY;
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270 }
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271
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272 #if 0
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273 if (bl->busy == bl->max_busy) {
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274 return NGX_BUSY;
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275 }
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276 #endif
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277
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278 ngx_memcpy(&bl->md5[free * 16], ctx->md5, 16);
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279 bl->md5_mask[free / 8] |= 1 << (free & 7);
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280 ctx->slot = free;
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281
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282 bl->cachable++;
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283 bl->busy++;
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284
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285 return NGX_OK;
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286 }
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287
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288
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289 static void ngx_event_busy_lock_handler(ngx_event_t *ev)
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290 {
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291 if (ngx_mutex_lock(ngx_posted_events_mutex) == NGX_ERROR) {
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292 return;
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293 }
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294
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295 ngx_post_event(ev);
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296
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297 ngx_mutex_unlock(ngx_posted_events_mutex);
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298
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299 ev->event_handler = ngx_event_busy_lock_posted_handler;
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300 }
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301
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302
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303 static void ngx_event_busy_lock_posted_handler(ngx_event_t *ev)
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304 {
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305 ngx_event_busy_lock_ctx_t *ctx;
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306
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307 ctx = ev->data;
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308 ctx->handler(ev);
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309 }
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