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546
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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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89 static ngx_int_t
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90 ngx_http_degradation_handler(ngx_http_request_t *r)
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91 {
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92 time_t now;
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93 static size_t sbrk_size;
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94 static time_t sbrk_time;
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95 ngx_http_degradation_loc_conf_t *dlcf;
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96 ngx_http_degradation_main_conf_t *dmcf;
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97
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98 dlcf = ngx_http_get_module_loc_conf(r, ngx_http_degradation_module);
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99
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100 if (dlcf->degrade == 0) {
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101 return NGX_DECLINED;
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102 }
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103
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104 dmcf = ngx_http_get_module_main_conf(r, ngx_http_degradation_module);
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105
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106 if (dmcf->sbrk_size) {
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107
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108 now = ngx_time();
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109
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110 /* lock mutex */
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111
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112 if (now != sbrk_time) {
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113
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114 /*
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115 * ELF/i386 is loaded at 0x08000000, 128M
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116 * ELF/amd64 is loaded at 0x00400000, 4M
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117 *
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118 * use a function address to substract the loading address
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119 */
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120
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121 sbrk_size = (size_t) sbrk(0) - ((uintptr_t) ngx_palloc & ~0x3FFFFF);
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122 sbrk_time = now;
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123 }
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124
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125 /* unlock mutex */
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126
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127 if (sbrk_size >= dmcf->sbrk_size) {
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128 ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
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129 "degradation sbrk: %uz", sbrk_size);
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130
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131 return dlcf->degrade;
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132 }
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133 }
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134
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135 return NGX_DECLINED;
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136 }
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137
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138
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139 static void *
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140 ngx_http_degradation_create_main_conf(ngx_conf_t *cf)
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141 {
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142 ngx_http_degradation_main_conf_t *dmcf;
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143
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144 dmcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_degradation_main_conf_t));
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145 if (dmcf == NULL) {
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146 return NULL;
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147 }
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148
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149 return dmcf;
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150 }
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151
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152
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153 static void *
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154 ngx_http_degradation_create_loc_conf(ngx_conf_t *cf)
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155 {
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156 ngx_http_degradation_loc_conf_t *conf;
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157
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158 conf = ngx_palloc(cf->pool, sizeof(ngx_http_degradation_loc_conf_t));
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159 if (conf == NULL) {
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160 return NULL;
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161 }
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162
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163 conf->degrade = NGX_CONF_UNSET_UINT;
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164
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165 return conf;
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166 }
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167
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168
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169 static char *
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170 ngx_http_degradation_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
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171 {
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172 ngx_http_degradation_loc_conf_t *prev = parent;
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173 ngx_http_degradation_loc_conf_t *conf = child;
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174
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175 ngx_conf_merge_uint_value(conf->degrade, prev->degrade, 0);
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176
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177 return NGX_CONF_OK;
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178 }
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179
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180
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181 static char *
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182 ngx_http_degradation(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
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183 {
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184 ngx_http_degradation_main_conf_t *dmcf = conf;
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185
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186 ngx_str_t *value, s;
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187
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188 value = cf->args->elts;
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189
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190 if (ngx_strncmp(value[1].data, "sbrk=", 5) == 0) {
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191
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192 s.len = value[1].len - 5;
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193 s.data = value[1].data + 5;
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194
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195 dmcf->sbrk_size = ngx_parse_size(&s);
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196 if (dmcf->sbrk_size == (size_t) NGX_ERROR) {
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197 ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
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198 "invalid sbrk size \"%V\"", &value[1]);
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199 return NGX_CONF_ERROR;
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200 }
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201 }
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202
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203 return NGX_CONF_OK;
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204 }
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205
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206
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207 static ngx_int_t
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208 ngx_http_degradation_init(ngx_conf_t *cf)
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209 {
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210 ngx_http_handler_pt *h;
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211 ngx_http_core_main_conf_t *cmcf;
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212
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213 cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);
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214
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215 h = ngx_array_push(&cmcf->phases[NGX_HTTP_PREACCESS_PHASE].handlers);
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216 if (h == NULL) {
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217 return NGX_ERROR;
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218 }
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219
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220 *h = ngx_http_degradation_handler;
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221
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222 return NGX_OK;
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223 }
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