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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_http.h>
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10
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11
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12 typedef struct {
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13 size_t sbrk_size;
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14 } ngx_http_degradation_main_conf_t;
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15
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16
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17 typedef struct {
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18 ngx_uint_t degrade;
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19 } ngx_http_degradation_loc_conf_t;
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20
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21
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22 static ngx_conf_enum_t ngx_http_degrade[] = {
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23 { ngx_string("204"), 204 },
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24 { ngx_string("444"), 444 },
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25 { ngx_null_string, 0 }
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26 };
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27
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28
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29 static void *ngx_http_degradation_create_main_conf(ngx_conf_t *cf);
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30 static void *ngx_http_degradation_create_loc_conf(ngx_conf_t *cf);
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31 static char *ngx_http_degradation_merge_loc_conf(ngx_conf_t *cf, void *parent,
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32 void *child);
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33 static char *ngx_http_degradation(ngx_conf_t *cf, ngx_command_t *cmd,
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34 void *conf);
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35 static ngx_int_t ngx_http_degradation_init(ngx_conf_t *cf);
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36
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37
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38 static ngx_command_t ngx_http_degradation_commands[] = {
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39
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40 { ngx_string("degradation"),
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41 NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE1,
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42 ngx_http_degradation,
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43 NGX_HTTP_MAIN_CONF_OFFSET,
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44 0,
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45 NULL },
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46
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47 { ngx_string("degrade"),
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48 NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
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49 ngx_conf_set_enum_slot,
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50 NGX_HTTP_LOC_CONF_OFFSET,
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51 offsetof(ngx_http_degradation_loc_conf_t, degrade),
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52 &ngx_http_degrade },
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53
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54 ngx_null_command
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55 };
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56
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57
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58 static ngx_http_module_t ngx_http_degradation_module_ctx = {
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59 NULL, /* preconfiguration */
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60 ngx_http_degradation_init, /* postconfiguration */
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61
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62 ngx_http_degradation_create_main_conf, /* create main configuration */
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63 NULL, /* init main configuration */
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64
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65 NULL, /* create server configuration */
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66 NULL, /* merge server configuration */
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67
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68 ngx_http_degradation_create_loc_conf, /* create location configuration */
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69 ngx_http_degradation_merge_loc_conf /* merge location configuration */
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70 };
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71
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72
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73 ngx_module_t ngx_http_degradation_module = {
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74 NGX_MODULE_V1,
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75 &ngx_http_degradation_module_ctx, /* module context */
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76 ngx_http_degradation_commands, /* module directives */
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77 NGX_HTTP_MODULE, /* module type */
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78 NULL, /* init master */
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79 NULL, /* init module */
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80 NULL, /* init process */
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81 NULL, /* init thread */
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82 NULL, /* exit thread */
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83 NULL, /* exit process */
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84 NULL, /* exit master */
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85 NGX_MODULE_V1_PADDING
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86 };
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87
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88
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3772
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89 static ngx_uint_t ngx_degraded;
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90
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91
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92 static ngx_int_t
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93 ngx_http_degradation_handler(ngx_http_request_t *r)
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94 {
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95 ngx_http_degradation_loc_conf_t *dlcf;
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96
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97 dlcf = ngx_http_get_module_loc_conf(r, ngx_http_degradation_module);
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98
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99 if (dlcf->degrade && ngx_http_degraded(r)) {
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100 return dlcf->degrade;
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101 }
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102
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103 return NGX_DECLINED;
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104 }
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105
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106
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107 ngx_uint_t
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108 ngx_http_degraded(ngx_http_request_t *r)
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109 {
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110 time_t now;
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111 ngx_uint_t log;
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112 static size_t sbrk_size;
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113 static time_t sbrk_time;
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114 ngx_http_degradation_main_conf_t *dmcf;
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115
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116 dmcf = ngx_http_get_module_main_conf(r, ngx_http_degradation_module);
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117
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118 if (dmcf->sbrk_size) {
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119
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120 log = 0;
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121 now = ngx_time();
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122
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123 /* lock mutex */
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124
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125 if (now != sbrk_time) {
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126
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127 /*
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128 * ELF/i386 is loaded at 0x08000000, 128M
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129 * ELF/amd64 is loaded at 0x00400000, 4M
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130 *
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131 * use a function address to substract the loading address
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132 */
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133
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134 sbrk_size = (size_t) sbrk(0) - ((uintptr_t) ngx_palloc & ~0x3FFFFF);
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135 sbrk_time = now;
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136 log = 1;
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137 }
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138
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139 /* unlock mutex */
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140
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141 if (sbrk_size >= dmcf->sbrk_size) {
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142 ngx_degraded = 1;
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143
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144 if (log) {
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145 ngx_log_error(NGX_LOG_NOTICE, r->connection->log, 0,
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146 "degradation sbrk:%uzM",
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147 sbrk_size / (1024 * 1024));
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148 }
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149
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150 return 1;
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151 }
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152 }
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153
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154 ngx_degraded = 0;
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155
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156 return 0;
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3326
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157 }
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158
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159
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160 static void *
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161 ngx_http_degradation_create_main_conf(ngx_conf_t *cf)
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162 {
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163 ngx_http_degradation_main_conf_t *dmcf;
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164
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165 dmcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_degradation_main_conf_t));
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166 if (dmcf == NULL) {
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167 return NULL;
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168 }
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169
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170 return dmcf;
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171 }
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172
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173
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174 static void *
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175 ngx_http_degradation_create_loc_conf(ngx_conf_t *cf)
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176 {
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177 ngx_http_degradation_loc_conf_t *conf;
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178
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179 conf = ngx_palloc(cf->pool, sizeof(ngx_http_degradation_loc_conf_t));
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180 if (conf == NULL) {
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181 return NULL;
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182 }
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183
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184 conf->degrade = NGX_CONF_UNSET_UINT;
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185
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186 return conf;
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187 }
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188
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189
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190 static char *
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191 ngx_http_degradation_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
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192 {
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193 ngx_http_degradation_loc_conf_t *prev = parent;
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194 ngx_http_degradation_loc_conf_t *conf = child;
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195
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196 ngx_conf_merge_uint_value(conf->degrade, prev->degrade, 0);
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197
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198 return NGX_CONF_OK;
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199 }
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200
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201
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202 static char *
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203 ngx_http_degradation(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
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204 {
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205 ngx_http_degradation_main_conf_t *dmcf = conf;
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206
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207 ngx_str_t *value, s;
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208
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209 value = cf->args->elts;
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210
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211 if (ngx_strncmp(value[1].data, "sbrk=", 5) == 0) {
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212
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213 s.len = value[1].len - 5;
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214 s.data = value[1].data + 5;
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215
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216 dmcf->sbrk_size = ngx_parse_size(&s);
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217 if (dmcf->sbrk_size == (size_t) NGX_ERROR) {
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218 ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
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219 "invalid sbrk size \"%V\"", &value[1]);
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220 return NGX_CONF_ERROR;
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221 }
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222
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223 return NGX_CONF_OK;
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224 }
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225
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226 ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
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227 "invalid parameter \"%V\"", &value[1]);
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228
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229 return NGX_CONF_ERROR;
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230 }
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231
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232
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233 static ngx_int_t
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234 ngx_http_degradation_init(ngx_conf_t *cf)
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235 {
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236 ngx_http_handler_pt *h;
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237 ngx_http_core_main_conf_t *cmcf;
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238
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239 cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);
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240
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241 h = ngx_array_push(&cmcf->phases[NGX_HTTP_PREACCESS_PHASE].handlers);
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242 if (h == NULL) {
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243 return NGX_ERROR;
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244 }
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245
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246 *h = ngx_http_degradation_handler;
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247
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248 return NGX_OK;
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249 }
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