1
2 /*
3 * Copyright (C) Igor Sysoev
4 * Copyright (C) Nginx, Inc.
5 */
6
7
8 #include <ngx_config.h>
9 #include <ngx_core.h>
10 #include <ngx_http.h>
11
12
13 typedef struct {
14 size_t sbrk_size;
15 } ngx_http_degradation_main_conf_t;
16
17
18 typedef struct {
19 ngx_uint_t degrade;
20 } ngx_http_degradation_loc_conf_t;
21
22
23 static ngx_conf_enum_t ngx_http_degrade[] = {
24 { ngx_string("204"), 204 },
25 { ngx_string("444"), 444 },
26 { ngx_null_string, 0 }
27 };
28
29
30 static void *ngx_http_degradation_create_main_conf(ngx_conf_t *cf);
31 static void *ngx_http_degradation_create_loc_conf(ngx_conf_t *cf);
32 static char *ngx_http_degradation_merge_loc_conf(ngx_conf_t *cf, void *parent,
33 void *child);
34 static char *ngx_http_degradation(ngx_conf_t *cf, ngx_command_t *cmd,
35 void *conf);
36 static ngx_int_t ngx_http_degradation_init(ngx_conf_t *cf);
37
38
39 static ngx_command_t ngx_http_degradation_commands[] = {
40
41 { ngx_string("degradation"),
42 NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE1,
43 ngx_http_degradation,
44 NGX_HTTP_MAIN_CONF_OFFSET,
45 0,
46 NULL },
47
48 { ngx_string("degrade"),
49 NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
50 ngx_conf_set_enum_slot,
51 NGX_HTTP_LOC_CONF_OFFSET,
52 offsetof(ngx_http_degradation_loc_conf_t, degrade),
53 &ngx_http_degrade },
54
55 ngx_null_command
56 };
57
58
59 static ngx_http_module_t ngx_http_degradation_module_ctx = {
60 NULL, /* preconfiguration */
61 ngx_http_degradation_init, /* postconfiguration */
62
63 ngx_http_degradation_create_main_conf, /* create main configuration */
64 NULL, /* init main configuration */
65
66 NULL, /* create server configuration */
67 NULL, /* merge server configuration */
68
69 ngx_http_degradation_create_loc_conf, /* create location configuration */
70 ngx_http_degradation_merge_loc_conf /* merge location configuration */
71 };
72
73
74 ngx_module_t ngx_http_degradation_module = {
75 NGX_MODULE_V1,
76 &ngx_http_degradation_module_ctx, /* module context */
77 ngx_http_degradation_commands, /* module directives */
78 NGX_HTTP_MODULE, /* module type */
79 NULL, /* init master */
80 NULL, /* init module */
81 NULL, /* init process */
82 NULL, /* init thread */
83 NULL, /* exit thread */
84 NULL, /* exit process */
85 NULL, /* exit master */
86 NGX_MODULE_V1_PADDING
87 };
88
89
90 static ngx_int_t
91 ngx_http_degradation_handler(ngx_http_request_t *r)
92 {
93 ngx_http_degradation_loc_conf_t *dlcf;
94
95 dlcf = ngx_http_get_module_loc_conf(r, ngx_http_degradation_module);
96
97 if (dlcf->degrade && ngx_http_degraded(r)) {
98 return dlcf->degrade;
99 }
100
101 return NGX_DECLINED;
102 }
103
104
105 ngx_uint_t
106 ngx_http_degraded(ngx_http_request_t *r)
107 {
108 time_t now;
109 ngx_uint_t log;
110 static size_t sbrk_size;
111 static time_t sbrk_time;
112 ngx_http_degradation_main_conf_t *dmcf;
113
114 dmcf = ngx_http_get_module_main_conf(r, ngx_http_degradation_module);
115
116 if (dmcf->sbrk_size) {
117
118 log = 0;
119 now = ngx_time();
120
121 /* lock mutex */
122
123 if (now != sbrk_time) {
124
125 /*
126 * ELF/i386 is loaded at 0x08000000, 128M
127 * ELF/amd64 is loaded at 0x00400000, 4M
128 *
129 * use a function address to subtract the loading address
130 */
131
132 sbrk_size = (size_t) sbrk(0) - ((uintptr_t) ngx_palloc & ~0x3FFFFF);
133 sbrk_time = now;
134 log = 1;
135 }
136
137 /* unlock mutex */
138
139 if (sbrk_size >= dmcf->sbrk_size) {
140 if (log) {
141 ngx_log_error(NGX_LOG_NOTICE, r->connection->log, 0,
142 "degradation sbrk:%uzM",
143 sbrk_size / (1024 * 1024));
144 }
145
146 return 1;
147 }
148 }
149
150 return 0;
151 }
152
153
154 static void *
155 ngx_http_degradation_create_main_conf(ngx_conf_t *cf)
156 {
157 ngx_http_degradation_main_conf_t *dmcf;
158
159 dmcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_degradation_main_conf_t));
160 if (dmcf == NULL) {
161 return NULL;
162 }
163
164 return dmcf;
165 }
166
167
168 static void *
169 ngx_http_degradation_create_loc_conf(ngx_conf_t *cf)
170 {
171 ngx_http_degradation_loc_conf_t *conf;
172
173 conf = ngx_palloc(cf->pool, sizeof(ngx_http_degradation_loc_conf_t));
174 if (conf == NULL) {
175 return NULL;
176 }
177
178 conf->degrade = NGX_CONF_UNSET_UINT;
179
180 return conf;
181 }
182
183
184 static char *
185 ngx_http_degradation_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
186 {
187 ngx_http_degradation_loc_conf_t *prev = parent;
188 ngx_http_degradation_loc_conf_t *conf = child;
189
190 ngx_conf_merge_uint_value(conf->degrade, prev->degrade, 0);
191
192 return NGX_CONF_OK;
193 }
194
195
196 static char *
197 ngx_http_degradation(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
198 {
199 ngx_http_degradation_main_conf_t *dmcf = conf;
200
201 ngx_str_t *value, s;
202
203 value = cf->args->elts;
204
205 if (ngx_strncmp(value[1].data, "sbrk=", 5) == 0) {
206
207 s.len = value[1].len - 5;
208 s.data = value[1].data + 5;
209
210 dmcf->sbrk_size = ngx_parse_size(&s);
211 if (dmcf->sbrk_size == (size_t) NGX_ERROR) {
212 ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
213 "invalid sbrk size \"%V\"", &value[1]);
214 return NGX_CONF_ERROR;
215 }
216
217 return NGX_CONF_OK;
218 }
219
220 ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
221 "invalid parameter \"%V\"", &value[1]);
222
223 return NGX_CONF_ERROR;
224 }
225
226
227 static ngx_int_t
228 ngx_http_degradation_init(ngx_conf_t *cf)
229 {
230 ngx_http_handler_pt *h;
231 ngx_http_core_main_conf_t *cmcf;
232
233 cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);
234
235 h = ngx_array_push(&cmcf->phases[NGX_HTTP_PREACCESS_PHASE].handlers);
236 if (h == NULL) {
237 return NGX_ERROR;
238 }
239
240 *h = ngx_http_degradation_handler;
241
242 return NGX_OK;
243 }
244
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