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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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660
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4 * Copyright (C) Nginx, Inc.
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546
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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 #include <ngx_http.h>
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11
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12
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13 typedef struct {
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14 size_t sbrk_size;
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15 } ngx_http_degradation_main_conf_t;
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16
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17
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18 typedef struct {
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19 ngx_uint_t degrade;
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20 } ngx_http_degradation_loc_conf_t;
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21
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22
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23 static ngx_conf_enum_t ngx_http_degrade[] = {
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24 { ngx_string("204"), 204 },
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25 { ngx_string("444"), 444 },
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26 { ngx_null_string, 0 }
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27 };
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28
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29
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30 static void *ngx_http_degradation_create_main_conf(ngx_conf_t *cf);
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31 static void *ngx_http_degradation_create_loc_conf(ngx_conf_t *cf);
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32 static char *ngx_http_degradation_merge_loc_conf(ngx_conf_t *cf, void *parent,
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33 void *child);
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34 static char *ngx_http_degradation(ngx_conf_t *cf, ngx_command_t *cmd,
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35 void *conf);
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36 static ngx_int_t ngx_http_degradation_init(ngx_conf_t *cf);
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37
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38
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39 static ngx_command_t ngx_http_degradation_commands[] = {
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40
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41 { ngx_string("degradation"),
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42 NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE1,
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43 ngx_http_degradation,
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44 NGX_HTTP_MAIN_CONF_OFFSET,
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45 0,
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46 NULL },
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47
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48 { ngx_string("degrade"),
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49 NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
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50 ngx_conf_set_enum_slot,
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51 NGX_HTTP_LOC_CONF_OFFSET,
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52 offsetof(ngx_http_degradation_loc_conf_t, degrade),
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53 &ngx_http_degrade },
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54
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55 ngx_null_command
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56 };
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57
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58
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59 static ngx_http_module_t ngx_http_degradation_module_ctx = {
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60 NULL, /* preconfiguration */
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61 ngx_http_degradation_init, /* postconfiguration */
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62
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63 ngx_http_degradation_create_main_conf, /* create main configuration */
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64 NULL, /* init main configuration */
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65
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66 NULL, /* create server configuration */
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67 NULL, /* merge server configuration */
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68
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69 ngx_http_degradation_create_loc_conf, /* create location configuration */
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70 ngx_http_degradation_merge_loc_conf /* merge location configuration */
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71 };
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72
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73
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74 ngx_module_t ngx_http_degradation_module = {
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75 NGX_MODULE_V1,
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76 &ngx_http_degradation_module_ctx, /* module context */
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77 ngx_http_degradation_commands, /* module directives */
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78 NGX_HTTP_MODULE, /* module type */
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79 NULL, /* init master */
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80 NULL, /* init module */
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81 NULL, /* init process */
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82 NULL, /* init thread */
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83 NULL, /* exit thread */
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84 NULL, /* exit process */
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85 NULL, /* exit master */
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86 NGX_MODULE_V1_PADDING
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87 };
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88
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89
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90 static ngx_int_t
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91 ngx_http_degradation_handler(ngx_http_request_t *r)
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92 {
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602
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93 ngx_http_degradation_loc_conf_t *dlcf;
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546
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94
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95 dlcf = ngx_http_get_module_loc_conf(r, ngx_http_degradation_module);
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96
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602
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97 if (dlcf->degrade && ngx_http_degraded(r)) {
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98 return dlcf->degrade;
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546
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99 }
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100
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602
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101 return NGX_DECLINED;
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102 }
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103
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104
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105 ngx_uint_t
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106 ngx_http_degraded(ngx_http_request_t *r)
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107 {
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108 time_t now;
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109 ngx_uint_t log;
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110 static size_t sbrk_size;
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111 static time_t sbrk_time;
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112 ngx_http_degradation_main_conf_t *dmcf;
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113
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546
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114 dmcf = ngx_http_get_module_main_conf(r, ngx_http_degradation_module);
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115
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116 if (dmcf->sbrk_size) {
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117
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602
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118 log = 0;
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546
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119 now = ngx_time();
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120
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121 /* lock mutex */
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122
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123 if (now != sbrk_time) {
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124
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125 /*
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126 * ELF/i386 is loaded at 0x08000000, 128M
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127 * ELF/amd64 is loaded at 0x00400000, 4M
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128 *
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129 * use a function address to substract the loading address
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130 */
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131
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132 sbrk_size = (size_t) sbrk(0) - ((uintptr_t) ngx_palloc & ~0x3FFFFF);
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133 sbrk_time = now;
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602
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134 log = 1;
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546
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135 }
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136
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137 /* unlock mutex */
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138
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139 if (sbrk_size >= dmcf->sbrk_size) {
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602
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140 if (log) {
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141 ngx_log_error(NGX_LOG_NOTICE, r->connection->log, 0,
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142 "degradation sbrk:%uzM",
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143 sbrk_size / (1024 * 1024));
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144 }
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145
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146 return 1;
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546
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147 }
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148 }
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149
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602
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150 return 0;
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546
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151 }
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152
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153
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154 static void *
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155 ngx_http_degradation_create_main_conf(ngx_conf_t *cf)
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156 {
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157 ngx_http_degradation_main_conf_t *dmcf;
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158
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159 dmcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_degradation_main_conf_t));
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160 if (dmcf == NULL) {
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161 return NULL;
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162 }
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163
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164 return dmcf;
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165 }
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166
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167
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168 static void *
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169 ngx_http_degradation_create_loc_conf(ngx_conf_t *cf)
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170 {
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171 ngx_http_degradation_loc_conf_t *conf;
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172
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173 conf = ngx_palloc(cf->pool, sizeof(ngx_http_degradation_loc_conf_t));
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174 if (conf == NULL) {
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175 return NULL;
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176 }
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177
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178 conf->degrade = NGX_CONF_UNSET_UINT;
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179
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180 return conf;
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181 }
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182
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183
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184 static char *
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185 ngx_http_degradation_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
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186 {
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187 ngx_http_degradation_loc_conf_t *prev = parent;
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188 ngx_http_degradation_loc_conf_t *conf = child;
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189
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190 ngx_conf_merge_uint_value(conf->degrade, prev->degrade, 0);
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191
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192 return NGX_CONF_OK;
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193 }
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194
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195
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196 static char *
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197 ngx_http_degradation(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
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198 {
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199 ngx_http_degradation_main_conf_t *dmcf = conf;
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200
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201 ngx_str_t *value, s;
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202
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203 value = cf->args->elts;
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204
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205 if (ngx_strncmp(value[1].data, "sbrk=", 5) == 0) {
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206
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207 s.len = value[1].len - 5;
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208 s.data = value[1].data + 5;
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209
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210 dmcf->sbrk_size = ngx_parse_size(&s);
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211 if (dmcf->sbrk_size == (size_t) NGX_ERROR) {
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212 ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
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213 "invalid sbrk size \"%V\"", &value[1]);
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214 return NGX_CONF_ERROR;
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215 }
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558
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216
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217 return NGX_CONF_OK;
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546
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218 }
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219
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558
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220 ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
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221 "invalid parameter \"%V\"", &value[1]);
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222
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223 return NGX_CONF_ERROR;
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546
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224 }
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225
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226
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227 static ngx_int_t
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228 ngx_http_degradation_init(ngx_conf_t *cf)
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229 {
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230 ngx_http_handler_pt *h;
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231 ngx_http_core_main_conf_t *cmcf;
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232
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233 cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);
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234
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235 h = ngx_array_push(&cmcf->phases[NGX_HTTP_PREACCESS_PHASE].handlers);
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236 if (h == NULL) {
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237 return NGX_ERROR;
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238 }
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239
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240 *h = ngx_http_degradation_handler;
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241
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242 return NGX_OK;
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243 }
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